Triaromatic compounds and pharmaceutical/cosmetic compositions comprised thereof

A triaromatic compound having the structural formula (I):

• ##STR7## in which R.sub.1 is (i) a --CH.sub.3 radical, (ii) a --CH.sub.2 OH radical, (iii) a radical --O--R.sub.4, or (iv) a radical --CO--R.sup.5, wherein R.sub.4 and R.sub.5 are as defined below;
• Ar.sub.1 is a radical selected from among those of the following formulae (a) to (d):
• ##STR8## wherein R.sub.6 is as defined below;
• X--Y is a bridging radical selected from among those of the following formulae (e) to (m), configured either from left-to-right or right-to-left:
• ##STR9## wherein R.sub.7, R.sub.8 and R, are as defined below;
• Ar.sub.2 is a radical selected from among those of the following formulae (n) to (q):
• ##STR10## with the proviso that Ar.sub.2 is in the ortho- or meta-position on the phenyl nucleus relative to the X-Y bridge and wherein R.sub.1 l and R.sub.11 are as defined below;
• R.sub.2 and R.sub.3, which may be identical or different, are each a hydrogen atom, a linear or branched alkyl radical having from 1 to 20 carbon atoms, a halogen atom, a hydroxyl radical optionally protected as an acetoxy moiety, an alkoxy radical, a polyether radical, a nitro radical, an amino radical optionally protected as an acetamide moiety or substituted with one or two lower alkyl radicals;
• R.sub.4 is a hydrogen atom, a lower alkyl radical or a radical --CO--R.sub.12, wherein R.sub.12 is as defined below;
• R.sub.5 is (i) a hydrogen atom, (ii) a lower alkyl radical,(iii) a radical of the formula:
• ##STR11## wherein R' and R" are as defined below, or (iv) a radical --OR.sub.13, wherein R.sub.13 is as defined below;
• R.sub.6 is a hydrogen atom, a halogen atom, a linear or branched alkyl radical having from 1 to 20 carbon atoms, a hydroxyl radical, a radical --OR.sub.14 or --OCOR.sub.1, or a polyether radical, wherein R.sub.14 is as defined below;
• R.sub.7 and R.sub.8, which may be identical or different, are each a hydrogen atom or a lower alkyl radical;
• R.sub.9 is a hydrogen atom or a lower alkyl radical;
• R.sub.10 and R.sub.11, which may be identical or different, are each a hydrogen atom, a linear or branched alkyl radical having from 1 to 20 carbon atoms, a halogen atom, a hydroxyl radical optionally protected as an acetoxy moiety, an alkoxy radical, a polyether radical, a nitro radical, an amino radical optionally protected as an acetamide moiety or substituted with one or two lower alkyl groups, a CF.sub.3 radical, an alkenyl radical or a radical --(CH.sub.2).sub.n --R.sub.15, wherein n and R.sub.15 are as defined below;
• R' and R", which may be identical or different, are each a hydrogen atom, a lower alkyl radical, a mono- or polyhydroxyalkyl radical, an optionally substituted aryl radical or an amino acid or peptide residue, with the proviso that R' and R" may together form, with the nitrogen atom from which they depend, a heterocycle;
• R.sub.12 is a lower alkyl radical;
• R.sub.13 is a hydrogen atom, a linear or branched alkyl radical having from 1 to 20 carbon atoms, an alkenyl radical, a mono- or polyhydroxyalkyl radical, an optionally substituted aryl or aralkyl radical, or a sugar residue;
• R.sub.14 is a lower alkyl radical;
• R.sub.15 is a hydroxyl radical optionally protected as an acetoxy moiety, an alkoxy radical, or a polyether radical;
• and n is an integer ranging from 1 to 6 inclusive;
• or a pharmaceutically/cosmetically acceptable salt or optical or geometric isomer thereof.