QUANTITATIVE DETERMINATION OF POLYPHENOL CONTENTS COMPARISON OF ANTIOXIDANT ACTIVITIES OF EXTRACTS OF XINHUI TANGERINE BUDS,GREEN TANGERINE PEEL AND TANGERINE PEEL

To provide references for the development of Xinhui tangerine industry,we studied the functional components and biological functions of four Xinhui tangerine products,i.e.Xinhui tangerine buds,one-year-old green tangerine peel,five-year-old tangerine peel,and 10-year-old tangerine peel.Using gallic acid asstandard,the polyphenol contents of the four products were determined by folin-phenol colorimetry method.Selecting Vc as positive reference,the DPPH and ABTS radicals scavenging activities of the four products were evaluated by spectrophotometry method.The polyphenol contents of ethanol extracts of the four products were as follows,from high to low:164 μg/mg (tangerine buds),98 μg/mg (10-year-old tangerine peel),66 μg/mg (1-year-old green tangerine peel) and 58 μg/mg (5-years-old tangerine peel).The DPPH radicalscavenging activities of four samples were as follows,from high to low:tangerine buds (IC₅₀=91 μg/mL),10-year-old tangerine peel (IC₅₀=234 μg/mL),5-year-oldtangerine peel (IC₅₀=384 μg/mL),and 1-year-old green tangerine peel (IC₅₀=473 μg/mL).The ABTSradicalscavenging activities of four samples were as follows,from high to low:tangerine buds (IC₅₀=18 μg/mL),1-year-old green tangerine peel (IC₅₀=53 μg/mL),10-year-old tangerine peel (IC₅₀=56 μg/mL) and 5-year-old tangerine peel (IC₅₀=90 μg/mL).The polyphenol content and antioxidative activity in vitro of Xinhui tangerine buds were much higher than that of other three products;and the antioxidative activity was in positive correlation with the polyphenol content.Xinhui tangerine buds have great potential in the research and development of functional foods.