Bio-assay guided isolation of α-glucosidase inhibitory constituents from Eclipta alba

Abstract

Eclipta alba (L.) Hassk is used traditionally in diabetes mellitus in India and the plant extract is reported to possess anti-diabetic activity. A bioactivity-guided isolation approach based on α-glucosidase inhibition was used to identify the constituents contributing towards the inhibition of the enzyme and probably contributing towards its anti-diabetic activity. Four echinocystic acid glycosides were thus isolated, of which eclalbasaponin VI, isolated from the n-butanol fraction, was found to be the most potent (IC 50 54.2 ± 1.3 μM). The compound is an uncompetitive type of inhibitor with Ki 26.1 μM. A quantitative estimation of the constituents was established using RP-HPLC.