Structure Revision and Absolute Configuration of Malhamensilipin A from the Freshwater Chrysophyte Poterioochromonas malhamensis

Malhamensilipin A (2), a bioactive chlorosulfolipid initially reported in 1994 front the freshwater alga Poterioochromonas malhamensis, was reinvestigated for its Structural and stereochemical feature. HRESIMS data revealed that 2 possesses two Sulfate groups rather than the one originally reported. A combination of J-based configurational and Mosher's analyses led us to assign its absolute configurational as 11R, 12S, 13S, 14R, 15S, and 16S. Finally, comparison of H-1 and C-13 NMR chemical shifts with synthetic standards confirmed that malhamensilipin A (2) possesses it terminal double bond of E configuration.