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Biomedical subjects

Michael Brands

Publications and source records attributed to Michael Brands.

13 recordsLinked to original sources
PubMed2006

Antibacterial natural products in medicinal chemistry--exodus or revival?

To create a drug, nature's blueprints often have to be improved through semisynthesis or total synthesis (chemical postevolution). Selected contributions from industrial and academic groups highlight the arduous but rewarding path from natural products to drugs. Principle modification types for natural products are discussed herein, such as decoration, substitution, and degradation. The biological, chemical, and socioeconomic environments of antibacterial research are dealt with in context. Natural products, many from soil organisms, have provided the majority of lead structures for marketed anti-infectives. Surprisingly, numerous "old" classes of antibacterial natural products have never been intensively explored by medicinal chemists. Nevertheless, research on antibacterial natural products is flagging. Apparently, the "old fashioned" natural products no longer fit into modern drug discovery. The handling of natural products is cumbersome, requiring nonstandardized workflows and extended timelines. Revisiting natural products with modern chemistry and target-finding tools from biology (reversed genomics) is one option for their revival.

Anti-Bacterial Agents↗
PubMed2006

Diet and lifestyle recommendations revision 2006: a scientific statement from the American Heart Association Nutrition Committee.

Improving diet and lifestyle is a critical component of the American Heart Association's strategy for cardiovascular disease risk reduction in the general population. This document presents recommendations designed to meet this objective. Specific goals are to consume an overall healthy diet; aim for a healthy body weight; aim for recommended levels of low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglycerides; aim for normal blood pressure; aim for a normal blood glucose level; be physically active; and avoid use of and exposure to tobacco products. The recommendations are to balance caloric intake and physical activity to achieve and maintain a healthy body weight; consume a diet rich in vegetables and fruits; choose whole-grain, high-fiber foods; consume fish, especially oily fish, at least twice a week; limit intake of saturated fat to <7% of energy, trans fat to <1% of energy, and cholesterol to <300 mg/day by choosing lean meats and vegetable alternatives, fat-free (skim) or low-fat (1% fat) dairy products and minimize intake of partially hydrogenated fats; minimize intake of beverages and foods with added sugars; choose and prepare foods with little or no salt; if you consume alcohol, do so in moderation; and when you eat food prepared outside of the home, follow these Diet and Lifestyle Recommendations. By adhering to these diet and lifestyle recommendations, Americans can substantially reduce their risk of developing cardiovascular disease, which remains the leading cause of morbidity and mortality in the United States.

Cardiovascular Diseases↗
PubMed2006

Effect of simvastatin on high glucose- and angiotensin II-induced activation of the JAK/STAT pathway in mesangial cells.

In the current study, we investigated the effect of simvastatin on the ability of high glucose (HG) and ANG II to activate the JAK2-STAT signaling cascade and induce glomerular mesangial cell (GMC) growth. We found that pretreatment with simvastatin significantly inhibited HG- and ANG II-induced collagen IV production, JAK2 activation, and phosphorylation of STAT1 and STAT3 in GMC. We also found that the activation of JAK2 by HG and ANG II was dependent on the Rho family of GTPases. Consistent with these in vitro results, both albumin protein excretion and phosphorylation of JAK2, STAT1, and STAT3 were attenuated in renal glomeruli by administration of simvastatin in a streptozotocin-induced rat model of HG diabetes. This study demonstrates that simvastatin blocks ANG II-induced activation of the JAK/STAT pathway in the diabetic environment, in vitro and in vivo, and, thereby, provides new insights into the molecular mechanisms underlying early diabetic nephropathy.

Angiotensin II↗
PubMed2006

Selective indole-based ECE inhibitors: synthesis and pharmacological evaluation.

Inhibition of the metalloprotease ECE-1 may be beneficial for the treatment of coronary heart disease, cancer, renal failure, and urological disorders. A novel class of indole-based ECE inhibitors was identified by high throughput screening. Optimization of the original screening lead structure 6 led to highly potent inhibitors such as 11, which bears a bisaryl amide moiety linked to the indole C2 position through an amide group. Docking of 11 into a model structure of ECE revealed a unique binding mode in which the Zn center of the enzyme is not directly addressed by the inhibitor, but key interactions are suggested for the central amide group. Testing of the lead compound 6 in hypertensive Dahl S rats resulted in a decrease in blood pressure after an initial period in which the blood pressure remained unchanged, most probably the result of ET-1 already present. Indole derivative 6 also displays a cardio-protective effect in a mouse model of acute myocardial infarction after oral administration. The more potent chloropyridine derivative 9 antagonizes big-ET-1-induced increase in blood pressure in rats at intravenous administration of 3 mg kg-1. All ECE inhibitors of the indole class showed high selectivity for ECE over related metalloproteases such as NEP and ACE. Therefore, these compounds might have further potential as drugs for the treatment of coronary heart diseases.

Aspartic Acid Endopeptidases↗
PubMed2005

Novel, selective indole-based ECE inhibitors: lead optimization via solid-phase and classical synthesis.

A novel class of indole-based endothelin-converting enzyme (ECE) inhibitors was identified by high throughput screening. We report systematic optimization of this compound class by means of classical and solid-phase chemistry. Optimized compounds with a bisarylamide side chain at the 2-position of the indole skeleton exhibit low-nanomolar activity on ECE.

Aspartic Acid Endopeptidases↗
PubMed2005

Biological characterization of novel inhibitors of the gram-positive DNA polymerase IIIC enzyme.

Novel N-3-alkylated 6-anilinouracils have been identified as potent and selective inhibitors of bacterial DNA polymerase IIIC, the enzyme essential for the replication of chromosomal DNA in gram-positive bacteria. A nonradioactive assay measuring the enzymatic activity of the DNA polymerase IIIC in gram-positive bacteria has been assembled. The 6-anilinouracils described inhibited the polymerase IIIC enzyme at concentrations in the nanomolar range in this assay and displayed good in vitro activity (according to their MICs) against staphylococci, streptococci, and enterococci. The MICs of the most potent derivatives were about 4 microg/ml for this panel of bacteria. The 50% effective dose of the best compound (6-[(3-ethyl-4-methylphenyl)amino]-3-{[1-(isoxazol-5-ylcarbonyl)piperidin-4-yl]methyl}uracil) was 10 mg/kg of body weight after intravenous application in a staphylococcal sepsis model in mice, from which in vivo pharmacokinetic data were also acquired.

Animals↗
PubMed2004

Identification and characterization of the first class of potent bacterial acetyl-CoA carboxylase inhibitors with antibacterial activity.

The multisubunit acetyl-CoA carboxylase, which catalyzes the first committed step in fatty acid biosynthesis, is broadly conserved among bacteria. Its rate-limiting role in formation of fatty acids makes this enzyme an attractive target for the design of novel broad-spectrum antibacterials. However, no potent inhibitors have been discovered so far. This report describes the identification and characterization of highly potent bacterial acetyl-CoA carboxylase inhibitors with antibacterial activity for the first time. We demonstrate that pseudopeptide pyrrolidine dione antibiotics such as moiramide B inhibit the Escherichia coli enzyme at nanomolar concentrations. Moiramide B targets the carboxyltransferase reaction of this enzyme with a competitive inhibition pattern versus malonyl-CoA (K(i) value = 5 nm). Inhibition at nanomolar concentrations of the pyrrolidine diones is also demonstrated using recombinantly expressed carboxyltransferases from other bacterial species (Staphylococcus aureus, Streptococcus pneumoniae, and Pseudomonas aeruginosa). We isolated pyrrolidine dione-resistant strains of E. coli, S. aureus, and Bacillus subtilis, which contain mutations within the carboxyltransferase subunits AccA or AccD. We demonstrate that such mutations confer resistance to pyrrolidine diones. Inhibition values (IC(50)) of >100 microm regarding an eukaryotic acetyl-CoA carboxylase from rat liver indicate high selectivity of pyrrolidine diones for the bacterial multisubunit enzyme. The natural product moiramide B and synthetic analogues show broad-spectrum antibacterial activity. The knowledge of the target and the availability of facile assays using carboxyltransferases from different pathogens will enable evaluation of the antibacterial potential of the pyrrolidine diones as a promising antibacterial compound class acting via a novel mode of action.

Acetyl-CoA Carboxylase↗
PubMed2004

Protective effect of an oral endothelin converting enzyme inhibitor on rat detrusor function after outlet obstruction.

PURPOSE: Endothelin (ET)-1, one of the most potent vasoconstrictors known, is converted from its less potent precursor big ET by the endothelin converting enzyme (ECE). In vitro studies suggest that ET has an important role in smooth muscle growth after bladder outlet obstruction (BOO). We investigated the effect of an orally administered ECE inhibitor by cystometry in conscious rats with and without BOO. MATERIAL AND METHODS: BOO was produced in female rats by a standardized method and the animals were divided into 2 groups. One group received the ECE inhibitor WO-03028719 and the remaining animals received vehicle daily by oral gavage. Five sham operated animals served as controls and were treated with WO-03028719. Two weeks after surgery cystometry was performed. RESULTS: BOO led to a significant increase in bladder weight in vehicle treated animals and a nonsignificant increase in the treatment group. Micturition interval and volume increased in each obstructed group. Micturition pressure was significantly decreased in the vehicle group but unchanged in the BOO treatment group. Residual urine occurred in 4 of 11 BOO vehicle animals but not in the sham operated or BOO treatment group. Spontaneous nonvoiding bladder contractions occurred in 37% of BOO treatment animals but in 82% of the BOO vehicle group. Voiding contractions were markedly prolonged in the BOO vehicle group, while they were normal in the BOO treatment group. CONCLUSIONS: ECE inhibition did not prevent an increase in bladder weight after BOO but it appeared to have a beneficial effect on detrusor function and decrease detrusor overactivity in conscious rats.

Administration, Oral↗
PubMed2004

New class of bacterial phenylalanyl-tRNA synthetase inhibitors with high potency and broad-spectrum activity.

Phenylalanyl (Phe)-tRNA synthetase (Phe-RS) is an essential enzyme which catalyzes the transfer of phenylalanine to the Phe-specific transfer RNA (tRNA(Phe)), a key step in protein biosynthesis. Phenyl-thiazolylurea-sulfonamides were identified as a novel class of potent inhibitors of bacterial Phe-RS by high-throughput screening and chemical variation of the screening hit. The compounds inhibit Phe-RS of Escherichia coli, Haemophilus influenzae, Streptococcus pneumoniae, and Staphylococcus aureus, with 50% inhibitory concentrations in the nanomolar range. Enzyme kinetic measurements demonstrated that the compounds bind competitively with respect to the natural substrate Phe. All derivatives are highly selective for the bacterial Phe-RS versus the corresponding mammalian cytoplasmic and human mitochondrial enzymes. Phenyl-thiazolylurea-sulfonamides displayed good in vitro activity against Staphylococcus, Streptococcus, Haemophilus, and Moraxella strains, reaching MICs below 1 micro g/ml. The antibacterial activity was partly antagonized by increasing concentrations of Phe in the culture broth in accordance with the competitive binding mode. Further evidence that inhibition of tRNA(Phe) charging is the antibacterial principle of this compound class was obtained by proteome analysis of Bacillus subtilis. Here, the phenyl-thiazolylurea-sulfonamides induced a protein pattern indicative of the stringent response. In addition, an E. coli strain carrying a relA mutation and defective in stringent response was more susceptible than its isogenic relA(+) parent strain. In vivo efficacy was investigated in a murine S. aureus sepsis model and a S. pneumoniae sepsis model in rats. Treatment with the phenyl-thiazolylurea-sulfonamides reduced the bacterial titer in various organs by up to 3 log units, supporting the potential value of Phe-RS as a target in antibacterial therapy.

Animals↗
PubMed2003

Pyrimidinone antibiotics--heterocyclic analogues with improved antibacterial spectrum.

We report the synthesis and pharmacological evaluation of new derivatives of the natural dipeptide antibiotic TAN 1057 A,B containing heterocycles either in the beta-amino acid side chain or as mimics of the urea function. In the course of this program, we identified novel analogues that display activity towards a broader panel of Gram-positive bacteriae.

Amino Acids↗
PubMed2003

Dihydropyrimidinones--a new class of anti-staphylococcal antibiotics.

We report the synthesis and pharmacological evaluation of new derivatives of natural dipeptide antibiotic TAN-1057 A, B. In the course of this program, we identified novel analogues of the natural product that display similar antibacterial activity and showed improved tolerability.

Anti-Bacterial Agents↗
PubMed2002

Novel antibiotics for the treatment of gram-positive bacterial infections.

The natural dipeptide antibiotic TAN 1057 A,B displays excellent antibacterial activity against staphylococci including methicillin resistant Staphylococcus aureus. However, the in vitro activity against additional Gram-positive strains, in particular pneumococci and Enterococcus faecalis, proved to be considerably lower. We report the synthesis and pharmacological evaluation of new derivatives of this natural product that displayed increased antibacterial potency against staphylococci and were also active against pneumococci. In particular, the analogues bearing modified beta-homoarginine side chains with methylated guanidine moieties were shown to be significantly more potent than the natural product TAN 1057 A,B.

Animals↗