Phenolic Compounds, Free Radical Scavenging Activity and α-Glucosidase Inhibition Properties of Green, Oolong and Black Sacha Inchi Tea Extract

Sacha Inchi leaves may possess antioxidant function which is naturally rich in bioactive ingredients and has been widely processed into herbal teas that has many benefits to human health. According to the global data from the World Health Organization (WHO), there has been a rise in the frequency of diabetes mellitus (DM) among adults. Sacha Inchi tea was prepared using several methods, with green tea not fermented, oolong partially fermented, and black tea completely fermented. The phenolic compounds (total phenolic content (TPC), total flavonoid content (TFC), tannin), free radical scavenging activity (DPPH) and inhibition properties of α-Glucosidase on green, oolong and black Sacha Inchi tea extract were determined. The green Sacha Inchi tea extract displayed the highest TPC and TFC values among the oolong and black Sacha Inchi tea extracts at a concentration of 500µg/mL, with values of 2.10±0.01 µg GAE/mL and 3.23±0.20 µg QE/mL, respectively. Meanwhile, at a concentration of 500µg/mL, Sacha Inchi black tea extract demonstrated strong antioxidant activity by DPPH with radical scavenging activity (%) (89.4±0.45). Furthermore, at a concentration of 15.625 µg/mL, black, oolong, and green tea extracts exhibited stronger inhibitory effects on α-Glucosidase (95%, 95%, 92%, respectively) than acarbose (90%). Therefore, the processing steps involved in tea production impact the phenolic compounds, free radical scavenging activity, and the ability to inhibit α-Glucosidase in green, oolong, and black tea extracts.