Hybrid isoprenoids from a reeds rhizosphere soil derived actinomycete Streptomyces sp. CHQ-64.

Indotertine A (1), a hybrid isoprenoid with a condensed pentacyclic skeleton, together with two related hybrid isoprenoids, drimentines F (2) and G (3), were isolated from a reeds rhizosphere soil derived actinomycete Streptomyces sp. CHQ-64. Their structures including absolute configurations were elucidated by spectroscopic methods, X-ray single crystal diffraction analysis, and TDDFT ECD calculations. Drimentines G (3) showed strong cytotoxicity against human cancer cells lines with IC(50)'s down to 1.01 μM, while 1 and 2 showed no significant activity.