Cytochalasins and polyketides from the fungus Diaporthe sp. GZU-1021 and their anti-inflammatory activity

Four new compounds: diaporthichalasins A-C (1-3) and biatriosporin N (7), along with six known compounds (4-6 and 8-10) were separated from the culture of the fungus Diaporthe sp. GZU-1021. The absolute configurations of 1-3 were determined by quantum chemical calculations, X-ray diffraction, and spectroscopic analysis. The structure of 4 was analyzed by X-ray crystallography analysis for the first time. All of the isolates were evaluated on the production of nitric oxide in lipopolysaccharide-induced microglial cells (RAW 264.7 cells). Compounds 5-10 exhibited significant inhibitory effects against nitric oxide production with IC50 values from 1.94 to 16.5 μM than positive control (indomethacin, IC50 = 29.7 μM). This is the first time tetrahydroxanthone dimer (10), as a novel carbon skeleton possessing NO inhibitory activity, was reported.