The effects of extraction solvents (hexane, ethyl-acetate, acetone, ethanol, methanol, and water) on the content of phytochemicals including total polyphenols, flavonoids and condensed tannins, as well as antioxidant activities of walnut green husk were investigated. The results showed that extraction solvents significantly affected phytochemicals content and antioxidant activities of walnut green husk. The acetone, ethanol, and methanol extracts had the higher content of phytochemicals, and they exhibited stronger antioxidant activities, followed by ethyl-acetate and water extracts, and the lowest for hexane extract. These results indicated that selective extraction from walnut green husk, by an appropriate solvent, is important for obtaining fractions with high antioxidant activity, which will be useful for the developing and application of walnut green husk.
Keywords: Antioxidant activity, Extraction Solvent, Walnut Green Husk, phytochemicals
