Diterpenoids from Roots of Salvia lachnocalyx; In-silico and In-vitro Toxicity against Human Cancer Cell Lines

Further investigations on phytochemical constituents of dichloromethane extract from roots of Salvia lachnocalyx (S. lachnocalyx) led to the isolation and identification of eight known diterpenoids from this plant for the first time. The chemical structures of the purified compounds were elucidated using spectroscopic analyses including EI-MS, 1H and 13C NMR and by comparison of the resulting spectra with those reported in the literature. Then, the cytotoxic activity of identified compounds was examined against two human cancer cell lines MCF-7 (human breast adenocarcinoma) and K562 (human chronic myelogenous leukemia). Molecular docking of promising cytotoxic compounds were performed by AutoDock Tools 1.5.4 program in the active site of Topoisomerase I. Eight known diterpenoids; 12-hydroxysapriparaquinone (1), 15-deoxyfuerstione (2), horminon (3), 7α-acetoxyroyleanone (4), 11β-hydroxymanoyl oxide (5), microstegiol (6), 1-keto-aethiopinone (7) and 14-deoxycoleon U (8) were isolated of dichloromethane extract from roots of salvia lachnocalyx. Compounds 2, 3, 6, and 8 showed cytotoxic activity against MCF-7 (human breast adenocarcinoma) and K562 (human chronic myelogenous leukemia) cell lines with IC50 values in the range of 2.63-11.83 μg/mL. The inhibition of” topoisomerase I” was suggested by molecular docking calculations as the mechanism of cytotoxicity of the tested compounds. According to cytotoxic assay and docking results, it is suggested that compounds 2, 3, 6, and 8 have good potential as anticancer agents.