Described are merocyanine derivatives of formula wherein R2 is hydrogen； C1-C22alkyl； cyclo-C3-C8alkyl； unsubstituted or C1-C6alkyl- or C1-C6alkoxy-substituted C6-C20aryl； a cyano group； or R1 and R2 together with the nitrogen atom linking them form a &mdash；(CH2)m&mdash； ring which is optionally interrupted by &mdash；O&mdash； or by &mdash；NR7&mdash；； R4 is a cyano group； or -Q1-R5； Q1 is &mdash；COO&mdash；； &mdash；CONH&mdash；； &mdash；CO&mdash；； &mdash；SO2&mdash；； or &mdash；CONR6&mdash；； R5 is C1-C22alkyl； cyclo-C3-C8alkyl； or unsubstituted or C1-C6alkyl-substituted C6-C20aryl； R6 is hydrogen； C1-C22alkyl； cyclo-C3-C8alkyl； unsubstituted or C1-C6alkyl- or C1-C6alkoxy-substituted C6-C20aryl； R7 is hydrogen； C1-C22alkyl； cyclo-C3-C8alkyl； unsubstituted or C1-C6alkyl- or C1-C6alkoxy-substituted C6-C20aryl； the cyclohexene radical C is not substituted or substituted by one or more C1-C5alkyl； m is from 3 to 7； n is from 2 to 4； and o is from 2 to 4. Said merocyanine derivatives are useful in protecting human and animal hair and skin from UV radiation and to cosmetic compositions comprising said derivatives.
