Phytochemical constituents of Opuntia ficus-indica var. saboten Makino and their hepatoprotective effects against tert-butylhydroperoxide-induced cytotoxicity in human HepG2 cells

The secondary metabolites of Opuntia ficus-indica var. saboten Makino (Cactaceae), were isolated by the various chromatographic separation of the ethyl acetate fraction prepared from the seeds of O. ficus-indica var. saboten to lead two new lignans, erythro-1-(4-hydroxy-3-methoxyphenyl)-2-{2-methoxy-4-[1-(E)-(3-methoxypropenyl)-phenoxy]-propane-1,3-diol, named sabotenin A and threo-1-(4-hydroxy-3-methoxyphenyl)-2-{2-methoxy-4-[1-(E)-(3-methoxypropenyl)-phenoxy]-propane-1,3-diol, named sabotenin B, and an alkaloid, methyl dioxindole-3-acetate along with 15 known compounds. All the isolates were assessed for the cytoprotective effects against tert-butylhydroperoxide (t-BHP)-induced toxicity in HepG2 cells. Among them, lignan compounds significantly protected the HepG2 cells against oxidative damage caused by t-BHP as indicated by the reduced cell growth suppression in a dose-dependent manner. 9'-O-methyl-isoamericanol A showed the most potent cytoprotective effect (36% increased cell viability at 10µM) and the potency was stronger than those of positive controls; quercetin and silybin.

Acknowledgements: This research was supported by a grant (PF06216–00) from Plant Diversity Research Center of 21 ^st Century Frontier Research Program funded by Ministry of Science and Technology of Korean Government.