Compositions and methods for stabilization of retinoids

Abstract

The present invention relates to a composition and method for stabilisation of compounds including retinoids using the synergistic effects of beta-carotene and sodium polyaspartate.

Claims

1. A cosmetic composition comprising: retinaldehyde; beta-carotene; and sodium polyaspartate.

2. The cosmetic composition according to claim 1, wherein the beta-carotene is synthetic beta-carotene, isolated beta-carotene, or a plant extract containing beta-carotene.

3. The cosmetic composition according to claim 2, wherein the ratio of synthetic beta carotene or isolated beta carotene to sodium polyaspartate is 1:0.1 to 1:10.

4. The cosmetic composition according to claim 2, wherein the plant extract is from carrot.

5. The cosmetic composition according to claim 4, wherein the carrot extract is at least one of carrot root extract and carrot seed oil extract.

6. The cosmetic composition according to claim 5, wherein the ratio of carrot extract to sodium polyaspartate is 100:1 to 10:1.

7. The cosmetic composition according to claim 6, wherein the ratio of carrot extract to sodium polyaspartate is 40:1 to 15:1.

8. The cosmetic composition according to claim 1, wherein the concentration of retinaldehyde is up to 0.1% weight, wherein the weight percentage is based on total composition weight.

9. The cosmetic composition according to claim 1, wherein the retinaldehyde is cyclodextrin encapsulated.

10. A stabilising composition comprising: beta-carotene; sodium polyaspartate; and retinaldehyde, wherein the beta-carotene and sodium polyaspartate stabilise the retinaldehyde.

11. The stabilising composition according to claim 10, wherein the beta-carotene is synthetic beta-carotene, isolated beta-carotene, or a plant extract containing beta-carotene.

12. A method of stabilising retinaldehyde, the method comprising: providing a composition comprising beta-carotene, sodium polyaspartate, and retinaldehyde.

13. The method according to claim 12, wherein the beta-carotene is synthetic beta-carotene, isolated beta-carotene, or a plant extract containing beta-carotene.

14. The method according to claim 13, wherein the ratio of synthetic beta carotene or isolated beta carotene to sodium polyaspartate is 1:0.1 to 1:10.

15. The method according to claim 13, wherein the plant extract is from carrot.

16. The method according to claim 15, wherein the carrot extract at least one of carrot root extract and carrot seed oil extract.

17. The method according to claim 16, wherein the ratio of carrot extract to sodium polyaspartate is 100:1 to 10:1.

18. The method according to claim 16, wherein the ratio of carrot extract to sodium polyaspartate is 40:1 to 15:1.

19. The method according to claim 12, wherein the concentration of retinaldehyde is up to 0.1% weight, wherein the weight percentage is based on total composition weight.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the present invention will now be described by way of example and with reference to FIGS. 1 to 5.

(2) FIG. 1 shows Table 1 having the ratios of the components of the emulsion compositions used in Example 1.

(3) FIG. 2 shows Table 3 having the ratios of the components of the gel compositions used in Example 2.

(4) FIG. 3 shows Table 5 having he ratios of the components of the gel compositions used in Example 3.

(5) FIG. 4 shows Table 7 having the ratios of the components of the gel compositions used in Example 4.

(6) FIG. 5 shows Table 9 having the ratios of the components of the emulsion compositions used in Example 5.

DETAILED DESCRIPTION

Example 1: Retinaldehyde with Carrot Seed OilPhoto-Degradation

(7) Preparation of Test Samples:

(8) A cosmetically acceptable emulsion composition was prepared through emulsification by combining oil phase and aqueous phase components. The composition viscosity was adjusted using a thickener. The compositions in Table 1 were utilised in the present Example. The carrot seed oil was sourced from Nepal.

(9) Test Protocol:

(10) Each composition was exposed to UV-radiation according to common UV weathering test conditions (UV range 200 nm to 400 nm) in a UV-chamber by leaving the test sample in a watch glass facing the UV radiation for 48 hours to simulate the effects of sunlight over a prolonged period of time. Retinaldehyde imparts a distinctive yellow colour to the composition. As retinaldehyde photo-degrades, the composition changes colour in a manner of fading/loss of yellow colour. The colour of the composition is indicative of the degree of degradation of retinaldehyde in the composition. A 20-point colour scale was used to compare the colour of each of the compositions in order to determine the extent of degradation of the composition over time when exposed to UV radiation. The colour scale ranged from deep yellow (labelled 20) which was indicative of a stable composition to off-white (labelled 1) which was indicative of a completely degraded composition. Colour scores were taken using visual analysis of three evaluators, with the final score being the average of the three.

(11) After 48 hrs, the colour of the composition was compared to the colour of the control a freshly prepared composition with deep yellow colour due to the non-degraded retinaldehyde. The colour score for each composition is shown in Table 2.

(12) The synergy column represents the improvement to stabilising retinaldehyde compositions, relative to the sum of the improvements from individual stabilisers. For example, if the individual colour score of a sample stabilised by carrot seed oil alone was 9, and by sodium polyaspartate alone was 2, and the score for a certain combination of the two was 18, the synergy level is +7.

(13) TABLE-US-00001 TABLE 2 UV Test Composition becomes lighter as it is degraded by UV light Colour Scale: Deep Yellow: 20 (starting colour) Off-white: 1 (fully degraded) Ratios Colour Score at the Synergy of Samples CSO:SPA:RAL end point CSO + SPA A1 0:0:1 1 (fully degraded) N/A B1 0:2:1 4 (very slightly stabilised) N/A C1 25:0:1 9 (partially stabilised) N/A D1 25:0.25:1 15 2 E1 20:0.5:1 17 (stabilised) 3 F1 15:1:1 17 (stabilised) 3 G1 5:1.5:1 13 0 H1 2.5:1.75:1 11 2

Example 2: Retinaldehyde with Carrot Seed OilThermal Degradation

(14) Preparation of Test Samples

(15) A cosmetically acceptable gel composition was prepared through a cold process gelling method by dispersing the thickener in solution and then neutralising by adding a buffering agent as required. The compositions in Table 3 were utilised in the present Example. The carrot seed oil was sourced from Nepal.

(16) Test Protocol

(17) Each composition was exposed to heat by leaving the test sample in a temperature-controlled oven at 45 C. for 7 days to simulate the effects of thermal oxidation over prolonged periods. Retinaldehyde imparts a distinctive yellow colour to the composition. As retinaldehyde degrades with heat, the composition changes colour from yellow to reddish brown which is converse to photo-degradation. A change in colour of the composition, towards reddish brown is, therefore, indicative of the degree of thermal degradation of retinaldehyde in the composition. A 20-point colour scale was used to compare the colour of each of the compositions in order to determine the extent of degradation of the composition over time when exposed to heat. The colour scale ranged from deep yellow (labelled 1) which was indicative of a stable composition to reddish brown (labelled 20) which was indicative of a completely degraded composition.

(18) After 7 days the colour of the composition was compared to the colour of the control a freshly prepared composition with deep yellow colour due to the non-degraded retinaldehyde. The colour score for each composition is shown in Table 4.

(19) The synergy column represents the improvement to stabilising retinaldehyde compositions, relative to the sum of the improvements from individual stabilisers. For example, if the individual colour score of a sample stabilised by carrot seed oil alone was 9, and by sodium polyaspartate alone was 2, and the score for a certain combination of the two was 18, the synergy level is +7.

(20) TABLE-US-00002 TABLE 4 Heat Test Composition becomes darker as it is degraded by heat Colour Scale: Deep Yellow: 1 (starting colour) Reddish-brown: 20 (fully degraded) Ratios Colour Score at the Synergy of Samples CSO:SPA:RAL end point CSO + SPA A2 0:0:1 20 (fully degraded) N/A B2 0:2:1 18 (very slightly stabilised) N/A C2 25:0:1 9 (partially stabilised) N/A D2 25:0.25:1 3 (stabilised) 6 E2 20:0.5:1 3 (stabilised) 6 F2 14:1:1 3 (stabilised) 6 G2 5:1.5:1 8 (partially stabilised) 1 H2 2.5:1.75:1 15 2

Example 3: Encapsulated Retinaldehyde with Carrot Seed OilThermal and Photo-Degradation

(21) A cosmetically acceptable gel composition was prepared through cold process gelling method using cyclodextrin encapsulated retinaldehyde. The compositions in Table 5 were utilised in the present Example. The carrot seed oil was sourced from Nepal.

(22) Test Protocol:

(23) Samples of A3 and B3 were subjected to either heat or light induced degradation as per the protocols below. The results for each condition were captured and then consolidated to compare the degree of stabilisation imparted by the combination of CSO and SPA.

(24) Heat Test:

(25) Each composition was exposed to heat by leaving the test sample in a temperature-controlled oven at 45 C. for 7 days to simulate the effects of thermal oxidation over prolonged periods. Retinaldehyde imparts a distinctive yellow colour to the composition. As retinaldehyde degrades with heat, the composition changes colour from yellow to reddish brown. The colour of the composition therefore be indicative of the degree of degradation of retinaldehyde in the composition. A 20-point colour scale was used to compare the colour of each of the compositions in order to determine the extent of degradation of the composition over time when exposed to heat. The colour scale ranged from deep yellow (labelled 1) which was indicative of a stable composition to reddish brown (labelled 20) which was indicative of a completely degraded composition.

(26) After day 7, the colour of the composition was compared to the colour of the control a freshly prepared composition with deep yellow colour due to the non-degraded retinaldehyde. The colour scores for each composition is shown in the Heat section of Table 6.

(27) UV-Test

(28) Each composition was exposed to UV-radiation according to common UV weathering test conditions (UV range 200 nm to 400 nm) in a UV-chamber by leaving the test sample in a watch glass facing the UV radiation for 48 hours to simulate the effects of sunlight over a prolonged period of time. Retinaldehyde imparts a distinctive yellow colour to the composition. As retinaldehyde photo-degrades, the composition changes colour in a manner of fading/loss of yellow colour. The colour of the composition can therefore be indicative of the degree of degradation of retinaldehyde in the composition. A 20-point colour scale was used to compare the colour of each of the compositions in order to determine the extent of degradation of the composition over time when exposed to UV radiation. The colour scale ranged from deep yellow (labelled 20) which was indicative of a stable composition to off-white (labelled 1) which was indicative of a completely degraded composition. Colour scores were taken using visual analysis of three evaluators, with the final score taken from the average of the three.

(29) After 48 hours, the colour of the composition was compared to the colour of the control a freshly prepared composition with deep yellow colour due to the non-degraded retinaldehyde. The colour scores for each composition is shown in the UV-test section of Table 6.

(30) TABLE-US-00003 TABLE 6 Heat Test and UV Test Retinaldehyde Retinaldehyde encapsulated in encapsulated in cyclodextrin without cyclodextrin with No Stabilisers CSO and SPA (A3) CSO and SPA (B3) Heat 20 (fully degraded) 3-4 (stabilised) 3-4 (stabilised) Test UV 1 (fully degraded) 3 (very slightly 17 (stabilised) Test stabilised)

Example 4: Retinaldehyde with Pure Beta-CarotenePhoto-Degradation

(31) Preparation of Test samples:

(32) A cosmetically acceptable gel composition was prepared through a cold process gelling method by dispersing the thickener in solution and then neutralising by adding a buffering agent as required. A 1% beta-carotene dilution in ethanol (BCD) was used to increase solubility in the gel composition. The beta-carotene was dissolved in ethanol because it has a poor solubility in water-based mediums. The compositions in Table 7 were utilised in the present Example.

(33) Test Protocol:

(34) Each composition was exposed to UV-radiation according to common UV weathering test conditions (UV range 200 nm to 400 nm) in a UV-chamber by leaving the test sample in a watch glass facing the UV radiation for 48 hours to simulate the effects of sunlight over a prolonged period of time. Retinaldehyde imparts a distinctive yellow colour to the composition. As retinaldehyde photo-degrades, the composition changes colour in a manner of fading/loss of yellow colour. The colour of the composition is indicative of the degree of degradation of retinaldehyde in the composition. A 20-point colour scale was used to compare the colour of each of the compositions in order to determine the extent of degradation of the composition over time when exposed to UV radiation. The colour scale ranged from deep yellow (labelled 20) which was indicative of a stable composition to off-white (labelled 1) which was indicative of a completely degraded composition. Colour scores were taken using visual analysis of three evaluators, with the final score being the average of the three.

(35) After 48 hrs, the colour of the composition was compared to the colour of the control a freshly prepared composition with deep yellow colour due to the non-degraded retinaldehyde. The colour score for each composition is shown in Table 8. The concentration of beta-carotene which could be used in this experiment was low due to the fact it imparts a distinct reddish-brown colour to solutions which makes it difficult to observe colour changes at high concentrations. However, as can be observed from the data even at low concentrations there was a synergistic effect between the beta-carotene and the sodium polyaspartate.

(36) TABLE-US-00004 TABLE 8 UV Test Composition becomes lighter as it is degraded by UV light Colour Scale: Deep Yellow: 20 (starting colour) Off-white: 1 (fully degraded) Ratios Colour Score at the Synergy of Samples BCD:SPA:RAL end point BCD + SPA A4 0:0:1 1 (fully degraded) N/A B4 0:2:1 3 (very slightly stabilised) N/A C4 25:0:1 6 (slightly stabilised) N/A D4 25:0.25:1 10 1 E4 20:0.5:1 11 (partially stabilised) 2 F4 15:1:1 9 0 G4 5:1.5:1 8 1 H4 2.5:1.75:1 8 1

Example 5: Retinaldehyde with Carrot Root ExtractPhoto-Degradation

(37) Preparation of Test samples:

(38) A cosmetically acceptable emulsion composition was prepared through emulsification by combining oil phase and aqueous phase components. The composition viscosity was adjusted using a thickener. The compositions in Table 9 were utilised in the present Example. The carrot root extract was sourced from Belgium.

(39) Test Protocol:

(40) Each composition was exposed to UV-radiation according to common UV weathering test conditions (UV range 200 nm to 400 nm) in a UV-chamber by leaving the test sample in a watch glass facing the UV radiation for 48 hours to simulate the effects of sunlight over a prolonged period of time. Retinaldehyde imparts a distinctive yellow colour to the composition. As retinaldehyde photo-degrades, the composition changes colour in a manner of fading/loss of yellow colour. The colour of the composition is indicative of the degree of degradation of retinaldehyde in the composition. A 20-point colour scale was used to compare the colour of each of the compositions in order to determine the extent of degradation of the composition over time when exposed to UV radiation. The colour scale ranged from deep yellow (labelled 20) which was indicative of a stable composition to off-white (labelled 1) which was indicative of a completely degraded composition. Colour scores were taken using visual analysis of three evaluators, with the final score being the average of the three.

(41) After 48 hrs, the colour of the composition was compared to the colour of the control a freshly prepared composition with deep yellow colour due to the non-degraded retinaldehyde. The colour score for each composition is shown in Table 10.

(42) The synergy column represents the improvement to stabilising retinaldehyde compositions, relative to the sum of the improvements from individual stabilisers. For example, if the individual colour score of a sample stabilised by carrot root extract alone was 9, and by sodium polyaspartate alone was 2, and the score for a certain combination of the two was 18, the synergy level is +7.

(43) TABLE-US-00005 TABLE 10 UV Test: Composition becomes lighter as it is degraded by UV light Colour Scale: Deep Yellow: 20 (starting colour) Off-white: 1 (fully degraded) Ratios Colour Score at the CRE:SPA Samples CRE:SPA:RAL end point Synergy A5 0:0:1 1 (fully degraded) N/A B5 0:2:1 4 (very slightly stabilised) N/A C5 25:0:1 8 (partially stabilised) N/A D5 25:0.25:1 14 2 E5 20:0.5:1 15 (stabilised) 3 F5 15:1:1 15 (stabilised) 3 G5 5:1.5:1 10 2 H5 2.5:1.75:1 9 3