| dc.description.abstract | Seven isolated xanthones; Dulcisxanthone B (1), -mangostin (2) Seven isolated xanthones; Dulcisxanthone B (1), -mangostin (2), 1,3,7-trihydroxy-2,4-di-(3-methylbut-2-eyl)-xanthone (3), Cudratricusxanthone E (4), cochinchinone A (5), 2-geranyl-1,3,7-trihydroxy-4-(3,3-dimethylallyl)-xanthone (6), and cochinchinone B (7) were isolated form twigs of Cratoxylum cochinchinense and Cratoxylum formosum. The structure of all isolated compounds were elucidated by spectroscopic methods (1H, 13C, 1H-1H COSY, 1H-13H HSQC, and 1H-13C HMBC techniques) and compared with previous literatures. All compounds showed antioxidant activity with IC50 values ranging from 9.50 to 134.41 M using DPPH assay. Relationship between structures of xanthones and their antioxidant activities using DPPH assay were corresponded with electrochemical behaviors using cyclic voltammetry. Compounds 4 and 7 displayed the highest antioxidant activity on DPPH assay and showed lower oxidation potentials compared to others compounds on cyclic voltammograms. Considering the structures of the compounds, It implied that the hydroxy group at C-6 was important role on antioxidant capacities. | en_US |
