Mevinolin, a fungal metabolite, was isolated from cultures of Aspergillus terreus. The structure and absolute configuration of mevinolm and its open acid form, mevinolinic acid, were determined by a combination of physical techniques.

Bardoxolone methyl was associated with improvement in the estimated GFR in patients with advanced CKD and type 2 diabetes at 24 weeks. The improvement persisted at 52 weeks, suggesting that bardoxolone methyl may have promise for the treatment of CKD. (Funded by Reata Pharmaceuticals; BEAM ClinicalTrials.gov number, NCT00811889.).

Background/Aims: Bardoxolone methyl, a novel synthetic triterpenoid, induces Nrf2, a transcription factor known to play a key role in decreasing oxidative stress and the production of pro-inflammatory molecules. Methods: This exploratory multi-center, open-label study assessed the clinical activity and safety of bardoxolone methyl in 20 patients with moderate to severe chronic kidney disease and type 2 diabetes. Patients received 25 mg of bardoxolone methyl daily for 28 days, followed by 75 mg daily for another 28 days. Results: The study achieved its primary efficacy endpoint, as demonstrated by a significant increase from baseline in estimated glomerular filtration rate (eGFR) of 7.2 ml/min/1.73 m² (p < 0.001). Improvements were seen in approximately 90% of patients and showed a dose- and time-dependent increase in eGFR. The eGFR change paralleled a significant reduction in serum creatinine (–0.3 mg/dl) and blood urea nitrogen (–4.9 mg/dl), along with an increase in creatinine clearance (+14.6 ml/min/1.73 m²), without a change in the 24-hour creatinine excretion rate. Markers of vascular injury and inflammation were improved by treatment with bardoxolone. No life-threatening adverse events or drug-related serious adverse events were reported. Conclusions: The results describe an apparent increase in kidney function following relatively short-term treatment with bardoxolone methyl, a promising new agent that warrants placebo-controlled studies to define its long-term effects on renal function.

Mevinolin is a potent inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMG-CoA reductase; EC 1.1.1.34), an enzyme that catalyzes the rate-limiting step in cholesterol biosynthesis. We have been studying the hepatic distribution of reductase with immunofluorescence microscopy and liver ultrastructure with electron microscopy in normal and drug-treated rats. In control animals, only about 20% of the hepatocytes were reductase positive. These cells were localized in the periportal lobular zones. The numbers of positive hepatocytes in animals given mevinolin or cholestyramine (or both) were directly proportional to the activities of the HMG-CoA reductase determined biochemically. This induction of HMG-CoA reductase immunofluorescence was centered periportally. Rats given 0.075% mevinolin alone had a homogeneous distribution of reductase staining in their hepatocyte cytoplasm, whereas a combination of 0.25% mevinolin and 3% cholestyramine caused a 150-fold increase in enzyme activity and induced prominent juxtanuclear immunofluorescent globules of HMG-CoA reductase in all hepatocytes. With electron microscopy, these bodies were composed of tightly packed stacks of smooth endoplasmic reticulum cysternae and aggregates of branched smooth endoplasmic reticulum tubules. Our data suggest that a subpopulation of periportal rat hepatocytes may be uniquely specialized for cholesterol synthesis.Mevinolin, a fungal metabolite isolated from Aspergillus terreus, is a potent competitive inhibitor of the rate-limiting enzyme of cholesterol biosynthesis, microsomal 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMG-CoA reductase; EC 1.1.1.34) (1). A similar but somewhat less active inhibitor, compactin (ML-236B), has been purified from Penicillium citrium (2). These compounds are effective cholesterol-lowering agents in several species, including dogs (1, 3, 4) and humans (5-10) but not rats (11,12). Furthermore, 50-70% reductions in the plasma cholesterol levels of dogs and humans have been obtained with combinations of bile acid sequestrants and mevinolin or compactin (4, 8-10).The synthesis of HMG-CoA reductase in rat liver is exquisitely sensitive to a number of factors, including diurnal variation (13,14). Treatment of rats with either an HMGCoA reductase inhibitor or a bile acid sequestrant (or both) results in a marked elevation of enzyme level (14-17). This induction is the result of a dramatic increase in reductase mRNA levels and an enhancement of enzyme stability (15-17). Similarly, in UT-1 cells, a compactin-resistant line, reductase levels are greatly elevated but may be repressed abruptly by low density lipoprotein administration (18). Microscopic studies of these cells reveal a dramatic development of the smooth endoplasmic reticulum (SER) associated with high concentrations of HMG-CoA reductase (19-21).The purpose of this study was to determine the hepatic distribution of HMG-CoA reductase and to correlate putative alterations in reductase patterns and ultrastructure with the extent of enzyme ...

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A series of 5-substituted 3,5-dihydroxypentanoic acids and their derivatives have been prepared and tested for inhibition of HMG-CoA reductase in vitro. In general, unless a carboxylate anion can be formed and the hydroxy groups remain unsubstituted in an erythro relationship, inhibitory activity is greatly reduced. Furthermore, only one enantiomer of the ring-opened form of lactone 6a(+/-) possesses the activity displayed by the racemate. Insertion of a bridging unit other than ethyl or (E)-ethenyl between the 5-carbinol moiety and an appropriate lipophilic moiety (e.g., 2,4-dichlorophenyl) attenuates activity.

Lovastatin is a potent competitive inhibitor of the rate-limiting enzyme of cholesterol synthesis, 3-hydroxy-3-methylglutaryl-coenzyme A reductase (NADPH) [HMG-CoA reductase; (S)-mevalonate:NADP+ oxidoreductase (CoA-acylating), EC 1.1.1.34]. We determined the subcellular distribution of HMG-CoA reductase at high resolution by means of immunoelectron microscopy on ultrathin frozen liver sections of rats treated with lovastatin and cholestyramine. High concentrations of reductase were located on the outer (cytoplasmic) surfaces of smooth endoplasmic reticulum (SER) membranes induced in hepatocytes by acute drug administration. The enzyme was specifically localized over the whorled SER membranes and was absent from nonwhorled SER, rough endoplasmic reticulum, and peroxisomes. Intense HMG-CoA reductase labeling was only observed in hepatocytes containing high levels of HMG-CoA reductase activity; no staining was detected in untreated livers. These observations show that HMG-CoA reductase is induced as an integral component of the SER membranes that form in rat hepatocytes subsequent to lovastatin treatment and suggest that the formation of SER whorls in rat hepatocytes is due to mechanism-based effects of lovastatin.

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