Effects of Saponin from Trigonella Foenum-Graecum Seeds on Dyslipidemia

BACKGROUND: Saponins identified from fenugreek (Trigonella foenum-graecum) seeds are reported effective on dyslipidemia. However, the definite mechanism is still not elucidated systematically. In this study, we evaluate the effects of saponin extract on cholesterol absorption, metabolism, synthesis, and reverse cholesterol transport in vivo. METHODS: Saponin extract was prepared according to a craft established in our previous study. After the establishment of dyslipidemia model, 40 male Sprague-Dawley rats were divided into five groups, namely the control group (normal diet plus normal saline), HFD group (high fat diet plus normal saline), Lipitor group (high fat diet plus Lipitor (2 mg/kg)), and L, M, and H-saponin groups (high fat diet plus saponin in dosages of 6, 12, and 24 mg/kg, respectively). Rats were sacrificed at the end of the 9th week after treatment. Biochemical characteristics of rats were tested, histopathological sections of liver tissue were observed, and the protein and mRNA expression of related factors of cholesterol in the intestine and liver were determined. One-way ANOVA test (SPSS software version 11.5, Chicago, IL, USA) was used to determine statistically significant differences between the HFD and other groups. RESULTS: In saponin groups, the serum lipid, bile acid efflux, anti-peroxide activities, and lipid area of liver tissue improved. Cholesterol 7alpha-hydroxylase and scavenger receptor class B type I elevated in the liver. 3-hydroxy-3-methylglutaryl coenzyme A reductase levels were suppressed in both the serum and liver. However, significant cholesterol efflux was not found and Niemann-Pick C1-Like 1 levels elevated in the intestine. CONCLUSION: The mechanisms of saponin in Fenugreek effect on ameliorating dyslipidemia are probably related to accelerated cholesterol metabolism, inhibited cholesterol synthesis, and facilitated reverse cholesterol transport, but not cholesterol absorption.