Berinag tea a store-house of antioxidant: Comparative evaluation of antioxidant activity and antioxidant constituents in different tea brands

The variation in antioxidant activity and phytoconstituents viz. phenolics, flavonoids and tannins, was studied in aqueous and alcoholic extracts of different brands of Berinag Tea, viz., Premium orthodox green tea, Orthodox green tea, Premium orthodox black tea, Orthodox black tea, Orthodox black tea fine collected from Berinag Tea Factory. The antioxidant activity of the different samples of Berinag tea was estimated by the 2,2-azino-bis-(3-eth-ylbenzothiazoline-6-sulphonic acid) (ABTS) method, 2,2-diphenyl-1-picryl hydrazyl (DPPH) method and reducing power assay (FRAP). The phytoconstituents, viz., total phenolic, flavonoid and tannin contents were estimated by the standard methods. The findings revealed that there was significant variation in the antioxidant activity and phyto-constituents among these different samples of Berinag tea. The aqueous and alcoholic extract of Premium orthodox green tea exhibited significant (P<0.05) and highest antioxidant activity and phytoconstituents followed by Premium orthodox black tea and further followed by Orthodox green tea and orthodox black tea samples. The aqueous extract of Premium orthodox green tea showed highest antioxidant activity, having minimum IC₅₀ values of 0.0159±0.00 mg/mL, and 0.0262±0.0002 mg/mL, by ABTS and DPPH method, respectively, followed by other samples. It can be concluded from the study that, among these different tea samples highest antioxidant activity and phytoconstituents exhibited by the aqueous extract followed by the alcoholic extracts. Therefore, the study provides an evidence that the different samples of Berinag tea can be a very good source of effective natural antioxidants.