Monacolin M, a new inhibitor of cholesterol biosynthesis.

Monacolin M, a new specific inhibitor of cholesterol biosynthesis structurally related to monacolin K (mevinolin), was isolated from cultures of a strain of Monascus ruber. The structure of monacolin M was determined to be beta-hydroxybutyryl ester of monacolin J by a combination of physical techniques. It was suggested that monacolin M is derived from monacolin J via a synthetic pathway distinct from that for the synthesis of monacolin K, alpha-methylbutyryl ester of monacolin J. The inhibitory effect of monacolin M on beta-hydroxy-beta-methylglutaryl-CoA reductase was slightly lower than that of monacolin K.