HIGHLY EFFECTIVE PHOTOPROTECTIVE AGENTS

Abstract

Disclosed are triazine compounds of formula (I):

##STR00001## wherein R is as defined in the description, as light stabilisers and photoprotectors against UV-visible radiation.

Claims

1. Compounds of formula (I): ##STR00007## wherein the two R groups are independently branched C.sub.5 alkyls.

2. Compounds according to claim 1 wherein each R is selected from the group consisting of: tert-pentyl of formula CH.sub.3CH.sub.2C(CH.sub.3).sub.2; neo-pentyl of formula (CH.sub.3).sub.3CCH.sub.2; iso-pentyl of formula (CH.sub.3).sub.2CHCH.sub.2CH.sub.2; sec-pentyl of formula CH.sub.3CH.sub.2CH.sub.2CH(CH.sub.3); 3-pentyl of formula (CH.sub.3CH.sub.2).sub.2CH;

3. Compound according to claim 1 of formula (II): ##STR00008## wherein R is tert-pentyl of formula CH.sub.3CH.sub.2C(CH.sub.3).sub.2.

4. Method of protecting skin action against UV-A and UV-B radiation with a compound according to claim 1.

5. Cosmetic formulations containing at least one compound of claim 1.

6. Formulations according to claim 5 further containing one or more UV-A and UV-B sunscreens.

7. Formulations according to claim 6 containing at least one of the following sunscreens: 2-ethylhexyl p-methoxycinnamate, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulphonic acid, 2-phenylbenzimidazole-5-sulphonic acid and the sodium and potassium salts thereof, terephthalylidene dicamphor sulphonic acid, 2,2-(1,4-phenylene)-bis(6-sulpho-1H-benzimidazole-4-sulphonate) disodium salt, ethylhexyl salicylate, 2-hydroxy-benzoic acid 3,3,5-trimethylcycloehexyl ester, ethylhexyldimethyl PABA, drometrizoletrisiloxane, dimethicone-diethylbenzalmalonate, 3-(4-methylben-zylidene)-d,l-camphor, diethylhexylbutamidotriazone, ethylhexyltriazone, 4-(tert-butyl)-4-methoxy-dibenzoylmethane, 2-cyano-3,3-diphenylacrylic acid 2-ethyl-hexyl ester, bis-ethylhexyloxyphenol-methoxyphenyl-triazine, methylene-bis-benzotriazolyl-tetramethylbutylphenol, benzoic acid 2-(4-diethylamino-2-hydroxybenzoyl)-hexyl ester, 2,4-bis-[4-[5-(1,1-dimethyl-propyl)benzoxazol-2-yl]phenylimino]-6-[(2-ethylhexyl)imino]-1,3,5-triazine, tris-biphenyltriazine, titanium dioxide and zinc oxide.

8. Formulations according to claim 5 further containing one or more light stabilisers.

9. Formulations according to claim 5 containing the light stabilisers diethylhexyl-2,6-naphthalate, diethylhexyl syringylidene malonate, benzotriazolyl-dodecyl p-cresol, Polyester-8, butyloctyl salicylate and ethylhexyl methoxycrylene.

10. Cosmetic formulations according to claim 5 in the form of creams or milky emulsions.

11. Formulations according to claim 5 in the form of oils.

12. Formulations according to claim 5 with an in-vitro SPF equal to or higher than 15.

13. A process for the preparation of compounds of formula (I) ##STR00009## which comprises the reaction of cyanuryl chloride or bromide with one equivalent of an amino reagent of formula (III): ##STR00010## and two equivalents of a compound of formula (IV): ##STR00011## wherein R has the meanings described above.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG. 1 shows the absorption spectrum of two creams F1 and F2.

[0029] FIG. 2 shows the absorption spectrum of formulations F3 and F4.

[0030] FIG. 3 shows the absorption spectrum of formulations F4, F5 and F6.

DETAILED DESCRIPTION OF THE INVENTION

[0031] The invention relates to the triazine compounds of Formula (I):

##STR00003##

wherein the two R groups are independently branched C.sub.5 alkyls.

[0032] The expression branched C.sub.5 alkyls means branched alkyl chains containing five carbon atoms.

[0033] The compounds of formula (I) are useful as photostabilising agents against UV-visible radiation.

[0034] Generally, p-aminophenylbenzoxazole groups cause the compounds of formula (I) to absorb mainly UV-A radiation, i.e. in the zone of light wavelengths ranging between 320 and 400 nm, while p-aminobenzoic groups cause the compounds of formula (I) to absorb mainly UV-B radiation, i.e. in the zone of light wavelengths ranging between 290 and 320 nm.

[0035] The compounds of formula (I), bearing two p-aminophenylbenzoxazole substituents and a p-aminobenzoic group, therefore exhibit high absorption in the interval between 320 and 400 nm, and also cover part of the interval between 290 and 320 nm.

[0036] Preferred compounds of formula (I) are those wherein the R groups, which are the same or different, are selected from:

[0037] tert-pentyl (2-methylbutan-2-yl or 1,1-dimethylpropyl or tert-amyl) of formula CH.sub.3CH.sub.2C(CH.sub.3).sub.2;

[0038] neo-pentyl (2,2-dimethylpropyl) of formula (CH.sub.3).sub.3CCH.sub.2;

[0039] iso-pentyl (3-methylbutyl) of formula (CH.sub.3).sub.2CHCH.sub.2CH.sub.2;

[0040] sec-pentyl (pentan-2-yl) of formula CH.sub.3CH.sub.2CH.sub.2CH(CH.sub.3);

[0041] 3-pentyl (pentan-3-yl) of formula (CH.sub.3CH.sub.2).sub.2CH;

[0042] Even more preferably, the compound of the invention is that of formula (I), wherein R is the tert-pentyl (2-methylbutan-2-yl or 1,1-dimethylpropyl) group of formula CH.sub.3CH.sub.2C(CH.sub.3).sub.2, or the compound of formula (II):

##STR00004##

[0043] The triazine compounds of formula (I) can be obtained by reacting cyanuryl chloride or bromide with one equivalent of amine reagent of formula (III):

##STR00005##

and two equivalents of a compound of formula (IV):

##STR00006##

wherein R has the meanings previously described.

[0044] The compound of formula (III) is 2-ethylhexyl p-aminobenzoic acid ester.

[0045] An example of a compound of formula (IV) is 2-(4-aminophenyl)-5-(tert-amyl)benzoxazole.

[0046] The order in which the compounds of formulas (III) and (IV) are reacted with cyanuryl chloride or bromide can follow any intermediate sequence and stoichiometry. Cyanuryl chloride and bromide have three reactive halogen atoms able to react selectively with ammonia, primary amines and secondary amines at very different temperatures, thus making it possible to substitute each halogen atom with the desired amine with quantitative yields.

[0047] The subsequent synthesis for the preparation of triazine compounds from amino intermediates such as aminobenzoates and aminobenzamides is well known, and described, for example, in DE 3206398, U.S. Pat. Nos. 4,617,390, 4,724,137, 5,233,040, 5,252,323, 5,332,568, IT 1255729, U.S. Pat. Nos. 5,346,691, 5,393,517, EP 832642, U.S. Pat. Nos. 5,744,127, 5,759,525, 5,801,244, 6,018,044, 6,193,960, US 2002085981 and US 2005143577.

[0048] As the reaction produces acidity, neutralising bases are used in many cases, optionally in an aqueous medium, such as sodium hydroxide, sodium carbonate, sodium bicarbonate, calcium hydroxide, calcium carbonate, and tertiary amines such as triethylamine or pyridine.

[0049] The solvents wherein the compounds of the invention can be prepared need not be capable of dissolving the compounds. However, it is essential that they do not interact chemically with the compounds under the reaction conditions. In this respect they must be inert. Examples of solvents which can be used are saturated linear and branched hydrocarbons such as hexane, cyclohexane, methylcyclohexane, heptane, octane, isooctane, decane, petrols and dearomatised white spirits, aromatic hydrocarbons such as benzene, toluene, xylenes, ethylbenzene and petrols and white spirits also containing aromatic hydrocarbons, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and diisobutyl ketone, ethers such as tetrahydrofuran and dioxane, esters such as ethyl acetate and butyl acetate, and nitriles such as acetonitrile and benzonitrile.

[0050] Different solvents can also be used for the various consecutive synthesis steps, optionally isolating the intermediate compounds.

[0051] The operating temperatures range between 0 C. and 200 C., preferably between 0 and 150 C. The pressures can range between 0 and 50 bars, preferably between 0 and 5 bars.

[0052] The compounds of the invention can be advantageously included in cosmetic formulations, either as the only sunscreen or in combination with other known sunscreens. These formulations are a further object of the invention.

[0053] Said formulations will preferably contain one or more conventional UV-A and UV-B sunscreens such as those listed in Annex VII to the European Cosmetics Directive (76/768/EEC) and Annex VI to European Regulation (EC) No. 1223/2009, as amended, in Household and Personal care Monographic Special Issue Skin CareThe encyclopedia of allowed sunfilters in the world by Giulio Pirotta and in ELECTRONIC CODE OF FEDERAL REGULATIONS (FDA) PART 352SUNSCREEN DRUG PRODUCTS FOR OVER-THE-COUNTER HUMAN USE; Subpart B-Active Ingredients. Even more preferably, the formulations may contain, in addition to the derivatives of the invention, one or more sunscreens selected from 2-ethylhexyl p-methoxycinnamate, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxyben-zophenone-5-sulphonic acid, 2-phenylbenzimidazole-5-sulphonic acid and the sodium and potassium salts thereof, terephthalylidene dicamphor sulphonic acid, 2,2-(1,4-phenylene)-bis(6-sulpho-1H-benzoimidazole-4-sulphonate) disodium salt, ethylhexyl salicylate, 2-hydroxy-benzoic acid 3,3,5-trimethylcyclohexyl ester, ethylhexyl dimethyl PABA, drometrizole trisiloxane, dimethicone-diethylbenzylmalonate, 3-(4-methylbenzylidene)-d.1-camphor, diethylhexyl butamido triazone, ethylhexyl triazone, 4-(tert-butyl)-4-methoxy-dibenzoylmethane, 2-cyano-3,3-diphenylacrylic acid 2-ethylhexyl ester, bis-ethylhexyloxyphenol-methoxyphenyl-triazine, methylene-bis-benzotriazolyl-tetramethylbutylphenol, benzoic acid 2-(4-diethylamino-2-hydroxybenzoyl)-hexyl ester, 2,4-bis-[4-[5-(1-dimethyl-propyl)benzoxazol-2-yl]phenylimino]-6-[(2-ethylhexyl)imi-no]-1,3,5-triazine, tris-biphenyltriazine, titanium dioxide and zinc oxide.

[0054] The compounds of the invention, alone or mixed with other sunscreens as just described, can also be formulated with light stabilisers (or SPF boosters) such as diethylhexyl-2,6-naphthalate, diethylhexyl syringylidene malonate, benzotriazolyl-dodecyl p-cresol, Polyester-8, butyloctyl salicylate and ethylhexyl methoxycrylene.

[0055] The compounds of the invention can also be used already in solution in the solvents allowed by European Regulation (EC) No. 1223/2009 on cosmetic products, as amended.

[0056] The invention will be now be described in greater detail in the following examples of cosmetic syntheses and preparations.

EXAMPLE 1

synthesis of 2,4-bischloro-6-(2-ethylhexyl-4-aminobenzoate)-1,3,5-triazine

[0057] 37.0 g of sodium bicarbonate is added to a solution of 73.8 g of trichlorotriazine in 900 ml of acetone cooled to 0 C., and 102.2 g of 2-ethylhexyl-p-aminobenzoate is then slowly added, maintaining the temperature at 0 C. by cooling. The mixture is then stirred for hour, 240 ml of water is added and stirring continues for a further hour; the precipitate formed is then filtered and washed several times with water, then with cold acetone, and dried under vacuum. 156.6 g of dichlorotriazine derivative is obtained in the form of a white solid with an MP of 245-248 C.

EXAMPLE 2

Synthesis of 2,4-bis[5-tert-amylbenzoxazol-2-yl(4-phenyl)iminol-6-(2-ethylhexyl-4-aminobenzoate)-1,3,5 -triazine

[0058] Compound of formula (I) with R=tert-amyl or compound of formula (II) of the present invention.

[0059] 79.5 g of the bis-chlorocyanuryl intermediate of example I, 112.2 g of 2-(4-aminophenyl)-5-tert-amylbenzoxazole and 530 g of anhydrous xylene are stirred at 125 C. for 3 hours in a nitrogen stream. The hydrochloric acid that develops is sent to a dilute solution of NaOH.

[0060] The mixture is cooled and neutralised with aqueous NaHCO.sub.3, and the aqueous phase is separated. After drying, the mixture is clarified hot, and the product is isolated by complete hot removal of the solvent under vacuum. The resulting product is ground, obtaining 177 g of a whitish powder. The chemical structure is confirmed by NMR. The product has an HPLC assay value of 99.2% and an E.sup.1.sub.1 extinction=1431 at 328 nm.

EXAMPLE 3 (COMPARATIVE)

Synthesis of 2,4-bis[5-tert-butyl-benzoxazol-2-yl(4-phenyl)iminol-6-(2-ethylhexyl-4-aminobenzoate)-1,3,5-triazine

[0061] Compound of formula (I) with R=tert-butyl, described in example 24 of U.S. Pat. No. 5,744,127.

[0062] Using a procedure similar to that of example 2, 27.8 g of the bis-chlorocyanuryl intermediate of example 1 and 37.3 g of 2-(4-aminophenyl)-5-tert-butylbenzoxazole are reacted, to obtain 49.2 g of end product as a whitish powder. The chemical structure is confirmed by NMR. The product has an HPLC assay value of 99.7% and an E.sup.1.sub.1 extinction=1395 at 328 nm.

EXAMPLE 4

Solubility Test

[0063] The solubility of the sunscreens obtained in example 2 and (comparative) example 3 were evaluated in various emollients commonly used in suncare and daily skincare products: C12-15 alkyl benzoate, dibutyl adipate, caprylic/capric triglyceride and ethylhexyl salicylate.

TABLE-US-00001 TABLE A Comparative Compound of compound of Emollients example 2 example 3 (cosmetic solvents) (w/w %) (w/w %) C12-15 Alkyl Benzoate 15% 5% Dibutyl Adipate 20% 5% Caprylic/Capric Triglyceride 15% <5% Ethylhexyl Salicylate 25% 10%

[0064] The results set out in Table A clearly show that the solubility of the compound of the present invention, with tert-amyl benzoxazole substituents, is greater than that of the similar compound described in example 24 of patent U.S. Pat. No. 5,744,127, with tert-butyl substituents. With the introduction of a branched C5 alkyl chain as described above, and the consequent increase in solubility in cosmetic oils, a sunscreen of formula (I) with greatly improved possibilities of use is therefore obtained. In particular, its high solubility produces protective sun oils with high SPF values, which cannot be achieved with the products of example 3 because of their lower solubility in said oils.

[0065] APPLICATION EXAMPLES

[0066] The compounds of example 2 of the present invention and the compound of (comparative) example 3 were tested for their ability to perform a photoprotective action.

[0067] Said compounds were added to standard cosmetic formulas to evaluate the SPF (sun protection factor) value with a Labsphere UV-2000S instrument, in the UV region from 280 to 400 nm. For the measurement of the in-vitro SPF, the sun formulations were applied on a PMMA plate at a concentration of 2.0 mg/cm.sup.2. Three different substrates were prepared for each formula tested, and 9 readings per substrate were conducted. The SPF data measured are set out in Tables 1, 2 and 3 relating to each application example. The instrument also produces the UV absorption spectra of the formulations shown in FIGS. 1, 2 and 3, relating to each application example.

EXAMPLE 5

ApplicationSun Cream

[0068]

TABLE-US-00002 TABLE 1 Sun cream formulations F1 and F2 and the corresponding in-vitro SPF values. Phase Ingredients F1 w/w % F2 w/w % I Aqua 70.50% 70.50% Glycerin 3.00% 3.00% Abiol 0.30% 0.30% II Caprylic Capric/Triglyceride 5.00% 5.00% C12-15 Alkyl Benzoate 4.00% 4.00% Ethylhexyl Salicylate 5.00% 5.00% Sunscreen of example 2 2.50% / Sunscreen of comparative / 2.50% example 3 HEB 5.00% 5.00% PEG-100 Stearate And Glyceryl 3.00% 3.00% Stearate Cetearyl Alcohol 1.00% 1.00% Behenyl Alcohol 0.50% 0.50% III Carbomer 0.20% 0.20% IV NaOH q.s. q.s. Mean SPF 7.6.sup. 5.8.sup.

[0069] Preparation: Phase I and phase II were heated to 75-80 C. under stirring. When phase II reached the temperature of 75 C., the carbomer was dispersed; phase II+III was then added to phase I, and the mixture was emulsified with the turboemulsifier. The formulation was concluded with the addition of sodium hydroxide, and then brought to room temperature under stirring.

[0070] Table 1 and FIG. 1 show that the two formulas in emulsion obtained with the two sunscreens have different absorption values and therefore different in-vitro SPF values, the performance of the sunscreen of example 2 being superior to that of the sunscreen of comparative example 3.

EXAMPLE 6

ApplicationSun Oil

[0071]

TABLE-US-00003 TABLE 2 Anhydrous sun oil formulations and corresponding in-vitro SPF values. Phase Ingredients F3 w/w % F4 w/w % I Caprylic/Capric Triglyceride 20.0% 20.0% Dicapryl Carbonate 20.0% 20.0% Dibutyl Adipate 20.0% 20.0% C12-15 Alkyl Benzoate 10.0% 10.0% Ethylhexyl Salicylate 5.0% 5.0% Sunscreen of example 2 5.0% Sunscreen of comparative 5.0% example 3 Uvasorb HEB 4.0% 4.0% II Ethanol .sup.16% .sup.16% Mean SPF 13.9 12.2

[0072] Preparation: Phase I was heated to 75-80 C. under stirring until a clear oil was obtained. The formulation was brought to room temperature under stirring, then added with ethanol.

[0073] Table 2 and FIG. 2, relating to oil formulations with medium sun protection, also exhibit differences in the absorption curve and in-vitro SPF favourable to formulation F3 containing the compound of example 2 of the invention. In particular, formulation F3 has a considerably higher SPF value and a higher UV absorption curve at all wavelengths.

EXAMPLE 7

ApplicationSun Oil with High SPF

[0074]

TABLE-US-00004 TABLE 3 Anhydrous sun oil formulations and corresponding in-vitro SPF values. F4 F5 F6 Phase Ingredients w/w % w/w % w/w % I Caprylic/Capric Triglyceride 20.0% 19.0% 18.0% Dicapryl Carbonate 20.0% 18.0% 16.0% Dibutyl Adipate 20.0% 19.0% 18.0% C12-15 Alkyl Benzoate 10.0% 9.0% 8.0% Ethylhexyl Salicylate 5.0% 5.0% 5.0% Sunscreen of example 2 10.0% 15.0% Sunscreen of comparative 5.0% example 3 Uvasorb HEB 4.0% 4.0% 4.0% II Ethanol .sup.16% .sup.16% .sup.16% Mean SPF 12.2 18.9 23.9

[0075] Preparation: Phase I was heated to 75-80 C. under stirring until a clear oil was obtained. The formulation was brought to room temperature under stirring, and concluded with the addition of ethanol.

[0076] The higher solubility of the sunscreen of example 2 also allows the level of the sunscreen in the sun oil formulation to be increased, leading to a marked increase in both UVA and UVB sun protection in formulas F5 and F6 (Table 3 and FIGS. 3).

[0077] In the case of formulation F4 of the sunscreen of comparative example 3, it was impossible to increase the dose, because its low solubility limited its use. In fact, after only two weeks at 25 C. after its production, formulation F4, unlike formulations F5 and F6, showed clear signs of precipitation of the sunscreen of comparative example 3. As in the above-mentioned case, the low solubility thereof leads to precipitation of the sunscreen in the formulation, prejudices its stability, and consequently reduces its SPF value.