Wychimicins E and F from a rare actinomycete of the genus Cryptosporangium.

Two new spirotetronate class compounds designated wychimicins E (1) and F (2) were isolated from the culture extract of an actinomycete Cryptosporangium sp. RD061707. Their structures were determined through extensive NMR analysis in comparison with wychimicin C. Both compounds lack one hydroxy group in the decalin moiety, and the relative configuration of the remaining hydroxy group was assigned by NMR analysis of triacetylwychimicin E (3). Compounds 1 and 2 showed potent antimicrobial activity against Kocuria rhizophila and Staphylococcus aureus. These compounds were also modestly cytotoxic against P388 murine leukemia cells.