Structural investigation of resin glycosides from Ipomoea lonchophylla

A fraction from Ipomoea lonchophylla, which was toxic to mice, contained an inseparable mixture of resin glycosides with differing numbers of C-5 ester groups on the hexasaccharide chain. After alkaline hydrolysis of the esters, the structure of the major component (1) was elucidated using high-field NMR spectroscopy, mass spectrometry, chemical studies, and comparison with known resin glycosides. Compound 1 was identified as 3,11-dihydroxytetradecanoic acid 11-O-beta-quinovopyranosyl-(1-->2)-beta-glucopyranosyl-(1-->3)-[alpha-rhamnopyranosyl-(1-->4)]-quinovopyranosyl-(1-->2)-beta-glucopyranosyl-(1-->2)-beta-fucopyranoside.