Journal of Experimental and Integrative Medicine DOI: 10.5455/jeim.200115.or.120 www.jeim.org J Exp Integr Med ● Jan-Mar 2015 ● Vol 5 ● Issue 1 55 INTRODUCTION Prevalence of Type 2 diabetes mellitus (T2DM) is increasing especially in the developing countries. In Indonesia, T2DM is predicted to be as much as 21.2 million in 2030. The increasing prevalence is due to population growth, aging, urbanization, obesity, and physical inactivity. Obesity is leading the risk for death; more than 4.3 million adults die yearly as a result of being obese [1]. Obesity is defined as excessive fat accumulation in adipocytes [2], and trigger to various diseases such as T2DM, cardiovascular disease, and cancer [3]. Excessive caloric intake such as carbohydrates and fat, and sedentary lifestyles will induce hyperglycemia and increase fatty acid level; these can increase free radical production by mitochondria and lead to oxidative stress. The oxidative stress may cause several problems such as beta cell damage and altered insulin production, increase insulin resistance and endothelial dysfunction. Accumulation of fat and the differentiation of adipocytes are related to obesity development [4]. All of these can lead to T2DM and metabolic syndrome [5]. Oral antidiabetic agents have different mechanisms including increasing the insulin secretion, decreasing the glucagon secretion, increasing the insulin receptor sensitivity, decreasing the glucose absorption, and inhibiting several glucosidase enzymes [6-9]. Many plants are known as the source of potent and powerful drugs that have fewer side effects and less toxicity compared to synthetic drugs [10-13]. Many phenolics are known to possess anti-obesity properties through mechanisms that inhibit adipogenesis, stimulate lipolysis or induce apoptosis [14]. Rambutan (Nephelium lappaceum L), belonging to the Sapindaceae family, is a tropical fruit widely distributed in South-East Asia. Its consumption results the vast amounts of waste from the seeds and peels of the fruit [15]. Rambutan seeds contain various phenolic compounds such as ellagic acid, corilagin, and geraniin [16]. In the previous study, rambutan seeds extract and fractions possess an inhibitory effect on α-glucosidase activity in vitro [17]. Hypoglycemic activity plays an important role in T2DM therapy [18]. Therefore, the present study is a continuing work designed to evaluate additional parameters Inhibitory potential of rambutan seeds extract and fractions on adipogenesis in 3T3-L1 cell line Sylvia Soeng 1 , Endang Evacuasiany 1 , Wahyu Widowati 1 , Nurul Fauziah 2 , Visi Tinta Manik 2 , Maesaroh Maesaroh 2 Original Article 1 Department of Biology, Faculty of Medicine, Maranatha Christian University, Bandung, Indonesia, 2 Department of Biomedical, Biomolecular and Biomedical Research Center, Aretha Medika Utama, Bandung, Indonesia Address for correspondence: Wahyu Widowati, Medical Research Center, Faculty of Medicine, Maranatha Christian University, Jl. Prof drg. Suria Sumantri No.65, Bandung - 40164, Indonesia. E-mail: wahyu_w60@yahoo. com Received: November 17, 2014 Accepted: April 03, 2015 Published: March 22, 2015 ABSTRACT Objective: Type 2 diabetes is a global health problem with increasing prevalence related to several conditions; one of these is due to obesity. Rambutan (Nephelium lappaceum L) seeds contain various phenolic compounds. The present study was designed to evaluate the phytochemical content and the inhibitory potential of rambutan seeds extract and fractions on glucose-6-phosphate dehydrogenase (G6PDH), α-glucosidase, and triglyceride activities ex vivo in 3T3-L1 cell line (pre-adipocytes) for an antidiabetic and antidiapogenesis agent screening. Materials and Methods: Phytochemical analysis was performed using modified Farnsworth method. Cytotoxicity or cell viability of rambutan seed extracts (distillated ethanol 70%) and fractions (hexane, ethyl acetate, butanol, and water fractions) were assayed using 3-(4,5-dimethylthiazol-2-yl)- 5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium assay. Triglyceride (TG) level, G6PDH and α-glucosidase activity and inhibitory activities were determined by commercial assay kits. Results: Extract and fractions of rambutan seed contained alkaloid, terpenoid, triterpenoid, and phenol; flavonoid, tannin, saponin, and steroid were undetected. The lowest cytotoxic activity and safe substances on 3T3-L1 cell were rambutan seed extract and hexane fraction. Rambutan seed extract at the dose of 50 µg/ml was the most active to lower G6PDH and α-glucosidase as well as TG level. Conclusion: Rambutan seed extract and hexane fraction have the phytochemical bioactive content to possess inhibitory potential on G6PDH and α-glucosidase as well as TG level in the present experimental set of 3T3-L1 cell lines. KEY WORDS: 3T3-L1, anti-adipogenesis, antidiabetic, Nephelium lappaceum L, triglyceride