Four new dammarane triterpenoid saponins cypaliurusides Z1-Z4 (1-4) and eight known analogs (5-12) were isolated from the leaves of Cyclocarya paliurus. The structures of the isolated compounds were determined using a comprehensive analysis of 1D and 2D NMR and HRESIMS data. The docking study demonstrated that compound 10 strongly bonded with PTP1B (a potential drug target for the treatment of type-II diabetes and obesity), hydrogen bonds, and hydrophobic interactions, verifying the importance of sugar unit. The effects of the isolates on insulin-stimulated glucose uptake in 3T3-L1 adipocytes were evaluated and three dammarane triterpenoid saponins (6, 7 and 10) were found to enhance insulin-stimulated glucose uptake in 3T3-L1 adipocytes. Furthermore, compounds 6, 7, and 10 exhibited potent abilities to promote insulin-stimulated glucose uptake in 3T3-L1 adipocytes in a dose-dependent manner. Thus, the abundant dammarane triterpenoid saponins from C. paliurus leaves exhibited stimulatory effects on glucose uptake with application potential as a antidiabetic treatment.
Keywords: 3T3-L1 adipocytes; Cyclocarya paliurus; dammarane triterpenoid saponins; glucose uptake.