Triterpene glycosides of Astragalus and their genins.: LXI.: Occurrence of cycloartane 6-O-monodesmosides

Cyclosiversigenin 6-O-alpha -L-rhamnopyranoside and 6-O-beta -D-glucopyranoside were isolated from Astragalus coluteocarpus Boiss. (Leguminosae) and Astragalus dissectus B. Fedtsch. et N. Ivanova, respectively. Cyclosiversigenin 5-O-alpha -L-rhamnopyranoside was shown to be an artifact for Astragalus coluteocarpus. Thus, the cyclosiversigenin 6-O-beta -D-glucopyranoside that was isolated from certain Astragalus species is hypothesized also to be an artifact, Glycosylation of the 6 alpha -hydroxyl group of cycloartanes by D-glucose and D-xylose, in contrast with other substituents, does not change the low-field position of the PMR signal of the 4 alpha -CH3 group (1.65 less than or equal to delta less than or equal to 2.01 ppm) that is caused by the influence of deuteropyridine directly on the 6 alpha -hydroxyl Obviously one of the hydroxyls of the beta -D-glucopyranoside or beta -D-xylopyranoside residues has the same effect in this instance.