Compounds useful as cytotoxic agents are selected from the group consisting of compounds of Formula I and compounds of Formula II: ##STR1## wherein: R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are each independently selected from the group consisting of: hydrogen, alkyl, carboxy, alkoxy, hydroxyalkyl, alkylcarbonyl; alkylcarbonyloxy; alkyl substituted with alkylcarbonyloxy, thiophenylcarbonyl; nitro and cyano; thiophenyl and thiophenylthiophenyl, each of which may be unsubstituted or substituted with alkyl, carboxy, alkoxy, hydroxyalkyl, alkylcarbonyl; alkylcarbonyloxy; alkyl substituted with alkylcarbonyloxy, nitro or cyano; subject to the proviso that at least one of R.sub.1, R.sub.2, R.sub.3 and R.sub.4 is not hydrogen; A.sub.1 and A.sub.2 are each selected from the group consisting of: .dbd.O, alkyl, alkoxy, and alkylcarbonyloxy; and the pharmaceutically acceptable salts thereof. When A.sub.1 and A.sub.2 are .dbd.O, the center ring has only two, and not three, double bonds.

Os compostos úteis como agentes cytotoxic são selecionados dos compostos consistindo do grupo da fórmula I e dos compostos da fórmula II: ## do ## STR1 wherein: R.sub.1, R.sub.2, R.sub.3 e R.sub.4 são cada um selecionado independentemente de consistir do grupo: hidrogênio, alkyl, carboxy, alkoxy, hydroxyalkyl, alkylcarbonyl; alkylcarbonyloxy; o alkyl substituiu com alkylcarbonyloxy, thiophenylcarbonyl; nitro e cyano; thiophenyl e thiophenylthiophenyl, cada um de que pode ser unsubstituted ou substituído com alkyl, carboxy, alkoxy, hydroxyalkyl, alkylcarbonyl; alkylcarbonyloxy; o alkyl substituiu com alkylcarbonyloxy, nitro ou cyano; assunto ao proviso que ao menos um de R.sub.1, R.sub.2, R.sub.3 e R.sub.4 não é hidrogênio; A.sub.1 e A.sub.2 cada um são selecionados de consistir do grupo: dbd.O, alkyl, alkoxy, e alkylcarbonyloxy; e os sais pharmaceutically aceitáveis disso. Quando A.sub.1 e A.sub.2 são dbd.O, o anel center tem somente dois, e não três, ligações dobro.