Acylated-oxypregnane Glycosides from the Roots of Araujia sericifera
Chemical and pharmaceutical bulletin
Araujia sericifera is distributed through out southeast Latin America. 1) In the course of our research on phytochemicals, especially steroidal glycosides, in Asclepiadaceaus plants, we have investigated the constituents of the roots of A. sericifera. The present paper describes the isolation and structural determination of 23 new pregnane glycosides. The MeOH extract from the dried roots of A. sericifera was suspended in water. The suspension was extracted with diethyl ether and partitioned
... and partitioned into an ether-soluble fraction and a water-soluble fraction. The residue of the ether-soluble fraction was chromatographed on a silica gel column to give a fraction of acylated-oxypregnane glycosides from which 23 new compounds were obtained. In order to acquire the component aglycones and sugars, the fraction containing the pregnane glycosides from silica gel column chromatography was subjected to acid hydrolysis. The obtained known aglycones were identified as 12-Obenzoyllineolon (1a), 2) 12-O-benzoyldeacylmetaplexigenin (2a), 3) kidjolanin (5a), 4) gagaminin (24a) 5) and 20-O-benzoyl-12-O-(E )-cinnamoyl-3b ,5a ,8b ,12b ,14b ,17b ,20-heptahydroxy-(20S)-pregn-6-ene (16a) 6,7) in view of the 1 H-and 13 C-NMR spectral data. In addition, two new acylatedoxypregnanes (11a, 18a) were obtained. Compound 11a was suggested to have the molecular formula C 28 H 38 O 6 based on high resolution (HR)-FAB-MS [m/z 471.2747 [MϩH] ϩ , 493.2545 [MϩNa] ϩ ]. On comparing the 1036 Twenty-three new acylated-oxypregnane glycosides were obtained from the roots of Araujia sericifera. (Asclepiadaceae). These glycosides were confirmed to be tetraglycosides possessing twelve known compounds, 12-Obenzoyllineolon, 12-O-benzoyldeacylmetaplexigenin, ikemagenin, kidjolanin, cynanchogenin, caudatin, rostratamine, penupogenin, 12-O-benzoylisolineolon, 12-O-tigloyldecylmetaplexigenin (incisagenin), 12-O-benzoyl-20-Oacetylsarcostin, 20-O-benzoyl-12-O-(E)-cinnamoyl-3b b,5a a,8b b,12b b,14b b,17b b,20-heptahydroxy-(20S)-pregn-6-ene and ten new acylated-oxypregnanes, 12-O-benzoyl-20S-hydroxyisolineolon, 12-O-tigloyllineolon, 12-O-salicyloyllineolon, 12-O-salicyloyldeacylmetplexigenin, 12-O-benzoyl-3b b,5a a,8b b,12b b,14b b,17b b-hexahydroxypregn-6-en-20-one, 12-O-benzoyl-19-benzoyloxydeacylmetapleligenin, 12-O-benzoyl-19-benzoyloxy-20-O-acetylsarcostin, 12-O-benzoyl-19-salicyloyloxy-20-O-acetylsarcostin, 12-O-benzoyl-5a a,6a a-epoxydeacylmetaplexigenin, and 12-O-benzoyl-5a a,6a a-epoxylineolon as their aglycones, using both spectroscopic and chemical methods.