Determination of Total Antioxidant Capacity of Green Teas by the Ferric Reducing/Antioxidant Power Assay

Green tea is one of the important sources of bioactive compounds which have been used in folk medicinefor many centuries. This study aimed to compare in vitro antioxidant power of different types of green tea (Camellia sinensis ). Antioxidant activity of methanolic (50%) extracts of five green tea samples wasinvestigated according to Ferric reducing ability power method. Total phenolic contents were analyzedusing a spectrophotometric technique, based on the Folin-ciocalteau reagent, and calculated as gallic acidequivalents per gram dry weight. Total flavonoid and antocyanidin were also investigated according toaluminum chloride and vanillin colorimetric assay respectively. Total antioxidant activity varied from0.554±0.042 in Avicen green tea sample to 3.082 ± 0.150 mmoL FeII /g in Chinas green tea and totalphenolic content ranged from the 0.030±0.001 in Avicen green tea sample to 0.196±0.012 g gallic acidper gram dry weight in Ahmad green tea. A linear positive relationship existed between the antioxidantactivity, total phenolic, flavonoid and antocyanidin content of the tested green tea samples. Green teasamples possess relatively high antioxidant activity due to contribution of phenolic compounds. Thepresent study showed that green tea samples which are more frequently consumed in Iran are strongradical scavengers and can be considered as good sources of natural antioxidants for medicinal andcommercial uses