[The structure and antitumor activity of antitumor antibiotics--recent progress]

Effort looking for new antitumor antibiotics useful for the treatment of curing cancer resulted to the discovery of a number of new compounds with newer action mechanism as well as newer structural feature. The antibiotics which have been discovered since 1984 are discussed under classifications of action mechanism and structural feature, as well. The first group, which belong to a novel class of antibiotics containing a bicyclodiynene carbon skeleton in the molecules exhibited the most strong anti-tumor activity comparing with the antitumor antibiotics so far discovered. The action mechanism of this was explained by the diradical formation of diynene-cyclization, which led to the scission of double strand DNA. Amongst, esperamicin A seems of great interest in view of the therapeutic development. Moreover, elsamicin A, a member of chatarin antibiotics, and FR-900482 compound, an antibiotic having a polycyclic alkalodal skeleton are under development for the new chemotherapeutic agents. Rhizoxin, the metabolite of Rhizopus chinensis is also a promising candidate as anticancer agent. Its action mechanism was classified as an inhibitor of mitosis by binding to the microtibline proteins. Rhizoxin A shows no cross resistance with vincristine. MX2 (KRN 8602), the morpholino derivative of 13-deoxo-10-hydroxy-carminomycin, shows anticancer activity against tumor cells resistant to P388/ADM as well as low cardial toxicity. Miscellaneous compounds whose action mechanism are unknown are described.