Journal Issue: No 2, Issue 6, APRIL-JUNE, 2004
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1812-2027
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Articles
Cholesterol-Lowering effect of organosulphur compounds from garlic: a possible mechanism of action
(Kathmandu University, 2004) BC,Mathew; NV, Prasad; R, Prabodh
Objectives: Hyperlipidemia constitutes a major etiopathological factor for atherosclerosis. The medicinal value of
garlic is best known for its lipid lowering effects and antiatherogenic effects. The mechanism by which lipid soluble
organosulphur compounds from garlic reduce plasma lipids has not been fully investigated. The author had
previously shown that the hepatic activity of β-hydroxy-β-methylglutaryl-CoA (HMG-CoA) reductase, the rate
limiting enzyme in cholesterol biosynthesis and the incorporation of radiolabeled (1, 2 14C ), acetate into hepatic free
and esterified cholesterol was significantly decreased in rat treated with garlic derived organosulphur compounds.
We hypothesised that the antiatherogenic effect of the organosulphur compounds may be attributed to the formation
of protein internal disulphide and thus inactivation of thiol (-SH) group enzymes such as HMG-CoA reductase and
the multienzyme complex of fatty acid synthesis. The objective of the present study is to elucidate the inhibitory
mechanism by in vitro studies.
Method: Lipid soluble organosulphur compounds from garlic were treated in vitro with Luke's cysteine reagent
(representing the thiol (-SH) group of enzymes) and the interaction products were separated by paper
chromatography.
Result: The result indicated that the organosulphur compounds were capable of interacting with the thiol (-SH)
group of cysteine and thus forming cysteine derivatives.
Conclusion: The antiatherogenic effects of these organosulphur compounds can be attributed to such reactions that
inhibit HMG-CoA reductase and other lipogenic enzymes. The anticarcinogenic effects of these compounds may
also be due to inhibitory reactions on enzymes that activate carcinogens.
Key Words: Garlic, Organosulphur compounds, Cholesterol, HMG-CoA reductase