Disclosed is the use of the compounds of formula wherein A is a radical of formula R1 and R5 independently from each other are hydrogen; C1-C18alkyl; or C6-C12aryl; R2, R3 and R4 independently from each other are hydrogen; or a radical of formula wherein, in formula (1a), at least one of the radicals R2, R3 and R4 are a radical of formula (1c); R6, R7, R8, R9 and R10 independently from each other are hydrogen; hydroxy; halogen; C1-C18alkyl; C1-C18alkoxy; C6-C12aryl; biphenylyl; C6-C12aryloxy; C1-C18alkylthio; carboxy; —COOM; C1-C18-alkylcarboxyl; aminocarbonyl; or mono- or di-C1-C18alkylamino; C1-C10acylamino; —COOH; M is an alkali metal ion; x is 1 or 2; and y is a number from 2 to 10; for the protection of human and animal hair and skin against the damaging effect of UV radiation. The compounds of formula (1) are high effective UV absorbers for cosmetic formulations aund can be—depending on their physical properties be used in micronized or soluble form.