INHIBITION OF ACYL COENZYME-A - CHOLESTEROL ACYL TRANSFERASE BY TRIMETHYLCYCLOHEXANYLMANDELATE (CYCLANDELATE)

Cyclandelate was an effective inhibitor of rat hepatic acycloenzyme A: cholesterol acyltransferase (ACAT) with a concentration of 80 μM being required for half maximal inhibition. A similar effect was seen with human and rabbit liver microsomal enzymes. The drug did not compete with oleoyl CoA or cholesterol and could be removed from enzyme preparations by washing. It was hydrolysed rapidly by rat liver microsomes to products which were non inhibitory. No hydrolysis of the drug was seen with non hepatic microsomes and the concentration of cyclandelate required to cause half maximal inhibition of ACAT in the transformed mouse macrophage J774 microsomal fraction was less than 30 μM. The possible significance of the differential actions of cyclandelate towards hepatic and extra hepatic ACAT in vivo is discussed. © 1990.