Physiological activity of the extract from Dolwoe (Gynostemma pentaphyllum Makino) leaves tea by different ethanol concentrations

The objective of this study was to compare the effects of different concentration of ethanol extraction on the total phenol and flavonoid contents and physiological activities. The total phenol content of the extracts ranged from 35.54 to 71.52 mg GAE/g. An increase in the ethanol concentration of the solvent led to an increase in the phenol content, with the highest content being found in the 80 and 99.5% ethanol extract. The same trend was observed for flavonoid content. DPPH, nitric oxide, superoxide, hydroxyl radical scavenging activity and TEAC, FRAP and ORAC were measured by antioxidant assay. Radical scavenging activity of aqueous ethanol extracts was better than that of water and 99.5% ethanol extracts. TEAC and FRAP were highly dependent on ethanol concentration and ORAC showed high activity in 40 ~ 80% ethanol extract. Antioxidant activity of Dolwoe leaves tea showed different results among the assay systems. In most experiments, the activities of water and 99.5% ethanol extracts was relatively low. α- Glucosidase inhibitory activity and microorganism inhibitory activity were highest in the 80% and 99.5% ethanol extracts. Therefore, it was considered that extraction with 80% ethanol was appropriate when considering the antioxidative and physiological activities of Dolwoe leaves tea. Based on these results, it can be used as a basic data for the development of food of Dolwoe leaves tea.