In-vitro antidiabetic activities, chemical compositions, antioxidant activities, and toxicity of black tea polysaccharides as a potential source of dietary ingredients
Type 2 diabetes (T2D) is one of the fast growing diet-related chronic diseases throughout the world. Tea contains several bioactive compounds, some of which render health benefits. Black tea polysaccharides (BTPS), extracted from low grade quality tea leaves, after processing, were examined for their in-vitro antidiabetic activities (α-glucosidase inhibitory and glucose uptake activities), chemical compositions (yield, monosaccharides, amino acids, and minerals), and antioxidant activities as well as toxicity (cytotoxicity and genotoxicity). In addition, 50% lethal dose (LD50) for BTPS was determined using an acute toxicity test to assess the safe use of it as a dietary ingredient. BTPS had strong α-glucosidase inhibitory activity with IC50 value of 3.4 µg/mL. This was much lower than that of the positive control, pharmaceutical glucosidase inhibitor acarbose with IC50 of 1.06 mM. BTPS also increased glucose uptake into the adipocyte differentiated 3T3-L1 MBX cells. Neither cytotoxic nor mutagenic effects were found for BTPS. The LD50 of BTPS for acute toxicity demonstrated that it was safe to use. The present work suggests that BTPS can be used as an antidiabetic dietary ingredient without posing any potential health risk.