Changes in antioxidant activity and components of methanolic extracts of peanut hulls irradiated with ultraviolet light

The antioxidant activity and the variations of components in methanolic extracts of peanut hulls (MEPH) after UV irradiation were investigated. MEPH of varied periods of irradiation (0, 3 and 6 days), exhibited 96.0% inhibition of peroxidation of linoleic acid. The relative remaining ratios of luteolin in MEPH after irradiation for 3 and 6 days were 87.9% and 69.5%, respectively, and those of total phenolic compounds were 96.5% and 90.4%, respectively. MEPH irradiated for 0, 3 and 6 days exhibited a similarly marked antioxidant activity as a result of a large content of total phenolic compounds. MEPH of varied periods of irradiation always showed the same UV-vis spectra and Rf values on a TLC plate. Thus the antioxidant activity of MEPH was unaffected by UV irradiation.