Cytotoxic Bromine- and Iodine-Containing Cytochalasins Produced by the Mangrove Endophytic Fungus Phomopsis sp. QYM-13 Using the OSMAC Approach.

Twelve new cytochalasins, phomopchalasins D-O ( 1 - 3 , 5 - 12 , and 14 ), including one brominated ( 2 ) and two iodinated cytochalasins ( 3 and 6 ), together with six known analogues ( 4 , 13 , and 15 - 18 ) were isolated from the mangrove-derived fungus Phomopsis sp. QYM-13 treated with 3% NaBr or 3% KI in potato liquid medium. Their structures and absolute configurations were established by extensive spectroscopic analysis (1D and 2D NMR, HRESIMS), electronic circular dichroism calculations, and a single-crystal X-ray diffraction experiment. Compounds 3 and 6 represent the first iodinated cytochalasins. Compounds 2 , 15 , 17 , and 18 exhibited significant cytotoxicity against human cancer cell line MDA-MB-435 with IC ₅₀ values ranging from 0.2 to 8.2 μM.