Evaluation of alpha amylase inhibition activity, antioxidant capacities and caffeine content of commercially available ready to drink green tea sample in collected from Nepal

The present study aim to evaluate the chemical constituents and biological activities of the commercially available green tea sample. High performance liquid chromatography equipped with UV detector was used to quantify the caffeine content in the tea extract. The caffeine content in the green tea sample range from 7.18 to 22.90 mg/g DW. Whereas, total phenolic, total flavonoids content varied from 9.19 to 11.41 mg GAE/g DW, 7.03 to 9.25 mg/g DW, respectively. Further, analyzed green tea extract revealed the range of in vitro antioxidant activities measured by DPPH with IC50 values from 53.46 to 64.54 mu g/ml. Furthermore, evaluated tea extract were found to be potent alpha amylase inhibitors.