Hypolipemic and antioxidant activities from Tamarindus indica L. pulp fruit extract in hypercholesterolemic hamsters

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Abstract

Dietary modifications may significantly reduce cardiovascular disease (CVD) risk factors, including cholesterol and atherosclerosis. The present study addressed the effects of the crude extract from the pulp fruit of Tamarindus indica L. on lipid serum levels and early atherosclerotic lesions in hypercholesterolemic hamsters in vivo, and the extract’s antioxidant action, in vitro. Animals were fed on either chow or atherogenic diet during 10 weeks and concomitantly received either water or T. indica L. extract for drinking. Treatment of hypercholesterolemic hamsters with the T. indica pulp fruit extract (5%) led to a decrease in the levels of serum total cholesterol (50%), non-HDL cholesterol (73%) and triglyceride (60%), and to an increase of high-density lipoprotein (HDL) cholesterol levels (61%). In vitro, the extract presented radical scavenging ability, as assessed by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and superoxide radicals assays, and led to decreased lipid peroxidation in serum, as assessed by the thiobarbituric acid reactive substances (TBARS) assay. In vivo, the extract improved the efficiency of the antioxidant defense system, as assessed by the superoxide dismutase, catalase and glutathione peroxidase activities. Together these results indicate the potential of tamarind extracts in diminishing the risk of atherosclerosis development in humans.

Introduction

Cardiovascular disease is a leading cause of global mortality, accounting for almost 17 million deaths annually (Smith et al., 2004); atherosclerosis, in particular, is the main contributor for the pathogenesis of myocardial and cerebral infarction. Elevated levels of plasma low-density lipoprotein cholesterol (LDL) and triglycerides, accompanied by reduced high-density lipoprotein (HDL) levels, is often associated with an increased risk of coronary heart disease (Smith et al., 2004).

Atherosclerosis represents a state of heightened oxidative stress, characterized by lipid and protein oxidation (Stocker and Keaney, 2004). Several studies indicate that LDL oxidation is an early event of the process. Indeed, oxLDL is cytotoxic to a variety of vascular cells (Morel et al., 1983), induces the synthesis of monocyte chemotatic protein-1 (Rajavashisth et al., 1990), recruits inflammatory cells (Navab et al., 1991), and stimulates the production of autoantibodies (Salonen et al., 1992).

Plant materials have long been used as traditional medicines for the treatment of a wide variety of ailments and diseases. Diets rich in vegetables and fruits can reduce cardiovascular disease (Howard and Kritchevsky, 1997, Hung et al., 2003, Mozaffarian et al., 2003, Katsube et al., 2004), notably by inhibiting LDL oxidation (Gorinstein et al., 1999, Marniemi et al., 2000, Landbo and Meyer, 2001, Southon, 2001, Shafiee et al., 2003, Nicolle et al., 2004).

The tamarind (Tamarindus indica L.) is a tree-type of plant which belongs to the Leguminosae, caesalpiniaceae family. It is indigenous to tropical Africa but has become naturalized in North and South America from Florida to Brazil, and is also cultivated in subtropical China, India, Pakistan, Indochina, Philippines, Java and Spain. Initially, the fruit shows a reddish-brown color that turns black or black brown, becoming more aromatic and sour on ripening. T. indica L. pulp fruit is used for seasoning, as a food component and in juices. Its fruit is regarded as a digestive, carminative, laxative, expectorant and blood tonic (Komutarin et al., 2004). Other parts of the plant present antioxidant (Tsuda et al., 1994), antihepatotoxic (Joyeux et al., 1995), antiinflammatory (Rimbau et al., 1999), antimutagenic (Ramos et al., 2003) and antidiabetic (Maiti et al., 2004) activities. The antiatherosclerosis potential of tamarind has not been previously investigated. In the present study we characterize tamarind fruit extracts by assessing the antiatherosclerosis potential in vivo, and the antioxidant action in vitro.

Section snippets

Preparation of T. indica fruit extract

Approximately 100 g of the fruit pulp were placed in a conical flask and soaked for three days in 400 ml of 70% alcohol, at 4 °C. The resulting extract was filtered through a sieve and then roto-evaporated until complete alcohol evaporation was obtained. In all experiments the extract was diluted in water.

HPLC analysis

HPLC analysis was performed in a Shimadzu LC-6AD apparatus with a Diode Array Detector (SPD-M10 Avp, Shimadzu), coupled with an auto injector (SIL-10AF, Shimadzu) and using the software CLASS-VP

Antioxidant activity of the T. indica L. extract in vitro

As an initial chemical characterization of the extract, an HPLC-UV chromatogram was performed. An UV spectra was obtained for each observed peak in the chromatogram. All spectra showed a similar absorption pattern, with two bands of maximum absorption around 230 and 290 nm, with the exception of the peak at 12.15 min, which comprises a single band of absorption at 282 nm. These data suggest the predominance of compounds like flavonoids that normally occurs as secondary metabolites in plants by the

Discussion

It is well established that elevated blood lipids levels constitute the major risk factor for atheroclerosis (Castelli et al., 1986). The search for new drugs capable of reducing and/or regulating serum cholesterol and triglycerides levels has gained momentum over the years, resulting in numerous reports on significant activities of natural agents (Jahromi et al., 1993). Although plan extracts constitute potential candidates, they very often contain highly complex mixtures of many different

Acknowledgments

We thank A. Zanardo Filho and N.M.F. Rodrigues for excellent technical assistance. We are grateful to Dr. Norberto P. Lopes and PhD Student Leonardo Gobbo Neto for HPLC Analysis. Flavia Martinello is a recipient of a PhD fellowship from the Fundação de Amparo à Pesquisa (FAPESP 02/03174-5). S.A. Uyemura is a fellow from the Conselho de Desenvolvimento Científico e Tecnológico (CNPq 475276/01-9).

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