Takashi Nishigaki

Synthesis and anti-HIV activity of arylpiperazinyl fluoroquinolones: a new class of anti-HIV agents.

Synthesis and anti-HIV activity of a series of novel arylpiperazinyl fluoroquinolones are reported. In the SAR study, the aryl substituents on the piperazine nitrogen were found to play an important role for the anti-HIV-1 activity. A few of the compounds exhibited potent anti-HIV activity: IC50=0.06 microM in chronically infected cells.

Anti-HIV-1 Activities and Pharmacokinetics of New Arylpiperazinyl Fluoroquinolones

Anti-HIV-1 activities and pharmacokinetics of a series of novel arylpiperazinyl fluoroquinolones are reported. Modification at the C-8 position with a trifluoromethyl group was superior to that with a difluoromethoxy group to achieve higher anti-HIV-1 activity. Two compounds studied exhibited quite high anti-HIV-1 activities (IC(50)<50 nM) in vitro and high bioavailabilities (BA>90%) in monkeys.

A New Fluoroquinolone Derivative Exhibits Inhibitory Activity against Human Immunodeficiency Virus Type 1 Replication

The inhibitory activity of several fluoroquinolone antibiotics against human immunodeficiency virus type 1 (HIV-1) replication was investigated. R-71762, (±) 9-fluoro-3-fluoromethyl-2,3-dihydro-10-[4-(2-pyridyl)-1-piperazinyl]-7-oxo-7H-pyrido[1,2,3-de][1,4]benzoxazine-6-carboxylic acid, protected MT-4 cells from HIV-1-induced cytopathic effects. Furthermore, the compound inhibited virus replication both in acutely and in chronically HIV-1-infected cells. On the other hand, ofloxacin, levofloxacin, ciprofloxacin, norfloxacin and enoxacin, that were previously reported to be protective against HIV-1-induced cytopathic effects, did not show any protective activity in our assay system. These results indicate that R-71762 is a novel inhibitor of HIV-1 replication and is effective even in HIV-1 chronically infected cells.

Regulation of in vitro and in vivo transcription of early-region IV of adenovirus type 5 by multiple cis-acting elements.

A series of deletion mutants spanning the promoter of the adenovirus early-region IV (EIV) gene were tested for transcriptional activity, using both in vitro and in vivo assays. Four distinct domains had additive effects on efficient transcription from the EIV promoter in HeLa whole-cell extracts. The first resided 20 to 27 bases upstream of the initiation site and included the TATA box. Deletion of the TATA box drastically reduced the transcriptional activity in vitro but had a lesser effect in vivo. The second region extended from -32 to -177 and contained two 17-base-pair inverted repeats, centered around -40 and -162. Sequences lying between -140 and -173 were important for efficient transcription since deletion of this region reduced the activity fourfold. Deletion of either one of the two inverted repeats or insertion of DNA fragments between them resulted in the synthesis of extra transcripts that initiated at sites upstream from the EIV site. The third region was located between -198 and -250 and contains three guanosine-plus-cytosine-rich sequences, present around -212 (GGGCGG), -233 (GGGCGG), and -251 (CGCGGG). The fourth, most upstream region was located between -260 and -307. Deletion of this region, which contains the NF-1 factor-binding site, slightly reduced transcriptional activity both in vivo and in vitro. The data indicate that multiple cis-acting elements are required for efficient transcription from the EIV promoter in both in vitro and in vivo systems.

Biologically Active Oligodeoxyribonucleotides - IV 1 : Anti-HIV-1 Activity of Tgggag Having Hydrophobic Substituent at Its 5′-End via Phosphodiester Linkage §

Abstract Hexadeoxyribonucleotides (6-mers) having a 5′-TGGGAG-3′ sequence bearing hydrophobic substituents at their 5′-ends via phosphodiester linkages were prepared and evaluated for anti-HIV-1 activity in vitro. Some of these modified 6-mers showed weak anti-HIV-1 activities and they were less potent than the 6-mer having a DMTr group directly attached at its 5′-terminus. 1. Part 111: Hotoda, H.; Koizumi, M.; Koga, R.; Momota, K.; Ohmine, T.; Furukawa, H.; Nishigaki, T.; Kinoshita, T.; Kaneko, M.; Kimura, S.; and Shimada, K. (1994) Proceedings of First International Antisense Conjierence of Japan p62 (Pl-24): In print in Antisense Research and Development. §This paper is dedicated to Dr. Yoshihisa Mizuno, Emeritus Professor of Hokkaido University, on the occasion of his 75th birthday.

Characterization of one monoclonal antibody against feline immunodeficiency virus p24 and its application to antigen capture ELISA

Several monoclonal antibodies (mAbs) were produced against feline immunodeficiency virus (FIV) p24 capsid antigen. One of these, F2710, reacted strongly, not only with viral p24 and recombinant p24, but also with p50 Gag precursor protein in Western blot. Epitope mapping analysis revealed that mAb F2710 recognizes a heptapeptide, SFIDRLF, in the FIV p24 amino acid sequence. As this portion of FIV p24 is highly conserved among various FIV strains, the mAb seems to be a useful tool for detecting FIV p24 antigen in various samples. By means of this mAb and rabbit anti-p24 polyclonal antibody, an antigen capture ELISA was developed. The ELISA detected viral p24 antigen with good linearity. The lower detection limit of this assay is 40 pg/ml of recombinant p24 antigen, which is at least as sensitive as the reverse transcriptase assay in detecting FIV virion. Thus, this system is valuable for monitoring FIV replication in vitro.

Structure–activity relationship of HIV-1 protease inhibitors containing AHPBA. Part III: modification of P2 site

The structure-activity relationship of HIV-1 protease (HIV-1 PR) inhibitors containing AHPBA (3-amino-2-hydroxy-4-phenylbutanoic acid) is discussed. In order to solve the problem of poor oral bioavailability, small-sized dipeptide HIV-1 protease inhibitors containing cyclic urethanes or benzamides at the P2 site were designed and prepared. The substitution patterns of the benzamides contributed significantly to their HIV-1 PR inhibitory activities, and it was shown that the choice of P2-residues was very important. Highly potent inhibitors possessing subnanomolar IC50 values and exhibiting good antiviral potency have been identified. In this class, inhibitor 18 was the most potent (IC90 (CEM/HIV-1 IIIB) 0.11 microM) and showed good oral bioavailability in dogs.