Methyl Benzoate from Acanthaster Planci Exhibits Lipid-lowering Activity in Hypercholesterolemic Sprague-Dawley Rat’s Hepatocyte by Increasing Scavenger Receptor Class B Type 1 (Sr-B1) Gene Expression

Abstract

Hypercholesterolemia occurs when a high cholesterol level in the blood may lead to atherosclerosis. Scavenger receptor class B type 1 (SR-B1) is a protein found on the surface of various cells that facilitates the reverse cholesterol transport or efflux of cholesterol from peripheral tissues back to the liver. SR-B1 receives cholesterol from high-density lipoprotein (HDL), which is then transported and metabolized in the liver cells. In this study, the compound methyl benzoate isolated from Acanthaster planci was investigated for its ability to reduce hypercholesterolemia by increasing the expression of the SR-B1 gene. Using MTS assay, methyl benzoate showed a non-cytotoxic effect on hepatocellular liver carcinoma (HepG2) cells. The luciferase assay revealed that methyl benzoate increased SR-B1 promoter activity by 1.23-fold compared to the negative control. The expression of SR-B1 gene examined by real-time polymerase chain reaction (RT-PCR) increased the expression by 1.24-fold higher than that of the positive control. In addition, HDL uptake increased by 5% in the methyl benzoate-treated cells. As for the in-vivo model, methyl benzoate was administered to hypercholesterolemic Sprague-Dawley rats for 28 days via oral gavage. Blood withdrawn after 28 days revealed an improved lipid profile of the rats where the level of HDL was increased. In contrast, total cholesterol and low-density lipoprotein (LDL) levels were decreased. In conclusion, methyl benzoate isolated from A. planci reduced the total cholesterol, which may be mediated by SR-B1, making its potential for future therapeutic use.