ANTIOXIDANT ACTIVITIES OF FLOWER EXTRACT AND POMEGRANATE JUICE

The relative high amounts of phenolic compounds in fruits and vegetables are responsible for some of their properties as preventing cardio- and cerebrovascular diseases as well as decreasing cancer mortalities. Many times, this ability of the phenolic compounds is attributed to their antioxidant properties. Pomegranate fruits are rich in coloured components, the anthocyanins, also possessing antioxidant activity. However, some compounds other than the phenolic ones are also characterized by possessing some antioxidant activity, and consequently used as antioxidants: some organic acids. In the present work, the anthocyanins and organic acids of fruits and flowers were evaluated by HPLC. The antioxidant activity of pomegranate juice and flower extracts was determined by measuring the hydrogen donating or radical scavenging ability using the stable radical DPPH, the scavenging of superoxide radical, using a non-enzymatic reaction of phenazine ethosulphate in the presence of NADH and molecular oxygen, and the reducing power. Concerning the anthocyanins, quantitative differences were found in fruits and flowers. In this sample, only pelargonidin-3,5-diglucoside was detected in large amounts when compared to pelargonidin-3-monoglucoside and cyanidin-3-monoglucoside, the sole anthocyanidins detected. In fruits, mono- and diglucosides of delphinidin, cyanidin and pelargonidin were detected. In this sample, delphinidin-3,5-diglucoside constituted the major anthocyanin. Concerning the organic acids, citric and tartaric acids were the main ones in the fruits, while in the flowers ascorbic acid predominated. Both samples showed antioxidant activity, independent on the method used. The antioxidant activity can be due to the anthocyanins and organic acids present in the samples, in spite of higher amounts of phenolic compounds had been detected in flower extracts than in the juice. Along with the anthocyanins and organic acids, other components, not determined by us, can also be responsible for such activities.