G. Pant et al., STRUCTURE ELUCIDATION AND PROTON AND C-13 ASSIGNMENT OF A PENTASACCHARIDE GLYCOSIDE FROM AGAVE AMERICANA, Magnetic resonance in chemistry, 32(4), 1994, pp. 213-219
A glycoside extracted from the rhizomes of Agave americana was identif
ied as 3-O-{{beta-D-xylosyl(1 --> 3)}{beta-D-xylosyl(1 --> 3)-beta-D-
glucopyranosyl(1 --> 2)}-beta-D-glucopyranosyl(1 --> 4)}-beta-D-galact
opyranosyl-(25R)-5 alpha-spirostan-3 beta-ol by concerted use of prot
on and carbon-13 2D NMR methods. Complete assignments for the sugar re
sonances were obtained with standard methods, but the presence of chem
ical shift degeneracies prevented an unequivocal determination of two
of the glycosidic linkage points by the HMBC experiment. Further two-d
imensional experiments failed to resolve the ambiguity, but a clear id
entification of the linkages was obtained using a selective reverse IN
EPT experiment with homonuclear double resonance.