Chemical characteristics of protoyuccoside E. IX

Abstract

The Ehrlich's reagent (I) gives a positive reaction [3], while yuccoside E does not react with this reagent. Its enzymatic hydrolysis with the fl-glueosidase from Helix pomatia yielded yuccoside E (II). Peracetylated (I) was subjected to oxidative cleavage [4] and a tetraacetylgluco side of methyl &hydroxy-~,-meth ylvalerate was obtained. The mass spectrum of the latter had characteristic peaks with m/e 331, 243,242, 200, 169, 157, 145, 141, 140, 115, 109, 103 and 98 for tetraacetylgluco se, and also for fragments with m/e 129 (CTH1302) and 97. These results show that (I) has the furostanol structure. In methanol systems, (I) behaves in the same way as glycosides of the furostanol series [4]. The acid hydrolysis of (I) formed an aglycone which was identical with sarsasapogenin in its specific rotation [a]~-74 ° (c 0.95, CHC13) , its mp of 199°C, its mass spectrum (M + 416), its IR spectra (912 and 892 cm -1 with an intensity of 3:1), and its chromatographic behavior. Analysis of the monosaccharides isolated by the GLC of the acetates of their aldononitrile derivatives showed that (I) contains galactose and glucose in a ratio of 2:3. When (I) was methylated by Kuhn's method [5] followed by methanolysis of the products obtained with 72% HC 104, methyl 2,3,4,6-tetra-O- methyl-D-galacto pyranoside, methyl 2,3,4, 6-tetra-O-methyl -D-glucopyranoside, methyl 2,3,6-tri-O-meth yl-D-glucopyrano side, and methyl 3,4-di-O-methyl- D-glucopyranosid e, were identified by GLC and TLC in the presence of markers. The presence of the latter two was also shown by mass and NMR spectrometry, as in the case of yuccoside E [2]. When (I) was subjected to periodate oxidation followed by hydrolysis, not one of the sugars named, was unaffected, which is in agreement with the results of methylation. The partial hydrolysis of (I) gave the same progenins as yuccoside E. The methanolysis of the permethylated progenins showed the same methyl glycosides as the progenins of yuccoside E [4]. The configurations of the glycosidic centers were determined by Klyne's rule [6] taking into account the molecular rotations of (I) itself and its progenins.