Isolation and structural analysis of ajugose from Vigna mungo L.

The hexasaccharide ajugose, alpha-D-galactopyranosyl-(1-->6)-alpha-D-galactopyranosyl-(1-->6)-O-alpha-D-galactopyranosyl-(1-->6)-alpha-D-galactopyranosyl-(1-->6)-alpha-D-glucopyranosyl-(1<-->2)-beta-D-fructofuranoside, generally uncommon in legumes, was detected in the seeds of Vigna mungo L. by TLC and paper chromatography. Ajugose was then isolated by silica gel chromatography and its structure was established by acid and enzymatic hydrolysis, fast atom bombardment mass spectrometry and both one- and two-dimensional 1H and 13C NMR techniques.