Ethyl Acetate Fraction of Longan (Dimocarpus longan Lour.) Flower Water Extract Attenuates Metabolic Syndrome in Fructose-Fed Rats
Date Issued
2009
Date
2009
Author(s)
Huang, Chieh-Yu
Abstract
Metabolic syndrome becomes an important issue recently. It has strong correlation with several chronic disease, for instance, diabetes and cardiovascular disease. The risk factors of metabolic syndrome contain abdominal obesity, hyperglycemia, dyslipidemia and hypertension. Previous study in our laboratory has shown that Longan (Dimocarpus Longan Lour.) flower had strong antioxidant activity in vitro. Furthermore, we also have demonstrated that Longan flower water extract (LFWE) can improve the symptoms of the metabolic syndrome in animal model. Therefore, the purpose of this study was to investigate the effect of each fraction of Longan flower water extract on metabolic syndrome. We expect to find effective compound in Longan flower in the future. he study was carried out into two parts. The first part was an acute study to examine the effects of LFWE and its fractions on glucose tolerance in rats. Male Sprague-Dawley rats were randomly divided into five groups, administered LFWE, ethyl acetate fraction, n-butanol fraction, water fraction and ddH2O by gavage respectly. Results of oral glucose tolerance test (OGTT) in rats showed that both EA and W fraction can improve glucose tolerance. Therefore, we choose these two fractions to do the following study.he following study was to investigate the effect of long-term treatment of EA and W fraction on rats with metabolic syndrome induced by high fructose diet. Male Sprague-Dawley rats were randomly divided into five groups: group B, fed with standard Purina chow; group C, fed with high fructose diet ; group LFWE, fed with high fructose diet plus LFWE 250 mg/ml/kg BW per day by gavage ; group EA, fed with high fructose diet plus EA 36.3 mg/ml/kg BW per day by gavage ; group W, fed with high fructose diet plus W 147.5 mg/ml/kg BW per day by gavage. The dietary manipulation lasted for 16 weeks. Results of this study showed that, high fructose feeding cause significant increase in abdominal fat mass, fasting plasma glucose, insulin, triglyceride, cholesterol levels and systolic blood pressure. These results indicated that fructose-rich diet could cause a cluster of disorders in metabolic syndrome. reatment with LFWE significantly improved abdominal fat accumulation, hypertriglyceridemia, hyperinsulinemia, hyperglycemia, hypercholesterolemia, hypertension and insulin resistance. To further evaluated the possible mechanism of LFWE, we found that the rats showed decreased oxidative stress and increased expression of insulin signaling pathway related protein, including insulin receptor (IR), insulin receptor substrate-1 (IRS-1), Akt and glucose transporter Ⅳ(GLUT4).he supplement of EA fraction showed many similar efficacies as LFWE on abdominal fat, fasting glucose, insulin, triacylglyceride, hypertension and insulin resistance. EA fraction also showed the ability to decrease plasma TBARS and enhance glutathione reductase activity in fructose-fed rats. And the expressions of insulin signaling pathway related protein were also enhanced. fraction significantly decreased fasting glucose, total cholesterol, abdominal fat and liver triacylglycerol accumulation. But it shown no effects on insulin resistance and hypertriglyceridemia induced by high fructose diet instead. According to these finding, we suggested the effective components for ameliorating metabolic syndrome should be in the ethyl acetate fraction.
Subjects
Longan flower
metabolic syndrome
ethyl acetate fraction
insulin resistance
SDGs
Type
thesis
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