The chemical profiling of loquat leaf extract by HPLC-DAD-ESI-MS and its effects on hyperlipidemia and hyperglycemia in rats induced by a high-fat and fructose diet.

In this study, the inhibitory effects of loquat leaf extract (LLE) on pancreatic α-amylase and α-glucosidase, and the preventative effects of LLE on hyperlipidemia and hyperglycemia in rats induced by a high fat and fructose diet have been evaluated. The LLE was chemically described using a high performance liquid chromatography-diode array detector coupled with a mass spectrometer (HPLC-DAD-MS/MS). 20 compounds including phenolic acids, flavonoids and triterpene acids were tentatively identified with authentic compounds or by referring to published articles and accessible databases (e.g. MassBank, METLIN). Enzyme activity measurements showed that the IC50 values of the LLE on α-amylase and α-glucosidase were 11.34 ± 1.04 mg mL-1 and 50.77 ± 1.04 μg mL-1, respectively. The calculated Michaelis-Menten constants indicated that the LLE is an effective inhibitor against α-glucosidase in a mixed-model competitive mode. The fluorescence data revealed that the LLE binds with α-amylase and α-glucosidase. The animal experiment results indicated that the LLE significantly decreased the levels of fasting blood glucose, and hepatic and serum triglycerides.