Secocycloartane Triterpenoidal Saponins from the Leaves of Astragalus membranaceusBunge

Abstract magnified image 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 (3 S ,5 R ,6 S ,10 R ,12 β ,16 β ,24 E )‐26‐( β ‐ 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 ), (3 S ,5 R ,6 S ,10 R , 16 β ,24 E )‐26‐( β ‐ D ‐glucopyranosyloxy)‐10,16‐dihydroxy‐4,4,14‐trimethyl‐9,19‐cyclo‐9,10‐secocholesta‐9(11), 24‐diene‐3,6‐diyl diacetate ( 2 ), (3 S ,5 R ,6 S ,10 R ,12 β ,16 β ,24 E )‐10,16,26‐trihydroxy‐4,4,14‐trimethyl‐9,19‐cyclo‐9,10‐secocholesta‐9(11),24‐diene‐3,6,12‐triyl triacetate ( 3 ), (3 S ,5 R ,6 S ,10 R ,16 β ,24 E )‐10,16,26‐trihydroxy‐4,4,14‐trimethyl‐9,19‐cyclo‐9,10‐secocholesta‐9(11),24‐diene‐3,6‐diyl diacetate ( 4 ), and (3 S ,5 R , 6 S ,10 R ,12 β ,16 β ,24 E )‐4,4,14‐trimethyl‐9,19‐cyclo‐9,10‐secocholesta‐9(11),24‐diene‐3,6,10,12,16,26‐hexol ( 5 ), resp.