Genes Nutr (2010) 5:331–341 DOI 10.1007/s12263-010-0187-5 R E S E A R C H P A P E R Gene expression proﬁles in human HepG2 cells treated with extracts of the Tamarindus indica fruit pulp Nurhanani Razali • Azlina A. Aziz • Sarni M. Junit Received: 11 June 2010 / Accepted: 29 September 2010 / Published online: 19 October 2010 The Author(s) 2010. This article is published with open access at Springerlink.com Abstract Tamarindus indica L. (T. indica) or locally known as asam jawa belongs to the family of Leguminosae. The fruit pulp had been reported to have antioxidant activities and possess hypolipidaemic effects. In this study, we attempted to investigate the gene expression patterns in human hepatoma HepG2 cell line in response to treatment with low concentration of the fruit pulp extracts. Micro- array analysis using Affymetrix Human Genome 1.0 S.T arrays was used in the study. Microarray data were vali- dated using semi-quantitative RT–PCR and real-time RT–PCR. Amongst the signiﬁcantly up-regulated genes were those that code for the metallothioneins (MT1M, MT1F, MT1X) and glutathione S-transferases (GSTA1, GSTA2, GST02) that are involved in stress response. APOA4, APOA5, ABCG5 and MTTP genes were also sig- niﬁcantly regulated that could be linked to hypolipidaemic activities of the T. indica fruit pulp. Keywords Tamarindus indica fruit pulp expression Microarray analysis RT–PCR Gene HepG2 cells Introduction Plants and herbs have been used for years traditionally as food and for various medicinal purposes. Many of these plants are excellent sources for polyphenols that are potent antioxidant compounds which exhibit a wide range of biological effects as consequences of their antioxidant properties [7, 21]. Tamarindus indica L. (T. indica) or N. Razali A. A. Aziz S. M. Junit (&) Department of Molecular Medicine, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia e-mail: sarni@um.edu.my locally known as asam jawa belongs to the family Leguminosae and grows naturally in many tropical and subtropical regions. Various parts of the plants are used as food components and in herbal medicine. The T. indica fruits have irregular curved pods. When ripe, the pods are ﬁlled with brown or reddish-brown pulp that coats the seeds. The pulp has a sweet/sour taste and is widely used as ﬂavouring in cooking. There are wide differences in fruit size and ﬂavour in seedling trees. The Indian types have longer pods with 6–12 seeds, while the West Indian types have shorter pods, containing only 3–6 seeds. The pulp is believed to be rich in vitamins and minerals such as niacin and calcium, respectively [27]. The T. indica fruit pulp is commonly used in traditional medicine including as a digestive, laxative, expectorant and an antipyretic agent. Biochemical analysis in support of the beneﬁcial effects of the T. indica fruit pulp extracts includes a study by Martinello et al. [26] who showed that the T. indica fruit extracts were able to decrease the levels of serum choles- terol and triglycerides in hypercholesterolaemic hamsters. The T. indica fruit pulps have also been shown to contain phenolic antioxidants such as epicatechins [44] that were able to inhibit low-density lipoprotein (LDL) oxidation in vitro [45]. Chan et al. [9] had shown that epicatechins from jasmine green tea were able to reduce serum levels of TG, and cholesterol in hamsters fed a high-fat diet, but the hypolipidaemic effects were not through the inhibition of liver HMGCoA reductase or intestinal ACAT. They further postulated that the observed hypolipidaemic effects of epicatechins were probably associated with the inhibition of absorption of dietary fat, cholesterol or reabsorption of bile acids [9]. Another group of researchers, Landi Librandi et al. [22], reported that the fruit pulp extract was able to modulate the activity of the complement system when tested both in vitro and in vivo. Scientiﬁc data based 123