Cytotoxic activities of xanthones isolated from calophyllum depressinervosum and calophyllum buxifolium against snu-1 and Is174t cell lines

A series of xanthones isolated from Calophyllum depressinervosum and Calophyllum buxifolium were studied for their cytotoxicities. Ananixanthone (1), caloxanthone B (2), caloxanthone I (3), caloxanthone J (4), xanthochymone B (5), thwaitesixanthone (6),1,3,5,6-tetrahydroxyxanthone (7) and dombakinaxanthone (8) were successfully isolated from both Calophyllum species. These eight compoundsand a synthetically derived compound, thwaitesixanthone monoacetate (9) were tested for cytotoxicity activities against stomach cancer, SNU-1and LS-174T cell lines. Caloxanthone B (2) gave the highest cytotoxic activity against SNU-1 with anIC50 valueof 1.47μg/ml. Meanwhile, xanthochymone B (5) shows the highest cytotoxic activity against LS-174T cell with an IC50 value of 0.45μg/ml. The structure-activity relationship (SAR) studies predicted that the presence and arrangements of furano, pyrano and prenyl substituents in the xanthone skeleton are important towardsthe cytotoxic activity. A molecular docking simulation was performed tomodel the probable binding models of compound 2 into the HER-2(PDB ID: 3PP0) and compound 5 into β-catenin (PDB ID: 1JDH).