Disclosed are merocyanine derivatives of formula (1), wherein R1 and R2 independently from each other are branched C4-C22alkyl; or branched C4-C12 alkenyl; R3 and R4 independently from each other are cyano; COR7, COOR7; CONR7R8; SO2(C6-C12)aryl; C2-C12alk-1-enyl; C3-C12cycloalk-1-enyl; C2-C12alk-1-inyl; C2-C12heteroalkyl; C3-C5heterocycloalkyl; C6-C10aryl; or C1-C9heteroaryl; wherein at least one of R3 and R4 is cyano; R5 and R6 independently from each other are hydrogen; C1-C6alkyl; C5-C8cycloalkyl which may be substituted by one or more than one C1-C4alkyl; and R7 and R8 independently from each other are hydrogen; C1-C22alkyl; C2-C12alkenyl; C2-C12alkinyl; C3-C12cycloalkyl; C3-C12cycloalkenyl; —(CH2)tCOOH; C7-C12aralkyl; C1-C12heteroalkyl; C2-C11heteroaralkyl; C6-C10aryl; C1-C9heteroaryl. The compounds are useful as UV absorbers for protecting human hair and skin against the damaging effect of UV radiation.