Cycloaspeptides F and G, Cyclic Pentapeptides from a Cordyceps-colonizing isolate of Isaria farinosa.

Cycloaspeptides F (1) and G (2), two new cyclic pentapeptides, and the known cycloaspeptides A (3), C (4), and bisdethiodi(methylthio)hyalodendrin (5) have been isolated from the crude extract of the fungus Isaria farinosa that colonizes Cordyceps sinensis. The structures of 1 and 2 were elucidated primarily by NMR and MS methods. The absolute configuration of 1 was assigned using Marfey's method on its acid hydrolysate. Compounds 1 and 2 showed cytotoxic effects against HeLa and MCF7 cell lines, displaying the same magnitude of activity toward the MCF7 cells as the positive control 5-fluorouracil.