In vivo biochemical and gene expression analyses of the antioxidant activities and hypocholesterolaemic properties of Tamarindus indica fruit pulp extract.

Chor Yin Lim,Mahmood Ameen Abdulla,Sarni Mat Junit,Azlina Abdul Aziz,Brenda Smith

doi:10.1371/journal.pone.0070058

Abstract

Background Tamarindus indica (T. indica) is a medicinal plant with many biological activities including anti-diabetic, hypolipidaemic and anti-bacterial activities. A recent study demonstrated the hypolipidaemic effect of T. indica fruit pulp in hamsters. However, the biochemical and molecular mechanisms responsible for these effects have not been fully elucidated. Hence, the aims of this study were to evaluate the antioxidant activities and potential hypocholesterolaemic properties of T. indica, using in vitro and in vivo approaches.Methodology/Principal FindingsThe in vitro study demonstrated that T. indica fruit pulp had significant amount of phenolic (244.9±10.1 mg GAE/extract) and flavonoid (93.9±2.6 mg RE/g extract) content and possessed antioxidant activities. In the in vivo study, hamsters fed with high-cholesterol diet for ten weeks showed elevated serum triglyceride, total cholesterol, HDL-C and LDL-C levels. Administration of T. indica fruit pulp to hypercholesterolaemic hamsters significantly lowered serum triglyceride, total cholesterol and LDL-C levels but had no effect on the HDL-C level. The lipid-lowering effect was accompanied with significant increase in the expression of Apo A1, Abcg5 and LDL receptor genes and significant decrease in the expression of HMG-CoA reductase and Mtp genes. Administration of T. indica fruit pulp to hypercholesterolaemic hamsters also protected against oxidative damage by increasing hepatic antioxidant enzymes, antioxidant activities and preventing hepatic lipid peroxidation.Conclusion/SignificanceIt is postulated that tamarind fruit pulp exerts its hypocholesterolaemic effect by increasing cholesterol efflux, enhancing LDL-C uptake and clearance, suppressing triglyceride accumulation and inhibiting cholesterol biosynthesis. T. indica fruit pulp has potential antioxidative effects and is potentially protective against diet-induced hypercholesterolaemia.

Highlights

Hyperlipidaemia refers to increased levels of lipids in the blood, including cholesterol and triglycerides
The T. indica fruit pulp extract contains considerable amounts of polyphenols and flavonoids (Table 2) and showed moderate antioxidant activities, which were comparable to the positive control butylated hydroxytoluene (BHT) but lower than ascorbic acid and quercetin
There were no significant differences in weight of livers among the control hamsters, hamsters treated with T. indica fruit pulp and hypercholesterolaemic hamsters treated with T. indica fruit pulp

Summary

Introduction

Hyperlipidaemia refers to increased levels of lipids in the blood, including cholesterol and triglycerides. This increase is one of the significant risk factors involved in the development of cardiovascular disease (CVD) [1] and diabetes [2]. It is well established that increased levels of blood cholesterol especially low density lipoprotein cholesterol (LDL-C) is an important risk factor for cardiovascular complications since it favours lipid deposition in blood vessels. Epidemiological studies have clearly established that reduction of total cholesterol or LDLC is associated with decreased risk of atherosclerosis and coronary heart disease [4,5]. A recent study demonstrated the hypolipidaemic effect of T. indica fruit pulp in hamsters. The aims of this study were to evaluate the antioxidant activities and potential hypocholesterolaemic properties of T. indica, using in vitro and in vivo approaches

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Discussion

Conclusion