Two Gracilioethers Containing a [2(5H)-Furanylidene]ethanoate Moiety and 9,10-Dihydroplakortone G: New Polyketides from the Caribbean Marine Sponge .

Gracilioether M () and 11,12-dihydrogracilioether M (), two polyketides with a [2(5H)-furanylidene]ethanoate moiety, along with known plakortone G () and its new naturally occurring derivative 9,10-dihydroplakortone G (), were isolated from the Caribbean marine sponge . The structures and absolute configuration of , , and were characterized by analysis of HRESIMS and NMR spectroscopic data, chemical derivatization, and side-by-side comparisons with published NMR data of related analogs. Compounds and and a mixture of and were evaluated for cytotoxicity against MCF-7 human breast cancer cells. In addition, the in vitro antiplasmodial activity against of these compounds was scrutinized using a drug luminescence assay.