Benzopyran Derivatives and an Aliphatic Compound from a Mangrove Endophytic Fungus Penicillium citrinum QJF-22.

Two new benzopyran derivatives, (2R,4S)-5-methoxy-2-methyl-3,4-dihydro-2H-1-benzopyran-4-ol and (2S,4R,2'S,4'R)-4,4'-oxybis(5-methoxy-2-methyl-3,4-dihydro-2H-1-benzopyran), and a new aliphatic compound, (3E,5Z,8S,10E)-8-hydroxytrideca-3,5,10,12-tetraen-2-one, together with three known benzopyran derivatives, were obtained from a mangrove endophytic fungus Penicillium citrinum QJF-22 collected in Hainan island. Their structures were determined by analysis of spectroscopic data and the relative configuration of (2R,4S)-5-methoxy-2-methyl-3,4-dihydro-2H-1-benzopyran-4-ol was also confirmed by single-crystal X-ray diffraction. The absolute configurations of four compounds were established by comparison of ECD spectra to calculations. The configuration of (3E,5Z,8S,10E)-8-hydroxytrideca-3,5,10,12-tetraen-2-one was confirmed by comparison of optical value to the similar compound. The configurations of the compounds (2S,4S)-5-methoxy-2-methyl-3,4-dihydro-2H-1-benzopyran-4-ol and (2R,4R)-5-methoxy-2-methyl-3,4-dihydro-2H-1-benzopyran-4-ol were first determined. (3R,4S)-3,4,8-Trihydroxy-3,4-dihydronaphthalen-1(2H)-one exhibited moderate inhibitory effects on LPS-induced NO production in RAW264.7 cells with IC50 of 44.7 μM, and without cytotoxicity to RAW264.7 cells within 50 μM.