Liquid antimicrobial composition

Abstract

The current invention relates to a liquid antimicrobial composition comprising: at least one alkanediol, wherein a first alkanediol is a 1,2-alkanediol or 1,3-alkanediol with a straight or branched carbon chain between 4 and 12 carbon atoms; and at least one bioflavonoid.

Description

[0001] LIQUID ANTIMICROBIAL COMPOSITION

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to a liquid antimicrobial composition, a method of production and a use thereof.

[0004] BACKGROUND

[0005] Contamination by microbes is a well-known risk for aqueous formulations, especially during manufacture or use. The addition of antimicrobial additives, so-called preservatives, is often required to maintain function, integrity and safety. However, many conventional preservatives are harmful and / or not readily biodegradable, and many are unsustainably produced petrochemicals. There is therefore a need for sustainably sourced antimicrobial additives that are safe for consumers and the environment.

[0006] C3-C12 1,2-alkanediols and 1,3-alkanediols with a straight or branched chain are non-toxic and environmentally friendly ingredients. Many of them can be produced from renewable raw materials by fermentation or green chemistry. Alkanediols are often used in personal care products where they have a nourishing, emollient and moisturizing effect. Alkanediols are also known for their intrinsic antimicrobial activity.

[0007] In addition to their widespread use in hygiene and personal care products, alkanediols can also be used as valuable additives in a wide range of other, preferably aqueous, formulations. Examples include household and cleaning products, coatings and agrochemical formulations.

[0008] The use of a single alkanediol as an antimicrobial additive requires high concentrations to achieve complete preservation. For example, a use-level of 4-5% of 1,2-pentanediol (C5) or 0,5% of Caprylyl Glycol (C8) is typically needed for creation of a fully preserved formulation. Such high concentrations often lead to skin irritation. In addition, the costs of many alkanediols are relatively high compared to traditional preservatives. Therefore, using single alkanediols as standalone preservatives leads to high costs and decreases the skin compatibility of the formulation. Nature is a rich source for antimicrobial additives. Plants have their own defense mechanisms to combat external stresses such as microbial infections or air oxidation. A common strategy is therefore to use plant extracts as antimicrobial additives, either alone or in combination with other antimicrobial components. However, the typical disadvantage of many unrefined plant extracts is their complex, variable and sometimes unknown composition. This can lead to potentially undesirable contaminants in consumer products. Such kind of harmful components may include food or fragrance allergens or toxic contaminants with acute or long-term adverse health effects. Other undesired side-effects may be unpleasant odors or discoloration.

[0009] The present invention aims to resolve at least some of the problems and disadvantages mentioned above.

[0010] SUMMARY OF THE INVENTION

[0011] The present invention and embodiments thereof serve to provide a solution to one or more of above-mentioned disadvantages. To this end, the present invention relates to composition according to claim 1. More particular, to a composition comprising at least one alkanediol and at least one bioflavonoid. Preferred embodiments of the invention are shown in any of the claims 2 to 11.

[0012] In a second aspect, the present invention relates to a method according to claim 12. In a third aspect the present invention relates to a use and a product according to claims 13 and 14-15 respectively.

[0013] It is an object of the invention to enable the antimicrobial protection of aqueous formulations, especially personal care and hygiene products, by using purified natural bioflavonoids in combination with C3-C12-alkanediols. The solutions should be safe and skin friendly and should not require any further antimicrobial additives.

[0014] Bioflavonoids are generally known for their low solubility. Therefore, another object of the invention is to stabilize bioflavonoids in solution. The solvent should preferably be skin friendly, and it should enhance the antimicrobial activity of the bioflavonoid(s).

[0015] The use of bioflavonoids as antimicrobial preservatives in complex products is not well documented. Only a limited number of applications of bioflavonoids for the protection of consumer products are known. It has now been found that is possible to dissolve bioflavonoids in alkanediols, with a synergistic antimicrobial effect and reduced side effects.

[0016] DETAILED DESCRIPTION OF THE INVENTION

[0017] Unless otherwise defined, all terms used in disclosing the invention, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. By means of further guidance, term definitions are included to better appreciate the teaching of the present invention.

[0018] As used herein, the following terms have the following meanings:

[0019] The term "homogeneous", as used in the text, is defined to mean that the composition is uniform in concentration and visual appearance throughout the entire composition.

[0020] "Alkanediols" are organic compounds that belong to the diol family, which means they contain two hydroxyl (-OH) groups.

[0021] The term "antimicrobial" refers to a composition that inhibits the growth of or kills microorganisms. Antimicrobials can target various types of organisms, including bacteria, viruses, fungi, and protozoa.

[0022] The term "liquid" describes the physical state or phase of the composition. A liquid is a fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure. In this setting, "liquid" indicates that the composition is not solid or gaseous but is in a flowable, liquid state, which can be easily applied, spread, or dispensed at ambient conditions.

[0023] "A", "an", and "the" as used herein refers to both singular and plural referents unless the context clearly dictates otherwise. By way of example, "a compartment" refers to one or more than one compartment.

[0024] "Comprise", "comprising", and "comprises" and "comprised of" as used herein are synonymous with "include", "including", "includes" or "contain", "containing", "contains" and are inclusive or open-ended terms that specifies the presence of what follows e.g. component and do not exclude or preclude the presence of additional, non-recited components, features, element, members, steps, known in the art or disclosed therein.

[0025] In the context of the present disclosure, the phrase "carbon chain between 4 and 12 carbon atoms" is to be understood as referring to a linear or branched chain consisting of 4 to 12 carbon atoms, inclusively. This means that both the lower and upper limits of the range are part of the definition, i.e., alkanediols with a four- carbon chain (C4) such as butanediols, as well as alkanediols with a twelve-carbon chain (C12) such as dodecanediols, fall within the intended scope. The chain length refers to the number of carbon atoms forming the main carbon backbone that links the hydroxyl groups in the alkanediol. Thus, specific examples like 1,2-butanediol and 1,2-dodecanediol are included, along with other intermediate chain lengths, such as 1,2-octanediol or 1,2-hexanediol, provided they have a carbon backbone within the stated range.

[0026] Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order, unless specified. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

[0027] The recitation of numerical ranges by endpoints includes all numbers and fractions subsumed within that range, as well as the recited endpoints.

[0028] The expression "% by weight", "weight percent", "%wt" or "wt%", here and throughout the description unless otherwise defined, refers to the relative weight of the respective component based on the overall weight of the formulation.

[0029] Whereas the terms "one or more" or "at least one", such as one or more or at least one member(s) of a group of members, is clear per se, by means of further exemplification, the term encompasses inter alia a reference to any one of said members, or to any two or more of said members, such as, e.g., any >3, >4, >5, >6 or >7 etc. of said members, and up to all said members.

[0030] Unless otherwise defined, all terms used in disclosing the invention, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. By means of further guidance, definitions for the terms used in the description are included to better appreciate the teaching of the present invention. The terms or definitions used herein are provided solely to aid in the understanding of the invention.

[0031] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to a person skilled in the art from this disclosure, in one or more embodiments. Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

[0032] In a first aspect, the invention provides a liquid composition, preferably a liquid antimicrobial composition. In particular the composition comprises at least one alkanediol and at least one bioflavonoid.

[0033] Flavonoids form a structurally diverse family of polyphenolic substances. They are biosynthesized via the shikimic acid pathway and can be extracted from many plant materials. Therefore, flavonoids are also called "bioflavonoids". A large number of bioflavonoids are available in purified form, i.e., free from harmful or otherwise undesirable impurities.

[0034] The alkanediol is preferably a 1,2-alkanediol or 1,3-alkanediol. The at least one alkanediol is preferably a C3-C12 alkanediol, more preferably selected from 1,2- propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,2-pentanediol, 1,2- hexanediol, 1,2-heptanediol, 1,2-octanediol, 1,2-nonanediol, 1,2-decanediol, 1,2- undecanediol and 1,2-dodecanediol.

[0035] The alkanediols described herein are preferably bio-sourced and produced from renewable raw materials, such as plant materials. The production process preferably includes chemical conversion by means of green chemistry and / or fermentation. In an embodiment, the composition comprises 1, 2, 3, 4 or 5 alkanediols, preferably the composition comprises 1 or 2 alkanediols.

[0036] In a particularly preferred embodiment, the composition comprises: a. at least one alkanediol, wherein a first alkanediol is a 1,2-alkanediol or 1,3-alkanediol with a straight or branched carbon chain consisting of 4 to 12 carbon atoms; and b. at least one bioflavonoid.

[0037] It was found that the above-mentioned technical problems were solved by dissolving sufficient amounts of at least one bioflavonoid in at least one C4-C12-alkanediol.

[0038] In a preferred embodiment the first alkanediol is a 1,2-alkanediol or 1,3-alkanediol with an unbranched or branched carbon chain between 4 and 12 carbon atoms (= C4-C12 alkanediol), preferably selected from 1,2-butanediol, 1,3-butanediol, 1,2- pentanediol, 1,2-hexanediol, 1,2-heptanediol, 1,2-octanediol, 1,2-nonanediol, 1,2- decanediol, 1,2-undecanediol and 1,2-dodecanediol. The carbon chain is preferably unbranched.

[0039] In another or further embodiment, the first alkanediol is a 1,2-alkanediol or 1,3- alkanediol with an unbranched or branched carbon chain between 4 and 10 carbon atoms, preferably selected from 1,2-butanediol, 1,3-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-heptanediol, 1,2-octanediol, 1,2-nonanediol, and 1,2- decanediol. In another or further embodiment, the first alkanediol is a 1,2-alkanediol or 1,3-alkanediol with an unbranched or branched carbon chain between 5 and 8 carbon atoms, preferably selected from 1,2-pentanediol, 1,2-hexanediol, 1,2- heptanediol, and 1,2-octanediol. In another or further embodiment, the first alkanediol is a C5-alkanediol or a C8-alkanediol, preferably 1,2-pentanediol or 1,2- octanediol.

[0040] It was found that the solubility of different bioflavonoids in single alkanediols (only one alkanediol present in composition) is quite high. It was further found that certain mixtures of at least two alkanediols act synergistically as solvents for bioflavonoids.

[0041] In one embodiment, the composition comprises a total amount of alkanediols, in an amount of between 90 and 99.9 wt.%, more preferably between 91 and 99.9 wt.%, more preferably between 92 and 99.9 wt.%, more preferably between 93 and 99.9 wt.%, more preferably between 94 and 99.9 wt.%, more preferably between 94 and 99.5 wt.%, more preferably between 94 and 99 wt.%, more preferably between 94 and 98 wt.%.

[0042] In another or further embodiment, the composition comprises a total amount of alkanediols, in an amount of at least 90 wt.%, preferably at least 91 wt.%, more preferably at least 92 wt.%, more preferably at least 93 wt.%, more preferably at least 94 wt.%.

[0043] In one preferred embodiment, the composition comprises a first alkanediol, wherein the first alkanediol is a 1,2-alkanediol or 1,3-alkanediol with a straight or branched carbon chain between 4 and 12 carbon atoms, and a second alkanediol, wherein the second alkanediol is a 1,2-alkanediol or 1,3-alkanediol with a straight or branched carbon chain between 3 and 12 carbon atoms. It is preferred that the carbon chain length of the second alkanediol is different from the carbon chain length of the first alkanediol.

[0044] In a preferred embodiment, if the composition comprises two alkanediols, the difference in carbon chain length between the two alkanediols is at least 2, preferably at least 3 carbon atoms. Thus, in a preferred embodiment, the first alkanediol has a longer carbon chain than the second alkanediol, preferably with at least 3 more carbon atoms.

[0045] It has been found that there is a synergistic increase in solvent properties if two (or more) alkanediols are combined. The difference in carbon chain length is preferably at least 3 carbon atoms. Otherwise, the solvent properties of the mixtures may be inferior to those of the individual components.

[0046] In a preferred embodiment the second alkanediol is a 1,2-alkanediol or 1,3- alkanediol with an unbranched or branched carbon chain between 3 and 12 carbon atoms (= C3-C12 alkanediol), preferably selected from 1,2-propanediol, 1,3- propanediol, 1,2-butanediol, 1,3-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2- heptanediol, 1,2-octanediol, 1,2-nonanediol, 1,2-decanediol, 1,2-undecanediol and 1,2-dodecanediol. The carbon chain is preferably unbranched.

[0047] In another or further embodiment, the second alkanediol is a 1,2-alkanediol or 1,3- alkanediol with an unbranched or branched carbon chain between 3 and 10 carbon atoms, preferably selected from 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-heptanediol, 1,2-octanediol,

[0048] 1.2-nonanediol, and 1,2-decanediol. In another or further embodiment, the second alkanediol is a 1,2-alkanediol or 1,3-alkanediol with an unbranched or branched carbon chain between 3 and 5 carbon atoms, preferably selected from 1,2- propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, and 1,2-pentanediol, more preferably selected from 1,3-propanediol, 1,3-butanediol, and 1,2- pentanediol.

[0049] In another or further embodiment, the second alkanediol is a C3-alkanediol or a C5- alkanediol, preferably selected from 1,3-butanediol or 1,2-pentanediol. Most preferably, the second alkanediol is 1,2-pentanediol.

[0050] In one embodiment, if the composition comprises two alkanediols, the first alkanediol is a 1,2-alkanediol or 1,3-alkanediol with an unbranched or branched carbon chain between 4 and 12 carbon atoms, preferably selected from 1,2-butanediol, 1,3- butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-heptanediol, 1,2-octanediol, 1,2- nonanediol, and 1,2-decanediol. In another or further embodiment, the first alkanediol is a 1,2-alkanediol or 1,3-alkanediol with an unbranched or branched carbon chain between 6 and 10 carbon atoms, preferably selected from 1,2- hexanediol, 1,2-heptanediol, 1,2-octanediol, 1,2-nonanediol and 1,2-decanediol. In another or further embodiment, the first alkanediol is a C8-alkanediol, preferably

[0051] 1.2-octanediol.

[0052] In this embodiment, the composition comprises, preferably consists of: a. at least one alkanediol, preferably two alkanediols, wherein a first alkanediol is a 1,2-alkanediol or 1,3-alkanediol with a straight or branched carbon chain between 4 and 12 carbon atoms, and a second second alkanediol, wherein the second alkanediol is a 1,2-alkanediol or 1,3- alkanediol with a straight or branched carbon chain between 3 and 12 carbon atoms, preferably wherein the carbon chain length of the second alkanediol is different from the carbon chain length of the first alkanediol; and b. at least one bioflavonoid.

[0053] In another or further embodiment, the composition comprises, preferably consists of: a. at least one alkanediol, preferably two alkanediols, wherein a first alkanediol is a 1,2-alkanediol or 1,3-alkanediol with a straight or branched carbon chain between 6 and 10 carbon atoms, preferably selected from

[0054] 1.2-hexanediol, 1,2-heptanediol, 1,2-octanediol, 1,2-nonanediol and 1,2- decanediol, and a second second alkanediol, wherein the second alkanediol is a 1,2-alkanediol or 1,3-alkanediol with a straight or branched carbon chain between 3 and 5 carbon atoms, preferably selected from

[0055] 1.3-propanediol, 1,3-butanediol, and 1,2-pentanediol; and b. at least one bioflavonoid.

[0056] In another or further embodiment, the composition comprises, preferably consists of: a. two alkanediols, wherein a first alkanediol is 1,2-octanediol, and a second second alkanediol, wherein the second alkanediol is 1,2-pentanediol; and b. at least one bioflavonoid.

[0057] In one embodiment, the composition comprises the first alkanediol in an amount of between 20 and 60 wt.%, more preferably between 25 and 55 wt.%, more preferably between 30 and 50 wt.%, more preferably between 35 and 45 wt.%, more preferably between 35 and 40 wt.%.

[0058] In another or further embodiment, the composition comprises the second alkanediol in an amount of between 40 and 80 wt.%, more preferably between 45 and 75 wt.%, more preferably between 50 and 70 wt.%, more preferably between 55 and 65 wt.%, more preferably between 55 and 60 wt.%.

[0059] In another or further embodiment, the composition comprises the first alkanediol and the second alkanediol in a ratio by weight of between 10 / 90 and 90 / 10, preferably between 10 / 90 and 50 / 50, preferably between 30 / 70 and 50 / 50, preferably between 35 / 65 and 45 / 55.

[0060] It was found that the solubility of different bioflavonoids in single alkanediols is quite high. In another preferred embodiment, the composition comprises one alkanediol, wherein the one alkanediol is a 1,2-alkanediol or 1,3-alkanediol with an unbranched or branched carbon chain between 4 and 12 carbon atoms, preferably selected from

[0061] 1.2-butanediol, 1,3-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-heptanediol,

[0062] 1.2-octanediol, 1,2-nonanediol, 1,2-decanediol, 1,2-undecanediol and 1,2- dodecanediol. In another or further embodiment, the one alkanediol is a 1,2-alkanediol or 1,3- alkanediol with an unbranched or branched carbon chain between 4 and 10 carbon atoms, preferably selected from 1,2-butanediol, 1,3-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-heptanediol, 1,2-octanediol, 1,2-nonanediol, and 1,2- decanediol. In another or further embodiment, the one alkanediol is a 1,2-alkanediol or 1,3-alkanediol with an unbranched or branched carbon chain between 5 and 8 carbon atoms, preferably selected from 1,2-pentanediol, 1,2-hexanediol, 1,2- heptanediol, and 1,2-octanediol. In another or further embodiment, the one alkanediol is a C5-alkanediol or a C8-alkanediol, preferably 1,2-pentanediol or 1,2- octanediol. Most preferred, is the composition comprises one alkanediol, the one alkanediol is 1,2-pentanediol.

[0063] In this embodiment, the composition comprises, preferably consists of: a. an alkanediol, wherein the alkanediol is a 1,2-alkanediol or 1,3-alkanediol with a straight or branched carbon chain between 4 and 12 carbon atoms; and b. at one least bioflavonoid.

[0064] In another or further embodiment, the composition comprises, preferably consists of: a. an alkanediol, wherein the alkanediol is a 1,2-alkanediol or 1,3-alkanediol with a straight or branched carbon chain between 5 and 8 carbon atoms, preferably selected from 1,2-pentanediol, 1,2-hexanediol, 1,2- heptanediol, and 1,2-octanediol; and b. at one least bioflavonoid.

[0065] In another or further embodiment, the composition comprises, preferably consists of: a. 1,2-pentanediol; and b. at one least bioflavonoid.

[0066] In one embodiment, the composition comprises said alkanediol in an amount of between 90 and 99.9 wt.%, more preferably between 91 and 99.9 wt.%, more preferably between 92 and 99.9 wt.%, more preferably between 93 and 99.9 wt.%, more preferably between 94 and 99.9 wt.%, more preferably between 94 and 99.5 wt.%, more preferably between 94 and 99 wt.%, more preferably between 94 and 98 wt.%. In another or further embodiment, the composition comprises said alkanediol, in an amount of at least 90 wt.%, preferably at least 91 wt.%, more preferably at least 92 wt.%, more preferably at least 93 wt.%, more preferably at least 94 wt.%.

[0067] Bioflavonoids differ from each other by different oxidation states, different substitutions on the aromatic rings and by being optionally linked to different sugars (glycosylation). The at least one bioflavonoid preferably has a flavan (1), an isoflavan (2) or a chaicone (3) backbone.

[0068] Preferably, the at least one bioflavonoid is selected from: flavanols, flavanones, flavones, isoflavones, flavonols, chaicones, or combinations thereof. Most preferably, the at least one bioflavonoid is selected from: flavanones, flavones and flavonols, or a combination thereof.

[0069] Examples of particularly preferred bioflavonoids according to the invention include Apigenin, Apiin, Baicalin, Baicalein, Catechin, Didymin, Diosmin, Diosmetin, Epicatechin, Eriocitrin, Eriodictyol, Fisetin, Genistein, Glabridin, Hesperidin, Hesperetin, Hesperidin Methylchalcone, Hidrosmin, Isoquercertin, Isorhamnetin, Kaempferol, Lutein, Luteolin, Methyl Hesperidin, Naringenin, Naringin, Narirutin, Neohesperidin, Quercetin, Rutin, Sinensetin, Tangeritin. Further suitable bioflavonoids include phlorizin, phloretin, catechin and epicatechin. Particularly preferred bioflavonoids are chosen from the list consisting of : naringenin, naringin, narirutin, quercetin, rutin, phloretin, phlorizin and mixtures thereof. Most preferred bioflavonoids are selected the list consisting of from: naringenin, naringin, phloretin, phlorizin and mixtures thereof.

[0070] Stereoisomers of bioflavonoids may be present either in one of their enantiomerically pure forms or as mixtures of enantiomers, including racemic mixtures. Preferably, both stereoisomers are present. In a preferred embodiment, the at least one bioflavonoid is a racemic mixture of said at least one bioflavonoid. It has been found that a racemic mixture of a bioflavonoid shows higher antimicrobial efficacy compared to enantiomerically pure bioflavonoid. The racemisation can occur before addition to the composition. Alternatively, racemisation can also occur during or after preparation of the composition, for example under the influence of heating and / or longer storage and / or a low pH-value.

[0071] Bioflavonoids are commercially available, either as purified extracts from plant materials or as isolates from fermentation processes. Preferably, the at least one bioflavonoid is obtained by extraction of plant materials. More preferably, the at least one bioflavonoid is obtained by extraction of Citrus aurantium, Citrus aurantifolia, Citrus australasica, Citrus bergamia, Citrus Clementina, Citrus deliciosa, Citrus depressa, Citrus glauca, Citrus grandis, Citrus hassaku, Citrus hassakadu, Citrus hystrix, Citrus inflata, Citrus iyo, Citrus jabara, Citrus japonica, Citrus junos, Citrus keraji, Citrus ki-mikan, Citrus latifolia, Citrus limon, Citrus limonfucus, Citrus madurensis, Citrus maxima, Citrus medica, Citrus natsudaidai, Citrus nobilis, Citrus paradisi, Citrus reticulata, Citrus shunkokan, Citrus sinensis, Citrus sphaerocarpa, Citrus sudachi, Citrus sunki, Citrus tamurana, Citrus tachibana, Citrus tangelo, Citrus tangerine, Citrus tankan, Citrus tumida, Citrus unshiu, Citrus wilsonii, Glycyrrhiza glabra, Lawsonia sp., Matricaria chamomilla, Petroselinum sp., Rhus cotinus, Sophora japonica (Styphnolobium japonicum), Scutellaria baicalensis Georgi and / or Trifolium pratense. In one embodiment, the at least one bioflavonoid is obtained by extracting and purifying waste from the processing of citrus fruits for food production.

[0072] In another embodiment of the invention, the at least one bioflavonoid comprises purified mixtures of bioflavonoids extracted from one or more plant sources. Preferred examples are bioflavonoids from citrus fruits. A particularly preferred purified extract consists of citrus bioflavonoids from lemon (Citrus limon), which typically comprise the following major components: Didymin, Eriodictyol, Eriocitrin, Hesperidin, Naringin, Narirutin, Quercetin, and Rutin.

[0073] Plant extracts comprising phlorizin and phloretin are commercially available, either as purified isolates or as extracts from natural sources. Preferably, these extracts are obtained by extraction from plant materials, more preferably from tree branches and fruit residues. In a particularly preferred embodiment, the phlorizin- and phloretin-containing extracts are derived from waste streams generated during the processing of fruits in the food industry, such as discarded apple and pear branches or cores and peels from juice production. In another embodiment, the phlorizin and phloretin are present in purified mixtures obtained from one or more botanical sources. These mixtures may be enriched through selective extraction and purification techniques. Suitable plant sources are those known to contain high levels of dihydrochalcones, in particular species within the Rosaceae family. Preferred examples include Malus domestica (apple), particularly from tree bark, twigs, and leaves, and Pyrus communis (pear), notably from branch trimmings and fruit peels. Other suitable sources include Prunus species such as Prunus domestica (plum), Prunus persica (peach), and Prunus armeniaca (apricot), which may also yield valuable quantities of phloretin or its glycosides. Extracts may be obtained from seasonal pruning waste, orchard maintenance byproducts, or residual materials from fruit processing operations such as juicing, drying, or compote production. A particularly preferred extract is obtained from apple tree pruning waste and comprises phlorizin as a major component, typically accompanied by phloretin and structurally related polyphenols.

[0074] Bioflavonoids occur in nature mainly in glycosylated form, i.e., chemically bound to a sugar molecule. In a preferred embodiment, the bioflavonoid is non-glycosylated. In this embodiment, natural glycosylated bioflavonoids can be converted to the nonglycosylated form prior to incorporation into the mixtures according to the invention.

[0075] Surprisingly, it was also found that the combination of at least one glycosylated bioflavonoid with at least one non-glycosylated bioflavonoid can be beneficial to increase the overall antimicrobial efficacy of the mixture in combination with at least one C4-C12 alkanediol.

[0076] In another or further embodiment, the composition comprises at least one glycosylated bioflavonoid and at least one non-glycosylated bioflavonoid. It has been found that a combination can increase antimicrobial efficacy. The effect seems to be especially present when the non-glycosylated bioflavonoid is enantiomerically pure, such that the addition of a glycosylated bioflavonoid to an enantiomerically pure non- glycosylated bioflavonoid results in a synergistic effect. In one embodiment, the composition comprises at least one glycosylated bioflavonoid and at least one non- glycosylated bioflavonoid, wherein the non-glycosylated bioflavonoid is enantiomerically pure.

[0077] "Enantiomerically enriched" refers to a sample of a chiral substance whose enantiomeric ratio is greater than 50:50 but less than 100:0. "Enantiomerically pure" refers to a sample for which all of its molecules have (within the limits of detection) the same chirality sense, such as an enantiomeric ratio is greater than 95:5, or even

[0078] 99: 1.

[0079] The glycosidic bonds in natural glycosylated bioflavonoids can be cleaved. Exemplary cleavage ways are acid hydrolysis or enzymatic cleavage. Acidic cleavage is more likely to deliver primarily racemic bioflavonoids, while the milder enzymatic cleavage leads to enantiomerically enriched free bioflavonoids. In a preferred embodiment, the glycosidic bonds in natural glycosylated bioflavonoids are cleaved acid hydrolysis. Alternatively, enzymatic cleavage followed by acidic treatment can be applied.

[0080] Preferably, bioflavonoids described herein comprise less than 1000 ppm of any of the fragrance allergens listed in annex III of the EC Regulation No 1223 / 2009 (30 November 2009) amended by the EU Regulation 2023 / 1545 of 26 July 2023. More preferably, the content of each individual fragrance allergen is below 100 ppm, even more preferably below 10 ppm. Most preferably, the total content of all fragrance allergens is below 100 ppm, even better below 10 ppm. Exemplary fragrance allergens are amyl cinnamal, benzyl alcohol, cinnamyl alcohol, citral, eugenol, hydroxycitronellal, isoeugenol, oak moss extract, geraniol, limonene.

[0081] It was found that the standalone antimicrobial efficacy of bioflavonoids in cosmetic products is low. This finding is in contradiction to literature data where very low minimum inhibitory concentrations are reported for various bioflavonoids. The low preservative efficacy may be due to incomplete dissolution of bioflavonoids in aqueous formulations. In contrast, the antimicrobial efficacy of bioflavonoids dissolved in one or more alkanediols was found to be significantly higher than that of the pure bioflavonoids.

[0082] In one embodiment, the composition comprises a total amount of bioflavonoids, in an amount of between 0.1 and 10 wt.%, preferably between 0.5 and 7.5 wt.%, more preferably between 1 and 5 wt.%.

[0083] In an embodiment, the composition comprises at least one additional antioxidant that is not a bioflavonoid. The addition of small amounts of an additional antioxidant can have a positive effect on the antimicrobial efficacy of the mixture. Apart from the antimicrobial effect, the additional antioxidant also increases storage stability of the composition and minimizes discoloration during prolonged storage. The additional antioxidant can be, for example, vitamin E (tocopherol), glutathione, beta-carotene, selenium, lycopene, vitamin A (retinol), manganese, coenzyme Q10 (CoQlO), alpha-lipoic acid, N-acetylcysteine (NAC), or ascorbic acid. Preferred antioxidant is ascorbic acid as well as salts and / or derivatives thereof. A particularly preferred antioxidant is ascorbic acid.

[0084] The solubility of the antioxidant, such as ascorbic acid, can be limited in the alkanediol(s). The solubility can be improved by adding water to the mixture. Therefore, in an embodiment, the composition further comprises: c. at least one additional antioxidant that is not a bioflavonoid, preferably ascorbic acid; and d. optionally, water.

[0085] In another embodiment, the composition consists of: a. at least one alkanediol, wherein a first alkanediol is a 1,2-alkanediol or 1,3-alkanediol with a straight or branched carbon chain between 4 and 12 carbon atoms; b. at least one bioflavonoid; c. at least one additional antioxidant that is not a bioflavonoid, preferably ascorbic acid; and d. water.

[0086] For example, the composition may comprise between 0,1 and 10 wt.% of water, preferably between 0,5 and 5 wt.% of water, most preferably between 1 and 3 wt.% of water.

[0087] The composition can comprise the at least one additional antioxidant in an amount of between 0.05 and 1 wt.%, preferably between 0.05 and 0.5 wt.%, more preferably between 0.05 and 0.25 wt.%.

[0088] The composition preferably has a melting point of less than 20°C at 1013 mbar, more preferably less than 0°C, and most preferably less than -10°C. Most preferably, the compositions as described herein is a homogenous composition at 20°C.

[0089] The origin of the components of the composition can vary. The components can be produced starting from various feedstock by means of various technologies such as, but not limited to, organic chemistry, extraction, fermentation or combinations thereof, resulting in a petrochemical and / or vegetal and / or biotechnological origin. Preferably, the components of the composition are derived from renewable feedstock and contain only modern carbon.

[0090] In a particular embodiment, the composition comprises bioflavonoids in an amount of at most 30 wt.%, more preferably at most 20 wt.%, more preferably at most 10 wt.%, more preferably at most 8 wt.%, more preferably at most 6 wt.%, more preferably at most 5 wt.%, more preferably at most 4 wt.%, more preferably at most 3 wt.%, and more preferably at most 2 wt.%, based on the total weight of the composition. In a further preferred embodiment, the total amount of alkanediols in the composition is at least 50 wt.%, more preferably at least 60 wt.%, more preferably at least 70 wt.%, more preferably at least 80 wt.%, and most preferably at least 90 wt.%, based on the total weight of the composition. The weight ratio of total alkanediols to total bioflavonoids is preferably at least 5: 1, more preferably at least 7: 1, more preferably at least 10: 1, more preferably at least 15: 1, more preferably at least 20: 1, more preferably at least 25: 1, more preferably at least 30: 1, more preferably at least 40: 1, and more preferably at least 50: 1. The most preferred weight ratio is between 50: 1 and 100: 1.

[0091] This range has been found to offer an optimal balance between the functional benefits of the alkanediols, such as solubilization capacity, formulation versatility, and physical stability, and the bioflavonoids, which contribute to a synergistic and broad-spectrum antimicrobial profile. Exceeding the preferred range of bioflavonoids can negatively impact the fluidity and homogeneity of the composition. It also drastically reduces the ease of formulation, requiring additional formulation effort and potentially limiting ease of use in standard cosmetic or pharmaceutical processing steps.

[0092] In a particular embodiment, the composition comprises water in an amount of at most 30 wt.%, more preferably at most 20 wt.%, more preferably at most 10 wt.%, more preferably at most 5 wt.%, more preferably at most 3 wt.%, more preferably at most 2 wt.%, more preferably at most 1.5 wt.%, more preferably at most 1.0 wt.%, more preferably at most 0.75 wt.%, and more preferably at most 0.5 wt.%, based on the total weight of the composition. A reduced water content offers significant formulation advantages, particularly in the development of selfpreserving compositions. While the composition is typically intended for use in watercontaining end formulations such as creams, lotions, or emulsions, its low intrinsic water content provides the formulator with maximal freedom and flexibility during the formulation process. It allows for seamless integration into various formulation steps, including the preparation of aqueous and oily phases, predispersions, or pre- mixes, without interfering with the process or requiring phase-specific adaptation. This enables precise control over composition development, regardless of the order or timing of phase combination. In addition, the absence of bulk water in the composition results in a more compact and lightweight intermediate. This not only simplifies handling and storage, but also reduces transport weight and space requirements, offering practical and economic advantages in production and logistics.

[0093] In a preferred embodiment, the composition comprises, preferably consists essentially of: a. at least one alkanediol, wherein a first alkanediol is a 1,2-alkanediol or 1,3- alkanediol with a straight or branched carbon chain consisting of 4 to 12 carbon atoms, and preferably a second alkanediol is a 1,2-alkanediol or 1,3-alkanediol with a straight or branched carbon chain consisting of 4 to 12 carbon atoms, wherein the carbon chains of the first and second alkanediols differ by at least 2 carbon atoms, preferably at least 3 carbon atoms, and wherein the total amount of alkanediols is at least 80 wt.%, more preferably at least 90 wt.% of the composition; and b. at least one bioflavonoid selected from the group consisting of naringin, naringenin, rutin, quercetin, narirutin, phlorizin, phloretin and mixtures thereof, preferably in a total amount of at least 1 wt.%, more preferably at least 2 wt.%, and most preferably between 2 wt.% and 5 wt.% based on the total weight of the composition.

[0094] In a preferred embodiment, the composition comprises, preferably consists essentially of: a. at least one alkanediol, wherein a first alkanediol is a 1,2-alkanediol or 1,3- alkanediol with a straight or branched carbon chain consisting of 4 to 12 carbon atoms, and preferably a second alkanediol is a 1,2-alkanediol or 1,3-alkanediol with a straight or branched carbon chain consisting of 4 to 12 carbon atoms, wherein the carbon chains of the first and second alkanediols differ by at least 2 carbon atoms, preferably at least 3 carbon atoms, and wherein the total amount of alkanediols is at least 80 wt.%, more preferably at least 90 wt.% of the composition; b. at least one bioflavonoid selected from the group consisting of naringin, naringenin, rutin, narirutin, phlorizin, phloretin and mixtures thereof, preferably in a total amount of at least 1 wt.%, more preferably at least 2 wt.%, and most preferably between 2 wt.% and 5 wt.% based on the total weight of the composition; and c. at least one antioxidant, preferably said antioxidant is ascorbic acid, in an amount of up to 10 wt.%, more preferably in an amount between 0.01 wt.% and 5.0 wt.%, more preferably between 0.05 wt.% and 2.0 wt.%, based on the total weight of the composition.

[0095] In a preferred embodiment, the composition comprises, preferably consists essentially of: a. a first alkanediol selected from 1,2-alkanediols and 1,3-alkanediols with a straight or branched carbon chain consisting of 4 to 6 carbon atoms, most preferably 1,2- pentanediol, in an amount of at least 45 wt.%, based on the total weight of the composition; b. a second alkanediol selected from 1,2-alkanediols and 1,3-alkanediols with a straight or branched carbon chain consisting of 7 to 10 carbon atoms, more preferably 1,2-octanediol, in an amount of at least 35 wt.%, based on the total weight of the composition; and c. at least one bioflavonoid selected from the group consisting of naringin, naringenin, rutin, narirutin, phlorizin, phloretin and mixtures thereof, most preferably naringenin, preferably in a total amount of at least 1 wt.%, more preferably at least 2 wt.%, and most preferably between 2 wt.% and 5 wt.%, based on the total weight of the composition; and d. optionally at least one antioxidant, preferably said antioxidant is ascorbic acid, in an amount of up to 10 wt.%, more preferably in an amount between 0.01 wt.% and 5.0 wt.%, more preferably between 0.05 wt.% and 2.0 wt.%, based on the total weight of the composition.

[0096] In a preferred embodiment, the composition comprises, and preferably consists essentially of: a. a first alkanediol selected from 1,2-alkanediols and 1,3-alkanediols having a straight or branched carbon chain with 4 to 6 carbon atoms, most preferably 1,2- pentanediol, in an amount of at least 45 wt.% based on the total weight of the composition; b. a second alkanediol selected from 1,2-alkanediols and 1,3-alkanediols having a straight or branched carbon chain with 7 to 10 carbon atoms, more preferably 1,2- octanediol, in an amount of at least 35 wt.% based on the total weight of the composition; c. an extract derived from one or more plant sources and comprising at least one bioflavonoid selected from the group consisting of naringin, naringenin, rutin, quercetin, narirutin, phlorizin, phloretin, and mixtures thereof, preferably in a total amount of at least 1 wt.%, more preferably at least 2 wt.%, and most preferably between 2 wt.% and 5 wt.% based on the total weight of the composition; and d. optionally, at least one antioxidant, preferably ascorbic acid, in an amount of up to 10 wt.%, more preferably between 0.01 wt.% and 5.0 wt.%, and even more preferably between 0.05 wt.% and 2.0 wt.% based on the total weight of the composition.

[0097] In a particularly preferred embodiment, the plant extract under item (c) is derived from one or more citrus sources, including but not limited to Citrus aurantium, Citrus limon, Citrus sinensis, Citrus paradisi, Citrus reticulata, and Citrus grandis, most preferably comprising Citrus grandis extract. These citrus-derived extracts are especially rich in flavonoids such as naringin, narirutin, and hesperidin.

[0098] In another particularly preferred embodiment, the composition comprises phlorizin and / or phloretin as the predominant bioflavonoid components. In this embodiment, the plant extract under item (c) is derived from botanical sources selected from Malus domestica (apple), Pyrus communis (pear), and other Rosaceae species such as Prunus domestica (plum) or Prunus armeniaca (apricot). Preferably, the extract is obtained from agricultural waste or by-products, such as apple tree prunings, bark, twigs, or pomace generated during fruit processing. The extract preferably comprises phlorizin and / or phloretin in a total amount of at least 1 wt.%, more preferably between 2 wt.% and 5 wt.% based on the total weight of the composition.

[0099] In a preferred embodiment, the composition comprises, preferably consists essentially of: a. 1,2-pentanediol in an amount of at least 30 wt.%, more preferably at least 35 wt.%, more preferably at least 40 wt.%, more preferably at least 45 wt.%, and most preferably at least 50 wt.%, based on the total weight of the composition; b. 1,2-octanediol in an amount of at least 25 wt.%, more preferably at least 30 wt.%, more preferably at least 35 wt.%, more preferably at least 40 wt.%, and most preferably at least 45 wt.%, based on the total weight of the composition; wherein the total amount of alkanediols is preferably at least 80 wt.%, more preferably at least 85 wt.%, and most preferably at least 90 wt.%, based on the total weight of the composition; and c. at least one bioflavonoid selected from the group consisting of apigenin, apiin, baicalin, baicalein, catechin, didymin, diosmin, diosmetin, epicatechin, eriocitrin, eriodictyol, fisetin, genistein, glabridin, hesperidin, hesperetin, hesperidin methylchalcone, hidrosmin, isoquercitrin, isorhamnetin, kaempferol, lutein, luteolin, methyl hesperidin, naringenin, naringin, narirutin, neohesperidin, quercetin, rutin, sinensetin, tangeritin, phlorizin, phloretin, catechin and epicatechin; and d. optionally at least one antioxidant, preferably said antioxidant is ascorbic acid, in an amount of up to 10 wt.%, more preferably in an amount between 0.01 wt.% and 5.0 wt.%, more preferably between 0.05 wt.% and 2.0 wt.%, based on the total weight of the composition. In a particular preferred embodiment, the bioflavonoid is naringenin. In another particular preferred embodiment, the bioflavonoid is selected from the group consisting of : phlorizin and phloretin.

[0100] In a preferred embodiment, the composition comprises, preferably consists essentially of: a. at least one alkanediol, wherein a first alkanediol is a 1,2-alkanediol or 1,3- alkanediol with a straight or branched carbon chain consisting of 4 to 12 carbon atoms, and preferably a second alkanediol is a 1,2-alkanediol or 1,3-alkanediol with a straight or branched carbon chain consisting of 4 to 12 carbon atoms, wherein the carbon chains of the first and second alkanediols differ by at least 2 carbon atoms, preferably at least 3 carbon atoms, and wherein the total amount of alkanediols is at least 80 wt.%, more preferably at least 90 wt.%, based on the total weight of the composition; b. at least one glycosylated bioflavonoid selected from the group consisting of apiin, baicalin, didymin, diosmin, eriocitrin, hesperidin, hesperidin methylchalcone, hidrosmin, isoquercitrin, narirutin, neohesperidin, phlorizin, and rutin, preferably in an amount of at least 0.5 wt.%, more preferably at least 1.0 wt.%, more preferably at least 1.5 wt.%, and most preferably at least 2.0 wt.%, based on the total weight of the composition; and c. at least one non-glycosylated bioflavonoid selected from the group consisting of apigenin, baicalein, catechin, epicatechin, diosmetin, eriodictyol, fisetin, genistein, glabridin, hesperetin, isorhamnetin, kaempferol, lutein, luteolin, methyl hesperidin, naringenin, quercetin, sinensetin, phloretin and tangeritin, preferably in an amount of at least 0.5 wt.%, more preferably at least 1.0 wt.%, more preferably at least 1.5 wt.%, and most preferably at least 2.0 wt.%, based on the total weight of the composition; d. optionally at least one antioxidant, preferably said antioxidant is ascorbic acid, in an amount of up to 10 wt.%, more preferably in an amount between 0.01 wt.% and 5.0 wt.%, more preferably between 0.05 wt.% and 2.0 wt.%, based on the total weight of the composition.

[0101] In a preferred embodiment, the composition comprises, preferably consists essentially of: a. 1,2-pentanediol in an amount of at least 30 wt.%, more preferably at least 35 wt.%, more preferably at least 40 wt.%, more preferably at least 45 wt.%, and most preferably at least 50 wt.%, based on the total weight of the composition; b. 1,2-octanediol in an amount of at least 25 wt.%, more preferably at least 30 wt.%, more preferably at least 35 wt.%, more preferably at least 40 wt.%, and most preferably at least 45 wt.%, based on the total weight of the composition; wherein the total amount of alkanediols is preferably at least 80 wt.%, more preferably at least 85 wt.%, and most preferably at least 90 wt.%, based on the total weight of the composition; c. at least one glycosylated bioflavonoid selected from the group consisting of apiin, baicalin, didymin, diosmin, eriocitrin, hesperidin, hesperidin methylchalcone, hidrosmin, isoquercitrin, narirutin, neohesperidin, phlorizin and rutin, preferably in an amount of at least 0.5 wt.%, more preferably at least 1.0 wt.%, more preferably at least 1.5 wt.%, and most preferably at least 2.0 wt.%, based on the total weight of the composition; and d. at least one non-glycosylated bioflavonoid selected from the group consisting of apigenin, baicalein, catechin, epicatechin, diosmetin, eriodictyol, fisetin, genistein, glabridin, hesperetin, isorhamnetin, kaempferol, lutein, luteolin, methyl hesperidin, naringenin, quercetin, sinensetin, phloretin and tangeritin, preferably in an amount of at least 0.5 wt.%, more preferably at least 1.0 wt.%, more preferably at least 1.5 wt.%, and most preferably at least 2.0 wt.%, based on the total weight of the composition; and e. optionally at least one antioxidant, preferably said antioxidant is ascorbic acid, in an amount of up to 10 wt.%, more preferably in an amount between 0.01 wt.% and 5.0 wt.%, more preferably between 0.05 wt.% and 2.0 wt.%, based on the total weight of the composition.

[0102] In a preferred embodiment, the composition comprises, preferably consists essentially of: a. at least one alkanediol, wherein a first alkanediol is a 1,2-alkanediol or 1,3- alkanediol with a straight or branched carbon chain consisting of 4 to 12 carbon atoms, and preferably a second alkanediol is a 1,2-alkanediol or 1,3-alkanediol with a straight or branched carbon chain consisting of 4 to 12 carbon atoms, wherein the carbon chains of the first and second alkanediols differ by at least 2 carbon atoms, preferably at least 3 carbon atoms, and wherein the total amount of alkanediols is at least 80 wt.%, more preferably at least 90 wt.%, based on the total weight of the composition; b. at least one glycosylated bioflavonoid selected from narirutin, naringin, and rutin, preferably in an amount of at least 0.5 wt.%, more preferably at least 1.0 wt.%, more preferably at least 1.5 wt.%, and most preferably at least 2.0 wt.%, based on the total weight of the composition; and c. at least one non-glycosylated bioflavonoid selected from naringenin and quercetin, preferably in an amount of at least 0.5 wt.%, more preferably at least 1.0 wt.%, more preferably at least 1.5 wt.%, and most preferably at least 2.0 wt.%, based on the total weight of the composition; and d. optionally at least one antioxidant, preferably said antioxidant is ascorbic acid, in an amount of up to 10 wt.%, more preferably in an amount between 0.01 wt.% and 5.0 wt.%, more preferably between 0.05 wt.% and 2.0 wt.%, based on the total weight of the composition.

[0103] In a preferred embodiment, the composition comprises, preferably consists essentially of: a. 1,2-pentanediol in an amount of at least 30 wt.%, more preferably at least 35 wt.%, more preferably at least 40 wt.%, more preferably at least 45 wt.%, and most preferably at least 50 wt.%, based on the total weight of the composition; b. 1,2-octanediol in an amount of at least 25 wt.%, more preferably at least 30 wt.%, more preferably at least 35 wt.%, more preferably at least 40 wt.%, and most preferably at least 45 wt.%, based on the total weight of the composition; wherein the total amount of alkanediols is preferably at least 80 wt.%, more preferably at least 85 wt.%, and most preferably at least 90 wt.%, based on the total weight of the composition; c. at least one glycosylated bioflavonoid selected from narirutin, naringin, and rutin, preferably in an amount of at least 0.5 wt.%, more preferably at least 1.0 wt.%, more preferably at least 1.5 wt.%, and most preferably at least 2.0 wt.%, based on the total weight of the composition; and d. at least one non-glycosylated bioflavonoid selected from naringenin and quercetin, preferably in an amount of at least 0.5 wt.%, more preferably at least 1.0 wt.%, more preferably at least 1.5 wt.%, and most preferably at least 2.0 wt.%, based on the total weight of the composition; and e. optionally at least one antioxidant, preferably said antioxidant is ascorbic acid, in an amount of up to 10 wt.%, more preferably in an amount between 0.01 wt.% and 5.0 wt.%, more preferably between 0.05 wt.% and 2.0 wt.%, based on the total weight of the composition.

[0104] In a preferred embodiment, the composition comprises, preferably consists essentially of: a. at least one alkanediol, wherein a first alkanediol is a 1,2-alkanediol or 1,3- alkanediol with a straight or branched carbon chain consisting of 4 to 12 carbon atoms, and preferably a second alkanediol is a 1,2-alkanediol or 1,3-alkanediol with a straight or branched carbon chain consisting of 4 to 12 carbon atoms, wherein the carbon chains of the first and second alkanediols differ by at least 2 carbon atoms, preferably at least 3 carbon atoms, and wherein the total amount of alkanediols is at least 80 wt.%, more preferably at least 90 wt.%, based on the total weight of the composition; b. at least one glycosylated bioflavonoid selected from phlorizin, preferably in an amount of at least 0.5 wt.%, more preferably at least 1.0 wt.%, more preferably at least 1.5 wt.%, and most preferably at least 2.0 wt.%, based on the total weight of the composition; and c. at least one non-glycosylated bioflavonoid selected from phloretin, preferably in an amount of at least 0.5 wt.%, more preferably at least 1.0 wt.%, more preferably at least 1.5 wt.%, and most preferably at least 2.0 wt.%, based on the total weight of the composition; and d. optionally at least one antioxidant, preferably said antioxidant is ascorbic acid, in an amount of up to 10 wt.%, more preferably in an amount between 0.01 wt.% and 5.0 wt.%, more preferably between 0.05 wt.% and 2.0 wt.%, based on the total weight of the composition.

[0105] The preferred compositions offer a range of distinct and synergistic advantages that make them highly suitable for use in modern cosmetic and pharmaceutical formulations. They provide effective and broad-spectrum antimicrobial protection, ensuring strong self-preserving performance even when used in small quantities. Their concentrated nature allows formulators to dose precisely and sparingly, while benefiting from ease of storage, handling, and transport. Due to their excellent compatibility with both aqueous and oily systems, the compositions blend readily into a wide variety of formulation types and processing steps, allowing for maximum flexibility in product development. Importantly, they are non-toxic, as they do not comprise traditional preservatives. This is an essential consideration for protecting sensitive ecosystems such as marine environments. The preservatives are also mild, supporting use in applications for sensitive skin. Finally, the compositions can be produced from nature-derived and bio-based inputs, including bioflavonoids sourced from food industry waste and alkanediols derived from renewable feedstocks, making them an ecologically responsible choice aligned with sustainable formulation goals. In a second aspect, the invention relates to a method of producing a liquid antimicrobial composition. The method comprises the step of mixing at least one bioflavonoid as described herein into at least one alkanediol as described herein.

[0106] Preferably, the at least one bioflavonoid is obtained or enriched from one or more citrus extracts, more preferably from plant materials selected from Citrus aurantium, Citrus grandis, Citrus reticulata, Citrus sinensis, Citrus paradisi, Citrus junos, Citrus limon, Citrus unshiu, and other citrus species known to comprise flavonoid glycosides and aglycones, such as narirutin, naringin, rutin and naringenin. The use of citrus- derived extracts enables targeted enrichment of bioflavonoid mixtures.

[0107] More preferably, citrus-derived food waste, in particular citrus peels, is utilized as the starting material for preparing the citrus extract. In this manner, valuable bioactive compounds are recovered from otherwise discarded or low-value biomass. Such reuse of edible-grade plant waste permits the use of high-quality, food-grade input material without ecological harm or competition with food supply chains. The use of high-quality input material is particularly advantageous for ensuring high purity, high quality and consistent bioflavonoid profiles in the final extract. This, in turn, provides a reliable and safe output suitable for use in sensitive applications, including cosmetic and pharmaceutical formulations, where reproducibility, safety, and traceability of active components are of critical importance.

[0108] In another preferred embodiment, the at least one bioflavonoid is obtained or enriched from one or more Rosaceae plant extracts, more preferably from plant materials selected from Malus domestica, Pyrus communis, Prunus domestica, Prunus armeniaca, and other tree species known to comprise phloretin and phlorizin. These dihydrochalcone-type bioflavonoids are typically found in the bark, twigs, leaves, and fruit tissues of said plants. The use of Rosaceae-derived extracts enables the targeted enrichment of phloretin and phlorizin as active components.

[0109] More preferably, agricultural side-streams or food industry waste, in particular apple and pear pruning waste, pomace, or peel fractions, are utilized as the starting material for preparing the extract. In this manner, phloretin- and phlorizin-rich fractions are recovered from biomass streams that are abundant, renewable, and otherwise underutilized. This approach allows for the valorisation of tree-derived waste material, especially from edible-grade fruit processing chains, ensuring that the input material meets food-quality standards while avoiding ecological or supplychain concerns. The resulting extracts can be tailored to exhibit high and consistent levels of phloretin and phlorizin, making them suitable for applications requiring robust antimicrobial or antioxidant performance, including in preservative-free or naturally derived cosmetic compositions.

[0110] In a third aspect, the invention relates to the use of a composition as described herein in a cosmetic, pharmaceutical, dermatological or hygienic preparation.

[0111] In a fourth aspect, the invention relates a cosmetic, pharmaceutical, dermatological or hygienic product comprising a composition as described herein. The cosmetic, pharmaceutical, dermatological or hygienic may comprise said composition, in an amount of between 0.5 and 5 percent by weight of said product, preferably in an amount of between 1 and 5 percent by weight of said product.

[0112] These products may be prepared by adding the composition as described herein to aqueous mixtures. The temperature of addition can be chosen according to the preparation process. The preferred temperature of addition is between 0°C and 100°C. Preferably, the compositions are incorporated below 50°C. The most preferred procedures include an addition of said compositions without any additional heating.

[0113] The present invention will be now described in more details, referring to examples that are not limitative.

[0114] EXAMPLES

[0115] Examples 1-26: solubility of bioflavonoids in alkanediols

[0116] Saturated solutions of bioflavonoids were prepared at 20 °C. Pure alkanediols and binary mixtures of different alkanediols were used as solvents. Naringin was used as an example of a glycosylated bioflavonoid and quercetin as an example of a nonglycosylated bioflavonoid. The concentrations of the saturated solutions were determined by HPLC-UV analysis. The results are summarized in Table 1 (1,2-HDO = 1,2-hexanediol, 1,2-PDO = 1,2-pentanediol, 1,2-ODO = 1,2-octanediol, 1,2-PrDO = 1,2-propanediol, 1,3-PrDO = 1,3-propanediol).

[0117] Table 1

[0118] C3-C8 alkanediols and binary mixtures of C3-C8 alkanediols are generally good solvents for bioflavonoids. It was found that the solubility of different bioflavonoids in some alkanediols is quite high (see examples 1-26). Particularly preferred single alkanediols are 1,2-pentanediol and 1,2-hexanediol.

[0119] It was further surprisingly found that certain mixtures of at least two alkanediols act synergistically as solvents for bioflavonoids. A synergistic increase in solvent properties was observed when two alkanediols are combined. The difference in carbon chain length is preferably at least 3 carbon atoms. Otherwise, the solvent properties of the mixtures may be inferior to those of the individual components (see examples 1-3 and 15-17). A good combination appears to be 1,2-octanediol as a first alkanediol and 1,2-propanediol, 1,3-propanediol or 1,2-pentanediol as a second alkanediol.

[0120] Examples 27-35: microbial challenge tests

[0121] 1,2-Pentanediol, the bioflavonoids Naringin and Naringenin, and optionally ascorbic acid were formulated in different ratios in an O / W emulsion (see Table 2). The emulsions were tested in microbial challenge tests according to ISO 11930. The tested compositions and results of challenge tests are summarized in Table 3A and 3B, respectively.

[0122] Table 2 - O / W emulsion

[0123] Table 3A

[0124]

[0125] Table 3B

[0126] The development of the microbial count in the formulations is given as the difference between the logarithmic microbial counts. Positive numbers indicate a decrease in the number of microorganisms. Negative numbers indicate an increase in the number of microorganisms in the sample. Numbers in bold indicate a deviation from the ISO 11930 standard, which leads to failure of the test or to a "B" rating instead of an "A" rating.

[0127] The alkanediol 1,2-pentanediol alone is not able to protect the tested formulation at a use-level of 2% or 3% (comparative examples 27 and 28). The bioflavonoid naringenin alone shows practically no standalone preservation effect (comparative example 29).

[0128] Combinations of 1,2-pentanediol and naringenin show a significant synergistic antimicrobial effect and are able to protect the tested formulation efficiently (examples 32 and 34). Addition of a small amount of ascorbic acid further increases the antimicrobial effect, especially against the germ E. coli (examples 33 and 35).

[0129] The glycosylated bioflavonoid naringin shows a lower antimicrobial efficacy than naringenin, which is its non-glycosylated equivalent (examples 30 and 31).

[0130] Surprisingly it was found that the standalone antimicrobial efficacy of bioflavonoids in cosmetic products is low (see example 29). This finding is in contradiction to literature data where very low minimum inhibitory concentrations are reported for various bioflavonoids. The low preservative efficacy may be due to incomplete dissolution of bioflavonoids in aqueous formulations. In contrast, the antimicrobial efficacy of bioflavonoids dissolved in one or more alkanediols was found to be significantly higher than that of the pure bioflavonoids (examples 32-35). Furthermore, the addition of small amounts of an additional antioxidant (ascorbic acid) can have a positive effect on the antimicrobial efficacy of the mixture according to the invention (see examples 33 and 35). Apart from the antimicrobial effect, the additional antioxidant also increases storage stability of the composition and minimizes discoloration during prolonged storage.

[0131] Examples 36-38: microbial challenge tests

[0132] Enantiomerically pure (S)-Naringenin, racemic Naringenin (= a 1 : 1 mixture of (R)- and (S)-Naringenin), and optionally Rutin were dissolved in 1,2-pentanediol together with 0.1% ascorbic acid. The resulting compositions (table 4A) were incorporated into an O / W emulsion analogous to Examples 27-35 at a usage level of 3% and pH 5.5. The obtained emulsions were subjected to microbial challenge tests (ISO 11930, see Table 4B).

[0133] Table 4A

[0134] Table 4B

[0135] Racemic Naringenin (example 36) shows higher antimicrobial efficacy compared to enantiomerically pure (S)-Naringenin (example 37).

[0136] Combinations of glycosylated and non-glycosylated bioflavonoids can increase antimicrobial efficacy. Example 38 shows that the addition of rutin (= glycosylated bioflavonoid) to (S)-naringenin (= non-glycosylated bioflavonoid) results in a synergistic effect.

[0137] Examples 39-42: microbial challenge tests

[0138] Mixtures of 1,2-pentanediol and 1,2-octanediol with and without Naringenin were incorporated into an O / W emulsion analogous to Examples 27-35, for usage level and pH see table 5A. The obtained emulsions were subjected to microbial challenge tests (ISO 11930, see Table 5B).

[0139] Table 5A Table 5B

[0140] A mixture of 60% 1,2-pentanediol and 40% 1,2-octanediol shows relatively weak activity against the mold A. brasiliensis (example 39). The addition of 2% naringenin increases the antifungal activity and thus closes the activity gap (example 40).

[0141] Optimization of the ratio of alkanediols and bioflavonoids can lead to increased antimicrobial efficacy. The mixture containing 2% naringenin failed to preserve the emulsion at 0.5% use level (example 41). By increasing the concentration of naringenin in the mixture to 3%, a broad-spectrum antimicrobial effect was achieved (example 42).

Claims

CLAIMS1. A liquid antimicrobial composition comprising: a. at least one alkanediol, wherein a first alkanediol is a 1,2-alkanediol or 1,3-alkanediol with a straight or branched carbon chain consisting of 4 and 12 carbon atoms; and b. at least one bioflavonoid.

2. Liquid antimicrobial composition according to claim 1, wherein the composition further comprises a second alkanediol, wherein the second alkanediol is a 1,2-alkanediol or 1,3-alkanediol with a straight or branched carbon chain consisting of 3 and 12 carbon atoms, wherein the carbon chain length of the second alkanediol is different from the carbon chain length of the first alkanediol.

3. Liquid antimicrobial composition according to claim 2, wherein the first alkanediol has a longer carbon chain than the second alkanediol with at least 3 more carbon atoms.

4. Liquid antimicrobial composition according to any of the previous claims, wherein the at least one bioflavonoid is chosen from flavanones, flavones, flavonols, or a combination thereof.

5. Liquid antimicrobial composition according to any of the previous claims, wherein the composition comprises at least two bioflavonoids, wherein the at least two bioflavonoids comprise at least one non-glycosylated bioflavonoid and at least one glycosylated bioflavonoid.

6. Liquid antimicrobial composition according to any of the previous claims, comprising alkanediols in an amount of at least 90 wt.% relative to the weight of the composition.

7. Liquid antimicrobial composition according to any of the previous claims, comprising: a. 1,2-pentanediol in an amount of at least 35 wt.%; b. 1,2-octanediol in an amount of at least 25 wt.%; wherein the total amount of alkanediols is at least 85 wt.%; and c. at least one bioflavonoid selected from the group consisting of apigenin, apiin, baicalin, baicalein, catechin, didymin, diosmin, diosmetin, epicatechin, eriocitrin, eriodictyol, fisetin, genistein, glabridin, hesperidin, hesperetin, hesperidin methylchalcone, hidrosmin, isoquercitrin, isorhamnetin, kaempferol, lutein, luteolin, methyl hesperidin, naringenin, naringin, narirutin, neohesperidin, quercetin, rutin, sinensetin, phloretin, phlorizin, and tangeritin; preferably in an amount of at least 1.0 wt.%.

8. Liquid antimicrobial composition according to any of the previous claims, comprising: a. 1,2-pentanediol in an amount of at least 35 wt.%; b. 1,2-octanediol in an amount of at least 25 wt.%; wherein the total amount of alkanediols is at least 85 wt.%; c. at least one glycosylated bioflavonoid selected from narirutin, naringin, phlorizin, and rutin, preferably in an amount of at least 0.5 wt; and d. at least one non-glycosylated bioflavonoid selected from naringenin, phloretin and quercetin, preferably in an amount of at least 0.5 wt.%.

9. Liquid antimicrobial composition according to any of the previous claims, wherein the composition comprises further: c. at least one additional antioxidant that is not a bioflavonoid; and d. water.

10. Liquid antimicrobial composition according to any of the previous claims, wherein the at least one bioflavonoid is a racemic mixture of at least one bioflavonoid.

11. Liquid antimicrobial composition according to claim 2 or 3, wherein the first alkanediol is 1,2-octanediol, and wherein the second alkanediol is 1,3- propanediol, 1,3-butanediol or 1,2-pentanediol.

12. A method for producing a liquid antimicrobial composition, wherein the method comprises the step of mixing at least one bioflavonoid into at least one alkanediol, wherein a first alkanediol is a 1,2-alkanediol or 1,3-alkanediol with a straight or branched carbon chain consisting of 4 and 12 carbon atoms.

13. Use of a composition according to any of the claims 1-11 in a cosmetic, pharmaceutical, dermatological or hygienic preparation.

14. Cosmetic, pharmaceutical, dermatological or hygienic product comprising a composition according to any of the claims 1-11.

15. Cosmetic, pharmaceutical, dermatological or hygienic product according to claim 14, wherein said product comprises said composition, in an amount of from 0.5 to 5 percent by weight of said product, preferably in an amount of from 1 to 5 percent by weight of said product.

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