Sulfonamidopyrrolidinone factor Xa inhibitors: potency and selectivity enhancements via P-1 and P-4 optimization.

Sulfonamidopyrrolidinones were previously disclosed as a selective class of factor Xa (fXa) inhibitors, culminating in the identification of RPR120844 as a potent member with efficacy in vivo. Recognizing the usefulness of the central pyrrolidinone template for the presentation of ligands to the S-1 and S-4 subsites of fXa, studies to optimize the P-1 and P-4 groups were initiated. Sulfonamidopyrrolidinones containing 4-hydroxy- and 4-aminobenzamidines were discovered to be effective inhibitors of fXa. X-ray crystallographic experiments in trypsin and molecular modeling studies suggest that our inhibitors bind by insertion of the 4-hydroxybenzamidine moiety into the S-1 subsite of the fXa active site. Of the P-4 groups examined, the pyridylthienyl sulfonamides were found to confer excellent potency and selectivity especially in combination with 4-hydroxybenzamidine. Compound 20b (RPR130737) was shown to be a potent fXa inhibitor (K(i) = 2 nM) with selectivity against structurally related serine proteinases (>1000 times). Preliminary biological evaluation demonstrates the effectiveness of this inhibitor in common assays of thrombosis in vitro (e.g. activated partial thromboplastin time) and in vivo (e.g. rat FeCl(2)-induced carotid artery thrombosis model).

Benzofuran based PDE4 inhibitors.

Replacement of the 3,4-dialkoxyphenyl substructure common to a number of PDE4 inhibitors with a 2-alkyl-7-methoxybenzofuran unit is described. This substitution can result in either enhancement or substantial reductions in PDE4 inhibitory activity depending on the system to which it is applied. An in vitro SAR study of a potent series of 4-(2-heteroaryl-ethyl)-benzoiurans 26 is also presented.

Quaternary substituted PDE IV inhibitors II: the synthesis and in vitro evaluation of a novel series of gamma-lactams.

This communication describes the synthesis and in vitro evaluation of a novel potent series of phosphodiesterase type (IV) (PDE IV) inhibitors. Several of the quaternary substituted lactams presented possess low nanomolar IC50's for PDE IV inhibition.

2-Substituted-4-methoxybenzimidazole-based PDE4 inhibitors.

A new family of PDE4 inhibitors based on a benzimidazole framework is described. Several of these compounds are orally bioavailable and show efficacy in in vivo models of inflammatory disease.

Anionic- and lipophilic-mediated surface binding inhibitors of human leukocyte elastase.

We report the synthesis of a series of diphenylmethane-based oligomers containing anionic and lipophilic functionalities that are potent inhibitors of human leukocyte elastase (HLE). The enzyme inhibition is regulated by the size of the oligomer, as well as, the number of charges. Lipophilicity is an important element in determining potency and specificity against other basic enzymes. Compounds whose scaffolds contain three phenoxyacetic acid groups and three alkyl ethers are competitive and specific inhibitors of HLE with Ki = 20 nM. The mechanism of action of this class of compounds is believed to involve multidendate interactions with the surface of HLE near the active site which prevents substrate access to the catalytic site.

Expression of liver carnitine palmitoyltransferase I and II genes during development in the rat.

The enzyme activity and the expression (protein and mRNA concentrations) of genes encoding for hepatic carnitine palmitoyl-transferases (CPT) I and II were studied during neonatal development, in response to nutritional state at weaning and during the fed-starved transition in adult rats. The activity, the protein concentration and the level of mRNA encoding CPT I are low in foetal-rat liver and increase 5-fold during the first day of extra-uterine life. The activity and gene expression of CPT I are high during the entire suckling period, in the liver of 30-day-old rats weaned at 20 days on to a high-fat diet and in the liver of 48 h-starved adult rats. The activity and CPT I gene expression are markedly decreased in the liver of rats weaned on to a high-carbohydrate diet. By contrast, the activity, the protein concentration and the level of mRNA encoding CPT II are already high in the liver of term foetuses and remain at this level throughout the suckling period, irrespective of the nutritional state of the animals either at weaning or in the adult.

Dual-action cephalosporins: cephalosporin 3'-quaternary ammonium quinolones.

When cephalosporins exert their biological activity by reacting with bacterial enzymes, opening of the beta-lactam ring can lead to expulsion of the 3'-substituent. A series of cephalosporins was prepared in which antibacterial quinolones were linked to the 3'-position through a quaternary nitrogen. Like the 3'-ester-linked dual-action cephalosporins reported earlier, these compounds demonstrated a broad spectrum of antibacterial activity derived from cephalosporin-like and quinolone-like components, suggesting a dual mode of action.

In vitro and in vivo activity of carbamate-linked dual-action antibacterial Ro 24-4383.

Ro 24-4383 contains desacetylcefotaxime linked by a carbamate bond at the 3' position to ciprofloxacin. Ro 24-4383 was active against 99% of the 363 gram-positive and gram-negative aerobes tested in vitro, while the comparative agents cefotaxime and ciprofloxacin were active against 77 and 97%, respectively. The activities (ED50: mg/kg s.c.) of Ro 24-4383, cefotaxime and ciprofloxacin in systemic murine infections were: Escherichia coli 257, 1.4, less than 0.5, less than 0.2; Klebsiella pneumoniae A, 11, 30, 0.7; Enterobacter cloacae 5699, 3.2, 35, less than 0.2; Citrobacter freundii BS16, 3, 41, less than 0.5; Serratia marcescens SM, 35, greater than 100, 1.6; Pseudomonas aeruginosa 5712, 67, 100, 10; P. aeruginosa 8780, 33, 193, 3; Staphylococcus aureus Smith (oxacillin-susceptible), 12, 3.7, 1; S. aureus 753 (oxacillin-resistant), 28, greater than 100, 2; Streptococcus pneumoniae 6301, 10, 15, greater than 50, and S. pyogenes 4, 3.3, 1.6, 54. Ro 24-4383, although inactive against the S.-pneumoniae-induced pneumonia following one administration of the agent, was highly active (ED50 = 1.5) when three treatments were given following infection. Ro 24-4383 was active against the K.-pneumoniae-induced pneumonia (ED50 = 37), as well as the meningitis induced by S. pneumoniae (ED50 = 158) or K. pneumoniae (ED50 = 100). The protective effect of Ro 24-4383 was demonstrated when administered 8 h before infection with E. coli (ED50 = 37) and 4 h before infection with S. pyogenes (ED50 = 199).

In vitro activities of a dual-action antibacterial agent, Ro 23-9424, and comparative agents.

The in vitro activity of the dual-action antibacterial agent Ro 23-9424 was compared with those of cefotaxime, ceftazidime, ciprofloxacin, fleroxacin, imipenem, and amikacin against 358 aerobes and anaerobes. The MIC ranges, MICs for 50 and 90% of the strains (MIC50s and MIC90s), and percentage of strains susceptible for each agent at the recommended susceptible MIC breakpoint were determined for each genus. The MIC90s (micrograms per milliliter) of the agents against members of the family Enterobacteriaceae were as follows: ciprofloxacin, 0.063; Ro 23-9424, fleroxacin, and imipenem, 0.5; ceftazidime, 2; amikacin, 4; and cefotaxime, 16. The MIC90s (micrograms per milliliter) against Pseudomonas and Acinetobacter spp. were as follows: ciprofloxacin, 2; ceftazidime and imipenem, 8; Ro 23-9424, 16; fleroxacin, 32; amikacin, 64; and cefotaxime, 128. Against gram-positive bacteria, excluding the enterococci, the MIC90s (micrograms per milliliter) were as follows: ciprofloxacin, 1; imipenem, 4; Ro 23-9424 and fleroxacin, 8; amikacin, 64; and ceftazidime and cefotaxime, greater than 128. Against gram-positive bacteria, including the enterococci, the MIC90s changed only for the following agents: Ro 23-9424, 16 micrograms/ml; and amikacin, 128 micrograms/ml. Strains of Branhamella catarrhalis, Haemophilus influenzae, and Neisseria gonorrhoeae were 100% susceptible to Ro 23-9424, cefotaxime, ciprofloxacin, and fleroxacin, while the other three agents showed somewhat less activity only against N. gonorrhoeae. Against anaerobes, imipenem was the most effective agent, while the activities of the other six agents were variable.

In vitro activity of Ro 19-5247 (T-2525) and interpretive criteria for disk diffusion susceptibility testing.

The activity of Ro 19-5247 (the active metabolite of the oral cephalosporin Ro 19-5248 [T-2588]) was compared with that of five orally active agents against a total of 331 bacterial strains. Ro 19-5247 was more active in vitro than amoxicillin, amoxicillin-clavulanate, cefaclor, cefuroxime, and cephalexin against members of the family Enterobacteriaceae. Amoxicillin-clavulanate and amoxicillin overall were more active than the other four agents against staphylococci. Ro 19-5247, amoxicillin-clavulanate, amoxicillin, and cefuroxime were equally active against nonenterococcal streptococci and more active than cefaclor and cephalexin. All six agents showed little or no activity against nonfermentative gram-negative bacteria. Against Streptococcus (Enterococcus) faecalis, only amoxicillin and amoxicillin-clavulanate were active. The interpretive criteria for in vitro susceptibility testing with 10- and 30-micrograms Ro 19-5247 disks were established by regression analysis to correlate the inhibitory zone sizes and MICs for the bacterial isolates. The suggested tentative zone size breakpoints for the 10-micrograms disk are as follows: susceptible, greater than or equal to 22 mm (MIC, less than or equal to 2 micrograms/ml); moderately susceptible, 20 to 21 mm (MIC, 4 micrograms/ml); and resistant, less than or equal to 19 mm (MIC, greater than or equal to 8 micrograms/ml).