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 IC50's down to 1.01 mu M, while 1 and 2 showed no significant activity.