Xanthones from the stems of Calophyllum membranaceum Gardn. et Champ. and their anti-inflammatory activity

Eighteen undescribed xanthones, including six pairs of xanthone enantiomers, three xanthones, and three xanthone glycosides, together with one pair of known xanthone enantiomers and 12 known xanthones, were isolated from the stems of Calophyllum membranaceum Gardn. et Champ. Their structures were elucidated by spectroscopic analysis, and the absolute configuration of the enantiomers was determined by using experimental and calculated electronic circular dichroism data. All compounds were screened for their anti-inflammatory effects on LPS-induced BV-2 microglial cells. Among them, six compounds showed remarkable activities with IC50 values of 7.8–36.0 μM. [Display omitted] Six pairs of undescribed xanthone enantiomers were isolated from the stems of Calophyllum membranaceum, and their anti-inflammatory effects were evaluated. •Six pairs of undescribed xanthone enantiomers were isolated from the stems of Calophyllum membranaceum.•The absolute configuration of the enantiomers was determined by experimental and calculated ECD spectra.•All isolated compounds were evaluated for anti-inflammatory activity.