Antiproliferative Activity of (-)-Rabdosiin Isolated from Ocimum sanctum L.

L. (holy basil; Tulsi in Hindi) is an important medicinal plant, traditionally used in India. The phytochemical study of the nonpolar (dichloromethane 100%) and polar (methanol:water; 7:3) extracts yielded fourteen compounds. Compounds , , , , , and , along with the methanol:water extract were evaluated for their cytotoxicity against the human cancer cell lines MCF-7, SKBR3, and HCT-116, and normal peripheral blood mononuclear cells (PBMCs). Five terpenoids, namely, ursolic acid (), oleanolic acid (), betulinic acid (), stigmasterol (), and -caryophyllene oxide (); two lignans, i.e., (-)-rabdosiin () and shimobashiric acid C (); three flavonoids, luteolin (), its 7---D-glucuronide (), apigenin 7---D-glucuronide (); and four phenolics, (-p-coumaroyl 4---D-glucoside (), 3-(3,4-dihydroxyphenyl) lactic acid (), protocatechuic acid (), and vanillic acid () were isolated. Compound was the most cytotoxic against the human cancer lines assessed and showed very low cytotoxicity against PBMCs. Based on these results, the structure of compound shows some promise as a selective anticancer drug scaffold.