α-Glucosidase Inhibitory Activity from Ethyl Acetate Extract of Antidesma bunius (L.) Spreng Stem Bark Containing Triterpenoids.

Background: Buni ( Antidesma bunius [L.] Spreng) has been used as a traditional antidiabetic agent in Asia.

Objective: The mechanism of antidiabetic properties was studied in this study by determine its α-glucosidase inhibitory activity.

Method: Inhibition of α-glucosidase was performed in all fraction of Buni stem bark with acarbose and miglitol as standards. The half maximal inhibitory concentration (IC50 ) value of acarbose and miglitol was 5.75 and 59.76 μg/mL respectively while ethyl acetate (EtOAc) fraction was the most active fraction with IC50 of 19.33 μg/mL. Three isolates (B1, B2, and B3) were found in the EtOAc fraction and elucidated by infrared,1 hydrogen-nuclear magnetic resonance,13 carbon-nuclear magnetic resonance, and two-dimensional nuclear magnetic resonance.

Result: The chemical structures of the isolates were identified by the spectrum then compared with literature which concluded that B1 is friedelin, B2 is β-sitosterol, and B3 is betulinic acid. Inhibition of the α-glucosidase assay showed IC50 values of B1, B2, and B3 were 19.51, 49.85, and 18.49 μg/mL, respectively.

SUMMARY: α-Glucosidase inhibitory activity assay was performed in n-hexane, ethyl acetate (EtOAc), methanol fraction of Buni ( Antidesma bunius (L.) Spreng) stem bark and miglitolEtOAc fraction from the liquid chromatography has the highest inhibitory activity against α-glucosidaseThe chemical structures of the isolates were identified by the spectrums infrared,1 hydrogen-nuclear magnetic resonance,13 carbon-nuclear magnetic resonance, and two-dimensional nuclear magnetic resonance, then compared with literature which concluded that B1 is friedelin, B2 is β-sitosterol, and B3 is betulinic acidBetulinic acid and friedelin showed the highest α-glucosidase inhibitory activity. Abbreviations used: IC50 : Half maximal inhibitory concentration; H-NMR: Hydrogen-nuclear magnetic resonance; C-NMR: Carbon nuclear magnetic resonance; 2D-NMR: Two dimensional-nuclear magnetic resonance; EtOH: Ethanol; EtOAc: Ethyl acetate; MeOH: Methanol; CHCl3 : Chloroform; DMSO: Dimethyl sulfoxide; EtF: Ethyl acetate fraction; Na2 CO3 : Sodium carbonate; IR: Infrared; TGR5: Transmembrane G protein-coupled receptor 5; EC50 : Half maximal effective concentration.