Antihyperlipidaemic And Antioxidant Activities Of Extracts Of Different Parts Of Averrhoa Carambola And Elucidation Of Their Mechanisms Of Action
Loading...
Date
2015-10
Authors
Mohammed Saghir, Sultan Ayesh
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Averrhoa carambola, commonly known as star fruit is one of the widely used herbs in the Malaysian traditional medicine, with the leaf and fruits being the most utilized parts. This study aims to investigate the antihyperlipidaemic effect, antioxidant activity and toxicity of methanolic and aqueous extracts of different parts of A. carambola with focus on elucidating the underlying mechanism of action. Of the tested extracts, the methanolic extract of A. carambola leaf showed the most potent antihyperlipidaemic activity in poloxamer-407-induced acute hyperlipidaemic rat model compared to the hyperlipidaemic control, which was comparable with that of atorvastatin. Upon chronic administration up to five weeks, no significant decrease was observed in the levels of the lipid parameters of normal rats treated with 1000 mg/kg of methanolic extract of leaf. In contrast, significant changes were observed in lipid parameters of high-fat diet induced hyperlipidemic rats after treated with 500 and 1000 mg/kg leaf methanolic extract as compared with the hyperlipidaemic control. These findings thus suggest that methanolic extract of A. carambola leaf works as an antihyperlipidaemic rather than a hypolipidaemic agent. Following fractionation, assessment using poloxamer-407 induced acute hyperlipidaemic rats showed that the ethyl acetate fraction of methanolic extract of A. carambola leaf exhibits the most potent significant effect in terms of reducing all lipid parameters except increasing high density lipoprotein cholesterol (HDL-C)
levels. For antioxidant evaluation, methanolic extract of A. carambola stem and leaf showed the highest antioxidant activity. The total phenolic and flavonoid contents of A. carambola extracts showed strong correlation with their antioxidant activities, but no correlation was found with their antihyperlipidaemic effects. Methanolic extract of leaf and its ethyl acetate fraction produced dose-dependent inhibitory effects on HMG-CoA reductase at 5 and 10 mg/mL concentrations, while weak inhibitory effect was detected on pancreatic lipase in vitro. In addition, methanolic extract of the leaf significantly increased the in vivo antioxidant enzymes levels and decreased the lipid peroxidation in liver homogenates and serum samples in a dose-dependent manner. On the other hand, methanolic extract of leaf given to high fat-diet rats at the doses of 500 and 1000 mg/kg was effective in reducing the synthesis of cholesterol and triglycerides in the liver and increasing the excretion of cholesterol and bile acids in faeces. An investigation using four cancer cell lines (K-562, HL-60, kasumi-1 and HCT-116) revealed that none of A. carambola extracts had cytotoxic effects. Acute and sub-chronic toxicity study of methanolic extract of A. carambola leaf showed that the extract was safe and no significant changes was observed in both biochemical and haematological parameters in treated rats compared with control group. Overall, this study suggests that the methanolic extract of A. carambola leaf has lipids lowering effect that could be further developed as an antihyperlipidaemic agent.
Description
Keywords
The antihyperlipidaemic effect, antioxidant activity and toxicity of methanolic and aqueous extracts , of different parts of A. carambola.