New cytotoxic obacunone-type limonoid and others constituents from the stem bark of Carapa procera DC (Meliaceae)

The phytochemical study of the CH2Cl2- MeOH (1:1, v/v) extract of the stem bark of Carapa procera DC (Meliaceae) led to the isolation and characterisation of a new natural limonoid 7 beta-obacunol (6), along with seven known compounds. Their structures were elucidated by spectroscopic means, including 1 D and 2 D NMR, HRESI-MS and by comparison with published data. The cytotoxicity of compounds 1-6 was assessed in vitro by the WST-1 assay on human lung adenocarcinoma A549 and Raw 264.7 mouse macrophage cell lines. Results suggested that obacunone (3) exhibited the most potent cytotoxic effect against A549 and Raw 264.7 cells with respective IC50 values of 25.24 mu M and 29.14 mu M, while the new natural limonoid 7 beta-obacunol (6) exhibited 32.75 mu M and 39.19 mu M, respectively on both cell lines. Therefore, limonoid derivatives might be promising sources of natural bioactive metabolites against cancer.