Antioxidant activity of Acanthopanax trifoliatus.

OBJECTIVE The aim of this study was to investigate the antioxidant activity of extracts of various parts of Acanthopanax trifoliatus obtained by different extraction methods. The total phenolic and flavonoid contents of the extracts were also determined. MATERIALS AND METHODS The leaves, stems, stem bark, roots and root bark of A. trifoliatus were extracted separately using decoction, maceration and refluxing methods. The extracts were analysed for free-radical-scavenging activity using the 1,1-diphenyl-2-picryl-hydrazyl scavenging assay and the thiobarbituric-acid-reactive substance method for the inhibition of lipid peroxidation of a rat brain homogenate. Total phenolic and total flavonoid contents of the extracts were measured by UV spectrophotometry. RESULTS The leaf decoction extracts possessed a significantly stronger antioxidant activity as revealed by both methods. Total phenolic and flavonoid contents of the extracts ranged from 2.16 to 21.79 g% chlorogenic acid equivalent and from 0.37 to 9.61 g% rutin equivalent, respectively. Analysis of the leaf decoction extract, which exhibited the most potent antioxidant activity, by thin-layer chromatography revealed flavonoid and polyphenolic compounds corresponding to rutin and chlorogenic acid. CONCLUSION The leaf aqueous extracts showed a high level of antioxidative activity and contained high levels of both phenolic and flavonoid compounds. The magnitude of antioxidant activity corresponded with the level of phenolic and flavonoid compounds.