Acylated pregnane glycosides from Caralluma quadrangula

In a previous study, the methanolic extract as well as the chloroform fraction of the aerial parts of Caralluma quadrangula (Forssk.) N.E.Br. indigenous to Saudi Arabia showed significant in vitro cytotoxic activity against breast cancer (MCF7) cell line. In a biologically-guided fractionation approach, four acylated pregnane glycosides were isolated from the chloroform fraction of C. quadrangula. The structures of the isolated compounds were elucidated by the analysis of their MS and NMR data. The compounds were identified as 12,20-di-O-benzoylboucerin 3-O-?-D-digitoxopyranosyl-(1?4)-?-D-canaropyranosyl-(1?4)-?-D-cymaropyranoside (1), 12,20-di-O-benzoylboucerin 3-O-?-D-cymaropyranosyl-(1?4)-?-D-canaropyranosyl-(1?4)-?-D-cymaropyranoside (2), 12,20-di-O-benzoylboucerin 3-O-?-D-glucopyranosyl-(1?4)-?-D-digitoxopyranosyl-(1?4)-?-D-canaropyranosyl-(1?4)-?-D-cymaropyranoside (3) and 12,20-di-O-benzoyl-3?,5?,12?,14?,20-pentahydroxy-(20R)-pregn-6-ene 3-O-?-D-glucopyranosyl-(1?4)-?-D-digitoxopyranosyl-(1?4)-?-D-canaropyranosyl-(1?4)-?-D-cymaropyranoside (4). The isolated compounds were tested for their cytotoxic activity against breast cancer (MCF7) cell line.