Red algae biomass extract, and cosmetic use thereof for eliminating skin imperfections

Abstract

The present invention relates to a photosensitizing polar biomass extract extracted from phycocyanin-producing organisms, in particular unicellular red algae (URA) or cyanobacteria, and to the cosmetic use thereof for preventing and / or eliminating skin imperfections, i.e. for improving the look of the skin.

Description

[0001] RED ALGAE BIOMASS EXTRACT AND ITS COSMETIC USE TO REMOVE SKIN IMPERFECTIONS

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to a photosensitizing polar extract of biomass extracted from phycocyanin-producing organisms, in particular unicellular red algae (URA) or cyanobacteria, and its cosmetic use for preventing and / or eliminating skin imperfections, i.e. improving the appearance of the skin.

[0004] STATE OF THE ART

[0005] Acne is associated with overproduction of sebum by the sebaceous glands, which leads to the clogging of skin pores. The pathogenesis of acne is multifactorial. Lesions include comedones, papules, pustules, and even nodules in the most severe forms.

[0006] Acne lesions can be complicated by inflammation, resulting from abnormal bacterial proliferation in the sebum which may be associated in particular with Cutibacterium acnes, Corynebacterium xerosis, Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus pyogenes, Streptococcus agalactiae or Acarus folliculorum.

[0007] During puberty, acne begins when the sebaceous glands mature due to hormonal stimulation by androgens. In adults, acne is caused by stimulation of the sebaceous glands, accompanied by poor sebum secretion due to makeup or increased synthesis of adrenal corticosteroid hormone due to stress.

[0008] Various acne treatments are available, including photodynamic therapy (PDT). This therapy involves exposing the skin to light with a photosensitizer, which results in the production of singlet oxygen and other reactive oxygen species that kill nearby microorganisms.

[0009] In such a PDT procedure for acne treatment, the photosensitizer is applied topically to the skin area to be treated. The skin is then exposed to an illumination source such as a laser or pulsed light, to allow the release of reactive oxygen species. The presence of singlet oxygen then causes the death of the bacteria responsible for the appearance of acne and localized peeling of the skin, freeing the clogged pores.

[0010] Examples of acne treatment using photodynamic therapies are described in particular in European patents EP 1 755 676, EP 2 152 259, EP 3 082 788 or application EP 3 558 374.

[0011] It is important that the photosensitizer preserves skin cells as much as possible and does not increase the inflammation resulting from acne.

[0012] A major drawback of photodynamic therapy is the occurrence of adverse effects, particularly at the treated area. These adverse effects include erythema, swelling, edema, burning, itching, severe peeling, hyperpigmentation, irritation, and / or hypersensitivity.

[0013] There is therefore a real need to provide new substances that would limit the occurrence of adverse effects.

[0014] Furthermore, the use of microalgae extracts in phototherapy for the treatment of acne has already been reported, but the process for preparing such an extract presents technical constraints such as the need to use an inert atmosphere to avoid the degradation of the active molecules and a long maceration step (for example, WO2021 / 209441 which shows the use of a polar extract of Skeletonema).

[0015] There is therefore a real need to develop new substances that are easier and less expensive to produce, and whose manufacturing process reduces the environmental impact.

[0016] To meet the needs of the prior art, the inventors have demonstrated that a polar extract of biomass from phycocyanin-producing organisms, in particular unicellular red algae (URA) or cyanobacteria, can be used for the prevention and / or elimination of skin imperfections in a subject, i.e. improving the appearance of the skin.

[0017] STATEMENT OF THE INVENTION

[0018] The invention relates to a photosensitizing polar extract of biomass from phycocyanin-producing organisms, in particular unicellular red algae (URA) or cyanobacteria.

[0019] Advantageously, the biomass is an ARU biomass and in that the ARUs are chosen from the families of Galdieriaceae or Cyanidiaceae, more preferably from the genera Galdieria, Cyanidioschyzon or Cyanidium, even more preferably Galdieria.

[0020] Advantageously, the ARUs are of the species Galdieria sulphuraria. Advantageously, the photosensitizing polar extract is a solution comprising a polar organic solvent, preferably a protic polar organic solvent chosen from alcohols, in particular methanol, ethanol and isopropanol, volatile organic acids, in particular formic acid, acetic acid, primary or secondary amines and PEGs (polyethylene glycol) and mixtures thereof.

[0021] Advantageously, the photosensitizing polar extract comprises up to 95%, preferably from 90% to 65%, even more preferably from 80% to 90% of lipids by weight relative to the total dry mass of the extract.

[0022] Advantageously, said lipids comprise monogalactosyldiglycerides, digalactosyldiglycerides, phosphatidylcholines and ceramides.

[0023] Advantageously, the photosensitizing polar extract comprises from 350 mg / g to 0.5 mg / g of pheophorbides-a and its derivatives by weight relative to the total weight of the extract, preferably from 175 mg / g to 1 mg / g and even more preferably from 85 mg / g to 5 mg / g.

[0024] The present invention also relates to a method for preparing a photosensitizing polar extract comprising the culture of a biomass of phycocyanin-producing organisms, in particular unicellular red algae (URA) or cyanobacteria, then the steps of: a) harvesting the biomass by separation of the culture medium to obtain a crude biomass; b) optionally, cell lysis of the crude biomass from step (a) to obtain a lysed biomass; c) optionally, dilution of the lysed biomass from step (b) to obtain a solubilized lysed biomass;and d) recovery of the insolubles suspended in the lysed biomass of step (b) or the solubilized biomass of step (c) to obtain an extracted biomass, e) extraction by bringing the extracted biomass obtained in step d) into contact with a polar solvent then recovery of the aqueous fraction by separation of the insolubles suspended to obtain the photosensitizing polar crude extract.;

[0025] Advantageously, the polar organic solvent used in step e) of the process is a protic polar organic solvent chosen from alcohols, in particular methanol, ethanol and isopropanol, volatile organic acids, in particular formic acid, acetic acid, primary or secondary amines and PEGs (polyethylene glycol) and mixtures thereof.

[0026] Advantageously, the method further comprises a step of heating the biomass before or during the extraction step e), i.e., at any one of steps a), b), c), d) or e).

[0027] The present invention also relates to a photosensitizing polar extract as defined above which can be obtained by the process defined above.

[0028] The invention also relates to a topical composition comprising said photosensitizing polar extract defined above and a topically acceptable carrier.

[0029] The present invention also relates to said photosensitizing polar extract or the composition comprising it for its use in the prevention and / or treatment of acne.

[0030] The present invention relates to said photosensitizing polar extract or the composition comprising it for its use in the prevention and / or elimination of skin imperfections.

[0031] Advantageously, said photosensitizing polar extract or the composition comprising it is applied to a skin surface to be treated of a subject, followed by exposure of said surface to a light source.

[0032] DETAILED DESCRIPTION OF THE INVENTION

[0033] Definitions

[0034] In the context of the present invention, the term "biomass" designates a set of microalgal cells, preferably produced by fermentation in a biological reactor. Said biomass can be seen as a mass of unicellular organisms. The biomass can undergo different treatments and be a raw biomass, a lysed biomass or an extracted biomass. It is understood in the context of the present application that the properties of the biomass correspond to the average of the properties of all the cells constituting said biomass, in other words, a lysed biomass is a biomass comprising at least 50% of lysed cells relative to the total number of cells and a raw biomass can comprise lysed cells due to the harvesting step without being considered as a lysed biomass as long as the number of lysed cells out of the number of non-lysed cells remains in the minority, i.e. less than 50%.

[0035] “Raw biomass” means biomass obtained after harvesting, i.e. after recovery of the culture and separation of the cells from at least part of the culture medium.

[0036] “Lysed biomass” refers to microalgal biomass in which at least 50% of the cells are lysed, preferably at least 70%, more preferably in which at least 80%, 85%, 90%, 95%, up to 100% of the cells are lysed.

[0037] For the purposes of the present invention, a “solubilized lysed biomass” or “solubilisate” refers to a lysed biomass that has undergone a dilution step with an aqueous solution of neutral, acidic or basic pH.

[0038] An “extracted biomass” corresponds to the insoluble fraction recovered from a lysed biomass after one or more washes with an aqueous solution of neutral, acidic or basic pH, in particular to extract water-soluble components such as phycocyanin.

[0039] According to the invention, the expression "dried biomass" designates a microalgal biomass which has been dried according to methods known to those skilled in the art and whose water content relative to the total weight of the biomass is less than 10%, preferably less than 7%, more preferably between 5% and 1% of water. Among the known drying methods, mention may be made of natural air drying, spray drying, fluidized air bed drying, drying using a roller dryer and freeze-drying. The dried biomass may be a dried raw biomass, a dried lysed biomass or a dried extracted biomass.

[0040] The term "thawed biomass" refers to biomass that has been frozen, possibly for storage and / or transport purposes, and then thawed to reach a suitable temperature for preparing a polar extract.

[0041] A “polar extract of a biomass” means a composition obtained by extraction of a biomass using a polar organic solvent.

[0042] A “photosensitizing extract” means an extract (or composition) which, when subjected to a light source, allows the production of reactive oxygen species. One way to characterize the photosensitizing properties of the extract is to determine the Minimum Inhibitory Concentration (MIC) or the Minimum Inhibitory Concentration (MIC) of the extract on bacteria in the growth phase. In particular, in the context of the invention the bacteria used can be selected from bacteria known to be involved in the aggravation of acne such as Cutibacterium acnes or Staphylococcus aureus.

[0043] Unicellular red algae or URA refers to eukaryotic microalgae of the URA taxon that can be cultivated industrially for the production of biomass and derived products, such as proteins or phycobilliproteins like phycocyanins.

[0044] By "Cyanobacteria", also called blue-green algae, we mean prokaryotic microalgae that can be cultivated industrially for the production of biomass and derived products, such as proteins or phycocyanins.

[0045] A "topical composition" means a composition intended to be applied to the skin of a subject for its use. It comprises so-called "topically acceptable" constituents suitable for this use on the skin of the subject, including one or more active ingredients and excipients or carriers. In the context of the present invention, a "cosmetic composition" means a topical composition consisting of components suitable for cosmetic use intended to be placed in contact with the superficial parts of the human body (epidermis, hair, nails, etc.) or with the teeth and oral mucous membranes, with a view, exclusively or mainly, to cleaning them, perfuming them, modifying their appearance, protecting them, keeping them in good condition or correcting body odors. The choice of the constituents of the composition is therefore very important, which distinguishes a medical composition from a composition suitable for topical cosmetic use.The cosmetic composition can also be sterile so as not to introduce pathogens that could develop during its use.

[0046] According to the invention, exposure to a light source or illumination means exposure to natural light or artificial light. In the case of exposure to artificial light, this is chosen from, in particular, lighting comprising a laser, pulsed light or a light-emitting diode (LED) and is preferably lighting comprising one or more LEDs.

[0047] By "skin imperfection(s)" we mean wrinkles, benign skin conditions such as brown spots - or lentigo - and port-wine stains, hidradenitis suppurativa, rosacea, skin irregularities, in particular irregularities associated with acne such as dilated pores, blackheads (open comedones), whiteheads (closed comedones), papules (red spots), pustules (white spots), nodules, cysts.

[0048] Photosensitizing polar extract

[0049] The present invention relates to a photosensitizing polar extract of biomass of phycocyanin-producing organisms, in particular unicellular red algae (URA) or cyanobacteria, preferentially of biomass of unicellular red algae (URA), such as the genera Cyanidioschyzon, Cyanidium or Galdieria.

[0050] The photosensitizing polar extract of biomass from phycocyanin-producing organisms, in particular ARU or Cyanobacteria, is obtained by extraction with a polar organic solvent of biomass extracted from phycocyanin-producing organisms.

[0051] In particular, said extract is capable of being obtained by a method according to the invention as described in the remainder of the description. According to one embodiment, the biomass is a biomass of Cyanobacteria, in particular of the genus Arthrospira and preferentially chosen from the species platensis (also called Spirulina), fusiformis and maxima.

[0052] Preferably, the biomass is an ARU biomass chosen from the Cyanidiaceae or Galdieriaceae families, more preferably from the Cyanidioschyzon, Cyanidium or Galdieria genera.

[0053] According to a more preferred embodiment, the ARUs are of the genus Galdieria and more preferably of the species Galdieria sulphuraria.

[0054] According to another embodiment, the ARUs are of the genus Cyanidioschyzon, preferably of the species Cyanidioschyzon merolae.

[0055] The polar organic solvent is an aprotic solvent or a protic solvent, preferably a practical polar solvent.

[0056] Among the polar aprotic solvents which can be used according to the present invention, mention will preferably be made of acetone, butanone, dimethyl sulfoxide (DMSO), N,N dimethyl formamide, acetonitrile, ethyl acetate, triethylamine and pyridine, 4-hydroxy-4-methyl-2-pentanone and their mixtures.

[0057] Among the practical polar organic solvents which can be used according to the present invention, mention will preferably be made of alcohols, in particular methanol, ethanol and isopropanol, volatile organic acids, in particular formic acid, acetic acid, primary or secondary amines and PEG (polyethylene glycol) and their mixtures.

[0058] ARUs, in particular microalgae of the order Cyanidiales such as those of the genera Galdieria, Cyanidioschyzon and Cyanidium, in particular the species Galdieria sulphuraria, Cyanidioschyzon merolae and Cyanidium caldarium, produce phycocyanin. The raw biomasses of these microalgae comprise phycocyanin. On the other hand, since phycocyanin is soluble in water, the biomasses extracted from these microalgae, in particular obtained by the process of the invention, will comprise little or no phycocyanin because the latter will already have been eliminated during the previous step(s) of washing with an aqueous solution.

[0059] The photosensitizing polar extract according to the invention can be concentrated by removing all or part of the polar organic solvent used for the extraction, for example by distillation; this is then referred to as a concentrated extract.

[0060] The photosensitizing polar extract according to the invention is photosensitizing and allows the production of reactive oxygen species when it is illuminated by light of one or more wavelengths between 380 and 800 nm (white light), preferably between 380 and 450 nm (blue light) or between 620 and 780 nm (red light).

[0061] Preferably, the photosensitizing polar extract according to the invention comprises pigments and lipids.

[0062] Preferably, the photosensitizing polar extract according to the invention comprises one or more degradation derivatives of chlorophyll-a (chl-a), in particular pheophorbides-a (phb-a) and pheophytins-a (pht-a) as well as their respective derivatives such as methyl ester pheophorbides, hydroxy-pheophorbides, pyropheophorbides or even pyropheophthyins, and mixtures thereof.

[0063] Preferably, the photosensitizing polar extract according to the invention comprises from 350 mg / g to 0.5 mg / g of pheophorbides-a and its derivatives (also called total pheophorbides-a) by weight relative to the total weight of the extract, still preferentially from 175 mg / g to 1 mg / g and even more preferentially from 85 mg / g to 5 mg / g.

[0064] Preferably, the photosensitizing polar extract according to the invention comprises from 250 mg / g to 0.35 mg / g of pheophorbides-a by weight relative to the total weight of the extract, still preferentially from 125 mg / g to 0.7 mg / g and even more preferentially from 60 mg / g to 3.5 mg / g.

[0065] Preferably, the photosensitizing polar extract according to the invention comprises 70% by weight of pheophorbides-a relative to the sum of total pheophorbides-a (corresponding to pheophorbides-a and their derivatives) and total pheophytins-a (corresponding to pheophytins-a and their derivatives), still preferentially from 40% to 90% by weight, even more preferentially from 60% to 75% by weight relative to the total weight of the extract.

[0066] Preferably, the photosensitizing polar extract according to the invention comprises 95% by weight of lipids (i.e. Fatty Matter, MF), still preferably from 90% to 65% by weight, even more preferably from 80% to 90% by weight relative to the total dry mass of the extract.

[0067] Preferably, the photosensitizing polar extract according to the invention comprises monogalactosyldiglycerides (MGDG), digalactosyldiglycerides (DGDG), phosphatidylcholines (PC), and ceramides (lipid amides), and this in particular in the case of a photosensitizing polar extract of a biomass extracted from Galdieria, preferentially Galdieria sulphuraria.

[0068] Preferably, the photosensitizing polar extract according to the invention comprises fatty acids. In particular, in the case of a photosensitizing polar extract of a biomass extracted from Galdieria, preferably Galdieria sulphuraria, said extract comprises, in order of predominance, palmitic acid, oleic acid, γ-linolenic acid, then α-linolenic acid and stearic acid. More preferably, this photosensitizing polar extract comprises fatty acids and the sum of the contents of palmitic acid, oleic acid, y-linolenic acid, a-linolenic acid and stearic acid represents at least 80% by weight of the total fatty acid content of the extract, still preferably between 85 and 95% of the total fatty acid content of the extract (analysis of fatty acids in GC-FID, percentage of fatty acids in the form of methyl esters (%FAMEs)).

[0069] Preferably, the photosensitizing polar extract according to the invention comprises less than 1% by weight of carotenoids (carrot) and their derivatives (also called total carotenoids), relative to the total dry mass of the extract.

[0070] Topical composition

[0071] The present invention also relates to a topical composition comprising said photosensitizing polar extract, as described above and in the examples, and a topically acceptable carrier, i.e. a carrier suitable for its application to the skin.

[0072] The topical composition according to the invention is in particular a cosmetic composition.

[0073] Advantageously, the topical composition according to the invention comprises from 0.0001% to 10%, preferably from 0.001% to 2% oand in particular between 0.01% and 0.5% by dry weight of photosensitizing polar extract according to the invention relative to the total weight of the composition.

[0074] Advantageously, the topical composition according to the invention comprises a concentration of pheophorbides-a of 1 nM to 50 pM, preferably of 10 nM to 10 pM and in particular between 25 nM and 5 pM relative to the total weight of the composition.

[0075] Advantageously, the topical composition according to the invention comprising the photosensitizing polar extract according to the invention has a pH of between 4.0 and 7.5, preferably between 5.5 and 7.5.

[0076] Advantageously, the topical composition comprises water. Depending on the form chosen, it preferably comprises from 60 to 98% water.

[0077] The topical composition according to the invention may optionally also comprise one or more water-miscible solvents, in addition to the polar organic solvent capable of being provided by the biomass extract according to the invention. Among these solvents (also called additional solvents), mention will be made of glycerin, alcohols (in particular C1-C4 alcohols), organic solvents, polyols, glycols or mixtures thereof, and in particular alcohols and polyols such as ethyl alcohol, isopropyl alcohol, propyl alcohol, benzyl alcohol, phenylethyl alcohol, or glycols or glycol ethers such as monomethyl, monoethyl and monobutyl ethers of ethylene glycol, propylene glycol or their ethers such as monomethyl ether of propylene glycol, butylene glycol, hexylene glycol, dipropylene glycol as well as alkyl ethers of diethylene glycol,for example diethylene glycol monoethyl ether or monobutyl ether, or polyhydric alcohols such as 1,2,6-hexanetriol, trimethylolpropane, ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, hexylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, dipropylene glycol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 3-methyl-1,3-butanediol, 1,5-pentanediol, tetraethylene glycol, 1,6-hexanediol, 2-methyl-2,4-pentanediol, polyethylene glycol, 1,2,4-butanetriol, 1,2,6-hexanetriol, 2-butene-1,4-diol, 2-ethyl-1 ,3-hexanediol, 2-methyl-2,4-pentanediol, (caprylyl glycol), 1,2-hexanediol, 1,2-pentanediol, and 4-methyl-1,2-pentanediol; alkyl alcohols having 1 to 4 carbon atoms such as ethanol, methanol, butanol, propanol and isopropanol; glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether,ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, ethylene glycol mono-isopropyl ether, diethylene glycol mono-isopropyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol mono-t-butyl ether, diethylene glycol mono-t-butyl ether, 1-methyl-1-methoxybutanol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-t-butyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-isopropyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether and dipropylene glycol mono-isopropyl ether dipropylene glycol; 2-pyrrolidone, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, formamide, acetamide, dimethyl sulfoxide, sorbit, sorbitan, acetin, diacetin, triacetin,sulfone, or mixtures thereof.,

[0078] The topical composition according to the invention may optionally further comprise one or more thickeners or gelling agents, for example chosen from gums, such as xanthan gum, cellulose gum, acacia seneca gum, guar gum, sclerotium gum, dehydroxanthan gum, gellan gum, agar, algin, synthetic thickeners based on polymers, polyvinylidene chloride / acrylonitrile, acrylic acid copolymers, polyorganosiloxane, and combinations thereof.

[0079] When the topical composition is in the form of an emulsion, it generally contains at least one emulsifier chosen from amphoteric, anionic, cationic or non-ionic emulsifiers, used alone or as a mixture, and optionally a co-emulsifier. The emulsifiers are chosen appropriately depending on the emulsion to be obtained (W / O or O / W). The emulsifier and the co-emulsifier are generally present in the topical composition, in a proportion ranging from 0.3 to 30% by weight, and preferably from 0.5 to 20% by weight relative to the total weight of the composition.

[0080] For W / O emulsions, examples of emulsifiers that may be mentioned are dimethicone copolyols such as the mixture of cyclomethicone and dimethicone copolyol, sold under the name "DC 5225 C" by Dow Corning, and alkyl-dimethicone copolyols such as Laurylmethicone copolyol sold under the name "Dow Corning 5200 Formulation Aid" by Dow Corning and Cetyl dimethicone copolyol sold under the name Abil EM 90R by Goldschmidt. It is also possible to use as surfactant for W / O emulsions a crosslinked solid elastomeric organopolysiloxane comprising at least one oxyalkylenated group, such as those obtained according to the procedure of examples 3, 4 and 8 of document US-A-5,412,004 and the examples of document US-A-5,811,487, in particular the product of example 3 (synthesis example) of patent US-A-5,412,004, and such as that marketed under the reference KSG 21 by the company Shin Etsu.

[0081] For O / W emulsions, examples of emulsifiers that may be mentioned include non-ionic emulsifiers such as oxyalkylenated (more particularly polyoxyethylenated) fatty acid and glycerol esters; oxyalkylenated sorbitan fatty acid esters; oxyalkylenated (oxyethylenated and / or oxypropylenated) fatty acid esters; oxyalkylenated (oxyethylenated and / or oxypropylenated) fatty alcohol ethers; sugar esters such as sucrose stearate; and mixtures thereof such as the mixture of glyceryl stearate and PEG-40 stearate.

[0082] The topical composition according to the invention may optionally also comprise one or more oils, natural or synthetic, in particular sunflower, wheat germ, grape seed, sesame, corn, apricot, castor, shea, cotton, hazelnut, macadamia, jojoba, avocado, olive, soybean, sweet almond, palm, rapeseed, alfalfa, poppy, pumpkin seed, marrow, blackcurrant, evening primrose, millet, barley, quinoa, rye, safflower, candlenut, passionflower and rosehip oils or microalgae oils, such as oils rich in omega-3;essential oils such as jasmine, juniper, lavender, lemon, lemongrass, marjoram, sunflower, sesame, peppermint, macadamia nut, tea tree, evening primrose, sage, rosemary, coriander, thyme, pimento berry, rose, anise, balsam, lime, mandarin, bergamot, rosewood, cedarwood, chamomile, sage, clary sage, clove, cypress, eucalyptus, fennel, sea fennel, frankincense, geranium, ginger, grapefruit, myrrh, neroli, orange, patchouli, pepper, black pepper, petitgrain, pine, rose otto, rosemary, sandalwood, mint green, nard, vetiver, wintergreen and ylang ylang; silicone oils such as dimethicone, cyclomethicone, polysilicone-11, phenyl trimethicone, trimethylsilylamodimethicone and stearoxytrimethylsilane; mineral oils, such as paraffin and its derivatives;and mixtures of these oils.;

[0083] The topical composition according to the invention may optionally further comprise one or more agents for adjusting the pH, acids or bases or pH buffers, such as citrate or phosphate buffers, preservatives, chelating agents such as EDTA and other usual adjuvants of cosmetic or pharmaceutical compositions.

[0084] The topical composition according to the invention is preferably in the form of a gel, an oil-in-water or water-in-oil emulsion, a lotion or a solution. More preferably, the composition according to the invention is in the form of a gel.

[0085] A person skilled in the art will be able to determine the constituents used for the formulation of the topical composition, whether it is a gel, an ointment or a lotion.

[0086] The topical composition according to the invention may optionally comprise, in addition to the photosensitizing polar biomass extract, one or more cosmetic or therapeutic active compounds, for example anti-acne agents such as asiatic acid, monoethanolamine salt of 1-hydroxy-4-methyl 6-trimethylpentyl 2-pyridone, 10-hydroxy-2 decanoic acid, sodium ursolate, zinc oxide, 2,4,4'-trichloro-2'-hydroxy diphenyl ether (or triclosan), 1-(3',4'-dichlorophenyl)-3-(4'-chlorophenyl)-(triclocarban), 3,4,4'-trichlorocarbanilide, 3',4',5'-trichlorosalicylanilide, metronidazole and its salts, miconazole and its salts, itraconazole, terconazole, econazole, ketoconazole, saperconazole, fluconazole, clotrimazole, butoconazole, oxiconazole, sulfaconazole, sulconazole, terbinafine, ciclopirox, ciclopiroxolamine, undecylenic acid and its salts, resorcinol, octoxyglycerin or octoglycerin,octanoylglycine, and mixtures thereof. The topical composition according to the invention may optionally further comprise one or more UV-filtering components, known as anti-UV filters, such as ethylhexyl triazone, ethylhexyl salicylate, butyl methoxydibenzoylmethane, bis-ethylhexyloxyphenol methoxyphenyl triazine, diethylamino hydroxybenzoyl hexyl benzoate, phenylene bis-diphenyltriazine and mixtures thereof.,

[0087] Biomass

[0088] According to the invention, “phycocyanin-producing organisms” include ARUs and Cyanobacteria.

[0089] ARUs include microalgae of the order Cyanidiales. The order Cyanidiales encompasses the families Cyanidiaceae or Galdieriaceae, themselves subdivided into the genera Cyanidioschyzon, Cyanidium or Galdieria, to which belong, among others, the species Cyanidioschyzon merolae, Cyanidium caldarum, Cyanidium daedalum, Cyanidium maximum, Cyanidium partitum, Cyanidium rumpens, Galdieria daedala, Galdieria maxima, Galdieria partita and Galdieria sulphuraria (notably UTEX 2919 and its variants).

[0090] Microalgae of the genus Galdieria are unicellular red algae (URAs) in particular Rhodophytes, of the subdivision Cyanidiophytina, of the class Cyanidiophyceae, of the order Cyanidiales and of the family Galdieriaceae.

[0091] Preferably, the microalgae of the Galdieria genus are chosen from the species Galdieria daedala, Galdieria maxima, Galdieria partita or Galdieria sulphuraria, and are more preferably of the species Galdieria sulphuraria.

[0092] Methods for producing ARU biomasses, in particular biomasses of microalgae of the genus Galdieria, are described in particular in applications WO2017 / 050917, WO2017 / 050918 and WO 2017 / 093345.

[0093] Preferably, the biomass culture medium according to the invention comprises a carbon source and a nitrogen source. In particular, the carbon source is glucose.

[0094] Process for preparing an extract according to the invention

[0095] According to another aspect, the invention relates to a method for preparing a photosensitizing polar extract comprising the culture of a biomass of phycocyanin-producing organisms, in particular ARU or Cyanobacteria, then the steps of: a) harvesting the biomass by separation of the culture medium to obtain a crude biomass; b) optionally, cell lysis of the crude biomass from step (a) to obtain a lysed biomass, preferably by mechanical grinding; c) optionally, dilution of the lysed biomass from step (b) to obtain a solubilized lysed biomass;and d) recovery of the insolubles suspended in the lysed biomass of step (b) or the solubilized biomass of step (c) to obtain an extracted biomass, e) extraction by bringing the extracted biomass obtained in step d) into contact with a polar solvent then recovery of the aqueous fraction by separation of the insolubles suspended to obtain the photosensitizing polar extract.;

[0096] The use of the extracted biomass obtained in step d) of the process of the invention also makes it possible to be in a sustainable development approach by using a co-product (the extracted biomass) usually discarded from the production cycle as waste. The process of the invention thus makes it possible to reduce the production costs of the photosensitizing polar extract.

[0097] According to a particular embodiment, the method may comprise a step of heating the biomass before or during the extraction step e), that is to say, at any one of the steps a), b), c), d) or e) and preferably during the extraction step e).

[0098] According to another particular embodiment, the method may comprise a step of drying the biomass obtained in one of steps a), b), c) or d) to obtain a dried biomass: dried raw biomass, dried lysed biomass or dried extracted biomass.

[0099] The invention relates to a process for preparing a photosensitizing polar extract of biomass extracted from phycocyanin-producing organisms, in particular from ARU or Cyanobacteria, which comprises the steps of bringing an extracted biomass, dried or not, into contact with a polar solvent, in particular under the conditions set out above, then separating the solvent and the insoluble matter to recover a crude extract which is optionally concentrated or dried.

[0100] The invention also relates to a method for preparing the photosensitizing polar extract of biomass extracted from phycocyanin-producing organisms, in particular ARU or Cyanobacteria, which comprises the following steps of preparing an extracted biomass - optionally dried, and a step of extraction with a polar solvent. a) Harvesting the biomass

[0101] A raw biomass according to the invention is obtained after cultivation and then harvesting of the biomass (step a) of the process of the invention). The harvesting of unicellular red algae can be carried out by any technique known to those skilled in the art, in particular by filtration, possibly gravimetric or under reduced pressure, decantation, precipitation followed by gravimetric filtration or even centrifugation.

[0102] Biomass harvesting therefore corresponds to the recovery of the culture followed by the separation of the cells from the biomass of at least part of the culture medium.

[0103] This step produces raw biomass. The raw biomass thus harvested can also undergo a washing step, preferably with water, in order to remove certain soluble impurities.

[0104] The raw biomass obtained after harvesting and optionally after one or more washings comprises at least 70% by weight of water, and up to 90% by weight of water, preferably it comprises from 75 to 88% by weight of water, relative to the total weight of the raw biomass.

[0105] Preferably, the raw biomass according to the invention has a dry matter content of 5 to 30% by weight relative to the total weight of the raw biomass, generally still preferentially 10 to 25% by weight, more preferentially 10 to 20% by weight. b) Cell lysis

[0106] A lysed biomass according to the invention is obtained after an optional step of cell lysis of the raw biomass (step b) of the method of the invention). The raw biomass may have undergone a step of washing, freezing, thawing, drying and / or rehydration. In other words, in the context of the present invention, the raw biomass may in particular be a thawed and / or dried biomass.

[0107] Cell lysis can be carried out by any means of lysis known to those skilled in the art, in particular by enzymatic, mechanical or chemical means.

[0108] Among the mechanical means that can be used according to the invention, we will mention in particular ball mills, mixer-dispersers, high-pressure homogenizers, bag mills, pin mills, impact mills, ultrasound, or even pulsed electric fields. As devices for implementing these methods, we will refer to the following devices for the ball mill: Discus-100 from Netzsch or ECM-AP60 from WAB, for the high-pressure homogenizer: Ariete from GEA, for the mixer-disperser: 700-X from Silverson, for the pin mill: Contraplex from Hosakawa and for the impact mill: Condux from Netzsch.

[0109] Preferably, for the preparation of the topical composition comprising a photosensitizing polar extract according to the invention, cell lysis is carried out by mechanical lysis, still preferentially by grinding and in particular with a ball mill.

[0110] Preferably, the lysed biomass obtained has a dry matter content of 5 to 30% by weight relative to the total weight of the lysed biomass, preferably 10 to 25% by weight, more preferably 10 to 20% by weight. c) Dilution of the biomass

[0111] According to the invention, the optionally lysed biomass may optionally undergo a dilution step (step c) of the method of the invention). In the context of the present invention, the dilution step refers to the addition of a solution to the optionally lysed biomass to reduce its dry matter content. Advantageously, the dilution step is carried out via the addition of an aqueous solution. Preferably, the aqueous solution is water.

[0112] Preferably, when present, dilution step c) is carried out on the lysed biomass whose dry matter content is 5 to 30% by weight relative to the total weight of the lysed biomass, preferably 12 to 25% by weight.

[0113] The aqueous solution may further comprise one or more pH adjusting compounds. The term “pH adjusting compounds” means any organic or inorganic compound that can modify the pH (acidity correcting agents, acids, bases, neutralizing agents or buffering agents). Examples of such compounds are sulfuric acid, acetic acid, citric acid, phosphoric acid, sodium citrate, potassium lactate, potassium malate, sodium chloride, disodium phosphate and potassium phosphate. The aqueous solution has an acidic or basic pH depending on the pH adjusting compound(s) present in the solution.

[0114] Preferably, when present, step c) of diluting the lysed biomass is carried out with an aqueous solution of pH less than or equal to 8, in particular between 0 and 6, preferably between 1 and 6, more preferably between 2 and 5. The pH of the aqueous solution to be added to the lysed biomass or lysed biomass may be approximately 2, approximately 3, approximately 4, approximately 5, approximately 6, or approximately 7. Examples of acid solutions which may be added to the lysed biomass are solutions comprising acids such as those described above.

[0115] Depending on the case, the solubilized lysed biomass has a pH close to neutrality with a neutral, acidic or basic pH.

[0116] Preferably, the solubilized lysed biomass has an acid pH of less than 7, in particular between 1 and 6, more preferably between 2 and 5, even more preferably between 3 and 4.

[0117] Preferably, the solubilized lysed biomass obtained has a dry matter content of 1 to 15% by weight relative to the total weight of the solubilized lysed biomass (also called solubilisate), preferably 3 to 12% by weight, more preferably 4 to 8% by weight. d) Recovery of the extracted biomass

[0118] The biomass extracted according to the invention is obtained after treatment of the biomass to remove an aqueous extract comprising water-soluble molecules of interest such as phycobilliproteins and in particular phycocyanin (step d) of the process of the invention).

[0119] The lysed biomass comprises an aqueous phase and an insoluble fraction. To obtain an extracted biomass, the insoluble fraction of the lysed biomass is recovered by one of the methods known to those skilled in the art. Among these methods, in particular, the methods of frontal filtration, tangential filtration, decantation and centrifugation may be mentioned, preferably separation is carried out by centrifugation.

[0120] Preferably, the recovery of the insoluble fraction of the lysed biomass to obtain an extracted biomass is carried out on a lysed biomass, solubilized or not, having an acid pH, that is to say a pH lower than 7, preferably between 1 and 6, still preferably between 2 and 5, still still preferably between 3 and 4.

[0121] - Drying of biomass

[0122] The extracted biomass obtained in step d) of the process may optionally also undergo a drying step before the polar extraction step. In this case, the drying is carried out at a temperature between 30 and 200°C, preferably between 100 and 200°C.

[0123] When the extracted biomass undergoes a drying step, this is preferably carried out for a period of less than 5 minutes, more preferably for a period of between 0.1 seconds and 2 minutes, even more preferably between 0.2 seconds and 1 minute.

[0124] According to one embodiment of the invention, the photosensitizing polar extract is obtained from dried biomass.

[0125] In this case, the photosensitizing polar extract is preferentially obtained from an extracted biomass having undergone a drying step in its preparation process.

[0126] - Biomass heating

[0127] Advantageously, the biomass undergoes a heating step before or during polar extraction step e), i.e., in any one of steps a), b), c), d) or e) and preferably during extraction step e). Preferably, the extracted biomass obtained in step d) of the process may optionally undergo a heating step before or during step e), preferably during step e).

[0128] When the heating step is present, the heating is carried out at a temperature above 40°C, preferably between 40 and 100°C, still preferably between 45 and 90°C.

[0129] When the biomass, preferably the extracted biomass, undergoes a heating step, this is carried out for a period of at least 5 minutes, preferably at least 10 minutes and at most 24 hours. Preferably, the heating is carried out for a period of less than 12 hours, more preferably for approximately 2 to 6 hours.

[0130] Very preferably, this heating step is carried out during step e) of polar extraction.

[0131] According to a particular embodiment, the drying and heating steps are concomitant. e) Extraction with a polar solvent

[0132] Preferably, the extraction step of the process according to the invention (step e) is carried out with a polar organic solvent for a period of at least 5 minutes, preferably at least 10 minutes. The maceration time is advantageously less than 24 hours, preferably less than 12, more preferably approximately 2 to 6 hours. The higher the extraction temperature, the more the extraction of compounds derived from the degradation of chlorophyll-a increases. Preferably, in order to obtain the best compromise between energy consumption and extraction efficiency of the degradation derivatives of chlorophyll-a, this extraction with a polar organic solvent is carried out at a temperature above 15°C, preferably between 15°C and 120°C, more preferably between 40 and 90°C.

[0133] According to the invention, the extraction is advantageously carried out using at least 1 L of polar solvent per kilogram of dry matter of biomass, preferably at least 2 L of polar solvent per kilogram of dry matter of biomass and, particularly preferably, at least 4 L of polar solvent per kilogram of dry matter of biomass.

[0134] According to the invention, in order to obtain the best compromise between the volume of polar extract recovered and the extraction efficiency of the compounds derived from the degradation of chlorophyll-a, the extraction is advantageously carried out using between 1 L and 200 L of polar solvent per kilogram of dry matter of biomass, preferably between 2 L and 50 L of polar solvent per gram kilogram of dry matter of biomass and, particularly preferably, between 4 L and 20 L of polar solvent per kilogram of dry matter of biomass. Indeed, for the same quantity of polar solvent, the more the quantity of biomass to be extracted increases, the more the extraction efficiency of the compounds derived from the degradation of chlorophyll-a increases but the more the volume of extract recovered decreases.

[0135] The extract is obtained by usual solvent extraction methods.

[0136] Preferably, the extraction step of the process according to the invention is carried out with stirring in order to improve the extraction yield of the chlorophyll-a degradation derivatives.

[0137] Extraction is advantageously carried out at room temperature but can also be carried out cold or hot. Heating can promote the extraction of biomass components, but should not affect the photosensitizing properties of the extract.

[0138] In a preferred embodiment, the extraction is carried out:

[0139] - at a temperature of 40°C to 90°C

[0140] - for a duration of 2 hours to 4 hours

[0141] - under agitation

[0142] - in a mass ratio of dry matter of biomass: polar organic solvent of 1:5 to 1:10

[0143] - said polar organic solvent preferably being a practical polar organic solvent, in particular an alcohol.

[0144] Advantageously, the extraction is carried out at room temperature, thus making the process easier to implement and requiring less energy.

[0145] According to the preferred embodiment of the invention, the polar organic solvent is chosen from alcohols, in particular ethanol and isopropanol. The alcohol used may comprise a proportion of water, less than 60% by weight, preferably less than 50% by weight, more preferably less than 10% by weight, relative to the total weight of the alcohol / water mixture.

[0146] The separation of insoluble matter is carried out in a known manner, in particular by filtration and / or by centrifugation.

[0147] Advantageously, to obtain a polar extract, the method according to the invention further comprises a step of separating the insolubles in suspension, in particular filtration (e.g. 0.3 mm, 0.8 mm or other filter) and / or centrifugation (with recovery of only the supernatant) following the extraction.

[0148] The extract obtained after separation of the biomass is a solution designated as “crude extract”.

[0149] The crude extract obtained can be concentrated by total or partial removal of the solvent. This is then referred to as a “concentrated extract”. In this case, preferably, after the extraction step in a polar solvent of the extraction process according to the invention, the photosensitizing polar crude extract is distilled to remove all or part of the polar solvent. Advantageously, this step allows the preparation of a concentrated extract comprising less than 50% by weight of polar solvent relative to the total weight of the concentrated extract, preferably less than 20% by weight, more preferably between 0.5 and 1% by weight.

[0150] The extract obtained raw or concentrated can also undergo various treatments before its cosmetic use, in particular sterilization using standard techniques.

[0151] According to the invention, the photosensitizing polar biomass extract is obtained from an extracted biomass, preferably having previously undergone a drying and / or heating step in its preparation process as described above.

[0152] Advantageously, according to the invention, the photosensitizing polar biomass extract is obtained from an extracted biomass, having undergone a pH adjustment step to an acidic pH in its preparation process as described previously.

[0153] Process for preparing a topical composition comprising a photosensitizing polar extract derived from biomass

[0154] According to another aspect, the present invention relates to a method for preparing a topical composition comprising a photosensitizing polar extract of a biomass extracted from phycocyanin-producing organisms, in particular unicellular red algae (URA) or cyanobacteria, comprising the following steps:

[0155] - extraction of the extracted biomass with a polar organic solvent to obtain a photosensitizing polar extract as described above according to the invention, and

[0156] - mixing said extract with at least one topically acceptable compound such as those described above. Uses

[0157] The invention also relates to the photosensitizing polar extract according to the invention or the composition comprising it for its use as a medicament.

[0158] The invention also relates to the photosensitizing polar extract according to the invention or the composition comprising it for use in the prevention and / or treatment of acne, in particular hormonal and / or inflammatory acne. The invention further relates to the use of the photosensitizing polar extract according to the invention or the composition comprising it for the manufacture of a medicament for the prevention and / or treatment of acne, in particular hormonal and / or inflammatory acne. The invention also relates to a method for treating acne, in particular hormonal and / or inflammatory acne, in a subject in need thereof, comprising a step of administering to said subject a therapeutically effective amount of the photosensitizing polar extract according to the invention or the composition comprising it.

[0159] Pheophorbides-a and their derivatives are known for their photosensitizing effect. Indeed, when exposed to a light source, they allow the production of reactive oxygen species leading to the death of nearby microorganisms and consequently the prevention and / or treatment of acne.

[0160] Surprisingly, and unlike pheophorbides-a alone, the photosensitizing polar extract according to the invention exhibits an antibacterial effect both in the presence and absence of light. In other words, after application to a skin surface to be treated, the photosensitizing polar extract according to the invention or a composition comprising it exhibits an antibacterial effect on skin bacteria with or without exposure of the skin surface on which the extract or the composition comprising it has been applied to a light source.

[0161] The present invention also relates to the cosmetic use of an effective dose of photosensitizing polar extract according to the invention or of the composition comprising it to prevent and / or eliminate skin imperfections, i.e. improve the appearance of the skin.

[0162] The use of the photosensitizing polar extract according to the invention in phototherapy consists of applying it to a skin surface to be treated on a subject, or applying a composition comprising said extract, then exposing this surface to a light source. In this case, and in order to limit the associated undesirable effects, the extract can be applied as a localized treatment on the imperfections.

[0163] The photosensitizing polar extract according to the invention is also used in the absence of a light source, e.g. as a night cream, in which case the use consists of applying said extract or a composition comprising it to a skin surface to be treated on a subject.

[0164] The present invention also relates to the use of the photosensitizing polar extract according to the invention or the composition comprising it for its antibacterial effect, in particular bacteriostatic and / or bactericidal. Thus, the present invention relates to the photosensitizing polar extract according to the invention or the composition comprising it for its use as an antibacterial, in particular for its bacteriostatic and / or bactericidal effect. The invention further relates to the use of the photosensitizing polar extract according to the invention or the composition comprising it for the manufacture of an antibacterial medicament, in particular a bacteriostatic and / or bactericidal medicament.The invention also relates to a method of antibacterial treatment, in particular bacteriostatic and / or bactericidal treatment, in a subject in need thereof, comprising a step of administering to said subject a therapeutically effective amount of the photosensitizing polar extract according to the invention or of the composition comprising it.

[0165] The present invention also relates to the photosensitizing polar extract according to the invention or the composition comprising it for killing and / or inhibiting the growth of certain bacteria, in particular Staphylococcus aureus and / or Cutibacterium acnes and / or Corynebacterium xerosis and / or Staphylococcus epidermidis on a surface exposed to a light source.

[0166] The present invention also relates to the use of an effective dose of photosensitizing polar extract according to the invention or of the composition comprising it to kill and / or inhibit the growth of certain bacteria, in particular Staphylococcus aureus and / or Cutibacterium acnes and / or Corynebacterium xerosis and / or Staphylococcus epidermidis on a surface not exposed to a light source.

[0167] Exposure to the light source activates the photosensitizing extract to help prevent and / or eliminate skin imperfections, particularly acne.

[0168] According to a particular embodiment, the invention relates to a method for preventing or treating skin imperfections in a subject, in particular acne, said method consisting of applying a photosensitizing polar extract according to the invention or a composition comprising it to the part of the subject's skin to be treated, then exposing to a light source the surface of the skin on which the extract or the composition comprising it has been applied.

[0169] Advantageously, the illumination wavelength(s) is / are preferably between 380 and 800 nm (white light), more preferably between 380 and 450 nm (blue light) or between 620 and 780 nm (red light).

[0170] Advantageously, the illumination wavelength(s) is / are between 380 and 450 nm, preferably 400 nm and 440 nm, more preferably 405 nm and 420 nm. This makes it possible to limit the occurrence of undesirable effects associated with the use of the extract according to the invention or a composition containing it combined with exposure to a light source. Indeed, the choice of this or these illumination wavelength(s) makes it possible to obtain an antibacterial and / or bacteriostatic effect localized in the superficial layers of the skin, with wavelengths from 200 to 400 nm only reaching the epidermal layer of the skin, while those from 400 to 600 nm penetrate the skin to the dermal layer, and those from 600 to 700 nm can reach the subcutaneous tissue of the skin (Francisco et al., 2021).

[0171] In the case where the illumination wavelength(s) is / are between 620 and 780 nm, it is / are preferably between 650 and 700 nm and even more preferably between 670 and 685 nm.

[0172] According to the invention, exposure to the light source is preferably carried out after a waiting time of 10 seconds to 240 minutes following the application of the extract or the composition comprising it to have a sufficient antibacterial effect, preferably between 1 minute and 180 minutes and, even more preferably between 2 and 60 minutes.

[0173] Exposure to a light source, particularly in the case of artificial light, can possibly last between 1 and 90 minutes, preferably between 10 and 30 minutes, preferably 15 to 25 minutes.

[0174] Exposure to a light source, particularly in the case of natural light, can possibly last between 10 and 420 minutes, preferably between 60 and 120 minutes, preferably 15 to 45 minutes.

[0175] The illumination dose of a light exposure by cosmetic treatment is preferably between 0.01 and 100 J / cm 2 , preferably less than 50 J / cm 2 and in particular between 10 and 30 J / cm 2 .

[0176] The intensity of light exposure by cosmetic treatment is preferably between 10 and 900 W / m 2 , preferably between 15 and 400 W / m 2 and in particular between 20 and 100 W / m 2 .

[0177] It is understood that the operation can be repeated, generally every 2 to 7 days, for several weeks, in particular up to 12 weeks or more depending on the desired result. This repetition can be repeated 3 to 6 months after the last treatment.

[0178] After exposure to the light source, the photosensitizing polar extract or the composition comprising it can be advantageously removed from the surface of the skin by any usual means of cleaning the skin.

[0179] According to a particular embodiment, the surface of the skin of the subject to be treated is pretreated to promote the absorption of the photosensitizing polar extract into the superficial layers of the skin. This pretreatment can be carried out by any means suitable for carrying out a superficial peeling, in particular by “chemical” means by applying a composition promoting this superficial peeling, such as compositions comprising peeling agents such as fruit acids, alpha-hydroxy acids (AHAs), such as glycolic acid and lactic acid, azelaic acid, retinoids such as tretinoin, adapalene, tazarotene, or vitamin D3 derivatives.Superficial peeling can also be performed by mechanical means such as curettage, (micro)dermabrasion (e.g. with suitable abrasive paper), micro-perforation (“micro-needling”, e.g. with a dermaroller), tape-stripping, pan-scrubber, exfoliating scrub or even low-energy non-ablative lasers.

[0180] Surprisingly, the present invention relates to a photosensitizing polar extract according to the invention for its use in skin regeneration, in particular thanks to its keratinocyte growth-stimulating properties. Indeed, the epidermis is composed of distinct and superimposed layers that reflect the progressive differentiation of keratinocytes, migrating from the basal layer to the superficial layer. The regeneration of the epidermis depends on a subtle balance between the proliferation and differentiation of epidermal stem cells, as well as the elimination of superficial dead cells by desquamation. This makes it possible to maintain and / or restore the structure and functions of the epidermis. Various factors, such as heredity, environment, lifestyle, acne, inflammation, scarring or aging, are known to influence the quality and speed of epidermal regeneration.

[0181] The invention therefore also relates to the use of the photosensitizing polar extract according to the invention or of a composition comprising it for the manufacture of a medicament allowing the regeneration of the skin, in particular thanks to its properties stimulating the growth of keratinocytes. The invention also relates to a method for regenerating the skin, in particular by stimulating the growth of keratinocytes, in a subject who needs it, comprising a step of administering to said subject a therapeutically effective amount of the photosensitizing polar extract according to the invention or of a composition comprising it.

[0182] Furthermore, also surprisingly, the polar extract according to the invention promotes the production of mitochondrial proteins involved in the production of skin energy and therefore the repair, regeneration and protection of the skin as well as the production of proteins involved in the proteasome, a proteolytic complex crucial for the degradation and recycling of proteins and therefore ensuring their renewal.

[0183] As a result of these surprisingly observed effects and in connection with skin regeneration, the polar extract according to the invention is also used to prevent and / or eliminate skin imperfections, in particular to prevent and / or eliminate signs of aging such as wrinkles or to promote skin healing. The present invention further relates to a photosensitizing polar extract according to the invention for its use in skin healing. The invention also relates to the use of the photosensitizing polar extract according to the invention for the manufacture of a skin healing medicament. The invention also relates to a method for healing the skin, in a subject in need thereof, comprising a step of administering to said subject a therapeutically effective amount of the photosensitizing polar extract according to the invention.

[0184] Removal of photosensitizer

[0185] Advantageously, the photosensitizing polar extract according to the present invention and / or the composition comprising it is removed from the surface of the skin to which it has been applied.

[0186] Surface decontamination

[0187] The present invention also relates to the use of a photosensitizing polar extract according to the invention for the decontamination of inert surfaces by application to the surface to be treated which is then optionally exposed to a light source so as to allow the activation of the photosensitizing extract.

[0188] For the purposes of the present invention, the term "inert surface" means all hard surfaces in the medical environment, in public, institutional (schools, collective kitchens, etc.) and domestic spaces; preferably in the medical environment, such as for example in medical practices, in hospitals and in medical establishments.

[0189] Conservative

[0190] The present invention also relates to the use of a photosensitizing polar extract according to the invention as a preservative in compositions, in particular cosmetic compositions.

[0191] Culture media

[0192] The present invention also relates to the use of a photosensitizing polar extract according to the invention as a growth booster for eukaryotic or mammalian cells, in particular keratinocytes.

[0193] Biocontrol

[0194] The present invention also relates to the use of a photosensitizing polar extract according to the invention as a biocontrol for preventing and / or treating diseases affecting the production of plants of agricultural interest. The present invention also relates to a photosensitizing polar extract according to the invention for its use as a biocontrol for preventing and / or treating diseases affecting the production of plants of agricultural interest.

[0195] Examples include the treatment of Pseudomonas syringae, which causes various diseases such as bacterial spot, cankers and fire blight on many plants, including tomatoes, peppers and cherries; Xanthomonas spp, which causes bacterial spot and cankers on various crops such as tomatoes, citrus fruits, cabbages, peppers and beans; Erwinia amylovora, which causes fire blight, a serious disease that mainly affects apple and pear trees; Ralstonia solanacearum, which causes bacterial wilt, a destructive disease affecting many crops, including potatoes, tomatoes, eggplants and bananas; Agro bacterium tumefaciens, which causes crown gall, a disease that causes the formation of tumours on the roots and stems of many plants, including vines, roses and fruit trees;of Clavibacter michiganensis, which causes bacterial canker and wilt, mainly affecting tomato and potato crops; of Xylella fastidiosa, which causes Pierce's disease in grapevines and other diseases in a variety of plants, including olive and citrus fruits; of Dickeya spp. and Pecto bacterium spp., which cause soft rot and black rot on crops such as potatoes, carrots, and cucurbits; of Burkholderia glumae, a bacterium that causes bacterial grain rot and mainly affects rice crops. BRIEF DESCRIPTION OF THE FIGURES;

[0196] Figure 1 is a graph representing the analysis of the fatty acid profile of photosensitizing polar extracts prepared according to the process of the invention at different temperatures (20°C, 50°C and 80°C).

[0197] Figure 2 is a graph representing the absorbance spectra of photosensitizing polar extracts according to the invention extracted with isopropanol or ethanol.

[0198] Figure 3 is a graph representing the analysis of the fatty acid profile of photosensitizing polar extracts prepared according to the process of the invention with different solvents (ethanol or isopropanol).

[0199] Figure 4 is a photograph representing the identification of the lipid classes present in a photosensitizing polar extract of Galdieria sulphuraria according to the invention by thin layer chromatography (5 μL (left band) or 10 μL (right band) of the extract were deposited on the layer and are compared to standards of glucocerebrosides, phosphatidylcholine (PC), ceramides, digalactosyldiglycerides (DGDG), monogalactosyldiglycerides (MGDG) and glycosylsterols).

[0200] Figure 5 is a graph representing the effect of a polar extract of Galdieria sulphuraria according to the invention (at different concentrations) on the growth of S. aureus with or without light.

[0201] Figure 6 is a graph representing the effect of a polar extract of Galdieria sulphuraria according to the invention (at different concentrations) on the growth of C. acnes with or without light.

[0202] Figure 7 is a graph representing the effect of a polar extract of Galdieria sulphuraria according to the invention (at different concentrations) on the growth of C. xerosis with or without light.

[0203] Figure 8 is a graph representing the effect of a polar extract of Galdieria sulphuraria according to the invention (at different concentrations) on the growth of S. epidermidis with or without light.

[0204] Figure 9 is a graph representing the effect of different polar extracts (polar extract of biomass extracted according to the invention and comparative polar extract of lysed biomass) and pheophorbides-a on a bacterial mix in the absence of light.

[0205] Figure 10 is a graph representing the effect of different polar extracts (polar extract of biomass extracted according to the invention and polar extract of comparative lysed biomass) and pheophorbides-a on a bacterial mix after exposure to light.

[0206] Figure 11 is a graph representing the effects of the polar extract according to the invention of Galdieria sulphuraria (at different concentrations) on NHEK-p Keratinocyte cells compared to the culture medium (positive control) or to TX-100 (negative control).

[0207] Figure 12 is a graph representing a comparative study of the proteome of Keratinocytes exposed and not exposed to a polar extract of biomass extracted according to the invention.

[0208] EXAMPLES

[0209] The present invention will be better understood by reading the following examples which illustrate the invention in a non-limiting manner.

[0210] EXAMPLE 1 Preparation of polar extracts under different conditions of time, temperature and concentration

[0211] An extracted Galdieria sulphuraria biomass powder is treated with ethanol for the preparation of polar extracts by varying 3 parameters: the extraction temperature, the extraction time, as well as the quantity of biomass for the same quantity of ethanol (10mL).

[0212] Extraction efficiency is assessed by measuring the absorbance at 410 nm of the centrifuged samples as well as the volume of solvent recovered.

[0213] The different experimental conditions and the results obtained are presented in Table 1 below.

[0214] Experiment 15 was repeated 3 times (tests 1.15.1; 1.15.2 and 1.15.3) in order to know the experimental variance of the tests. The analysis of variance for the maximum absorbance and recovered solvent volume responses shows that the chosen factors allow us to understand the variations in the experimental results.

[0215] Table 1: Results of the experimental design.

[0216] The above results show that the process according to the invention makes it possible to obtain good extraction of chlorophyll-a degradation derivatives regardless of the temperature and time conditions.

[0217] The extraction of chlorophyll-a degradation derivatives is even further improved when the temperature is above 50°C and the extraction time is longer than 250 min.

[0218] EXAMPLE 2 Study of the composition of different polar extracts of Galdieria sulphuraria

[0219] An extracted Galdieria sulphuraria biomass powder is treated with ethanol for the preparation of photosensitizing polar extracts under stirring at 20°C (Test 2.1), 50°C (Test 2.2) and 80°C (Test 2.3) for 2 hours, with stirring. The powder / absolute ethanol volume ratio is 1 / 5 for the three conditions.

[0220] The extracts obtained are distilled at 35°C, 30mbar until complete evaporation of the ethanol, resolubilized in DSMO and then analyzed by absorbance spectrometry to determine the maximum absorbance at 410nm, the percentage of total lipids relative to the total weight of dry matter (% DM) and the fatty acid profile are analyzed respectively by the Folch method and by GC-FID after transmethylesterification and internal calibration). The method used to analyze and quantify the pigment composition of the extracts is that described by Van Heukelem & Thomas Computer-assisted high-performance liquid chromatography method development with applications to the isolation and analysis of phytoplankton pigments. J Chromatogr A. 2001 Feb 23;910(1):31-49).

[0221] The results are presented in Table 2 below and in Figure 1. Table 2. Pigment composition of polar extract of extracted biomass produced at different temperatures under stirring.

[0222]

[0223] The results in the table above and Figure 1 show that the extracts obtained have a similar composition of pigments and fatty acids regardless of the temperature used (20°C, 50°C or 80°C) thanks to homogeneous stirring.

[0224] EXAMPLE 3: Comparison of absorbance spectra and fatty acid composition of polar extracts obtained with different polar solvents

[0225] An extracted Galdieria sulphuraria biomass powder is treated with ethanol or isopropanol for the preparation of polar extracts under stirring at 50°C for 2 hours. The powder / solvent volume ratio is 1 / 5. The extracts obtained are distilled at 35°C, 30 mbar until complete evaporation of the solvent (ethanol or isopropanol) and then analyzed by absorbance spectrometry. The extracts obtained are also analyzed to know their fatty acid profiles. These analyses are carried out respectively by the Folch method and by GC-FID after transmethylesterification and internal calibration. The results are presented in Figures 2 and 3. It is found that there is no significant difference in the shape of the absorbance spectra or in the lipid characteristics studied between an extract obtained by extraction with ethanol and one with isopropanol.

[0226] EXAMPLE 4: Comparison of polar extracts according to the invention and the prior art

[0227] The polar extract prepared in Example 2 (test 2.3) is analyzed in order to identify, in addition to its pigment composition, the different families of lipids present in this extract according to the invention; a thin-layer chromatography analysis is carried out. For this, the sample is taken up in a chloroform / methanol mixture (volume ratio 2 / 1) at a concentration of 10 mg / ml before being deposited twice on the plate with 5 μl and 10 μl respectively. The standards of glucocerebrosides, ceramides, phosphatidylcholine (PC), monogalactosyldiglycerides (MGDG), digalactosyldiglycerides (DGDG) and glycosylsterols are deposited individually on the plate. The mobile phase used for migration is a chloroform / methanol / water / acetic acid mixture (volume ratio 65 / 16 / 2 / 1). The plate is then air dried, transferred into the derivatization reagent (50% H2SO4), then drained and heated for 5 minutes at 140°C.The heating is stopped when the spots appear.

[0228] The results are shown in Figure 4.

[0229] Ambrosino et al. disclose the preparation of a polar extract of unextracted lysed biomass of Galdieria sulphuraria with acetone Ambrosino. et al. Galdieria sulphuraria: An Extremophilic Alga as a Source of Antiviral Bioactive Compounds. Mar. Drugs 2023, 21, 383.) and its characterization. This extract was reproduced in the laboratory and its pigment composition analyzed as described in Example 2. The results are shown in Table 3 below. Table 3: Characterization of the extract prepared according to Ambrosino et al.

[0230] 1 Results presented in Ambrosino et al.

[0231] By comparing the migration profile of the polar extract produced according to the invention with that of the standards (Figure 4), we can determine that the lipid fraction is composed mainly of MGDG, DGDG, PC and ceramides (amide lipids).

[0232] The lipid composition of the extract according to the invention is therefore different from that of the extract prepared according to Ambrosino et al.. Indeed, the latter is composed solely of amide lipids, free fatty acids and chlorophyll-a derivatives.

[0233] The contents of chlorophyll-a derivatives in the extract according to the invention (Example 2.3) are also different from those of the extract prepared according to Ambrosino. Indeed, the latter has a ratio of pheophorbides-a (phb-a) to (total phb-a + total pheophytin a (pht A)) of less than 40%.

[0234] EXAMPLE 5: Production of the photosensitizing polar extract on a pilot scale

[0235] An extracted Galdieria sulphuraria biomass powder is treated with ethanol for the preparation of a photosensitizing polar extract under stirring at 75°C for 120 minutes with a powder / solvent volume ratio of 1 / 10. This extract is distilled at 35°C, 30 mbar until complete evaporation of the ethanol, then analyzed by absorbance spectrometry (Test 5.1). The extract obtained is also analyzed to know its percentage of lipids relative to the dry mass (%) (Folch method), its fatty acid profile in comparison with an extract according to the invention obtained on a laboratory scale (Test 2.3) (GC-FID after transmethylesterification and internal calibration) and its pigment composition (method described in Example 2).

[0236] The results are presented in Table 4 and Table 5.

[0237] Table 4: Extraction results and macroscopic composition of the polar extract.

[0238]

[0239] Table 5. Fatty acid composition (%FAMEs) of samples extracted at laboratory scale (Test 2.3) and pilot scale (Test 5.1).

[0240] Using a high-performance pilot mixing system, we can observe that the extraction is more efficient than on a smaller scale, thus making it possible to obtain pheophorbide contents at least 3 times higher from the same initial material (Table 2 and Table 5).

[0241] The main fatty acids represented in extract 5.1 are palmitic acid, oleic acid, linoleic acid, α-linolenic acid and stearic acid; acids which represent approximately 92% of the total fatty acids (%FAMEs).

[0242] EXAMPLE 6: Study of the bactericidal and / or bacteriostatic effects of polar extracts of a biomass extracted from Galdieria sulphuraria on different bacteria

[0243] The presolubilized polar extract 2.3 of Example 2 is dissolved in a Mueller-Hinton medium.

[0244] Five different concentrations of polar extract of extracted biomass are added to a microbial suspension of Staphylococcus aureus (ATCC 6538): 0% (Control), 0.0014% o , 0.007% o , 0.036%o and 0.36%o by weight relative to the total weight of the culture medium corresponding respectively to 0 nM, 0.17 nM, 83 nM, 0.41 pM and 4.1 pM of pheophorbides-a relative to the volume of culture medium (n=3). Each culture is then pre-incubated for 3 hours at 37°C, 280 rpm then exposed or not to white light (10 or 25 J / cm2). Finally, the cultures are incubated for an additional 24 hours at 37°C. To monitor microbial growth, the optical density at 600 nm is measured over time (microplate spectrometer, EPOCH2, BioTek Instruments) and the area under the curve (AUC) is calculated from t=0 to t=16 hours.

[0245] The same test is applied independently on 3 other bacteria: Cutibacterium acnes (ATCC 6919), Corynebacterium xerosis (ATCC 373) and Staphylococcus epidermidis (ATCC 14990). Note that for the C. xerosis and C. acnes strains, 5% sheep blood is added to the culture medium and their incubation is continued for 72 hours at 37°C instead of 24 hours.

[0246] The results are presented in Figure 5, 6, 7, and 8 respectively.

[0247] We note that, in the absence of light, the area under the curve decreases significantly when the pro-acne strains, S. aureus and C. acnes, are brought into contact with the polar extract according to the invention compared to the control condition without extract. This indicates that in the presence of the polar extract according to the invention the growth of these strains is significantly reduced. In particular, between 13% and 74% inhibition of the growth of these bacteria is observed depending on the concentration used and the strain concerned. We can therefore conclude that, in the absence of light, the polar extract has bacteriostatic properties on S. aureus and C. acnes limiting their proliferation and with the development of acne (Figure 5 and Figure 6). In the presence of light 10 J / cm2 and 25 J / cm2 this bacteriostatic effect is even more marked (Figure 5 and Figure 6).

[0248] As previously, in the presence of light and the polar extract according to the invention, C. xerosis and S. epidermidis see their growth reduced or even totally inhibited (Figure 7 and Figure 8).

[0249] EXAMPLE 7: Study of the bactericidal and / or bacteriostatic effects of polar extracts of a biomass extracted from Galdlerla sulphuraria, of a biomass not extracted from Galdlerla sulphuraria, and of pure pheophorbides-a on a mixture of bacteria.

[0250] Unextracted Galdieria sulphuraria biomass powder is treated with ethanol for the preparation of photosensitizing polar extracts at 80°C (Test 7.1) for 2 hours, with stirring. The powder / absolute ethanol volume ratio is 1 / 5 for all three conditions.

[0251] The extracts obtained are distilled at 35°C, 30mbar until the ethanol has completely evaporated.

[0252] The method used to analyze and quantify the pigment composition of the extracts is that described by Van Heukelem & Thomas Computer-assisted high-performance liquid chromatography method development with applications to the isolation and analysis of phytoplankton pigments. J Chromatogr A. 2001 Feb 23;910(1):31-49).

[0253] The pure pheophorbide-a used is a commercial product from ChemCruz (lot K0223, purity >90%). The sample of polar extract of extracted Galdieria sulphuraria biomass is the one used in Test 2.3 of Example 2. All samples are pre-diluted in DMSO to obtain an equivalent pheophorbide-a concentration for each sample. The polar extracts and the pheophorbide-a solution are resolubilized and dissolved in Epilife medium. The bacteria used are the same as those used in Example 6, and added to the medium at an equivalent optical density.

[0254] A concentration of 0.036% of polar extract of extracted biomass corresponding to 0.41 pM of pheophorbides-a is added to the culture medium (n=3). The culture is then pre-incubated for 3 hours at 37°C, 280 rpm then exposed or not to white light (25 J / cm2). Finally, the cultures are incubated for an additional 20 hours at 37°C.

[0255] To monitor microbial growth, optical density at 600 nm is measured over time (microplate spectrometer, EPOCH2, BioTek Instruments).

[0256] The results are presented in Figure 9 and 10.

[0257] Monitoring the growth of the bacterial mixture in the presence of the different polar extracts and pure pheophorbides-a clearly shows the bacteriostatic effect of the polar extract of extracted biomass compared to the control condition in the absence of light (Figure 9). This confirms the results obtained on independent cultures of these same bacteria (Example 6). We can also note that the polar extract of unextracted biomass, as well as pure pheophorbides-a, have no effect on the growth of bacteria in the absence of light. This demonstrates that the bacteriostatic effect is not solely linked to the presence of pheophorbides-a in the culture medium. Indeed, we have the same concentration of this element in all the conditions tested except the control condition.The polar extract of unextracted biomass also having no effect in the presence of light, shows us that the bacteriostatic activity is also linked to the fact that the biomass has been previously processed.

[0258] Following exposure to light, bacterial cultures incubated with the polar extract of unextracted biomass and pure pheophorbides-a show a pronounced growth delay in the first growth phase, i.e. up to approximately 10 hours (Figure 10). Since the growth kinetics in this phase are similar, we can conclude that, in both cases, the effect is directly linked to the photoactivation of pheophorbides-a. After this phase, we can observe a growth recovery until reaching levels similar to those observed in control conditions. The growth kinetics of cells incubated with the polar extract of extracted biomass is distinguished by an absence of growth delay in the first 4 to 6 hours but the achievement of a very rapid plateau phase between 10 and 12 hours, indicating either a halt in cell division or cell death.

[0259] EXAMPLE 8: Effect of the polar extract according to the invention on keratinocytes

[0260] Normal, adult human keratinocytes from a single donor (Promocell) were cultured and maintained as a monolayer at less than 75% confluence in the recommended culture medium. Keratinocytes were cultured at 37°C, 5% CO2. Cells were subcultured with a combination of purified trypsin and trypsin inhibitors / BSA and used below passage 6.

[0261] An amount equivalent to 0.00084% o , 0.0042% o , 0.0084% o and 0.042% o of polar extract (Test 2.3) according to the invention prepared in accordance with Example 2 was added to the culture medium. The cells were then cultured for 24 hours. Each condition was tested at least in triplicate, with reference positive controls and untreated controls. The cultures were not illuminated.

[0262] Cell viability was measured using the CelITox™ Green cytotoxicity assay (Promega) according to the manufacturer's instructions. The CelITox Green cytotoxicity assay measures cell death using a fluorescent dye that penetrates dead cells and binds to DNA, emitting fluorescence. This fluorescence correlates with the number of dead cells, allowing for quantitative assessment of cytotoxicity. Where indicated, cells were treated with 0.1% v / v (water) Triton-Xi 00 (Sigma-Aldrich), which induces membrane damage and cell death. Fluorescence reading and imaging were performed on a Cytation Multi-Mode Cell Imaging Reader (Agilent / Biotek).

[0263] The experiments and data processing were carried out by the company Elysia Bioscience (40 Avenue Ferdinand Lesseps 33610 CANEJAN).

[0264] The results are shown in Figure 1 1 .

[0265] The results show that following Triton-X100 treatment (negative control), there is a reduction in cell labeling, reflecting cell death. Surprisingly, we can observe that the number of cells increases significantly compared to the control, when incubated with concentrations of 0.00084% o at 0.0084% o of polar extract according to the invention of extracted biomass. We can therefore conclude that the polar extract of biomass extracted from Galdieria sulphuraria according to the invention under these conditions promotes the growth of keratinocytes and therefore the skin regeneration cycle.

[0266] EXAMPLE 9: Study of the keratinocyte proteome following exposure of cells to a polar extract of extracted biomass.

[0267] Reconstructed human epidermis (RHE, Episkin) was treated with 0.036% of polar extract (Test 2.3) according to the invention prepared according to Example 2 under the predetermined application conditions in a sterile cell culture environment. Proteins were extracted under denaturing conditions compatible with SDS-PAGE and downstream proteomics applications. Protein concentration was determined by the BCA (bicinchonic acid) method and standardized for all samples. Samples were separated by SDS-PAGE and digested overnight. The generated peptides were acidified and separated using a Fusion Lumos mass spectrometer (Thermo Fisher), with a 146-minute gradient.

[0268] Mass spectra were analyzed using Proteome Discoverer (version 2.5). The resulting MS / MS data were compared to the Homo sapiens proteome UP000005640 (20371 revised entries). Search parameters were: monoisotopic mass; trypsin as the cleaving enzyme; maximum two missed cleavages; cysteine ​​carbamidomethylation as a fixed modification; and N-terminal acetylation and methionine oxidation as variable modifications. Results were filtered based on unique peptides >2 and overall peptide scores.

[0269] A proprietary bioinformatics processing pipeline (including protein database searching, protein interaction networks, quantitative analysis, and statistics) was used to analyze and construct a comprehensive interpretation of the relevant biological activities of the tested products.

[0270] The experiments and data processing were carried out by the company Elysia Bioscience (40 Avenue Ferdinand Lesseps 33610 CANEJAN).

[0271] The results are shown in Figure 12.

[0272] Protein abundance in each group is represented by a white circle if there is no change from control conditions and or gray circle when there is an increase. The size of the circle indicates the relative number of proteins associated with each group.

[0273] Following exposure of keratinocyte cells to the polar extract of extracted biomass, we observed an increase in the abundance of 6 to 10% of proteins involved in energy production such as the TCA cycle, respiration and mitochondrial organization (Figure 12).

[0274] An increased abundance of mitochondrial proteins increases skin energy levels, which can promote overall skin repair, regeneration, and protection. Energy-dependent processes are also essential for maintaining skin barrier integrity, resulting in a 14-15% increase in the abundance of proteins related to skin barrier maintenance.

[0275] The abundance of proteins involved in the proteasome is also up 4-5%. The proteasome is a proteolytic complex crucial for protein degradation and recycling, thus ensuring intracellular protein quality control. It degrades and recycles abnormal or damaged proteins to prevent their accumulation.

[0276] Overall, these results show that a polar extract of Galdieria sulphuraria has a beneficial effect on different cellular metabolisms involved in skin repair, regeneration and protection.

Claims

CLAIMS 1. Photosensitizing polar extract of biomass extracted from phycocyanin-producing organisms, particularly unicellular red algae (URA) or cyanobacteria.

2. Photosensitizing polar extract according to claim 1, characterized in that the biomass is an ARU biomass and in that the ARUs are chosen from the Galdieriaceae or Cyanidiaceae families, more preferably from the Galdieria, Cyanidioschyzon or Cyanidium genera, even more preferably Galdieria.

3. Photosensitizing polar extract according to claim 2, characterized in that the ARUs are of the species Galdieria sulphuraria.

4. Photosensitizing polar extract according to any one of claims 1 to 3, characterized in that it is a solution comprising a polar organic solvent, preferably a protic polar organic solvent chosen from alcohols, in particular methanol, ethanol and isopropanol, volatile organic acids, in particular formic acid, acetic acid, primary or secondary amines and PEG (polyethylene glycol) and mixtures thereof.

5. Photosensitizing polar extract according to any one of claims 1 to 4, characterized in that it comprises up to 95%, preferably from 90% to 65%, even more preferably from 80% to 90% of lipids by weight relative to the total dry mass of the extract.

6. Photosensitizing polar extract according to claim 5, characterized in that said lipids comprise monogalactosyldiglycerides, digalactosyldiglycerides, phosphatidylcholines and ceramides.

7. Photosensitizing polar extract according to any one of claims 1 to 6, characterized in that it comprises from 350 mg / g to 0.5 mg / g of pheophorbides-a and its derivatives by weight relative to the total weight of the extract, preferably from 175 mg / g to 1 mg / g and even more preferably from 85 mg / g to 5 mg / g.

8. Process for the preparation of a photosensitizing polar extract comprising the cultivation of a biomass of phycocyanin-producing organisms, in particular unicellular red algae (URA) or cyanobacteria, then the steps of: a) harvesting the biomass by separation of the culture medium to obtain a crude biomass; b) optionally, cell lysis of the crude biomass from step (a) to obtain a lysed biomass; c) optionally, dilution of the lysed biomass from step (b) to obtain a solubilized lysed biomass; and d) recovery of the insolubles suspended in the lysed biomass from step (b) or the solubilized biomass from step (c) to obtain an extracted biomass, e) extraction by bringing the extracted biomass obtained in step d) into contact with a polar solvent then recovery of the aqueous fraction by separation of the insolubles suspended to obtain the photosensitizing polar crude extract.

9. Method according to claim 8, characterized in that the polar organic solvent is a practical polar organic solvent chosen from alcohols, in particular methanol, ethanol and isopropanol, volatile organic acids, in particular formic acid, acetic acid, primary or secondary amines and PEG (polyethylene glycol) and mixtures thereof.

10. Method according to claim 8 or 9, characterized in that it further comprises a step of heating the biomass before or during step e) of extraction, that is to say, at any one of steps a), b), c), d) or e). 1 1. Photosensitizing polar extract according to one of claims 1 to 7 capable of being obtained by the process according to one of claims 8 to 10.

12. Topical composition characterized in that it comprises a photosensitizing polar extract according to one of claims 1 to 7 or 11 and a topically acceptable carrier.

13. Photosensitizing polar extract according to one of claims 1 to 7 or 11 or topical composition according to claim 12 for its use in the prevention and / or treatment of acne. 14.Photosensitizing polar extract according to one of claims 1 to 7 or 11 or topical composition according to claim 12 for its use in the prevention and / or elimination of skin imperfections.

15. Photosensitizing polar extract for its use or topical composition for its use according to claim 13 or 14, characterized in that said extract or said composition is applied to a skin surface to be treated of a subject, followed by exposure of said surface to a light source.

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