Cosmetic skincare compositions

Abstract

According to the present invention there is provided a cosmetic composition comprising: (i) a polyphenolic antioxidant agent; and (ii) a sphingosine compound.

Claims

1. A cosmetic composition comprising: (i) a polyphenolic antioxidant agent comprising extracts of green tea; and (ii) a sphingosine compound of Formula (I), or a salt or derivative thereof: ##STR00005## wherein: R.sup.1 is a linear, branched or cyclic, saturated or unsaturated C4-30 hydrocarbon group, which may optionally be substituted by a hydroxyl, carbonyl or amino group, Y is any one of a methylene group (CH.sub.2), a methine group (CH) and an oxygen atom, X.sup.1, X.sup.2 and X.sup.3 are each independently a hydrogen atom, a hydroxyl group or an acetoxy group, X.sup.4 is a hydrogen atom, an acetyl group, a glyceryl group or a substituent forming an oxo group together with the adjacent oxygen atom, R.sup.2 and R.sup.3 are each independently a hydrogen atom, a hydroxyl group, a hydroxymethyl group or an acetoxymethyl group, a is an integer which is 2 or 3, and each R is each independently a hydrogen atom, or an amidino group, or a linear or branched, saturated or unsaturated hydrocarbon group having 1 to 8 carbon atoms in total and optionally having a substituent selected from hydroxyl, hydroxyalkoxy, alkoxy and acetoxy groups, wherein the sphingosine compound is selected from the group consisting of phytosphingosine, phytosphingosine hydrochloride, dihydrosphingosine (sphinganine) and combinations thereof; wherein the sphingosine compound is present in an amount 25 to 100 times the amount of the polyphenolic antioxidant agent comprising extracts of green tea, and wherein the sphingosine compound is present in an amount of from about 0.01% to about 3% by weight of the composition.

2. The cosmetic composition of claim 1, wherein the sphingosine compound is present in an amount 40 to 80 times the amount of the polyphenolic antioxidant agent comprising extracts of green tea.

3. A method of using the cosmetic composition as defined in claim 1 by applying the cosmetic composition as a topical application on the skin.

4. The cosmetic composition of claim 1, wherein the polyphenolic antioxidant agent is present in an amount from about 0.0001% to about 2% by weight of the composition.

Description

(1) There now follows by way of example only a description of the present invention with reference to the accompanying drawings, in which:

(2) FIG. 1 shows a list of example cosmetic compositions according to the invention;

(3) FIG. 2 is a graph comparing the IL-6 inhibition activity of individual active agents and combined active agents; and

(4) FIG. 3 is a graph comparing the IL-6 inhibition activity when exposed to phytosphingosine and green tea at varying ratios.

EXAMPLES

(5) Interleukin-6 (IL-6) Assay

(6) Interleukin-6 (IL-6) bioactivity in skin cells was measured. IL-6 is a cytokine and used as a biomarker for inflammation. Skin cells (keratinocytes or fibroblasts) were placed under UV stress to induce an IL-6 response in the presence of an active or blend of actives to determine the activity of that active or blend of actives in inhibiting an IL-6 response.

(7) Skin cells (keratinocytes or fibroblasts) were taken from culture, seeded in a 96-well plate at a density of 5000 cells per well in cell growth media with supplements and left to incubate for 24 hours at 37° C. Determination of cell number for the purpose of plating was performed in accordance with standard methods known in the art.

(8) After incubation, the cell growth media was replaced with 100 μl of PBS without calcium and magnesium and containing the relevant concentration of active(s) required. Controls include untreated irradiated and non-irradiated samples which require 100 μl pure PBS without calcium and magnesium or containing a maximum of 0.1%. Dimethyl sulfoxide (DMSO) was used where necessary to dissolve the active(s). Salicylic acid is the positive control for this assay.

(9) The cells were incubated with the actives for 30 minutes at 37° C. before being irradiated with a UV dose of 61,500 Joules/m.sup.2. The concentration of agent used in the assay is 10 to 100-fold less than the concentration of agent typically present in a cosmetic composition because this assay involved direct application of the agents onto the cells compared to the indirect contact that takes place in vivo (this is known in the art).

(10) After irradiation, the PBS and actives were replaced with 100 μl of pre-warmed (37° C.) media without supplements and incubated for 24 hours at 37° C.

(11) Media supernatant containing the 11-6 expressed from the cells was then collected and transferred to a fresh 96-well plate and stored at −20° C. until the ELISA was performed.

(12) The IL-6 ELISA was performed according to the manufacturer's protocol provided with the kit and as standard in the art.

(13) A cell viability assay was performed on remaining cells where necessary to determine the cytotoxic effects of tested actives.

(14) Results

(15) Compositions comprising actives were tested in accordance with the above method to determine the activity of that active or blend of actives in inhibiting an IL-6 response. In one experiment (FIG. 2), the active used was green tea, present at a concentration of 0.0001% by weight of the composition. In another experiment, the active used was phytosphingosine hydrochloride, present at a concentration of 0.0001% by weight of the composition. In another experiment (FIG. 2) compositions according to the invention were used—the actives used were a combination of green tea as the polyphenolic antioxidant agent and phytosphingosine hydrochloride as the sphingosine compound. Green tea was present in the combination at a concentration of 1×10.sup.−5% by weight of the tested composition. Phytosphingosine hydrochloride was present in the combination at a concentration of 5×10.sup.−6% by weight of the tested composition.

(16) The blend of green tea and phytosphingosine hydrochloride were combined in an amount selected to achieve substantially the same level of IL-6 inhibition as when the agents were used individually. The IL-6 assay results showed that the green tea alone inhibited IL-6 activity by 67%, that phytosphingosine hydrochloride alone inhibited IL-6 activity by 58% and that the combination of green tea and phytosphingosine hydrochloride inhibited IL-6 activity by 51%. Surprisingly, the level of inhibition produced by the combination was substantially the same as when the ingredients were used individually. Therefore, despite the agents being present at significantly lower concentrations in the combination than individually, the same technical effect was still achieved.

(17) It can be seen therefore that the percentage inhibition of the active combination is advantageously greater than the sum of the individual actives tested alone and shows synergy.

(18) FIG. 3 presents IL-6 inhibition in a separate study where the phytosphingosine is present at a concentration that is either 10-fold, 50-fold or 100-fold the concentration of green tea extract (combination samples). Surprisingly a clear trend is seen where an increase in the ratio of sphingosine compound compared to polyphenolic antioxidant agent leads to an increase in IL-6 inhibition. What is especially surprising here is that the 50-fold and 100-fold examples have a greater-fold increase in the ratio as a result of decreasing green tea extract concentration rather than increasing phytosphingosine concentration. In other words, decreasing green tea extract in a phytosphingosine-containing sample (an extract shown to effectively inhibit IL-6 as shown in FIG. 3) surprisingly leads to an increase in IL-6 inhibition. This shows a novel ratio-specific synergistic effect between the sphingosine compound and the polyphenolic antioxidant agent. Note here that the concentration of phytosphingosine in the phytosphingosine only sample (0.0001%) is ten-fold greater than the phytosphingosine concentration of the combination samples and that the concentration of green tea extract in the green tea extract only sample (0.0001%) is 100-fold greater than the combination sample with the highest concentration of green tea extract (0.000001%).

(19) It is important to note that the skin cells used in the study that led to the FIG. 3 results were different to those used in the study that led to the FIG. 2 results (differences include age of donor, the passage number of the cultured cells etc.) and so the FIG. 2 results are not directly comparable with the FIG. 3 results.