α-Glucosidase inhibitory activities, functional properties, and safety of green tea polysaccharides as a potential source of dietary supplement

Abstract

Procuring valuable bioactive compounds from low quality green tea is of great interest. Green tea polysaccharides (GTPS), obtained from low quality tea leaves, were examined for their yield, monosaccharide composition, total phenolic content, antioxidant potential, and structures as well as molecular weight distribution and in vitro anti-diabetic activities. GTPS were also evaluated for their toxicity by performing cytotoxicity and genotoxicity. Additionally, 50% lethal dose (LD50) for GTPS was determined using an acute toxicity test to assess the safe use of it as a dietary supplement. Monosaccharides of GTPS were mainly composed of xylose, glucose, ribose, galactose, arabinose, and glucuronic acid. GTPS exhibited 91.86% α-glucosidase inhibition at 0.5 mg/mL concentration. The α-glucosidase inhibitory activity of GTPS was higher than that of pharmacological glucosidase inhibitor, acarbose, which exhibited only 47.86% inhibition at 2.5 mg/mL concentration. Neither cytotoxic nor no mutagenic effects were found for GTPS. The acute toxicity also showed that LD50 of GTPS was greater than 5,000 mg/kg. The present work suggests that GTPS can be considered as an anti-diabetic dietary supplement without posing any potential health risk.