Isolation and Characterization of Flavonol glycoside as Antioxidant and Antidiabetic Compounds from Ebony (DiospyroscelebicaBakh.) Leaf Ethanol Extract

Abstract

Ebony (Diospyroscelebica.Bakh) is an Indonesian medicinal plant used as antidiabetic herbs. A previous study found that the ethanol extract of ebony leaf has strong antioxidant and α-glucosidase inhibitory activity. The aim of this study was to isolate and characterize antioxidant and antidiabetic compounds from the leaves of Ebony. Powdered ebony leaves were extracted with 96% ethanol, and then fractionated with ethyl acetate. The ethyl acetate fraction was purified by column chromatography which led to the isolation of compound Fr.36-13a.The structure of compoundFr.36-13awas elucidated through a combination of1H-NMR,13C-NMR, and 2D-NMR spectroscopy. The antioxidant activity of compound Fr.36-13awas determined by DPPH (1,1-diphenyl-2-picryl hydrazyl) radical scavenging assay. The antidiabetic activity of the compound was assessed in vitro by the α-glucosidase inhibitory assay. Compound Fr.36-13a was identified as kaempferol-3-O-β-glucoside through the 1D and 2D NMR data, and by comparison of the spectroscopic data with literature values. Compound Fr.36-13a (Kaempferol-3-O-β-glucoside) showed strong antioxidant and antidiabetic activities by scavenging DPPH radical and inhibiting α-glucosidase enzyme. Kaempferol-3-O-β-glucoside could serve as a potential therapeutic agents for the treatment of diabetes mellitus.