Evaluation of in vitro antioxidant potential of Tea (Camelia sinensis) leaves obtained from different heights of Darjeeling Hill, West Bengal

Tea (Camelia sinensis) is the most consumed beverage and is also known for its medicinal value. Tea plants grown at higher altitude are subject to enhanced oxidative stress due to high UV radiation, climatic changes, and soil conditions, compared to places at low altitude. The present study was undertaken to find out whether the antioxidant activity and the content of bioactives change with the variations of altitudes in a district of Darjeeling, where tea is cultivated most. The samples were collected from six different altitudes of Darjeeling hill, viz. 6900, 5800, 4500, 3600, 2500 and 500 feet. The assays performed included ABTS radical cation decolorization assay, DPPH radical decolorization assay, reducing power assay, total polyphenols content, tannin content and total flavonoid content. It was observed that ABTS and DPPH radical scavenging abilities were reduced with increasing altitude, suggesting probable depletion of the antioxidant bioactives on exposure to extreme climatic conditions as well as elevated UV radiations. However, changes in the major bioactives of tea like tannins and flavonoids with altitude were non-significant, suggesting that although the plant tries to cope up with extreme climatic conditions, its medicinal value remains almost unchanged with altitude.