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

Abstract

Three new compounds; epi-mukulin, (Z)- 1,2 dehydroguggulsterone and 6,7dehydro-20-hydroxygugglsterone were isolated from the n-hexane-soluble fraction (HSF) of the methanol extract of guggul, the oleogum resin of Commiphora wightii together 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 significant a-glucosidase inhibitory effect [IC50 value of 140 μg/ml (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 known α-glucosidase inhibitor (p<0.05). The IC50 values of epi-mukulin and (Z)-guggulsterone were found to be 159.33 and 132.14 μM, respectively. Other compounds showed weak α-glucosidase inhibitory effects; < 30% inhibition of the enzyme activity at 0.1 mg/ml.