STABILIZATION OF THIOPYRIDINONE COMPOUND AND YELLOWING REDUCTION OF COMPOSITION COMPRISING SAME

Abstract

The present invention relates to a composition comprising: (a) at least one thiopyridinone compound; and (b) at least one fatty acid comprising 18 or more carbon atoms, wherein the amount of the (b) fatty acid(s) comprising 18 or more carbon atoms in the composition is 10% by weight or more, preferably 12% by weight or more, and more preferably 14% by weight or more, relative to the total weight of the composition. The present invention can provide a composition including (a) thiopyridinone compound(s) with increased stability of the (a) thiopyridinone compound(s) over time, in particular even when the composition is maintained for a relatively long period of time under elevated temperature, and with reduced yellowing just after adding the thiopyridinone compound to the composition.

Claims

1. A composition, comprising: (a) at least one compound of formula (I) ##STR00029## wherein R.sub.1 denotes a radical chosen from: a) a hydrogen atom; and b) a saturated linear C.sub.1-C.sub.6 alkyl group, and R.sub.2 denotes a radical chosen from: a) a hydrogen atom; b) a saturated linear C.sub.1-C.sub.10 alkyl group; c) a saturated branched C.sub.3-C.sub.10 alkyl group; and d) a C.sub.1-C.sub.6 phenylalkyl group, or a salt thereof, a solvate thereof, an optical isomer thereof, or a racemate thereof, and (b) at least one fatty acid comprising 18 or more carbon atoms, wherein the amount of the (b) fatty acid(s) comprising 18 or more carbon atoms in the composition is 10% by weight or more, relative to the total weight of the composition.

2. The composition according to claim 1, wherein: R.sub.1 denotes a radical chosen from: a) a hydrogen atom; and b) a saturated linear C.sub.1-C.sub.4 alkyl radical, and R.sub.2 denotes a radical chosen from: a) a hydrogen atom; b) a saturated linear C.sub.1-C.sub.6 alkyl group; and c) a saturated branched C.sub.3-C.sub.6 alkyl group.

3. The composition according to claim 1, wherein: R.sub.1 denotes a radical chosen from: a) a hydrogen atom; and b) a methyl radical, and R.sub.2 denotes a radical chosen from: a) a hydrogen atom; b) a saturated linear C.sub.1-C.sub.4 alkyl group; c) a saturated branched C.sub.3-C.sub.4 alkyl group.

4. The composition according to claim 1, wherein the (a) compound of formula (I) is chosen from the following compounds: TABLE-US-00009 Structure Compound No. Chemical Name 1 N-[(2-thioxo-1,2- dihydropyridin- 3-yl) carbonyl]glycine 2 N-methyl-N-[(2- thioxo-1,2- dihydropyridin- 3-yl) carbonyl]glycine 3 Ethyl N-[(2-thioxo- 1,2- dihydropyridin- 3-yl) carbonyl]glycinate 4 Ethyl N-methyl-N- [(2-thioxo-1,2- dihydropyridin- 3-yl) carbonyl]glycinate and salts thereof, solvates thereof, optical isomers thereof, and racemates thereof.

5. The composition according to claim 1, wherein the (a) compound of formula (I) is chosen from the following compounds: TABLE-US-00010 Structure Compound No. Chemical Name 1 N-[(2-thioxo-1,2- dihydropyridin-3-yl) carbonyl]glycine 2 N-methyl-N-[(2- thioxo-1,2- dihydropyridin-3-yl) carbonyl]glycine and salts thereof, solvates thereof, optical isomers thereof, and racemates thereof.

6. The composition according to claim 1, wherein the amount of the (a) compound(s) of formula (I) in the composition is from 0.01% to 20% by weight, relative to the total weight of the composition.

7. The composition according to claim 1, wherein the (b) fatty acid comprising 18 or more carbon atoms comprises 30 or less carbon atoms.

8. The composition according to claim 1, wherein the (b) fatty acid comprising 18 or more carbon atoms is selected from the group consisting of stearic acid, oleic acid, linoleic acid, arachidic acid, arachidonic acid, behenic acid, lignoceric acid, and nervonic acid.

9. The composition according to claim 1, wherein the amount of the (b) fatty acid(s) comprising 18 or more carbon atoms in the composition is from 10% to 35% by weight, relative to the total weight of the composition.

10. The composition according to claim 1, wherein the composition further comprises (c) at least one oil.

11. The composition according to claim 1, wherein the composition further comprises (d) water.

12. The composition according to claim 1, wherein the composition further comprises (e) at least one surfactant.

13. The composition according to claim 1, wherein the composition is for whitening a keratin substance.

14. A cosmetic process for a keratin substance, comprising: applying to the keratin substance the composition according to claim 1.

15. A method for stabilizing (a) at least one compound of formula (I) and reducing yellowing of a composition containing the (a) at least one compound of formula (I), comprising: adding (b) at least one fatty acid comprising 18 or more carbon atoms to the composition comprising the (a) at least one compound of formula (I) ##STR00036## wherein R.sub.1 denotes a radical chosen from: a) a hydrogen atom; and b) a saturated linear C.sub.1-C.sub.6 alkyl group, and R.sub.2 denotes a radical chosen from: a) a hydrogen atom; b) a saturated linear C.sub.1-C.sub.10 alkyl group; c) a saturated branched C.sub.3-C.sub.10 alkyl group; and d) a C.sub.1-C.sub.6 phenylalkyl group, or a salt thereof, a solvate thereof, an optical isomer thereof, or a racemate thereof, wherein the amount of the (b) fatty acid(s) comprising 18 or more carbon atoms in the composition is 10% by weight or more, relative to the total weight of the composition.

Description

EXAMPLES

[0425] The present invention will be described in a more detailed manner by way of examples. However, these examples should not be construed as limiting the scope of the present invention.

Examples 1-3 and Comparative Examples 1-4

[0426] [Preparation]

[0427] Each of the compositions according to Examples 1-3 and Comparative Examples 1-4 was prepared by mixing the ingredients shown in Table 1 in accordance with the following steps 1-8.

[0428] 1. The ingredients for Phase A were mixed and heated to 80 C+/5 C. to obtain a mixture of Phase A.

[0429] 2. The ingredients for Phase B were mixed and heat to 80 C+/5 C. to obtain a mixture of Phase B.

[0430] 3. The mixture of Phase B was added to the mixture of Phase A, and the mixture thus obtained was homogenized with a homogenizer (TK robomix, PRIMIX) under 8,000 rpm at 80 C+/5 C. for 10 minutes.

[0431] 4. The ingredients for Phase C was further added to the above mixture obtained in Step 3, followed by homogenizing with the homogenizer under 8,000 rpm for 10 minutes.

[0432] 5. The mixture obtained in Step 4 was cooled to 60 C+/5 C. under slow agitation.

[0433] 6. The ingredients for Phase D were mixed to obtain a mixture of Phase D.

[0434] 7. The mixture of Phase D was added to the mixture obtained in Step 5 and mixed well under slow agitation.

[0435] 8. The mixture obtained in Step 7 was cooled to room temperature under slow agitation.

[0436] The numerical values for the amounts of the ingredients are all based on % by weight as active raw materials.

TABLE-US-00005 TABLE 1 Comp. Comp. Comp. Comp. Phase Ingredients Ex. 1 Ex. 2 Ex. 3 Ex. 1 Ex. 2 Ex. 3 Ex. 4 A Tetrasodium EDTA 0.04 0.04 0.04 0.04 0.04 0.04 0.04 A Phenoxyethanol 0.50 0.50 0.50 0.50 0.50 0.50 0.50 A Water 57.09 56.24 62.24 65.24 68.26 56.26 56.26 A Glycerin 1.00 1.00 1.00 1.00 1.00 1.00 1.00 A Hydroxyacetophenone 0.40 0.40 0.40 0.40 0.40 0.40 0.40 A Potassium Cetyl Phosphate 1.00 1.00 1.00 1.00 1.00 1.00 1.00 B Stearic Acid 16.00 16.00 10.00 7.00 4.00 B Myristic Acid 16.00 B Palmitic Acid 16.00 B Cetyl Alcohol 0.50 0.50 0.50 0.50 0.50 0.50 0.50 B Glyceryl Stearate (and) PEG-100 Stearate 1.00 1.00 1.00 1.00 1.00 1.00 1.00 B Isopropyl Myristate 1.00 1.00 1.00 1.00 1.00 1.00 1.00 C Dimethicone 0.5 0.5 0.5 0.5 0.5 0.5 0.5 C Acrylates/C10-30 Alkyl Acrylate Crosspolymer 0.12 0.12 0.12 0.12 0.12 0.12 0.12 D Water 20.00 20.00 20.00 20.00 20.00 20.00 20.00 D Potassium Hydroxide 0.35 0.70 0.70 0.70 0.68 0.68 0.68 D Compound No. 1 0.50 1.00 1.00 1.00 1.00 1.00 1.00 (N-[(2-thioxo-1,2-dihydropyridin-3-yl) carbonyl]glycine)

[0437] [Evaluations]

[0438] (Thiopyridinone Quantification)

[0439] The amount of thiopyridinone in each of the compositions according to Examples 1-3 and Comparative Examples 1-4 was determined by an HPLC-UV assay at the following timing.

[0440] (1) Just after the preparation of the composition (T0)

[0441] (2) 2 months after the preparation, where the composition was maintained at room temperature

[0442] (3) 2 month after the preparation, where the composition was maintained at 45 C.

[0443] The details of the HPLC-UV assay are as follows.

[0444] Apparatus/Reagents

TABLE-US-00006 HPLC System HPLC with UV detector HPLC Column C8 column 5 m, 4 mm 250 mm Acetonitrile HPLC grade Monopotassium phosphate Special grade

[0445] HPLC Conditions

TABLE-US-00007 UV detector 220 nm Column Temp. 30 C. Flow Rate 1.0 mL/min Injection Volume 5 L Mobile Phase Gradient mode A: 0.01 mol/L monopotassium phosphate solution, pH = 3.0 with phosphoric acid B: Acetonitrile

[0446] The results are shown in Table 2.

[0447] (Color Evaluations)

[0448] (1) Instrumental Evaluation

[0449] 10 g each of the compositions according to Examples 1-3 and Comparative Examples 1-4 just after the preparation thereof was filled in a 20 ml transparent glass vial. The b* value based on CIE1976 of the composition was measured by a spectrocolorimeter CM-700d (Konica Minolta) via the vial.

[0450] The results are shown in the line of b*T0 in Table 2.

[0451] (2) Visual Evaluation

[0452] 10 g each of the compositions according to Examples 1-3 and Comparative Examples 1-4 just after the preparation thereof was filled in a 20 ml transparent glass vial. The color of the composition was visually evaluated by 5 panelists in accordance with the following score criteria, and the scores were averaged.

[0453] 0: white

[0454] 1: very slightly yellow

[0455] 2: slightly yellow

[0456] 3: rather yellow

[0457] 4: yellow

[0458] 5: intense yellow

[0459] The results are shown in the Aspect line in Table 2.

TABLE-US-00008 TABLE 2 Comp. Comp. Comp. Comp. Ex. 1 Ex. 2 Ex. 3 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Thiopyridinone (%) T0 0.5 1.08 1.07 1.07 1.05 1.03 1.06 Thiopyridinone (%) RT, 0.51 1.00 1.04 1.03 1.01 0.94 0.99 2 M (+2.0%) (7.4%) (2.8%) (3.7%) (3.8%) (8.7%) (6.6%) Thiopyridinone (%) 0.47 0.97 0.94 0.93 0.86 0.90 0.89 45 C., 2 M (6.0%) (10.2%) (12.1%) (13.1%) (18.1%) (12.6%) (16.0%) b* T0 9.38 15.66 17.62 19.03 19.65 21.15 21.02 Aspect 1 2 2.4 2.8 3.6 3.4 4 Thiopyridinone (%) T0: Just after the preparation of the composition Thiopyridinone (%) RT, 2 M: 2 months after the preparation, where the composition was maintained at room temperature Thiopyridinone (%) 45 C., 2 M: 2 month after the preparation, where the composition was maintained at 45 C.

[0460] (Results)

[0461] The compositions according to Examples 1-3 each of which included a thiopyridinone compound and stearic acid (C18) in an amount of 10% by weight or more relative to the total weight of the composition were stable.

[0462] Specifically, the thiopyridinone compound in the compositions according to Examples 1-3 was more stable over time under both room temperature and elevated temperature than that in the compositions according to Comparative Examples 1-4.

[0463] Also, the color of the compositions according to Example 1-3 was only slightly yellow.

[0464] Comparative Example 1 shows that the amount (7% by weight) of stearic acid was insufficient to stabilize the thiopyridinone compound over time under elevated temperature and reduce yellowing to the level shown in Examples 1-3.

[0465] Comparative Example 2 also shows that the amount (4% by weight) of stearic acid was insufficient to stabilize the thiopyridinone compound over time under elevated temperature. Also, the composition according to Comparative Example 2 showed intense yellowing.

[0466] Comparative Example 3 shows that the use of myristic acid (C14) instead of stearic acid did not work to stabilize the thiopyridinone compound. Specifically, the thiopyridinone compound in the composition according to Comparative Example 3 was less stable over time under both room temperature and elevated temperature than that in the compositions according to Examples 1-3. Also, the composition according to Comparative Example 3 showed intense yellowing.

[0467] Comparative Example 4 shows that the use of palmitic acid (C16) instead of stearic acid did not work to stabilize the thiopyridinone compound. Specifically, the thiopyridinone compound in the composition according to Comparative Example 4 was less stable over time under elevated temperature than that in the compositions according to Examples 1-3. Also, the composition according to Comparative Example 4 showed intense yellowing.