Antioxidant, hypolipidemic, and anti-angiotensin-1-converting enzyme properties of lemon (Citrus limon) and lime (Citrus aurantifolia) juices

Abstract

Lemon (Citrus limon) and lime (Citrus aurantifolia) juices are used in folk medicine for the management of hypertension and other cardiovascular diseases, but the mechanism of action by which they exert their therapeutic action is unclear. The aim of this study is to investigate the effect of lemon and lime juices on angiotensin-1-converting enzyme (ACE) activity in vitro and investigate the hypocholesterolemic properties of the juices in a high-cholesterol diet rat model. The phenolic content and antioxidant properties of the manually squeezed juices were also determined. Lemon juice had higher total phenol content (64.5 mg/l), while lime juice had higher total flavonoid content (29.5 mg/l). Both juices inhibited ACE activity in a dose-dependent manner and also exhibited antioxidant activities as typified by their ferric reducing power, and radicals (DPPH·, ABTS·, OH·, and NO·) scavenging abilities, as well as inhibition of Fe2+- and sodium nitroprusside-induced lipid peroxidation in rat’s liver in vitro. Administration of the juices to rats fed with a high-cholesterol diet caused a significant reduction in plasma total cholesterol, triglyceride, and LDL-cholesterol levels and an increase in plasma HDL-cholesterol levels. The inhibition of ACE activity in vitro and in vivo hypocholesterolemic effect of the juices could explain the use of the juices in the management of cardiovascular diseases.