The metabolites of mangrove endophytic fungus Zh6-B1 from the South China Sea.

Two new metabolites, 3R,5R-Sonnerlactone (1) and 3R,5S-Sonnerlactone (2), were isolated from the mangrove endophytic fungus Zh6-B1 obtained from the South China Sea. Their structures were elucidated by MS and NMR. The absolute configuration of compound 1 was determined by single-crystal X-ray analysis using Cu Kalpha radiation. The absolute configuration of compound 2 was determined by NOESY analysis and comparing circular dichroism spectroscopy with compound 1. The antiproliferative activity of compound 1 and 2 against the multi-drug resistant human oral floor carcinoma cells (KV) was evaluated.