Octyl substituted butenolides from marine-derived Streptomyces koyangensis.

A new butenolide derivative (1) featuring octyl substitution at γ-position, together with four known analogues (2-5) were isolated from marine-derived Streptomyces koyangensis SCSIO 5802. The structure of 1 was elucidated by HR-MS and NMR spectroscopic data analyses. The absolute configuration of the stereo centre in lactone ring of 1 was determined by comparison of CD spectrum with those of known compounds. Compound 1 exhibited mild antiviral activity against herpes simplex virus with EC50 value of 25.4 µM.