Total polyphenol content, antioxidant activity and lipid peroxidation inhibition efficacy of branded tea (Camellia sinensis) available in India

Abstract

Natural phenols and polyphenols are compounds found naturally in plants. A group of natural polyphenols called "flavonoids" are of most popular interest because researchers have found them to be of health-contributing potential. One of the natural sources of polyphenols is tea and the polyphenol contents of various teas from China and Japan are well documented. Such documentation on Indian tea from Assam and Darjeeling is not reported extensively. In the present study the total polyphenol content, antioxidant activities and lipid peroxidation inhibition efficacy of five most popular branded tea samples from Darjeeling and Assam (BGT-1, BBT-1, BBT-2, BBT-3, and BBT-4) available in India are estimated and compared with reports on tea from other parts of the world. Antioxidant activity (IC50 values) of these tested samples measured the highest for BGT-1 and the lowest for BBT-4. The total polyphenol content of the samples ranged from 20.7 mg GAE/g to 36 mg GAE/g, the highest being recorded for green tea followed by leafy Darjeeling tea. Similarly, the highest reducing power of tea antioxidants was recorded for green tea (0.95 ABU) and the lowest (0.48 ABU) for Assam CTC tea. Lipid peroxidation could be inhibited up to 29.8% by the tested green tea sample. Inhibition of lipid peroxidation showed positive correlation (r2 = 0.9479) with hydroxyl radical scavenging activity which ranged from 20.91% to 81.16%. The antioxidant activity and the total polyphenol content were observed to be positively and highly correlated (r2 = 0.9958). This study has made it possible to understand the functional properties of Indian tea with respect to teas from other parts of the world