Diaromatic compounds derived from a salicylic unit and their use in human and veterinary medicine and in cosmetics

A diaromatic compound, having the following formula:

• ##STR9## in which:
• R.sub.1 represents --CH.sub.3, --CH.sub.2 OH, --COR.sub.8 or --CH.sub.2 OCOR.sub.9,
• R.sub.8 representing a hydrogen atom, OH, --OR.sub.10, ##STR10## or a lower alkyl radical, R.sub.10 representing an alkyl radical having 1 to 20 carbon atoms, an alkenyl radical having 2 to 20 carbon atoms, or an aryl or aralkyl radical,
• r and r', identical or different, representing a hydrogen atom, a lower alkyl radical, an aryl radical, an aralkyl radical, an .alpha.-aminoacid residue, a sugar residue or a heterocycle or r and r' taken together forming a heterocycle,
• R.sub.9 representing an alkyl radical having 1 to 20 carbon atoms, an alkenyl radical having 2 to 20 carbon atoms or a sugar residue,
• R.sub.2 represents --OR.sub.11 or --OCOR.sub.11
• R.sub.3 represents a hydrogen atom, --OR.sub.11 or --OCOR.sub.11
• R.sub.11 representing a hydrogen atom, a lower alkyl radical, a fluoroalkyl radical having 1 to 6 carbon atoms and 3 to 7 fluorine atoms, an aryl radical or an aralkyl radical,
• R.sub.4 represents a hydrogen atom, OH, a lower alkyl radical, an alkoxy radical having 1 to 6 carbon atoms, a fluorine or chlorine atom or the --CF.sub.3 group,
• R.sub.5 and R.sub.6 or R.sub.6 and R.sub.7 taken together form, with the adjacent aromatic ring, a ring with 5 or 6 members optionally substituted by methyl groups and optionally interrupted by an oxygen or sulphur atom, R.sub.5 or R.sub.7, whichever does not form the ring, is hydrogen,
• X is a divalent radical which from left to right or conversely is selected from the group consisting of:
• (i) --C(R.sub.13 R.sub.14)--C(R.sub.16 R.sub.18)--W--, and
• (ii) --C(R.sub.13 R.sub.14)--C(R.sub.15 R.sub.16)--C(R.sub.18 R.sub.20)--
• in which:
• W represents an oxygen atom, --NR.sub.12 or S(S).sub.n, n being 0, 1 or 2,
• R.sub.13, R.sub.15 and R.sub.20 represent a hydrogen atom, --OR.sub.11, ##STR11## an aralkyl radical, a lower alkyl radical, a monohydroxyalkyl radical or a polyhydroxyalkyl radical,
• r" and r"', identical or different, representing a hydrogen atom, a lower alkyl radical, an alkenyl radical having 2 to 6 carbon atoms or an alkynyl radical having 2 to 6 carbon atoms,
• R.sub.14, R.sub.16 and R.sub.18 represent a hydrogen atom, an aralkyl radical, a lower alkyl radical, or a monohydroxyalkyl or polyhydroxyalkyl radical,
• when X represents (i), R.sub.13 and R.sub.14 together can form a .dbd.N--OR.sub.11 group or a .dbd.N--OCOR.sub.11 group,
• and when X represents (ii) R.sub.14, R.sub.16 and R.sub.18 can also represent --0R.sub.11 or --OCOR.sub.11 or R.sub.13 and R.sub.14 or R.sub.15 and R.sub.16 taken together can form a .dbd.NOR.sub.11 group or a .dbd.N--OCOR.sub.11 group,
• R.sub.12 representing a hydrogen atom, a lower alkyl radical, an aralkyl radical, an alkenyl radical having 2 to 6 carbon atoms, an alkynyl radical having 2 to 6 carbon atoms or a fluoroalkyl radical having 1 to 6 carbon atoms and 3 to 7 fluorine atoms,
• or a salt of the compound of formula (I) when R.sub.1 represents a carboxylic acid function or when R.sub.13, R.sub.16 or R.sub.20 represents an amine function, or an optical isomer of the compound of formula (I).