RESUMO
Evaluation the antioxidant activity of different polar extracts from Varthemia [Varthemia iphionoides] using different model in vitro. The extract exhibited a strong antioxidant activity will be fractioned and purified to identify the active compounds that could be responsible for such antioxidant activity. Ethanol, ethyl acetate and hexane extracts from the aerial parts of medicinal plant Varthemia were investigated using the accelerated oven storage method on soybean oil and beef tallow, the linoleic acid system, DPPH-radical scavenging activity and total phenolic contents. Ethanol extract was fractioned with mixture of chloroform: methanol: water [9:1: 0.1, v/v] using a normal open column chromatography packed with silica gel 60. Fractions with DPPH radical-scavengers activity were traced by measuring the DPPH-radical-scavenger activity for each of the collected fractions. Fractions showed potential DPPH radical-scavenging activities were further fractioned using a second silica gel column eluted with gradient mixture of benzene and acetone. The chemical identity of the isolated and purified compounds was confirmed by UV, IR, MS, 1H-NMR and 13C-NMR spectra. Two pure compounds were isolated and identified namely, 5,7,4'-trihydrroxy-3,6-dimethoxyflavone and 5,7,4'- trihydrroxy-3,3'-dimethoxyflavone. In this experiment we found the antioxidant activities of extracts are directly correlated to the phenolic compound contents of extracts. Antioxidant activity is a several mechanisms which work together to produce a synergistic effect, for that it is important to evaluate these mechanisms separately for each extract and for each isolated compounds