Guava (Psidium guajava Linn.) leaf extract promotes glucose uptake and glycogen accumulation by modulating the insulin signaling pathway in high-glucose-induced insulin-resistant mouse FL83B cells

The effects of aqueous guava leaf extract (GvEx) on insulin resistance were evaluated in high glucose-induced insulin-resistant mouse FL83B cells. Glucose uptake and glycogen content were determined and western blot analysis was performed to study the anti-diabetic effects of GvEx. Our results showed that administration of 200 and 400 mu g/mL GvEx resulted in a significant increase in glucose uptake in both normal and insulin-resistant cells. Glycogen content in cells was significantly higher after incubation with GvEx (200, 400 mu g/mL) than that in control group (p < 0.05). Further, western blot analysis revealed that 200 and 400 mu g/mL GvEx significantly enhanced the levels of insulin-related signaling components, including insulin receptor (IR), as well as enhancing the phosphorylation of the insulin receptor (p-IR (Tyr)), insulin receptor substrate (p-IRS (Tyr)), p85 regulatory subunit of phospho-inositide 3 kinase (PI3K (p85)), protein Irinase B (p-Akt (Ser)), glucose transporter 2 (Glut 2), and total glycogen synthase. In conclusion, GvEx improved insulin resistance by promoting glucose uptake and enhancing glycogen content via modulation of the insulin signaling pathway in high glucose-induced insulin-resistant mouse FL83B cells. (C) 2015 Elsevier Ltd. All rights reserved.