The extensive chemical investigation on the branches and leaves of Terminalia chebula var. tomentella (Combretaceae) led to the isolation of two new lignan glucosides with a furofuran skeleton, termitomenins F (1) and G (2). In addition, 19 known compounds including five lignan glucosides (3-7), six hydrolyzable tannins (8-13) and eight simple phenolics (14-21) were also identified. Their structures were determined by comprehensive spectroscopic analyses. It is noted that 8 and 9 were C-glycosidic hydrolyzable tannins with one hexahydroxydiphenoyl and one gallagyl group linked to an open-chain glucosyl C-1/O-2/O-3 and O-4/O-6, respectively, which were rarely found in plants. Nine known compounds, 6-9, 13, and 18-21, were procured from the titled plant for the first time, while 3-5, 10-12 and 14-17 were also found in the fruits. Notably, the known hydrolyzable tannins 8-13 exhibited stronger α-glucosidase inhibitory activities with IC50 values ranging from 0.10 to 3.12 μM, than the positive control, quercetin (IC50 = 9.38 ± 0.33 μM).
Keywords: Calculated ECD; Hydrolyzable tannins; Lignan glucosides; Terminalia chebula var. tomentella; α-Glucosidase inhibitory activity.
© 2021. The Author(s).