<![CDATA[Four xanthones and two benzophenones from the stem bark of kandis gajah (Garcinia griffithii) by extraction and chromatographic methods have been isolated. The six compounds were determined as: 1,7-dihydroxyxanthone (1), 1,6,7-trihydroxyxanthone (2), 1,6-dihydroxy-3-methoxy-4,7-di-(3-methylbut-2-enyl)xanthone (3), 1,5-dihydroxy-3,6-di-methoxy-2,7-di-(-3-methylbut-2-enyl)xanthone (4), guttipherone I (5), and isoxanthochymol (6). All of the isolated compounds were submitted to antioxidant activity assay using three methods: (i) free radical scavenging method, (ii) xanthine-xanthine oxidase (XO) method, and (iii) nitroblue tetrazolium xanthine oxidase (NBT/ XO). Guttipherone I (5) and isoxanthochymol (6) have strong antioxidant activity (IC50 ≤10.2 µg/mL), 1,6,7-trihydroxyxanthone (2) and 1,6-dihydroxy-3-methoxy-4,7-di-(3-methylbut-2-enyl)xanthone (3) as active compounds (IC50 ≤ 100 µg/mL), while 1,7-dihydroxyxanthone (1) and 1,5-dihydroxy-3,6-dimethoxy-2,7-di-(3-methylbut-2-enyl)xanthone (4) were inactive (IC50 > 100 µg/mL). Base on the data, antioxidant activity of isolated compounds was inhuenced by dihydroxyl groups at ortho position, number of hydroxyl group, and hydroxyl group at para position to C carbonyl at heterocyclic.]]>
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