Chemical Constituents from Solanum glabratum Dunal var. sepicula

In the course of screening program of Saudi plants for their potential biological activity, the methanolic extract of Solanum glabratum Dunal var. sepicula as well as its different fractions were tested for its possible cytoxicity in prostate cancer (PC3) and colon cancer (HT29) cell lines using the MTT assay. In the present study, three spirostan saponins and one flavonoid glycoside were isolated from the active n-butanol fraction through a bio-guided fractionation approach. Two new saponin glycosides were identified as 23-β-Dglucopyranosyl (23S, 25R)-spirost-5-en-3, 23 diol 3-O-α-L-rhamnopyranosyl-(1→2)-O-[α-L-rhamnopyranosyl(1→4)]-β-D-glucopyranoside (2) and (25R)-spirost-5-en-3-ol 3-O-α-L-rhamnopyranosyl-(1→2)-O-[β-Dglucopyranosyl-(1→3)]-β-D-galactopyranoside (3). In addition, two known compounds were also isolated and identified as isorhamnetin-3-O-α-L-rhamnopyranosyl (1→6) β-D-glucopyranoside (1) and (23S, 25R)-spirost-5en-3, 23 diol 3-O-α-L-rhamnopyranosyl-(1→2)-O-[α-L-rhamnopyranosyl-(1→4)]-β-D-glucopyranoside (4). The structures of the isolated compounds were elucidated based on their MS, one dimensional and extensive two dimensional NMR spectral data. Among the isolated metabolites, compound 3 showed the highest cytotoxic activity in both PC3 and HT29 cell lines with an IC50 values of 14.8 and 19.5 μg/mL, respectively.