Antidiabetic and antihyperlipidemic effects of the flower extract of Eriobotrya japonica in streptozotocin-induced diabetic mice and the potential bioactive constituents in vitro

Abstract

This study was designed to evaluate the effects of flower extracts of Eriobotrya japonica (EJ) on diabetes and hyperlipidemia for 4 weeks in streptozotocin (STZ)-induced diabetic mice. EJ treatment significantly lowered levels of blood glucose, HbA1C, plasma triglyceride (TG), and total cholesterol (TC) but increased the size of the islets of Langerhans within the pancreas. Membrane expression levels of glucose transporter 4 (GLUT4) and phospho-Akt in the skeletal muscles from EJ-treated STZ mice were increased, but G6Pase mRNA levels were decreased, contributing to EJ’s antidiabetic activity. EJ caused an increase in hepatic expression of peroxisome proliferator-activated receptor α (PPARα) but a decrease in lipogenic FAS and mRNA levels of SREBP2, which decreased plasma TG and TC levels. One explanation for EJ’s antidiabetic and hypolipidemic activity is that tormentic acid represents the major component of EJ. These findings support the amelioration of the diabetic and dyslipidemic state by EJ in STZ-induced diabetic mice.