Compound A from Plantago asiatica essential oils reduced plasma triglyceride and cholesterol levels and suppressed the expression of 3‐hydroxy‐3‐methyl‐glutaryl‐Coenzyme A reductase in the liver of diet‐induced obese mice

Abstract

Plantago asiatica is a commonly used folk medicine in Eastern Asia and its essential oils have various bioactive compounds. Previously, we have showed that Plantago asiatica essential oils (PAEO) have hypolipidemic effects. Since compound A(82.6%) was a major component in the PAEO, we further examined hypolipidemic effects of compound A as well as the PAEO in diet‐induced obese mice. Mice (C57BL/6CrSlc) were fed a high fat diet for 5 weeks and then compound A and the PAEO were orally administered for 6 weeks under high fat diet. The PAEO and the compound A feeding significantly reduced plasma total cholesterol and triglyceride levels after 3 and 6 weeks, respectively, compared with the controls. Compound A reduced plasma cholesterol concentrations by approximately 20%. We investigated the effects of the PAEO and compound A on the expression of cholesterol metabolism genes. The expression of the HMG‐CoA reductase, assessed by RT‐PCR, was significantly reduced by 50% in the livers of compound A‐fed mice compared with the control livers after 6 weeks. Our data suggest that compound A, a major compound in the PAEO, may exert hypocholesterolaemic effects by downregulation of the HMG‐CoA reductase expression in diet‐induced obese mouse.