Lignans and Flavonoids from Cajanus cajan (L.) Millsp. and Their α-Glucosidase Inhibitory Activities

A pair of new lignan conformers (1-2), one new flavonoid glycoside (3), as well as nineteen known compounds were purified from the twigs and leaves of Cajanus cajan (L.) Millsp.. The planar structures of the unknown compounds were determined via NMR and high-resolution mass spectrometry, while their absolute configurations were elucidated via comparison between their experimental and calculated electronic circular dichroism (ECD) values. All the isolated compounds were assayed for their alpha-glucosidase inhibitory activities. The results demonstrated that compounds 8-12, 15-16, 18-19, 21-22 had strong inhibition activities, with compound 10 (IC50=0.4 +/- 0.21 mu M) most active. The structure-activity relationships were preliminarily summarized. Enzyme kinetics showed that compounds 8, 9, 15-16, 18-19, 21-22 were non-competitive inhibitors and compounds 10-12 were anti-competitive ones.

Automated summary

A pair of new lignan conformers and one new flavonoid glycoside, along with nineteen known compounds, were isolated from the twigs and leaves of Cajanus cajan (L.) Millsp.. The structures and configurations of these unknown compounds were determined using NMR and high-resolution mass spectrometry, and their α-glucosidase inhibitory activities were evaluated. Compound 10 exhibited the most potent inhibition activity, followed by compounds 8-12, 15-16, 18-19, 21-22. Enzyme kinetics revealed that compounds 8, 9, 15-16, 18-19, 21-22 were non-competitive inhibitors, while compounds 10-12 were anti-competitive ones.