Identification of Flavonoid from Leaves of Gedi (Abelmoschus manihot L.) and Its Antioxidant Activity

摘要

A flavonoid compound had been isolated from Abelmoschus manihotL. leaves. The leaves extract was obtained by maceration in methanol to obtain n-hexane-acetone-methanol sequential extracts. Further separation was done by flash chromatography using silica gel G - 60 as a stationary phase. The column was eluted subsequently using several mixture solvents including ethyl acetate, ethyl acetate/methanol (3:1,v/v,), ethyl acetate/methanol (1:1, v/v), ethyl acetate/methanol (1:3) and methanol at 2 mL/min flow rate. At the end of this fractionation, 112 fractions of 10 mL each was collected. Using bioassay-guided fractionation, seven isolates from fraction four were obtained. The isolate five showed the highest antioxidant activity in the 2,2-diphenyl-1-picrylhydarzyl (DPPH) radical scavenging test and then it was chosen for structure elucidation. The structure of the compound was determined based on spectroscopic data of UV, IR, ~1H-NMR, and ~(13)C-NMR. The isolated compound was proposed as 3,3',5' trihydroxy-4' methoxy flavone. It exhibited antioxidant activity, with IC_(50) of 727.53 μg/mL.