ผลของสารสกัดจากเปลือกผลไม้ในเขตร้อนบางชนิดที่มีต่อโรคอ้วน

บทคัดย่อ

Obesity has become an important public health problem that can cause a number of obesity-related diseases. The use of commercial anti-obesity drugs, such as orlistat and sibutramine, can cause unpleasant side effects. To overcome these problems, the use of plant extracts is probably a better way to replace these anti-obesity drugs. The fruit rind of rambutan (Nephelium lappaceum L.) contains phenolic compounds that can help to prevent obesity. Therefore, this experiment aimed to study effects of the rambutan rind extract on obesity in vitro and in vivo. This study consisted of 3 main experiments:Experiments 1 investigated acute and sub-chronic toxicities of the rambutan rind extract in male Wistar rats. The acute toxicity data indicated that the no-observed-adverse-effect level (NOAEL) for the oral dose of the rambutan rind extract was 3000 mg/kg and the lowest-observed-adverse-effect level (LOAEL) was 4000 mg/kg. The evaluated oral LD 50 of the rambutan rind extract was then greater than 5000 mg/kg. The sub-chronic toxicity indicated that the NOAEL of the rambutan rind extract was 1000 mg/kg and the LOAEL was 2000 mg/kg. Experiment 2 investigated effects of the rambutan rind extract on pancreatic lipase, alpha-amylase, and alpha-glucosidase activities in vitro and plasma biochemical parameters in lipid emulsion-induced hyperlipidemia rats. The results showed that the rind of rambutan extracted by 85% ethanol had a yield of18.05%. The rambutan rind extract contained total phenolic content (416.18 ? 0.01 mg gallic acid/g dry extract), total anthocyanin content (14.90 ? 0.8 ?g/g dry extract), with IC50 value of 0.288 ? 0.04 mg/ml extract. In vitro study, the rambutan rind extract, tannin, and orlistat showed potent inhibitory effects on pancreatic lipase, alpha-amylase, and alpha-glucosicdase activities. In vivo study, the rambutan rind extract, tannin, and orlistat significantly suppressed the increased plasma level of triglyceride (TG) caused by lipid emulsion administration.Experiments 3 investigated effect of the rambutan rind extract on the rat hypothalamic expression of the neuronal activation marker Fos. The rambutan rind extract induced Fos expression only in the arcuate nuclei (ARC). A significant increase in the number of Fos-positive neurons was shown in the area of the ARC ranging from -3.60 to -3.96 mm from bregma following the rambutan rind extract compared to the control. In conclusion, the present findings suggested that the rambutan rind extract displayed beneficial effects in prevention and treatment of obesity.

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