Three new α-glucosidase inhibitors from guggul, the oleogum resin of Commiphora wightii.

Three new compounds;epi-mukulin, (Z)-Δ1,2dehydroguggulsterone andΔ6,7dehydro-20-hydroxygugglsterone were isolated from then-hexane-soluble fraction (HSF) of the methanol extract of guggul, the oleogum resin ofCommiphora wightiitogether with six known compounds: diasesartemin, (+)-epi-magnolin, (+)-diayangambin, gugglsterol I, (E)-guggulsterone and (Z)-guggulsterone. Their structures were elucidated on the basis of different spectroscopic data.α-Glucosidase inhibitory effects of HSF and the isolated compounds were evaluated calorimetrically. The HSF showed significantα-glucosidase inhibitory effect [IC50value of 140 µg mL−1(p < 0.05)]. Under the assay conditions, diasesartemin (IC50 = 60.6 ± 0.01 µM) was found to be more potent than the positive control, acarbose (IC50 = 92.94 ± 0.01 µM); a knownα-glucosidase inhibitor (p < 0.05). The IC50values ofepi-mukulin and (Z)-guggulsterone were found to be 159.33 and 132.14 µM, respectively. Other compounds showed weakα-glucosidase inhibitory effects, <30% inhibition of the enzyme activity at 0.1 mg mL−1. [ABSTRACT FROM PUBLISHER]