Compounds

Abstract

The present invention relates to novel compounds which effectively inhibit the melanin synthesis in human melanocytes and are thus suitable for the treatment of senile lentigines, for smoothening skin color irregularities and/or for lightening natural skin color.

Claims

1. A compound of formula (I): ##STR00029## wherein R.sup.1 is a C.sub.9-C.sub.23acyl, R.sup.2 and R.sup.3 are, independently of each other, H or a heteroarylC.sub.1-C.sub.6alkyl, wherein the heteroaryl residue may optionally be substituted, R.sup.4 is H or a C.sub.1-C.sub.6alkyl, R.sup.5 is an amino acid side chain of a basic amino acid, and R.sup.6 and R.sup.7 are, independently of each other, selected from the group consisting of H, a C.sub.1-C.sub.12alkyl and a C.sub.3-C.sub.6cycloalkylC.sub.1-C.sub.3alkyl or a cosmetically acceptable salt thereof, with the proviso that only one of the residues R.sup.2 and R.sup.3 as well as only one of the residues R.sup.6 and R.sup.7 is H and/ or at least one of R.sup.3, R.sup.4 or R.sup.7 is not H.

2. The compound according to claim 1, wherein the C.sub.9-C.sub.23acyl is selected from the group consisting of nonanoyl, decanoyl, undecanoyl, dodecanoyl, myristoyl, palmitoyl, stearoyl and eicosanyl.

3. The compound according to claim 1, wherein the heteroarylC.sub.1-C.sub.6alkyl is unsubstituted or substituted with one substituent selected from the group consisting of F, CI, hydroxy, cyano, C.sub.1-C.sub.3alkyl, C.sub.1-C.sub.3alkoxy and C.sub.1-C.sub.3alkanoyloxy.

4. The compound according to claim 3, wherein the heteroarylC.sub.1-C.sub.6alkyl is selected from the group consisting of (1 H-indol-3-yl)(m)ethyl, 5-fluoro(1 H-indol-3-yl)(m)ethyl, 6-fluoro(1 H-indol-3-yl)(m)ethyl, 5-hydroxy(1 H-indol-3-yl)(m)ethyl, (pyridin-2-yl)(m)ethyl, (pyridin-3-yl)(m)ethyl, (quinolin-2-yl)(m)ethyl and (quinolin-3-yl)(m)ethyl.

5. The compound according to claim 1, wherein R.sup.4 is H or a C.sub.1-C.sub.2alkyl.

6. The compound according to claim 1, wherein the amino acid side chain is selected from the side chains of arginine, lysine, and histidine, 2,4-diaminobutyric acid, homolysine and ornithine.

7. The compound according to claim 1, wherein R.sup.6 is H or a branched C.sub.6-C.sub.10alkyl.

8. The compound according to claim 1, wherein R.sup.7 is selected from the group consisting of H, a branched C.sub.3-C.sub.10alkyl and a C.sub.3-cycloalkylC.sub.1-C.sub.2alkyl.

9. The compound according to claim 1, which is a compound of one of the formulas (I-a) through (I-x): ##STR00030## ##STR00031## ##STR00032## ##STR00033## ##STR00034## ##STR00035## ##STR00036##

10. The compound according to claim 1, wherein R.sup.4 is H or CH.sub.3.

11. The compound according to claim 1, wherein the amino acid side chain is selected from the side chains of arginine and lysine.

12. The compound according to claim 1, wherein R.sup.6 is H or 3,5,5-trimethylhexyl.

13. The compound according to claim 1, wherein R.sup.7 is selected from the group consisting of H, isobutyl, 2,4,4-trimethylpentyl and cyclopropylmethyl.

14. A cosmetic composition comprising at least one compound according to claim 1 and a cosmetically acceptable carrier.

15. The cosmetic composition according to claim 14, wherein the total amount of the at least one compound of formula (I) is in a range of about 0.00001 to 0.5 wt.-%, based on the total weight of the cosmetic composition.

16. The cosmetic composition according to claim 14, wherein the total amount of the at least one compound of formula (I) is in a range of 0.0001 to 0.25 wt.-%, based on the total weight of the cosmetic composition.

17. The cosmetic composition according to claim 14, wherein the total amount of at least one compound of formula (I) is in a range of 0.0001 to 0.1 wt.-%, based on the total weight of the cosmetic composition.

18. The cosmetic composition according to claim 14, wherein the composition further comprises at least one ingredient selected from the group consisting of polysilicones-15, phenylbenzimidazol sulfonic acid, 3-benzylidene camphor, octocrylene, ethylhexyl methoxycinnamate, ethyl hexylsalicylate, homosalate, zinc oxide, bis-ethylhexyloxyphenol methoxyphenyl triazine, methylene bis-benzotriazolyl tetramethylbutylphenol, titanium dioxide, butyl methoxydibenzoylmethane, niacinamide, arbutin, resveratrol, vitamin C (ascorbic acid) as well as derivatives thereof, (skin whitening) plant extracts, retinol, thymus hydrolysate as well as mixtures thereof.

19. A method for the treatment of senile lentigines, for smoothening skin color irregularities and/or for lightening the natural skin color, said method comprising the step of applying a cosmetic composition according to claim 14 to the affected area.

Description

EXPERIMENTAL PART

1. General Information

Abbreviations

(1) AA Amino acid ATMPA (all-rac) 2-amino-2,6,10,14-tetramethyl pentadecanoic acid DCM dichloromethane DIPE diisopropylether DIPEA N,N-diisopropylethylamine EtOAc ethyl acetate Fmoc fluorenylmethoxycarbonyl HOAc acetic acid HPLC High Pressure Liquid Chromatography MeCN acetonitrile TIPS triisopropylsilane? TFA trifluoroacetic acid TBTU O-(Benzotriazol-1-yl)-N,N,N,N-tetramethyluronium tetrafluoroborat 2PyAla 3-(2-Pyridyl)-alanine 3PyAla 3-(3-Pyridyl)-alanine IMGly N-(1H-indoly-3-yl methyl)glycine 3QMGly N-(quinolin-3-yl methyl)glycine 2QMGly N-(quinolin-2-yl methyl)glycine

(2) Preparative HPLC Purifications: Performed on a Waters High Performance Liquid

(3) Chromatography LC-2525 equipped with a Waters 2767 Sample Manager and a Waters FCII automated fraction collector, using a Grom Saphir 110 C18 10 m 50300 mm.sup.2 preparative column and a Waters 2487 double wavelength UV-Vis detector operating at 220 and 254 nm.

(4) H.sub.2O+0.07% TFA (A phase) and MeCN+0.07% TFA (B phase) were used as eluents, with a flow of 55 mL/min.

(5) Synthetic Strategies

(6) All compounds are prepared using a commercially available peptide synthesizer to prepare the tripeptide with free N-terminus or N-terminal fatty acid. In cases where the desired single stereoisomer was not commercially available, the racemic mixture was coupled to the side-chain protected dipeptide on the resin and the epimers were separated by preparative HPLC.

(7) Procedure 0: Typical Synthesis of the Precursor: H-AA1-AA2-AA3-NH-Resin

(8) 1.4 g of Fmoc ramage amide polystyrene resin (approx. 0.51 mmol/g) is swollen in DCM for 2 h in a peptide synthesizer reaction vessel. The peptide synthesizer runs the synthesis program for tripeptides using 1.25 equivalents of each Fmoc-protected amino acid. Expensive or home-made amino acids can be used as limiting reagent followed by acetylation of excess of unreacted amine.

(9) Procedure 1: Free Peptide:

(10) 1.5 mmoles of Fmoc ramage resin were treated as described in the precursor procedure, then cleaved from the resin with 30 ml 95% TFA and precipitated with 350 ml DIPE. The crude peptide is filtered off, dried, treated 30 mins with 2N HOAc and purified with preparative HPLC. Pure fractions are combined, evaporated and dried at the lyophilizer yielding the peptides as outlined in Table 2a.

(11) TABLE-US-00002 TABLE 2a # Name Yield Ref-5 H-D-Trp-Arg-Leu-NH.sub.2 *2TFA 673 mg, 0.95 mmol, 63%

(12) Procedure 2: Desired Stereoisomer Commercially Available or all-Rac Mixture

(13) 1.0-1.5 mmoles of Fmoc ramage resin were treated as described in the previous procedure. The N-terminal fatty acid is coupled via standard peptide coupling procedure. The crude peptide is then cleaved from the resin with 30 ml 95% TFA and precipitated with 350 ml DIPE. The crude peptide is filtered off, dried, treated 30 mins with 2N HOAc and purified by preparative HPLC. Pure fractions are combined, evaporated and dried onat the lyophilizer yielding the peptides as outlined in Table 2b

(14) TABLE-US-00003 TABLE 2b # Name Yield (I-a) Decanoyl-D-Trp-Arg-Leu-NH.sub.2 *TFA 353 mg, 0.47 mmol, 64% (I-b) Lauroyl-D-Trp-Arg-Leu-NH.sub.2 *TFA 310 mg, 0.40 mmol, 40% (I-c) Myristoyl-D-Trp-Arg-Leu-NH.sub.2 *TFA 203 mg, 0.25 mmol, 25% (I-d) Palmitoyl-D-Trp-Arg-Leu-NH.sub.2 *TFA 236 mg, 0.28 mmol, 22% (I-e) Stearoyl-D-Trp-Arg-Leu-NH.sub.2 *TFA 45 mg, 0.05 mmol, 5% (I-f) Eicosanoyl-D-Trp-Arg-Leu-NH.sub.2 *TFA 74 mg, 0.08 mmol, 11% (I-o) Palmitoyl-D-Trp-Arg-cyclopropyl-alanin-NH.sub.2 *TFA 125 mg, 0.14 mmol, 69% (I-p) Palmitoyl-D-Trp-Arg-(all-rac)-2-amino-4,6,6- 172 mg, 0.19 mmol, 24% trimethyl-heptanoic acid-NH.sub.2 *TFA (I-q) Palmitoyl-D-Trp-Arg-(rac)-N-3,5,5- 112 mg, 0.12 mmol, 12% trimethylhexylglycin-NH.sub.2 *TFA (I-r) Palmitoyl-D-Trp-Lys-Leu-NH.sub.2 *TFA 387 mg, 0.48 mmol, 48% (I-s) Palmitoyl-D-3-PyAla-Arg-Leu-NH.sub.2 *2TFA 155 mg, 0.16 mmol, 51% (I-w) Palmitoyl-2QMGly-Arg-Leu-NH2 *2TFA 67 mg, 0.06 mmol, 13% (I-x) Palmitoyl-3QMGly-Arg-Leu-NH2 *TFA 225 mg, 0.23 mmol, 47% Ref-1 Palmitoyl-D-Trp-Met-Leu-NH2 249 mg, 0.36 mmol, 36% Ref-2 Hexanoyl-D-Trp-Arg-Leu-NH2 *2TFA 72 mg, 0.10 mmol, 8% Ref-3 Palmitoyl-D-Trp-NLe-Leu-NH2 39 mg, 0.06 mmol, 6% Ref-4 Octanoyl-D-Trp-Arg-Leu-NH2 *TFA 306 mg, 0.43 mmol, 43% Ref-6 Palmitoyl-D-Trp-Arg-ATMPA-NH2 *2TFA 110 mg, 0.17 mmol, 17%

(15) Procedure 3: Synthesis Via Separation of Epimers

(16) 1.0-1.5 mmoles of Fmoc ramage resin were treated as described in the previous procedure. The crude peptide is then cleaved from the resin with 30 ml of 95% TFA and precipitated with 350 ml DIPE. The crude peptide is filtered off, dried, treated 30 mins with 2N HOAc and purified by preparative HPLC. By comparison, we concluded the D-epimer elutes first in the (rac)Trp-derivative-Arg-Leu-NH.sub.2 series. The N-terminal palmitic acid is coupled via standard peptide coupling procedure using 1.2 eq of TBTU and palmitic acid and 4.5 eq DIPEA. After final preparative HPLC, the pure fractions are combined, evaporated and dried at the lyophilizer yielding the peptides as outlined in Table 2c.

(17) TABLE-US-00004 TABLE 2c Name Yield (I-g) Palmitoyl--Me-D-Trp-Arg-Leu- 92 mg, 0.11 mmol, 50% NH.sub.2 *TFA (I-h) Palmitoyl--Me-L-Trp-Arg-Leu- 72 mg, 0.14 mmol, 58%) NH.sub.2 *TFA (I-i) Palmitoyl-5F-D-Trp-Arg-Leu- 92 mg, 0.11 mmol, 52% NH.sub.2 *TFA (I-j) Palmitoyl-5F-L-Trp-Arg-Leu- 101 mg, 0.21 mmol, 57% NH.sub.2 *TFA (I-k) Palmitoyl-6F-D-Trp-Arg-Leu- 108 mg, 0.13 mmol, 61% NH.sub.2 *TFA (I-l) Palmitoyl-6F-LTrp-Arg-Leu-NH.sub.2 *TFA 103 mg, 0.12 mmol, 58% (I-m) Palmitoyl-5OH-D-Trp-Arg-Leu- 83 mg, 0.10 mmol, 48% NH.sub.2 *TFA (I-n) Palmitoyl-5OH-L-Trp-Arg-Leu- 95 mg, 0.11 mmol, 53% NH.sub.2 *TFA (I-t) Palmitoyl-D-2-PyAla-Arg-Leu- 61 mg, 0.17 mmol, 41%) NH.sub.2 *2TFA (I-u) Palmitoyl-L-2-PyAla-Arg-Leu- 41 mg, 0.10 mmol, 46% NH.sub.2 *2TFA

(18) Procedure 4: Compounds Requiring Special Treatment

(19) 1.5 mmoles of Fmoc ramage resin were treated as described in the precursor procedure, then cleaved from the resin with 25.8 ml (TFA/TIPS/DCM=22/0.8/3 ml) saturated with dry ice. The cleavage mixture was added dropwise to an ice-cooled mixture of 100 ml water and 120 ml of 1M NaOH and adjusted to a pH=8 with additional NaOH. The mixture is evaporated to a volume of approx. 200 ml, and directly feed into prep. HPLC using HOAc as modifier for Water and MeCN. Pure fractions are neutralized, combined and extracted with EtOAc. Organic layer is dried with Na.sub.2SO.sub.4, and all volatile compounds are removed under reduced pressure.

(20) The N-terminal palmitic acid was coupled via standard peptide coupling procedure using 1.1 eq of TBTU and palmitic acid and 3 eq DIPEA yielding the peptide as outlined in Table 2d.

(21) TABLE-US-00005 TABLE 2d Name Yield (I-v) Palmitoyl-IMGly-Arg-Leu-NH.sub.2 *AcOH 5 mg, 0.001 mmol, 5%

3. Melanin Inhibition

(22) Melanocytes (Normal human epidermal melanocytes, lightly pigmented, 8.sup.th passage) were seeded in 24 well plates and cultured for 24 hours in culture medium (M254 supplemented with PMA free HMGS-2, Insulin 5 g/ml, Penicilline 50 U/ml-Streptomycine 50 g/ml Gentamycine 25 g/ml) at 37 C., 5% CO.sub.2. The medium was then replaced by culture medium containing the test compounds or the reference (lipoic acid at 5 g/ml) in presence of L-tyrosine (1 mM). The cells were then incubated for 240 hours with 2 renewals of culture medium containing the test compounds or the reference in presence of L-tyrosine after 96 and 168 hours of incubation. A non-stimulated and a stimulated control were performed in parallel. All experimental conditions were performed in n=3, except for control conditions in n=6. At the end of incubation, the culture supernatants were removed and the melanin was extracted by cell lysis using a 0.5 N NaOH solution. The optical density (OD) of each experimental point was measured at 405 nm and melanin quantity was calculated using melanin standards (standard curve from 0.39 to 100 g/ml melanin). Results were expressed in g/ml of melanin and in percentage of inhibition compared to stimulated control.

(23) TABLE-US-00006 Melanin inhibition [%] # Name 1 M 10 M (I-a) Decanoyl-D-Trp-Arg-Leu-NH.sub.2 *TFA na 75 (I-b) Lauroyl-D-Trp-Arg-Leu-NH2 *TFA 51 73 (I-c) Myristoyl-D-Trp-Arg-Leu-NH.sub.2 *TFA 62 70 (I-d) Palmitoyl-D-Trp-Arg-Leu-NH.sub.2 *TFA 76 na (I-e) Stearoyl-D-Trp-Arg-Leu-NH.sub.2 *TFA 66 64 (I-f) Eicosanoyl-D-Trp-Arg-Leu-NH.sub.2 *TFA 28 55 (I-g) Palmitoyl--Me-D-Trp-Arg-Leu-NH2 *TFA 94 na (I-h) Palmitoyl--Me-L-Trp-Arg-Leu-NH2 *TFA 70 na (I-i) Palmitoyl-5F-D-Trp-Arg-Leu-NH2 *TFA 77 na (I-j) Palmitoyl-5F-L-Trp-Arg-Leu-NH2 *TFA 60 na (I-k) Palmitoyl-6F-D-Trp-Arg-Leu-NH2 *TFA 70 na (I-l) Palmitoyl-6F-L-Trp-Arg-Leu-NH2 *TFA 59 na (I-m) Palmitoyl-5OH-D-Trp-Arg-Leu-NH.sub.2 *TFA 75 na (I-n) Palmitoyl-5OH-L-Trp-Arg-Leu-NH.sub.2 *TFA 42 na (I-o) Palmitoyl-D-Trp-Arg-cyclopropyl-alanin- 65 65 NH.sub.2 *TFA (I-p) Palmitoyl-D-Trp-Arg-(all-rac)-2-amino- 71 na 4,6,6-trimethyl-heptanoic acid-NH.sub.2 *TFA (I-q) Palmitoyl-D-Trp-Arg-(rac)-N-3,5,5- 73 na trimethylhexylglycin-NH.sub.2 *TFA (I-r) Palmitoyl-D-Trp-Lys-Leu-NH.sub.2 *TFA 61 na (I-s) Palmitoyl-D-3-Py-Ala-Arg-Leu-NH.sub.2 *2TFA 64 75 (I-t) Palmitoyl-D-2-PyAla-Arg-Leu-NH.sub.2 *2TFA 59 na (I-u) Palmitoyl-L-2-PyAla-Arg-Leu-NH.sub.2 *2TFA 32 na (I-v) Palmitoyl-IMGly-Arg-Leu-NH.sub.2 *AcOH 58 na (I-w) Palmitoyl-2QAla-Arg-Leu-NH.sub.2 *2TFA 58 na (I-x) Palmitoyl-3QAla-Arg-Leu-NH.sub.2 *TFA 65 na

2. References (Comparative Example)

(24) Various reference compounds (see above Ref-x compounds) have been prepared and tested in the melanogenese assay. As can be retrieved from table 3, these compounds showed only little or no activity at all (at 1 M concentration). Some of the reference compounds even increased the melanin content in the human melanocytes, thus exhibited a tanning effect.

(25) TABLE-US-00007 TABLE 3 Melanin inhibition [%] # Name 1 M 10 M Ref-1 Palmitoyl-D-Trp-Met-Leu-NH.sub.2 25 43 Ref-2 Hexanoyl-D-Trp-Arg-Leu-NH.sub.2 18 8 Ref-3 Palmitoyl-D-Trp-NLe-Leu-NH.sub.2 13 na Ref-4 Octanoyl-D-Trp-Arg-Leu-NH.sub.2 13 na Ref-5 H-D-Trp-Arg-Leu-NH.sub.2 3 14 Ref-6 Palmitoyl-D-Trp-Arg-ATMPA-NH.sub.2 3 12

3. Cosmetic Composition

(26) Table 4 outlines exemplary O/W emulsions, wherein one compound selected from the group of (I-a) to (I-x) as outlined in table 1 is incorporated in the indicated amount.

(27) TABLE-US-00008 TABLE 4 Exemplary O/W emulsion O/W Emulsions 1 2 3 4 5 6 7 8 Glyceryl Stearate 2.5 2 1.2 1 1 1 PEG-40 Stearate 1 PEG-100 Stearate 2.5 1 Ceteareth-20 1 Glyceryl Stearate Citrate 0.5 Potassium Cetyl Phosphate 3 1.5 Stearic Acid 2.5 3 Cetearyl Alcohol 4 2 2 Stearyl Alcohol 2 1 Cetyl Alcohol 1 1 0.5 Acrylates/C.sub.10-30 Alkyl Acrylate 0.2 0.2 0.4 0.2 Crosspolymer Carbomer 0.1 0.2 Xanthan Gum 0.3 0.3 C.sub.12-15 Alkyl Benzoate 5 2 5 5 10 5 Petrolatum 5 3 Butylene Glycol Dicaprylate/Dicaprate 4 2 9 9 Hydrogenated Polydecene 3 2 2 Caprylic/Capric Triglyceride 1 3 5 5 5 Cyclomethicone 5 2 10 Methylpropanediol 2 3 3 Glycerine 4 7 3 4 3 5 3 Glyceryl Glucoside 3.5 3 1 1 2 2 Alcohol denat. 1 3 0.5 10 4 8 4 Butylene Glycol 3 Ascorbylglucoside 0.5 1.0 1.5 0.1 Ubiquinone (Coenzyme 10) 0.1 0.05 0.01 Hyaluronic acid 0.2 Bisabolol 0.5 0.2 Isotridecylsalicylate 1 3 5 2 3 5 Compound selected from the group of 0.001 0.25 0.0001 0.05 0.1 0.0003 0.03 0.002 (I-a) to (I-x) Dibutyl Adipate 1.5 3 Diisopropyl sebacate 1 1 2 3 Ethylhexyl Benzoate 0.75 1.5 1 Titanium Dioxide (PARSOL TX) 0.5 2 Methylene Bis-Benztriazoyl 0.5 4 6 2 Tetramethylbutylphenol Ethylhexyl methoxycinnamate 2 Phenylbenzimidazole Sulfonic Acid 2 2 2 Butyl Methoxydibenzoylmethane 1 2 2 3 3 3 Methylbenzylidene Camphor 2 3 Octocrylene 5 2 10 Polysilicone-15 2 3 Ethylhexyl Salicylate 5 Homosalate 4 2 Bis-Ethylhexyloxyphenol 1.5 2 Methoxyphenyltriazine Silica 1 2.5 0.5 Silica & Methicone 4 1 2.5 Methyl Methacrylate Crosspolymer 1 2 Disodium EDTA 0.1 0.5 Fragrance, Preservatives q.s. Sodium Hydroxide q.s. Water Ad 100