Methyl-3,4-dihydroxybenzoate and 9-10-dihydrophenanthrene-2,4,7-triol two phenolic compounds from Dioscorea alata L. and their antioxidant activity

Two phenolic compounds namely: methyl-3,4-dihydroxybenzoate (1) and 9,10-dihydrophenanthrene-2,4,7-triol (2) had been isolated for the first time from the tuber of Dioscorea alata L. The extraction of two compounds were done by maceration method using methanol as solvent, followed by partition with n-hexane and ethyl acetate. The ethyl acetate extract was separated and purified using various chromatographic techniques yielded pure compounds. The structure of isolated compounds were determined based on spectroscopic data, including UV-Vis, 1D and 2D NMR spectra. Compounds (1), (2) and ascorbic acid as a comparator were evaluated for their antioxidant properties against ^{DPPH, showing their IC₅₀ were 9,41 ± 0,08; 23,52 ± 0,05; and 10,95 ± 0,08 ppm, respectively.}