Abstract: Antineoplastic cyclolignan derivatives are of formula (I): ##STR1## in which Ar is a 3,4,5-trialkoxyphenyl or 4-hydroxy-3,5-dialkoxyphenyl; X is an oxygen, sulphur or nitrogen atom, a methine group .dbd.CH-- or an alkylmethine group .dbd.C(alkyl)--; Y is a hydrogen atom or an alkyl, alkenyl, (poly)haloalkyl, aryl, hydroxy, alkoxy, amino, monoalkylamino, dialkylamino, (poly)haloalkylamino, arylamino, acyl or acetamido group, or the group Y is absent; Z is an alkyl, hydroxyalkyl, acyl, carboxy, alkoxycarbonyl or aryloxycarbonyl group; and the dotted lines indicate one double bond located at position .DELTA..sup.7-8 or .DELTA..sup.8-8'.

Abstract: Immunosuppressive cyclolignan derivatives are provided of formula (I) or (II): ##STR1## in which R.sup.1 is hydrogen, hydroxy, alkoxy; R.sup.2 and R.sup.3 are hydrogen, alkyl, acyl, or together R.sup.2 and R.sup.3 form a group --CHR.sup.4 --; R.sup.4 is hydrogen, alkyl, alkenyl, hydroxyalkyl, (poly)haloalkyl, aryl, acyloxyalkyl, alkoxy, carboxyalkyl, alkoxycarbonyl, carbamoyl; R.sup.5 when present is hydrogen, alkyl, alkenyl, aryl, (poly)haloalkyl, acyl, carbamoyl, or thiocarbamoyl; R.sup.6 is alkyl, hydroxyalkyl, haloalkyl, acyl, acyloxyalkyl, carboxy or alkoxycarbonyl; Ar is 3,4,5-trialkoxyphenyl or 4-hydroxy-3,5-dialkoxyphenyl; and X is nitrogen or oxygen.