Alfred W. Alberts

Bio: Alfred W. Alberts is an academic researcher from Merck & Co.. The author has contributed to research in topics: Lovastatin & HMG-CoA reductase. The author has an hindex of 25, co-authored 43 publications receiving 4046 citations.

Mevinolin: a highly potent competitive inhibitor of hydroxymethylglutaryl-coenzyme A reductase and a cholesterol-lowering agent.

Abstract: Mevinolin, a fungal metabolite, was isolated from cultures of Aspergillus terreus. The structure and absolute configuration of mevinolini and its open acid form, mevinolinic acid, were determined by a combination of physical techniques. Mevinolin was shown to be 1,2,6,7,8,8a-hexahydro-beta, delta-dihydroxy-2,6-dimethyl-8-(2-methyl-1-oxobutoxy)-1-naphthalene-hepatanoic acid delta-lactone. Mevinolin in the hydroxy-acid form, mevinolinic acid, is a potent competitive inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A reductase [mevalonate: NADP+ oxidoreductase (CoA-acylating), EC 1.1.1.34]; its Ki of 0.6 nM can be compared to 1.4 nM for the hydroxy acid form of the previously described related inhibitor, ML-236B (compactin, 6-demethylmevinolin). In the rat, orally administered sodium mevinolinate was an active inhibitor of cholesterol synthesis in an acute assay (50% inhibitory dose = 46 microgram/kg). Furthermore, it was shown that mevinolin was an orally active cholesterol-lowering agent in the dog. Treatment of dogs for 3 weeks with mevinolin at 8 mg/kg per day resulted in a 29.3 +/- 2.5% lowering of plasma cholesterol.

Hypocholesteremic fermentation products and process of preparation

Abstract: Substances isolated after cultivation of a microorganism belonging to the genus Aspergillus in a culture medium comprise a compound designated MSD803 which has the lactone structure: ##STR1## as well as its free hydroxy acid form. Together with salts and esters of the free acid form, these compounds form a class of highly active hypocholesteremic and hypolipemic medicaments.

Discovery, biochemistry and biology of lovastatin

Abstract: Cholesterol is a 27-carbon steroid that is an essential component of the cell membrane, the immediate precursor of steroid hormones, the substrate for the formation of bile acids, and is required for the assembly of very low density lipoprotein in the liver. Because as much as two-thirds of total body cholesterol in patients is of endogenous origin, an effective means to control cholesterogenesis may occur by inhibition of its biosynthesis. Cholesterol is biosynthesized in a series of more than 25 separate enzymatic reactions that initially involve the formation of 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA). Early attempts to pharmacologically block cholesterol synthesis focused only on steps later in the biosynthetic pathway and resulted in compounds with unacceptable toxicity. Recent research had identified that HMG CoA reductase is a key rate-limiting enzyme in this pathway and is responsible for the conversion of HMG CoA to mevalonate. Additional research with fungal metabolites identified a series of compounds with potent inhibiting properties for this target enzyme, from which lovastatin was selected for clinical development. A reduction in cholesterol synthesis by lovastatin has been subsequently confirmed in cell culture, animal studies and in humans. A resultant decrease in circulating total and low-density lipoprotein (LDL) cholesterol has also been demonstrated in animals and humans. Because hepatic LDL receptors are the major mechanism of LDL clearance from the circulation, further animal research has confirmed that these declines in cholesterol are accompanied by an increase in hepatic LDL receptor activity. Lovastatin effectively diminishes endogenous cholesterol synthesis providing useful therapeutic properties for patients with hypercholesterolemia.

Preclinical evaluation of lovastatin.

Abstract: Administration of lovastatin to animals at high dosage levels produces a broad spectrum of toxicity. This toxicity is expected based on the critical nature of the target enzyme (HMG CoA reductase) and the magnitude of the dosage levels used. The information reviewed in this paper demonstrates that these adverse findings in animals do not predict significant risk in humans. The reason for this derives from the fact that all the available evidence suggests that the adverse effects observed are produced by an exaggeration of the desired biochemical effect of the drug at high dosage levels. The presence of clear and high no-effect doses for these toxic effects along with the fact that most of the changes observed are clearly mechanism-based (directly attributable to inhibition of mevalonate synthesis) indicate that it is unlikely that similar changes will be observed at the therapeutic dosage levels in humans. This hypothesis is supported by the extensive human safety experience described by Tobert in the following report.

A receptor-mediated pathway for cholesterol homeostasis.

Abstract: In 1901 a physician, Archibald Garrod, observed a patient with black urine. He used this simple observation to demonstrate that a single mutant gene can produce a discrete block in a biochemical pathway, which he called an “inborn error of metabolism”. Garrod’s brilliant insight anticipated by 40 years the one gene-one enzyme concept of Beadle and Tatum. In similar fashion the chemist Linus Pauling and the biochemist Vernon Ingram, through study of patients with sickle cell anemia, showed that mutant genes alter the amino acid sequences of proteins. Clearly, many fundamental advances in biology were spawned by perceptive studies of human genetic diseases (1). We began our work in 1972 in an attempt to understand a human genetic disease, familial hypercholesterolemia or FH. In these patients the concentration of cholesterol in blood is elevated many fold above normal and heart attacks occur early in life. We postulated that this dominantly inherited disease results from a failure of end-product repression of cholesterol synthesis. The possibility fascinated us because genetic defects in feedback regulation had not been observed previously in humans or animals, and we hoped that study of this disease might throw light on fundamental regulatory mechanisms. Our approach was to apply the techniques of cell culture to unravel the postulated regulatory defect in FH. These studies led to the discovery of a cell surface receptor for a plasma cholesterol transport protein called low density lipoprotein (LDL) and to the elucidation of the mechanism by which this receptor mediates feedback control of cholesterol synthesis (2,3). FH was shown to be caused by inherited defects in the gene encoding the LDL receptor, which disrupt the normal control of cholesterol metabolism. Study of the LDL receptor in turn led to the understanding of receptor-mediated endocytosis, a genera! process by which cells communicate with each other through internalization of regulatory and nutritional molecules (4). Receptor-mediated endocytosis differs from previously described biochemical pathways because it depends upon the continuous and highly controlled movement of membraneembedded proteins from one cell organelle to another in a process termed

Drug Discovery: A Historical Perspective

Abstract: Driven by chemistry but increasingly guided by pharmacology and the clinical sciences, drug research has contributed more to the progress of medicine during the past century than any other scientific factor. The advent of molecular biology and, in particular, of genomic sciences is having a deep impact on drug discovery. Recombinant proteins and monoclonal antibodies have greatly enriched our therapeutic armamentarium. Genome sciences, combined with bioinformatic tools, allow us to dissect the genetic basis of multifactorial diseases and to determine the most suitable points of attack for future medicines, thereby increasing the number of treatment options. The dramatic increase in the complexity of drug research is enforcing changes in the institutional basis of this interdisciplinary endeavor. The biotech industry is establishing itself as the discovery arm of the pharmaceutical industry. In bridging the gap between academia and large pharmaceutical companies, the biotech firms have been effective instruments of technology transfer.

Pleiotropic effects of statins

Abstract: ▪ Abstract Statins are potent inhibitors of cholesterol biosynthesis. In clinical trials, statins are beneficial in the primary and secondary prevention of coronary heart disease. However, the over...