Evaluation of in vitro/in vivo anti-diabetic effects and identification of compounds from Physalis alkekengi

Abstract

The aims of the present study were to assess the anti-diabetic effects of Physalis alkekengi L. (PA) in 3T3-L1 pre-adipocyte cells and HepG2-GFP-CYP2E1 (E47) cells and in a pre-diabetic rat model, as well as to identify the active chemical constituents. The in vitro results showed that PA has a strong anti-diabetic capacity to relieve oxidative stress and inhibit α-glucosidase activity. Mechanistic analysis also showed that ethyl acetate extracts of aerial parts and fruit of PA (PAG-EA and PAF-EA) enhanced glucose transporter 4 expression and function as well as enhanced insulin sensitivity by inhibiting the expression of cytochrome P450-2E1 (CYP2E1) mRNA and protein. In vivo, PAG-EA and PAF-EA significantly decreased the levels of fasting blood glucose and fasting insulin, as well as total cholesterol and triglyceride, in the pre-diabetic rats. The results from insulin sensitivity index and homeostasis model assessment-insulin resistance index along with an oral glucose tolerance test also showed that PAG-EA and PAF-EA could significantly enhance the insulin sensitivity, which confirmed the in vitro findings. Moreover, HPLC-ESI-QTOF-MS analysis identified flavonoids, physalins and phenolic acids as the main plant constituents. Our findings support the ethnopharmacological use of PA fruit, along with its aerial parts, as a strong anti-diabetic agent. The EA fraction, especially the constituent polyphenols and flavonoids, may have a good potential to treat diabetes.