Photoprotective/cosmetic compositions comprising substituted polyorganosiloxanes/polyorganosilanes

A topically applicable sunscreen/cosmetic composition adopted for the photoprotection of human skin and/or hair, comprising a photoprotecting effective amount of a compound having one of the formulae (1) to (3):

• ##STR23## in which the radicals R, which may be identical or different, are each C.sub.1 -C.sub.10 alkyl, phenyl or 3,3,3-trifluoropropyl radicals, at least 80% by number of the radicals R being methyl radicals;
• the radicals B, which may be identical or different, are each a radical R or a radical A as defined below;
• the radicals R', which may be identical or different, are each a C.sub.1 -C.sub.8 alkyl radical or a phenyl radical;
• r is an integer ranging from 0 to 50, inclusive, and s is an integer ranging from 0 to 20, inclusive, with the proviso that, if s is zero, then at least one of the two radicals B is a radical A;
• u is an integer ranging from 1 to 6, inclusive, and t is in integer ranging from 0 to 10 inclusive, with the proviso that t+u is equal to or greater than 3;
• and the radical A is a univalent radical bonded directly to a silicon atom, and which has the following formula (4):
• ##STR24## wherein the radicals Y, which may be identical or different, are each a C.sub.1 -C.sub.8 alkyl radical, a halogen atom or a C.sub.1 -C.sub.4 alkoxy radical, with the proviso that, in the latter event, two adjacent radicals Y on the same aromatic nucleus can together form an alkylidenedioxy radical in which the alkylidene group has from 1 to 2 carbons atoms;
• X is O or NH;
• Z is hydrogen or a C.sub.1 -C.sub.4 alkyl radical;
• n is an integer ranging from 0 to 3, inclusive;
• m is 0 or 1, with the proviso that when m is zero, or when m is equal to 1 and X is NH, necessarily (i) n cannot be zero and (ii) at least one of the radicals Y is an alkoxy radical;
• and p is an integer ranging from 1 to 10, inclusive, in a cosmetically acceptable vehicle, carrier or diluent therefor.