Antioxidant Activity of Leaves of Calophyllum rubiginosum

Cytotoxic xanthones isolated from Calophyllum depressinervosum and Calophyllum buxifolium with antioxidant and cytotoxic activities

The stem bark of Calophyllum depressinervosum and Calophyllum buxifolium were extracted and examined for their antioxidant activities, together with cytotoxicity towards human cancer cells. The methanol extract of C. depressinervosum exhibited good DPPH and NO scavenging effects. The strongest BCB inhibition and FIC effects were shown by dichloromethane and ethyl acetate extracts of both species. Overall, DPPH, FRAP and FIC assays showed strong correlation with TPC. For cytotoxicity, hexane extract of C. depressinervosum possessed the strongest anti-proliferative activities towards SNU-1 cells while the hexane extract of C. buxifolium showed the strongest activity towards LS-174T and K562 cells with the IC₅₀ values ranging from 7 to 17 μg/mL. The purification of plant extracts afforded eight xanthones, 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). All the xanthones, except 1 were reported for the first time from both Calophyllum species. The xanthones were examined for their cytotoxic effect against K562 leukemic cells. Compounds 1 and 2 showed strong cytotoxicity with the IC₅₀ values of 2.96 and 1.23 μg/mL, respectively. The molecular binding interaction of 2 was further investigated by performing molecular docking study with promising protein receptor Src kinase.

Cytotoxic Compounds from the Stem Bark of Calophyllum soulattri

Chemical investigation of the stem bark of Calophyllum soulattri resulted in the isolation of a new phloroglucinol, namely calosubellinone (1) along with two known compounds, garsubellin B (2) and soulattrone A (3). The structures of these compounds were established on the basis of spectroscopic methods. Compounds 1 and 2 displayed growth inhibitory activities against HeLa cancer cells comparable to the positive control cisplatin, with IC50 values of 19.3 and 16.5 μM, respectively. In addition, compound 2 also showed antiproliferative activity against a MDA-MB-231 cancer cell line with an IC50 value of 17.7 μM. Compounds 1 and 2 were found to exhibit good cancer-specific cytotoxicity when tested against noncancerous HEK293 cells. These findings have highlighted the therapeutic potential of compounds 1 and 2 as anticancer agents.