Four New Chromones from the Endophytic Fungus DHS-48 Isolated from the Chinese Mangrove Plant .

Four new chromones, phomochromenones D-G (-), along with four known analogues, diaporchromone A (), diaporchromanone C (), diaporchromanone D (), and phomochromenone C (), were isolated from the culture of DHS-48 from Chinese mangrove . Their structures were elucidated on the basis of comprehensive spectroscopic analysis. The absolute configurations of and were assigned on the basis of experimental and calculated electronic circular dichroism (ECD) data, and those of enantiomers and were determined by a modified Mosher's method and basic hydrolysis. To the best of our knowledge, phomochromenones D-F (-) possessing a 3-substituted-chroman-4-one skeleton are rarely found in natural sources. Diaporchromone A () showed moderate to weak immunosuppressive activity against T and/or B lymphocyte cells with IC of 34 μM and 117 μM.