Study on the antidiabetic potential of Tadehagi triquetrum (L.) H.Ohashi: preliminary investigation of α -glucosidase inhibitory and glucose uptake-promoting activities

Sixteen compounds were separated and purified from the petroleum ether and ethyl acetate extracts of Tadehagi triquetrum (L.) H.Ohashi (T. triquetrum) with hypoglycaemic activity. These included a new compound 1, and seven compounds isolated from T. triquetrum for the first time. The α-glucosidase inhibitory and glucose uptake-promoting effects of the isolates were assessed. Compounds 10, 1, and 7 exhibited strong α-glucosidase inhibitory activity, yielding IC50 figures of 1.89 ± 0.51 µM, 6.99 ± 0.74 µM, and 7.21 ± 0.66 µM, respectively. At the concentration of 20 μM, 5 and 6 markedly elevated glucose uptake in mature 3T3-L1 adipocytes, achieving uptake rates of 56.19% ± 1.66 and 50.54% ± 2.05, respectively. The α-glucosidase inhibitory effects of 1 and 2, and the glucose uptake activity of 5 and 6, are reported here for the first time. These findings emphasise the potential value of T. triquetrum in antidiabetic research.