Discovery of a novel 9-position modified second-generation anti-HCV candidate via bioconversion and semi-synthesis of FR901459.

Evidence that hepatitis C virus (HCV) utilizes cellular cyclophilin proteins in the virus replication cycle has increased attention on cyclophilin inhibitors as attractive therapeutic targets in the treatment of HCV. Previous reports have described a number of non-immunosuppressive cyclophilin inhibitors, most of which require many synthetic steps for their preparation. Sasamura et al. have previously reported the isolation of bioconversion derivative 4. This analog is a convenient starting point for optimization due to the presence of the readily modifiable primary hydroxyl group and because it shows moderate anti-HCV activity and decreased immunosuppressive activity. We have also established an efficient C-alkylation reaction at the 3-position. Through a detailed structure-activity relationship study, we discovered a new type of clinical candidate 14 which requires a short synthetic process and has potent anti-HCV activity and reduced immunosuppressive activity, as well as improved aqueous solubility and pharmacokinetics.

Discovery of ASP5286: A novel non-immunosuppressive cyclophilin inhibitor for the treatment of HCV.

Evidence indicates that hepatitis C virus (HCV) utilizes cellular cyclophilin proteins in its replication, and cyclophilin inhibitors represent a new class of anti-HCV agents. We have established an efficient synthetic methodology to generate FR901459 derivatives via N, O-acyl migration reaction while avoiding total synthesis. Through a detailed structure-activity relationship study, we improved anti-HCV activity while decreasing immunosuppressive activity. Additionally, we discovered the importance of substitution at the 3 position for not only improving anti-HCV activity but also pharmacokinetic profile. Finally, by striking an appropriate balance between potency, solubility, and permeability, we discovered ASP5286 (13) as a potential clinical candidate for anti-HCV therapy.

Development of an efficient semisynthetic modification of FR901459 via a novel regioselective N, O-acyl migration.

HCV utilizes cellular protein cyclophilins in the virus replication cycle and cyclophilin inhibitors have become a new class of anti-HCV agents. In our screening of natural products, we identified a unique cyclosporin analogue, FR901459, as a cyclophilin inhibitor with potent anti-HCV activity. In this work, we developed an efficient synthetic methodology to prepare FR901459 derivatives via an N, O-acyl migration reaction. This method allows us to efficiently manipulate the amino acid residues at the 3 position while avoiding lengthy total synthesis for each compound. By using this methodology, we discovered 4, which has superior anti-HCV activity and decreased immunosuppressive activity compared to FR901459.

Displacement ventilation with radiant panel for hospital wards: Measurement and prediction of the temperature and contaminant concentration profiles.

Displacement ventilation (DV) is known to provide high air quality and ventilation efficiency. With DV, a contaminant interface is formed in a room, and the air quality in the occupant zone below the contaminant interface height can be kept clean. This paper proposes a DV system to solve the serious odor problem in hospital wards. A vertical radiant panel that can be controlled individually is suggested as a complementary heating system. In order to study the influence of the panel on the displacement ventilated room, the temperature and contaminant concentration profiles were examined under different panel conditions: the distance between the panel and bed, height of the panel, surface temperature of the panel, and supply airflow rate. When the radiant panel was heated, it created a stronger plume than the human body, which produced contaminated air. When there was space between the radiant panel and bed, the contaminated air was locked up before reaching the ceiling. Personal exposure of a standing person was also investigated because the contaminated interface is generally lower than the breathing zone of a standing person with DV. The zonal model and improved zonal model were validated by a comparison of their results with the measured contaminant concentrations.

Synthesis and SAR of novel parenteral anti-pseudomonal cephalosporins: discovery of FR264205.

We describe herein the synthesis and biological evaluation of a series of novel cephalosporins with potent activity against Pseudomonas aeruginosa. Introduction of various amino groups to the 4-position of a 3-amino-2-methylpyrazole cephalosporin 3-side chain resulted in enhanced MIC values against multiple Pseudomonas aeruginosa strains and ultimately led to the discovery of FR264205 (15) with excellent anti-bacterial activity and weak convulsion effect by direct intracerebroventricular injection assay.

Structural requirements for the stability of novel cephalosporins to AmpC beta-lactamase based on 3D-structure.

AmpC beta-lactamase is one of the leading causes of Pseudomonas aeruginosa (P. aeruginosa) resistance to cephalosporins. FR259647 is a cephalosporin having a novel pyrazolium substituent at the 3-position and exhibits excellent activity (MIC=1 microg/mL) against the AmpC beta-lactamase overproducing P. aeruginosa FP1380 strain in comparison with the third-generation cephalosporins FK518 [Abstracts of Papers, 30th Interscience Conference on Antimicrobial Agents and Chemotherapy, Atlanta, GA, October 21-24, 1990, Abs. 454; Abstracts of Papers, 30th Interscience Conference on Antimicrobial Agents and Chemotherapy, Atlanta, GA, October 21-24, 1990, Abs. 455; Abstracts of Papers, 30th Interscience Conference on Antimicrobial Agents and Chemotherapy, Atlanta, GA, October 21-24, 1990, Abs. 456; Abstracts of Papers, 30th Interscience Conference on Antimicrobial Agents and Chemotherapy, Atlanta, GA, October 21-24, 1990, Abs. 457] (MIC=16 microg/mL) and ceftazidime (CAZ) (MIC=128 microg/mL). The stability of FR259647 and FK518 to AmpC beta-lactamase was evaluated using MIC assays against both the P. aeruginosa PAO1 strain and a PAO1 mutant strain overproducing AmpC beta-lactamase as a differential assay, which indicates that the main difference derives from their stability to AmpC beta-lactamase. A structural analysis using computer simulations indicated that the difference in stability may be due to steric hindrance of the 3-position substituents causing differential affinity. This steric hindrance may disturb entry of the cephalosporins into the binding pocket. We predicted the possibility of inhibition of entry as a potential means of enhancing stability by conformational analysis. In order to validate this speculation, novel FR259647 derivatives 4-9 were designed, calculated, synthesized, and evaluated. As a result, we demonstrated that their probability of entry correlated with the MIC ratio of the mutant strain to the parent strain and supports the validity of our model.

Design, synthesis, and structure-activity relationships of potent GPIIb/IIIa antagonists: discovery of FK419.

The discovery of the non-peptide antiplatelet injectable agent FK419 is reported. Based on the beta-turn structure of RGD peptide sequences in the alpha chain of fibrinogen, which binds the glycoprotein IIb/IIIa (GPIIb/IIIa) on the surface of platelets to induce platelet aggregation, the prototype 2 was designed. After further substituent effects were investigated at the alpha-position of the carboxylic acid in 2, we enhanced platelet aggregation inhibition, and discovered the useful feature of reduced prolongation of bleeding time. Finally, the potent platelet aggregation inhibitor FK419 (3) could be discovered. FK419 shows a safe feature of reduced prolongation of bleeding time, as well as potent inhibition of platelet aggregation.

Inhibition of arterial thrombosis by a protease-activated receptor 1 antagonist, FR171113, in the guinea pig.

The antiplatelet and antithrombotic effects of FR171113, 3-(4-chlorophenyl)-2-(2,4-dichlorobenzoylimino)-5-(methoxycarbonyl methylene)-1,3-thiazolidin-4-one, a non-peptide protease-activated receptor 1 (PAR1) antagonist, were evaluated in guinea pigs. FR171113 inhibited Ser-Phe-Leu-Leu-Arg-Asn-NH2 (a synthetic PAR1 agonist peptide)-induced and thrombin-induced aggregation of guinea pig platelets in a concentration-dependent manner in vitro (IC50=1.5 and 0.35 microM, respectively). Subcutaneous administration of FR171113 (0.1-3.2 mg/kg) produced a dose-dependent inhibition of platelet aggregation ex vivo. The ED50 value of FR171113 for platelet aggregation was 0.49 mg/kg s.c. However, FR171113 did not have an inhibitory effect on ADP- or collagen-induced platelet aggregation in vitro and ex vivo. One hour after FR171113 treatment at 1.0 mg/kg s.c., significant inhibition of arterial thrombosis without a prolongation of thrombin time or coagulation time was seen in the FeCl3-induced carotid artery thrombosis model in guinea pigs. Furthermore, FR171113 did not prolong bleeding time even at 32 mg/kg s.c., which is a much higher dose than that required in the thrombosis model. These observations indicate that FR171113 has desirable antiplatelet effects both in vitro and in vivo and that its in vivo antithrombotic activity is efficacious without causing a prolongation of bleeding time.