Described herein are compounds of the formula ##STR1## wherein R.sup.1 signifies hydrogen, lower-alkyl or a cation; R.sup.2 signifies hydrogen, lower-alkyl, lower-alkoxy or halogen; M signifies --CONH-- or --NHCO--; X and Y are each independently selected from the group consisting of >CR.sup.3 R.sup.4 and --CONR.sup.5 --; Z signifies >CR.sup.6 R.sup.7 ; R.sup.3, R.sup.4, R.sup.6 and R.sup.7 are each independently selected from the group consisting of hydrogen and lower-alkyl; R.sup.5 signifies alkyl; and n signifies 0, 1 or 2; provided that at least one of X or Y is --CONR.sup.5 -- which is bonded to the phenyl ring via the N atom. These compounds are useful in the treatment and prophylaxis of neoplasms, dermatoses and aging of the skin.