α-Glucosidase inhibitory terpenoids from Potentilla fulgens and their quantitative estimation by validated HPLC method

• Extracts of P. fulgens root inhibits α-glucosidase in vitro.
• Five triterpenes including saponins were isolated and spectrally characterised.
• Hyptadienic acid was found to effect maximum inhibition of enzyme.
• These terpenoids may be responsible for the antidiabetic activity of P. fulgens.
• The terpenoids were quantified by HPLC and the method was validated.

Potentilla fulgens is used extensively in traditional system of medicine and as a food additive for the treatment of diabetes mellitus and other ailments. The present study was aimed to isolate and identify the constituents with α-glucosidase inhibitory activity. The methanolic extract demonstrated potent inhibitory activity against α-glucosidase. Fractionation and purification by silica gel column chromatography and HPLC led to the isolation of five terpenes, namely, hyptadienic acid, tormentic acid, rosamultic acid, 2α,19α-dihydroxy-3-oxo-12-ursen-28-oic acid β-d-glucopyranoside ester and kajiichigoside F1 for the first time from this plant. Among these hyptadienic acid, which is an A-ring contracted triterpenoid, was found to be the most potent against α-glucosidase. This suggests that the A-ring contracted triterpenes may serve as a class of triterpenes with α-glucosidase inhibitory activity. Also, identification of enzyme inhibitory activity of these constituents explains the traditional use of P. fulgens in the management/treatment of diabetes. Quantitative estimation of the compounds was performed using HPLC and the method was validated.