Effect of onion peel extract and quercetin at an equivalent concentration in the extract on the improvement of dyslipidemia induced by high fat diet in rats

In this study, we quantified quercetin content in onion peel extract (OPE) and investigated the effects of OPE and the equivalent amount of quercetin on lipid disorder induced by high fat diet (HDF). OPE reduced triglyceride (TG) level in oral lipid tolerance test. OPE administration improved lipid profile by lowering the level of total cholesterol (T-Chol) and LDL and by improving HDL/T-Chol ratio in HFD-fed rats. OPE also regulated hepatic expression of sterol regulatory element-binding protein 1 (SREBP-1), fatty acid synthase (FAS), peroxisome proliferator-activated receptor α (PPARα), and carnitine palmitoyltransferase-1A (CPT1A). More importantly, quercetin at the same concentration with OPE exerted similar efficacies in lipid profiles and expression of SREBP-1, FAS, PPARα, and CPT1A. Taken together, OPE possessing the key functional constituent quercetin inhibited lipid absorption and lowered serum levels of TG, cholesterol, and LDL by regulation of de novo lipogenesis and fatty acid β-oxidation, contributing to dyslipidemia improvement.