Merocyanine derivatives for cosmetic use

A method of protecting human and animal hair or skin from UV radiation, which comprises contacting said hair or skin with an effective UV-protective amount of a compound of formula

• wherein
• R1 and R2 are each independently of the other hydrogen;
• C1-C22alkyl;
• cyclo-C3-C8alkyl;
• or unsubstituted or C1-C6alkyl- or C1-C6alkoxy-substituted C6-C20aryl;
• or R1 and R2 together with the nitrogen atom linking them form a —(CH2)m— ring which is uninterrupted or interrupted by —O— or by —NH—;
• R3 is a cyano group;
• —COOR5;
• —CONHR5;
• —COR5;
• —SO2R5;
• or —CONR1R5;
• R4 is a cyano group;
• —COOR6;
• —CONHR6;
• —COR6;
• —SO2R6;
• or —CONR2R6;
• R5 and R6 are each independently of the other C1-C22alkyl;
• cyclo-C3-C8alkyl;
• or unsubstituted or C1-C6alkyl-substituted C6-C20aryl;
• or R3 and R4 together or R5 and R6 together form a 5- to 7-membered, monocyclic, carbocyclic or heterocyclic ring;
• Z1 and Z2 are each independently of the other a —(CH2)1— group which is uninterrupted or interrupted by —O—, —S—, or by —NR7—, and/or is unsubstituted or substituted by C1-C6alkyl;
• R7 is C1-C5alkyl;
• l is a number from 1 to 4;
• m is a number from 1 to 7;
• n is a number from 1 to 4;
• when n=2, R1, R5 or R6 is a bivalent alkyl group;
• or R1 and R2 together with the 2 nitrogen atoms linking them form a —(CH2)m— ring;
• when n=3, R1, R5 or R6 is a trivalent alkyl group;
• when n=4, R1, R5 or R6 is a tetravalent alkyl group;
• and
• R1 and R2 in formula (1) are not simultaneously hydrogen.