Secocycloartane Triterpenoidal Saponins from the Leaves of Astragalus membranaceus BUNGE

Two new 9,10-secocycloartane triterpenoidal saponins. named huangqiyenins E (1) and F (2) were isolated from the leaves of Astragalus membranaceus BUNGE. Enzymatic hydrolysis of 1 and 2 afforded the aglycones huangqiyegenins III (3) and IV (4), resp. Further alkaline hydrolysis of 3 provided trideacetylhuangqiyegenin III (5). Their structures were established by detailed spectroscopic analysis as (3S,5R,6S,10R,12 beta,16 beta,24E)-26-(beta-D-glucopyranosyloxy)-10,16-dihydroxy-4,4,14-trimethyl-9,19-cyclo-9,10-secocholesta-9(11),24-diene-3,6,12-triyl triacetate (1), (3S,5R,6S10R, 16 beta,24E)-26-(beta-D-glucopyranosyloxy)-10,16-dihydroxy-4,4,14-trimethyl-9,19-cyclo-9,10-secocholesta-9(11), 24-diene-3,6-diyl diacetate (2), (3S,5R,6S,10R,12 beta,16 beta,24E)-10, 16,26-trihydroxy-4,4,14-trimethyl-9,19-cyclo-9,10-secocholesta 9(11),24-diene-3,6,12-triyl triacetate (3), (3S,5R,6S,10R,16 beta,24E)-10,16,26-trihydroxy-4,4,14-trimethyl-9,19-cyclo-9,10-secocholesta-9(11),24-diene-3,6-diyl diacetate (4), and (3S,5R, 6S,10R12 beta,16 beta,24E)-4,4,14-trimethyl-9,19-cyclo-9,10-secocholesta-9(11),24-diene-3,6,10,12,16,26-hexol (5), resp.