INDUCTION OF GERANYL PYROPHOSPHATE PYROPHOSPHATASE ACTIVITY BY CHOLESTEROL-SUPPRESSIVE ISOPRENOIDS

Diets supplemented (1 mmol/kg) with thymol, carvacrol, and beta-ionone significantly decreased the serum cholesterol levels oi cockerels. Th ese mevalonate-derived end products of plant secondary metabolism (iso prenoids) had no impact on two cytosolic prenyl alcohol (and ethanol) dehydrogenase activities; each treatment increased microsomal geranyl pyrophosphate pyrophosphatase activity by greater than twofold. The st ructural diversity of the isoprenoids which suppress cholesterol synth esis may be reconciled by their ability to increase pyrophosphatase ac tivity, thus leading to the production of the endogenous, post-transcr iptional regulator of 3-hydroxy-3-methylglutaryl coenzyme A reductase activity.