TRITERPENE GLYCOSIDES OF Astragalus AND THEIR GENINS. XII. ASKENDOSIDE B FROM Astragalus taschkendicus

Article abstract of DOI:10.1007/BF00575698

On the basis of chemical transformations and with the aid of physicochemical characteristics it has been established that a new glycoside of the cycloartane series - askendoside B (I) - isolated from the roots of Astragalus taschkendicus Bge., is 20S,24R-epoxycycloartane-3β,6α,16β,25-tetraol 3-O-2)-(3'-O-acetyl-β-D-xylopyranoside)> 6-O-β-D-xylopyranoside, C47H76O18, mp 215-218 deg C, <α>²⁰_D -45.5 deg (c 1.1; pyridine).The acid hydrolysis of (I) yielded cyclosiversigenin (II) with mp 239-241 deg C, <α>²⁰_D +54.5 deg (c 1.2; MeOH), and cyclosiversigenin 3-O-β-D-xylopyranoside (III) with mp 262-264 deg C, <α>²⁰_D +41 deg (c 0.4; MeOH).The periodate oxidation of glycoside (I) followed by acid hydrolysis likewise led to (II) and to D-xylose.The alkaline hydrolysis of (I) yielded askendoside D (IV), with mp 235-236 deg C, <α>²³_D -8.5 deg (c 1.0; pyridine).The Smith degradation of (I) led to (III).The IR and PMR spectra of (I) are given.