Two neuraminidase (NA) inhibitors, zanamivir (Relenza) and oseltamivir phosphate (Tamiflu), have been licensed for the treatment of and prophylaxis against influenza. In this paper, the new potent NA inhibitor R-125489 is reported for the first time. R-125489 inhibited the NA activities of various type A and B influenza viruses, including subtypes N1 to N9 and oseltamivir-resistant viruses. The survival effect of R-125489 was shown to be similar to that of zanamivir when administered intranasally in a mouse influenza virus A/Puerto Rico/8/34 infection model. Moreover, we found that the esterified form of R-125489 showed improved efficacy compared to R-125489 and zanamivir, depending on the acyl chain length, and that 3-(O)-octanoyl R-125489 (CS-8958) was the best compound in terms of its life-prolonging effect (P < 0.0001, compared to zanamivir) in the same infection model. A prolonged survival effect was observed after a single administration of CS-8958, even if it was given 7 days before infection. It is suggested that intranasally administered CS-8958 works as a long-acting NA inhibitor and shows in vivo efficacy as a result of a single intranasal administration.
Two neuraminidase (NA) inhibitors, zanamivir (Relenza) and oseltamivir phosphate (Tamiflu), have been licensed for use for the treatment and prophylaxis of influenza. We have reported on laninamivir (code name, R-125489), a novel neuraminidase inhibitor, and have discovered that the laninamivir prodrug CS-8958 worked as a long-acting neuraminidase inhibitor in a mouse influenza virus infection model when it is intranasally administered. In this study, CS-8958 was administered just once 7 days before infection and showed significant efficacy in vivo. The efficacy of a single administration of CS-8958 after viral infection was then compared with that of repeated administrations of oseltamivir phosphate or zanamivir in mice and ferrets. CS-8958 showed efficacy superior or similar to the efficacies of the two licensed NA inhibitors. CS-8958 also significantly reduced the titers of an oseltamivir-resistant H1N1 virus with a neuraminidase H274Y substitution in a mouse infection model. These results suggest that since CS-8958 is characteristically long lasting in the lungs, it may be ideal for the prophylaxis and treatment of influenza.
Proteolytic activation of hemagglutinin, an envelope glycoprotein of the influenza virus, by host proteases is essential for infection and proliferation of the virus. However, there is no well-defined, inherent source of host proteases in man or swine, both of which are natural hosts for human influenza viruses. We have recently isolated a 32 kDa protein in a high salt extract from porcine lungs, which possess the hemagglutinin processing activity. In this study, we attempted to purify another hemagglutinin processing enzyme from porcine lung. The purified enzyme, named tryptase TC30, exhibited a molecular mass of about 30 kDa by SDS-PAGE and 28.5 kDa by gel filtration chromatography, suggesting that it is a monomer. Tryptase TC30 cleaved peptide substrates with Arg at the P1 position, and preferentially substrates with the Ser-Ile-Gin-Ser-Arg sequence corresponding to the HA cleavage site sequence of the A/PR/8/34 influenza virus. Among various inhibitors tested, trypsin-type serine protease inhibitors, such as aprotinin, antipain, benzamidine and leupeptin, efficiently inhibited the proteolytic activity of the enzyme. The N-terminal 40 amino acid sequence of tryptase TC30 exhibits more than 60% homology to mast cell tryptases from mice MCP-6 and human tryptase-alpha and -beta. These data indicate that tryptase TC30, the 30 kDa enzyme from porcine lung, is a novel hemagglutinin-cleaving enzyme.
The postantibiotic effect (PAE) of tomopenem was determined after a 2 h exposure of two strains of meticillin-susceptible and meticillin-resistant Staphylococcus aureus (MSSA and MRSA), and imipenem-susceptible and imipenem-resistant Pseudomonas aeruginosa, to tenfold the respective MIC. The PAEs on MSSA and P. aeruginosa were approximately 1 h and they were comparable to those of meropenem. The PAE on MRSA was 1.5 to 3 h, equal to or longer than those of vancomycin. The PAEs of tomopenem not only were found for MRSA, but also were present in the imipenem-resistant P. aeruginosa tested.
Zanamivir. -The preparation of tetrahydro-furan-2-yl derivatives (X) related to zanamivir by ring-closing metathesis as key step and following selective oxidation to diols (VI) in moderate to good yields and evaluation of their biological activities are presented. Compound (Xa) in particular showed comparable efficacy in vivo relative to that of oseltamivir phosphate. -(MASUDA, T.; SHIBUYA, S.; ARAI, M.; YOSHIDA, S.; TOMOZAWA, T.; OHNO, A.; YAMASHITA, M.; HONDA*, T.; Bioorg. Med. Chem. Lett. 13 (2003) 4, 669-673; Med. Chem. Res. Lab., Sankyo Co., Ltd., Shinagawa, Tokyo 140, Japan; Eng.) -M. Schroeter 24-109
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