Synthesis and in vitro evaluation of inhibitors of intestinal cholesterol absorption

We have utilized our recently developed in vitro assay to address two key questions in the design of small-molecule cholesterol absorption inhibitors using ezetimibe, the only drug yet approved for the inhibition of cholesterol absorption in the small intestine, as a starting point: (1) the role of glycosylation and (2) the importance of the beta-lactam scaffold of ezetimibe for inhibitory activity. A wide range of nonhydrolyzable phenolic glycosides of ezetimibe were synthesized and demonstrated to be active inhibitors of cholesterol absorption using the brush border membrane vesicle assay. The analogous azetidines provided access to a variety of inhibitors in vitro, suggesting that the beta-lactam of ezetimibe merely serves as a ring scaffold to appropriately position the required substituents. Our findings highlight several promising strategies for the design of alternative small-molecule cholesterol absorption inhibitors that could ultimately be useful in preventing cardiovascular disease by lowering blood cholesterol levels.