New antitumoral cyciopeptides Short Communication

Summary. Chlamydocin is a powerful in vitro antitumoral agent, quickly inactivated in vivo. A series of cyclic tetrapeptides related to chlamydocin or HC toxin and bearing a bioactive alkylating group on an e-amino-lysyl function have been examined for their antitumoral activity on L1210 and P388 murine leukemia cell lines. One analog was found to be potent at inhibiting L1210 cell proliferation and had a higher therapeutic index than the reference compound bis-flchloroethylnitrosourea on the in vivo P388-induced leukemia model.