Use of mono-rhamnolipids to retain substances on a surface

Abstract

The invention relates to the use of mono-rhamnolipids to prevent substances to be washed off a surface.

Description

[0001] Use of mono-rhamnolipids to retain a substances on a surface

[0002] Field of the invention

[0003] The invention relates to the use of mono-rhamnolipids to prevent substances to be washed off a surface.

[0004] Prior art

[0005] Using surfactant-based cleansing formulations has an impact on the condition of skin and hair during the washing process.

[0006] The ingredients used are primarily designed to clean body surfaces. However, modern formulations should fulfil further tasks beside cleaning. These also include providing beneficial agents and in best case ensure, that these ingredients remain on the desired surface, for example hair or skin.

[0007] WO2010119000A2 describes the deposition of hydrophobic active ingredients and fragrances and silicones from a surfactant system by using cationic modified starch. One disadvantage of the method is the usage of chemically modified polymers and their lower biodegradability.

[0008] EP0552024A2 describes cosmetic composition with enhanced deposition of cosmetic agents by using emulsion technology. One disadvantage of the aforementioned method is the high fraction of oil in the formulation.

[0009] W02000033798A1 discloses compositions comprising at least one organic phospholipid capable of forming bilayers in aqueous solution; at least one amphoteric surfactant present in an amount by weight equal to or greater than the amount of said at least one phospholipid, at least one nonionic surfactant present in an amount by weight equal to or greater than the amount of said at least one phospholipid; and at least one cationic polymer. One disadvantage of the method is the usage of chemically modified polymers and their lower biodegradability.

[0010] W02020178048 discloses a method comprising depositing at least one substance from a medium onto a surface, wherein the medium comprises a rhamnolipid. Preferably, di-rhamnolipids are used and the substance to be deposited is preferably a cationic substance.

[0011] WO2018145966 discloses oral care compositions containing at least one biosurfactant and at least one fluoride ion source. There still is a lack of technical solution which fulfils the requirements mentioned above.

[0012] It is an object of the instant invention to provide a solution to secure the presence of substances on the desired surface after a washing process.

[0013] Description of the invention

[0014] It was found, surprisingly, that mono-rhamnolipids are advantageous for preventing the rinsing of substances off a surface.

[0015] The present invention therefore provides the use of at least one mono-rhamnolipid to reduce the rinseability of a substance off a surface.

[0016] One advantage of the use according to the instant invention is the enhanced adherence of ceramides to skin.

[0017] A further advantage of the use according to the instant invention is the improved penetration of ceramides into the skin due to the presence of mono-rhamnolipids.

[0018] Another advantage of the use according to the instant invention is the improved foam quality of the compositions on the skin.

[0019] A further advantage of the use according to the instant invention is an enhancement of skin barrier protection.

[0020] Another advantage of the use according to the instant invention is the good compatibility of the compositions used with other ingredients.

[0021] A further advantage of the use according to the instant invention is the enhanced adherence of ceramides to hair.

[0022] A further advantage of the use according to the instant invention is the enhanced adherence of ceramides to the scalp.

[0023] A further advantage is the improved skin feel during the use according to the invention.

[0024] A further advantage is the improved conditioning effect on hair resulting from the use according to the invention.

[0025] A further advantage is the improved thickenability of the formulations used according to the invention.

[0026] The present invention thus provides the use of at least one rhamnolipid to reduce the rinseability of a substance off a surface characterised in that the content of all mono-rhamnolipids is at least 75 wt.-% preferably in the range of from 85 wt.-% to 100 wt.-%, more preferably from 95 wt.-% to 100 wt.-%, wherein the weight percentages refer to all rhamnolipids used.

[0027] The term "rhamnolipids" in the context of the present invention preferably is understood to mean particularly compounds of the general formula (I) and salts thereof, Formula (I) where mRL = 2, 1 or 0, preferably 1 or 0, nRL = 1 or 0,

[0028] R1RLand R2RL= mutually independently, identical or different, organic residues having 2 to 24, preferably 5 to 13 carbon atoms, in particular optionally branched, optionally substituted, particularly hydroxy-substituted, optionally unsaturated, in particular optionally mono-, bi- or triunsaturated alkyl residues, preferably those selected from the group consisting of pentenyl, heptenyl, nonenyl, undecenyl and tridecenyl and (CH2)O-CH3 where o = 1 to 23, preferably 4 to 12. If nRL = 1 , the glycosidic bond between the two rhamnose units is preferably in the a-configuration. The optically active carbon atoms of the fatty acids are preferably present as R-enantiomers (e.g. (R)-3-{(R)-3-[2-O-(a-L-rhamnopyranosyl)-a-L-rhamnopyranosyl]oxydecanoyl}oxydecanoate).

[0029] The term "di-rhamnolipid" in the context of the present invention preferably is understood to mean compounds of the general formula (I) or salts thereof, where nRL = 1 .

[0030] The term "mono-rhamnolipid" in the context of the present invention preferably is understood to mean compounds of the general formula (I) or salts thereof, where nRL = 0.

[0031] Distinct rhamnolipids are abbreviated according to the following nomenclature:

[0032] "diRL-CXCY" are understood to mean di-rhamnolipids of the general formula (I), in which one of the residues R1RLand R2RL= (CH2)o-CH3 where o = X-4 and the remaining residue R1or R2= (CH2)O-CH3where o = Y-4. "monoRL-CXCY" are understood to mean mono-rhamnolipids of the general formula (I), in which one of the residues R1RLand R2RL= (CH2)o-CH3 where o = X-4 and the remaining residue R1RLor R2RL= (CH2)O-CH3where o = Y-4.

[0033] The nomenclature used therefore does not distinguish between "CXCY" and "CYCX". For rhamnolipids where mRL=0, monoRL-CX or diRL-CX is used accordingly.

[0034] If one of the abovementioned indices X and / or Y is provided with ":Z", this signifies that the respective residue R1RLand / or R2RLis equal to an unbranched, unsubstituted hydrocarbon residue having X-3 or Y-3 carbon atoms having Z double bonds.

[0035] Rhamnolipids applicable in the context of the instant invention can be produced by fermentation of Pseudomonas, especially Pseudomonas aeruginosa, which are preferably non genetically modified cells, a technology already disclosed in the eighties, as documented e.g. in EP0282942 and DE4127908. Rhamnolipids produced in Pseudomonas aeruginosa cells which have been improved for higher rhamnolipid titres by genetical modification can also be used in the context of the instant invention; such cells have for example been disclosed by Lei et al. in Biotechnol Lett. 2020 Jun;42(6):997-1002.

[0036] Rhamnolipids produced by Pseudomonas aeruginosa are commercially available from Jeneil Biotech Inc., e.g. under the tradename Zonix, from Logos Technologies (technology acquired by Stepan), e.g. under the tradename NatSurFact, from Biotensidion GmbH, e.g. under the tradename Rhapynal, from AGAE technologies, e.g. under the name R90, R95, R95Md, R95Dd, from Locus Bio-Energy Solutions and from Shanghai Yusheng Industry Co. Ltd., e.g. under the tradename Bio- 201 Glycolipids.

[0037] To be used according to the instant invention the rhamnolipids have to be brought to the applicable content if mono-rhamnolipids, which can be easily achieved by the use of a rhamnosidase, for example the commercial product ThermoActive™ Rhamnosidase A, Prokazyme.

[0038] Preferably the use according to the instant invention is characterised in that the rhamnolipids comprise 51 wt.-% to 81 wt.-%, preferably 55 wt.-% to 75 wt.-%, particularly preferably 60 wt.-% to 70 wt.-%, of monoRL-C10C10, where the percentages by weight refer to the sum of all of the rhamnolipids used.

[0039] Preferably the use according to the instant invention is characterised in that the rhamnolipids comprise 10 wt.-% to 30 wt.-%, preferably 12 wt.-% to 25 wt.-%, particularly preferably 15 wt.-% to 22 wt.-%, of monoRL-C8C10, where the percentages by weight refer to the sum of all of the rhamnolipids used.

[0040] Preferably the use according to the instant invention is characterised in that the rhamnolipids comprise 1 wt.-% to 25 wt.-%, preferably 2 wt.-% to 20 wt.-%, particularly preferably 3 wt.-% to 9 wt.-%, of monoRL-C10C12:1 , where the percentages by weight refer to the sum of all of the rhamnolipids used.

[0041] Preferably the use according to the instant invention is characterised in that the rhamnolipids comprise 1 wt.-% to 25 wt.-%, preferably 2 wt.-% to 20 wt.-%, particularly preferably 3 wt.-% to 9 wt- %, of monoRL-C10C12, where the percentages by weight refer to the sum of all of the rhamnolipids used.

[0042] When determining the weight content of rhamnolipids the counter cation of the salt form - if present - is disregarded.

[0043] The use according to the instant invention is carried out with the at least one rhamnolipid being comprised in a composition together with the substance the rinseability of which is being reduced.

[0044] Preferably said composition comprises water.

[0045] Preferably said composition has a pH which is greater than the pH of said surface.

[0046] The “pH” in connection with the present invention is defined as the value which is measured for the relevant composition at 25 °C after stirring for five minutes using a pH electrode calibrated in accordance with ISO 4319 (1977).

[0047] In case said surface is a skin of a human the pH of said skin is determined by Skin pH-Meter® 905 from Courage & Khazaka, Koln, Germany according to the current manual of the device.

[0048] Preferably said composition has a pH which is in the range of from 4.0 to 10.0, preferably from 4.5 to 9.0, more preferably from 5.0 to 8.0.

[0049] Preferably the use according to the instant invention is characterised in that said substance is a cosmetic active substance.

[0050] Preferably the use according to the instant invention is characterised in that said substance has a solubility in water at 25 °C and 1 bar from 1 mg / L to 50 mg / L.

[0051] Preferably the use according to the instant invention is characterised in that said substance is solid at 25 °C and 1 bar.

[0052] Preferably the use according to the instant invention is characterised in that said substance in total is not electrically charged in a pH range of from 4.0 to 9.0.

[0053] Charge selection techniques such as ion exchange chromatography and cationic chromatography can be utilized to determine the charge status of a substance: Ion exchange chromatography involves separating charged substances using column materials that carry an opposing charge. The exchanger columns contain ionic groups that are covalently bound to the gel matrix and are compensated by small concentrations of counter ions present in the buffer. When a sample is added to the column, an exchange occurs with the weakly bound counter ions. Substances that are not electrically charged do not interact with the matrix, which allows them to be separated and identified.

[0054] Preferably the use according to the instant invention is characterised in that said substance is selected from the group comprising, preferably consisting of, 3-o-ethyl ascorbic acid, adenosine, allantoin, arbutin, arginine, ascorbic acid, ascorbyl glucoside, ascorbyl palmitate, azelaic acid, bisabolol, butylene glycol (and) aqua (and) laureth-3 (and) hydroxyethylcellulose (and) acetyl dipeptide-1 cetyl ester, caffeine, carnosine, centella asiatica extract, ceramides, cholesterol, copper tripeptide-1 , diaminopyrimidine oxide, epigallocatechin gallate, farnesol, dipotassium glycyrrhizate, ferulic acid, glycine, glycolic acid, glycyrrhetinic acid, glycyrrhiza glabra root extract, green tea extract, hydrolyzed hyaluronic acid, kojic acid^madecassoside, minoxidil, morus alba leaf extract, niacinamide, palmitoyl pentapeptide-4, palmitoyl tripeptide-1 (and) palmitoyl tetrapeptide-7, panthenol, piroctone olamine, resveratrol, retinol, rhamnose, salicylic acid, salix alba bark extract, sodium hyaluronate, Scutellaria baicalensis root extract, threonine, tranexamic acid, ubiquinone, urea, vitamin A and its derivatives, zinc glyconate, zinc pea and zinc sulfate±preferably 3-o-ethyl ascorbic acid, arbutin, ascorbyl glucoside, ascorbyl palmitate, bisabolol, butylene glycol (and) aqua (and) laureth-3 (and) hydroxyethylcellulose (and) acetyl dipeptide-1 cetyl ester, caffeine, carnosine, centella asiatica extract, ceramides, cholesterol, copper tripeptide- 1 , diaminopyrimidine oxide, epigallocatechin gallate, farnesol, glycyrrhiza glabra root extract, green tea extract, madecassoside, minoxidil, morus alba leaf extract, niacinamide, palmitoyl pentapeptide-4, palmitoyl tripeptide-1 (and) palmitoyl tetrapeptide-7, panthenol, piroctone olamine, resveratrol, retinol, rhamnose, salix alba bark extract, Scutellaria baicalensis root extract, ubiquinone, urea and vitamin A.

[0055] Preferably the use according to the instant invention is characterised in that said substance is selected from the group of ceramides.

[0056] In the context of the present invention, the term “ceramide” is understood to mean acylated sphingoid bases, where the sphingoid bases are preferably selected from sphingosine, sphinganine, 6-hydroxysphingosine and phytosphingosine, also in glycosylated form, for example as glucosylceramides.

[0057] Said ceramide preferably used in the context of the instant invention is preferably selected from the group comprising, preferably consisting of, ceramide NP, ceramide AP, ceramide EOP, ceramide NDS, ceramide ADS, ceramide EODS, ceramide NS, ceramide AS, ceramide EOS, ceramide NH, ceramide AH and ceramide EOH, preferably selected from the group comprising ceramide NP, ceramide AP, ceramide NS, ceramide EOP and ceramide EOS. Preferably the use according to the instant invention is characterised in that a mixture of said at least one rhamnolipid and lactic acid is used.

[0058] Preferably the use according to the instant invention is characterised in that said mixture has a weight ratio of said at least one rhamnolipid and said lactic acid of from 10 : 1 to 100 : 1.

[0059] Preferably the use according to the instant invention is characterised in that the surface is selected from skin, hair, nails and teeth, preferably skin and hair, even more preferably of a human.

[0060] Preferably the use according to the instant invention is characterised in that the surface is a human scalp.

[0061] Most preferably the use according to the instant invention is characterised in that the surface is a human scalp and the substance is selected from the group of ceramides.

[0062] The examples adduced hereinafter describe the present invention by way of example, without any intention that the invention, the scope of application of which is apparent from the entirety of the description and the claims, be restricted to the embodiments specified in the examples.

[0063] Example 1:

[0064] The test was performed with a total number of 6 persons. The forearms were prewashed with a mixture of 9% Sodium Laureth Sulfate (SLES) and 3% Cocamidopropyl Betaine (CAPB) for 10 seconds. The solutions were rinsed off for 10 s with water. The test person remained in a climatized room at 22 °C and 50% relative humidity for 15 minutes. Testing areas (6.25 cm2) were labelled on the forearms. With the help of Corneofix® (Courage+Khazaka, Colgone, Germany) test stripes samples of the untreated skin were taken by using the stripes three times. The tests stripes were transferred to a GC vial. Table 2 displays the results in the column labeled 'before rinsing'.A volume of 200 pL test formulations were applied on the marked areas by using an Eppendorf pipette. The formulation was massaged gently after each dose by performing five circles with a glove. In consequence the whole amount of ceramide is deposited on the skin’s surface. The formulation was rinsed off by using 60 mL of water. The labelled areas were dried carefully for 10 min. Again, samples were taken from the labelled areas by using Corneofix® three times in the area.

[0065] The stripes were transferred into GC vials. Table 1 displays the results in the column labeled 'after rinsing'.

[0066] All stripes were extracted by using a suitable solvent and the content of Ceramides was analyzed by using HPLC.

[0067] Di-rhamnolipids were prepared as described in example 1 of EP3023431.

[0068] Mono-rhamnolipids were prepared as in example 2 of EP3061442.

[0069] Table 1 shows the formulations which were applied in the test protocol. Table 2 shows the results from the testing protocol.

[0070] Table 1 : Formulations

[0071] Table 2: Results for Ceramide NP (111 B) / pg / 6.25 cm2

[0072] All formulations were applied at identical concentrations leading to the same amount on the skin.

[0073] However, the results presented in Table 2 demonstrate that the formulation according to the invention, when combined with mono-rhamnolipid, retains a significantly higher amount of ceramide on the skin after rinsing compared to the other formulations. In contrast, when di-rhamnolipid is used, the ceramide is almost completely washed off. This indicates that the composition containing mono-rhamnolipids is more effective at preserving ceramides on the skin surface during the washing process.

[0074] Example 2:

[0075] Formulations were created based on mono-rhamnolipid, di-rhamnolipid, Ceramide NG and Hydroxypropyl Guar.

[0076] Five hair tresses (n = 5) were pre-washed twice with 12% SLES solution (1 min massage, 30 s rinse, repeat, then 1 min rinse) and dried overnight under controlled conditions. Each tress was then split lengthwise for paired pre- and post-treatment analysis. For the measurements, hair was cut into small pieces and weighed into vials without further treatment.

[0077] Sample preparation for the examples which represent the examples after application are prepared as follows:

[0078] 2 g of the pre-treatment part of the hair was treated with the formulations from table 3 and dried overnight.

[0079] Lipids were extracted using organic solvent and ultrasonic treatment. Extracts were analyzed by LC-MS using an HPLC-based method optimized for Ceramides. Quantification was performed via external calibration with certified reference materials.

[0080] The relative amount of Hydroxypropyl Guar after rinse-off compared to the deposited amount is determined by measuring the zeta potential as described in US2022183958. The dose-response relationship between hair zeta potential and Guar concentration was evaluated by applying varying amounts of Guar to hair samples and subsequently measuring their zeta potential.

[0081] Sample preparation for the examples which represent the examples after rinsing are prepared as follows:

[0082] The dried hair samples were rinsed with 100 mL of water and dried overnight. The measurements were repeated in the way described before.

[0083] For comparison, the amount of deposited ingredients after application was normalized to 100%, and all subsequent values were expressed relative to this reference. The results are summarized in table 4. The control (Formulation 5 was tested using the lipid analysis method (a) and zeta potential measurements (b).

[0084] Table 3: Formulations

[0085] Table 4: Results for Ceramide NG and Guar

[0086] * calculated based on the amount applied, ** normed, determined by zeta potential and dose- response experiment.

[0087] Mono-rhamnolipid formulations retained a higher proportion of deposited substances on the hair surface compared to other combinations, particularly when combined with ceramides.

Claims

AMENDED CLAIMS received by the International Bureau on 05 February 2026 (05.02.2026)

1. Use of at least one rhamnolipid to reduce the rinseability of a substance off a surface characterised in that the content of all mono-rhamnolipids is at least 75 wt.-% preferably in the range of from 85 wt.-% to 100 wt.-%, more preferably from 95 wt.- % to 100 wt.-%, wherein the weight percentages refer to all rhamnolipids used.

2. Use according to claim 1 wherein the at least one rhamnolipid is comprised in a composition together with the substance the rinseability of which is being reduced, characterised in that said composition has a pH which is greater than the pH of said surface.

3. Use according to claim 2 characterised in that said composition has a pH which is in the range of from 4.0 to 10.0, preferably from 4.5 to 9.0, more preferably from 5.0 to 8.0.

4. Use according to any one of the preceding claims characterised in that said substance is a cosmetic active substance.

5. Use according to any one of the preceding claims characterised in that said substance has a solubility in water at 25 °C and 1 bar from 1 mg / L to 50 mg / L.

6. Use according to any one of the preceding claims characterised in that said substance is solid at 25 °C and 1 bar.

7. Use according to any one of the preceding claims characterised in that said substance in total is not electrically charged in a pH range of from 4.0 to 9.0.

8. Use according to any one of the claims 1 to 4 characterised in that the substance is selected from the group comprising 3- o-ethyl ascorbic acid, adenosine, allantoin, arbutin, arginine, ascorbic acid, ascorbyl glucoside, ascorbyl palmitate, azelaic acid, bisabolol, butylene glycol (and) aqua (and) laureth-3 (and) hydroxyethylcellulose (and) acetyl dipeptide- 1 cetyl ester, caffeine, carnosine, centella asiatica extract, ceramides, cholesterol, copper tripeptide- 1, diaminopyrimidine oxide, epigallocatechin gallate, farnesol, dipotassium glycyrrhizate, ferulic acid, glycine, glycolic acid, glycyrrhetinic acid, glycyrrhiza glabra root extract, green tea extract, hydrolyzed hyaluronic acid, kojic acid^madecassoside, minoxidil, morus alba leaf extract,niacinamide, palmitoyl pentapeptide-4, palmitoyl tripeptide- 1 (and) palmitoyl tetrapeptide-7, panthenol, piroctone olamine, resveratrol, retinol, rhamnose, salicylic acid, salix alba bark extract, sodium hyaluronate, Scutellaria baicalensis root extract, threonine, tranexamic acid, ubiquinone, urea, vitamin A and its derivatives, zinc glyconate, zinc pea and zinc sulfate.

9. Use according to any one of the preceding claims characterised in that the substance is selected from the group of ceramides, preferably from the group comprising ceramide NP, ceramide AP, ceramide EOP, ceramide NDS, ceramide ADS, ceramide EODS, ceramide NS, ceramide AS, ceramide EOS, ceramide NH, ceramide AH and ceramide EOH, preferably selected from the group comprising ceramide NP, ceramide AP, ceramide NS, ceramide EOP and ceramide EOS.

10. Use according to any one of the claims 1 to 5 characterised in that a mixture of said at least one rhamnolipid and lactic acid is used.

11. Use according to claim 10 characterised in that said mixture has a weight ratio of said at least one rhamnolipid and said lactic acid of from 10 : 1 to 100 : 1.

12. Use according to any one of the preceding claims characterised in that the surface is selected from skin, hair, nails and teeth, preferably skin and hair, even more preferably of a human.

13. Use according to any one of the preceding claims characterised in that the surface is a human scalp.

14. Use according to any one of the preceding claims characterised in that the surface is a human scalp and the substance is selected from the group of ceramides.

15. Use according to claim 9 with improved penetration of ceramides into the skin.

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