New iridoids from Patrinia scabiosaefolia and their hypoglycemic effects by activating PI3K/Akt signaling pathway

Abstract

Growing in regions of Asia and North America, Patrinia scabiosaefolia is a wild vegetable and herb that has demonstrated health-promoting properties. Iridoids are one of the most bioactive phytochemicals in P. scabiosaefolia but the in-depth study is scarce. Herein we reported the separation and characterization of nine iridoids (compounds 1–9) from P. scabiosaefolia, and two compounds (2 and 6) were new. All the structures of the nine iridoids were characterized and confirmed with NMR (1D & 2D), HRMS, IR and UV. Compound 2 is a five-member ring iridoid, reminiscent of a broken C-1 and C-2 bond. Compound 6 has a typical monoene valerian iridoid, but the 5-deoxyglucose moiety at C-11 position is uncommon in this genus. The anti-diabetic evaluation of the isolated compounds revealed that compounds 1, 2, and 9 significantly increased the glucose absorption in 3 T3-L1 cells (P < 0.01). Further mechanism investigations have demonstrated that compound 1 promoted glucose uptake in dexamethasone-treated 3 T3-L1 adipocytes by activating PI3K/Akt signaling pathway. The expression of GLUT4 mRNA and protein was also upregulated. These results provide scientific references for the potential use of P. scabiosaefolia as a functional food to manage hyperglycemia.