[Antitumor activity of yungumycin]

Yungumycin, produced by a Streptomyces strain which was isolated from a soil sample collected in Guanping Nature Conservation Zone, Yunnan Province, China, has been verified to be identical with gougerotin. Determined by clonogenic assay, the IC50 of yungumycin to KB cells was found to be 1 microgram.ml-1. By spermatogonial assay, the activity of yungumycin was very close to that of 5-FU and MTX. Administered by i.p. route, yungumycin showed moderate inhibition against colon carcinoma 26 in mice. However, yungumycin by oral administration exerted highly inhibitory effects on both colon carcinoma 26 and sarcoma 180 (solid tumor) in mice and the inhibition rates reached 85% and 83%, respectively, at tolerable dose. Compared at equitoxic dose of 1/6 LD50, the inhibitory effect of yungumycin (15 mg.kg-1) on sarcoma 180 was similar to that of 5-FU (40 mg.kg-1), showing 72% and 70% tumor inhibition, respectively. Initially, gougerotin was reported as an antibacterial antibiotic without mentioning its antitumor activity. The present studies demonstrate that yungumycin (gougerotin), by oral administration, may be useful in cancer chemotherapy.