Inhibition of dietary cholesterol ester absorption by 3-BCP, a suicide inhibitor of cholesterol-esterase.

Cholesterol esters, which can comprise over 75% of total cholesterol in diets rich in organ meats, must first be hydrolyzed by pancreatic cholesterol esterase (EC 3.1.1.13) before being absorbed (1). In its hydrolytic mode, catalysis by the enzyme involves a classical serine esterase mechanism in which the seroxide anion displaces the sterol moiety to give an acyl-enzyme intermediate, followed by nucleophilic displacement. In the absence of bile salt co-factor, the enzyme behaves like a simple esterase and readily hydrolyzes p-nitrophenyl acetate (2). 3-benzyl-6-chloropyrone(3-BCP) and 5-benzyl-6-chloropyrone (5-BCP) were synthesized as potential suicide inhibitors of the enzyme, according to the precedents of Katzenellenbogen (3,4). ABSORPTION BY 3-BCP, A SUICIDE INHIBITOR OF Inhibition was selective, and pancreatic lipase was unaffected at concentrations up to 2 mM.