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.

Thermal processing effects on in vitro Antioxidant activities of five common Indian Pulses.

Five different types of pulses commonly used in daily cuisine in India, viz. Lentil (Lens culinaris), Green gram (Vigna radiate), Bengal gram (Cicer arietinum), Red kidney beans (Phaseolus vulgaris) and Soybean (Glycine max), were analyzed for their in vitro antioxidant profile before and after thermal processing in water. The thermal processing included methods commonly employed in India for cooking, viz. pressure cooking, microwave treatment, boiling in water and boiling after overnight soaking. The assays performed included ABTS radical decolorization assay, DPPH radical decolorization assay, hydrogen peroxide scavenging assay and hydroxyl radical scavenging assay. The antioxidant profile of the five pulses improved significantly after microwave treatment as evident from all assays except DPPH assay. In case of Bengal gram, improvement was also observed after pressure cooking. In case of soybean, however, apart from microwave treatment, no significant improvement was observed. Enhanced activity of the pulses shown after thermal processing in water might be due to enhanced extraction of polyphenols like gallo-ellagitannins, phenolic acids or flavonoid glycosides, which have less solubility in normal water but enhanced solubility in hot water. The study indicated a systematic approach to ascertain antioxidant quality of pulses after thermal treatment with water.