MANUMYCIN-E, MANUMYCIN-F AND MANUMYCIN-G, NEW MEMBERS OF MANUMYCIN CLASS ANTIBIOTICS, FROM STREPTOMYCES SP

Three new manumycin class antibiotics, namely manumycins E, F and G, w ere isolated from the culture broth of Streptomyces sp. strain WB-8376 . Their structures were established by spectroscopic methods, and the S configuration of C-4 in the epoxycyclohexenone moiety was determined by CD exciton chirality method for each of the three compounds. Manum ycins E, F and G are active against Gram-positive bacteria, and have m oderate inhibitory effects on the farnesylation of p21 ras protein. Th ey demonstrated weak cytotoxic activity against human colon tumor cell HCT-116.