Axinellasins A-D, Immunosuppressive Cycloheptapeptide Diastereomers, Discovered via a Precursor Ion Scanning-Supercritical Fluid Chromatography Strategy from the Marine Sponge species.

The precursor ion scanning-supercritical fluid chromatography (PI-SFC) method was applied to explore new methionine sulfoxide-containing cycloheptapeptides, axinellasins A-D (-), from the marine sponge sp. Their structures, including absolute configurations, were elucidated by detailed spectroscopic analyses and X-ray crystallography. The total synthesis of was completed via an Fmoc solid/solution-phase synthesis. Compounds - exhibited immunosuppressive effects via inhibition of T and B cell proliferation, and and showed better inhibitory activities than their corresponding diastereomers.