Bicyclic aromatic compounds and pharmaceutical/cosmetic compositions comprised thereof

Novel pharmaceutically/cosmetically-active bicyclic aromatic compounds having the structural formula (I): ##STR1##

in which Ar₁ is a radical having one of the structural formulae (a)-(c): ##STR2##

and Ar₂, X₁, R¹, R₄, R₅, R₆, R₇, R₈, R₉, R₁₀ and R₁₁ are as defined in the specification.