RESUMEN
The present study investigated the antidiabetic properties of the extracts and fractions from leaves and stem bark of M. glabra based on dipeptidyl peptidase-4 (DPP-4) and α-Amylase inhibitory activity assays. The chloroform extract of the leaves was found to be most active towards inhibition of DPP-4 and α-Amylase with IC50 of 169.40 µg/mL and 303.64 µg/mL, respectively. Bioassay-guided fractionation of the leaves' chloroform extract revealed fraction 4 (CF4) as the most active fraction (DPP-4 IC50: 128.35 µg/mL; α-Amylase IC50: 170.19 µg/mL). LC-MS/MS investigation of CF4 led to the identification of trans-decursidinol (1), swermirin (2), methyl 3,4,5-trimethoxycinnamate (3), renifolin (4), 4',5,6,7-tetramethoxy-flavone (5), isorhamnetin (6), quercetagetin-3,4'-dimethyl ether (7), 5,3',4'-trihydroxy-6,7-dimethoxy-flavone (8), and 2-methoxy-5-acetoxy-fruranogermacr-1(10)-en-6-one (9) as the major components. The computational study suggested that (8) and (7) were the most potent DPP-4 and α-Amylase inhibitors based on their lower binding affinities and extensive interactions with critical amino acid residues of the respective enzymes. The binding affinity of (8) with DPP-4 (-8.1 kcal/mol) was comparable to that of sitagliptin (-8.6 kcal/mol) while the binding affinity of (7) with α-Amylase (-8.6 kcal/mol) was better than acarbose (-6.9 kcal/mol). These findings highlight the phytochemical profile and potential antidiabetic compounds from M. glabra that may work as an alternative treatment for diabetes.