Kazuhiro Haraguchi

Bio: Kazuhiro Haraguchi is an academic researcher from Nihon Pharmaceutical University. The author has contributed to research in topics: Uracil & Nucleophilic substitution. The author has an hindex of 17, co-authored 80 publications receiving 900 citations. Previous affiliations of Kazuhiro Haraguchi include Showa University & Kagoshima University.

Genetic effects of oxidative DNA damages: comparative mutagenesis of the imidazole ring-opened formamidopyrimidines (Fapy lesions) and 8-oxo-purines in simian kidney cells

Abstract: National Institute of Environmental Health Sciences (ES09127, ES013324 (to A.K.B), ES03775 (to E.L.L.); National Cancer Institute (CA74954 (to M.M.G), CA50432 (to E.L.L.), CA76163, CA47995 (to M.M.))

Efficient removal of formamidopyrimidines by 8-oxoguanine glycosylases.

Abstract: Under conditions of oxidative stress, the formamidopyrimidine lesions (FapyG and FapyA) are formed in competition with the corresponding 8-oxopurines (OG and OA) from a common intermediate. In order to reveal features of the repair of these lesions, and the potential contribution of repair in mitigating or exacerbating the mutagenic properties of Fapy lesions, their excision by three glycosylases, Fpg, hOGG1 and Ntg1, was examined in various base pair contexts under single-turnover conditions. FapyG was removed at least as efficiently as OG by all three glycosylases. In addition, the rates of removal of FapyG by Fpg and hOGG1 were influenced by their base pair partner, with preference for removal when base paired with the correct Watson-Crick partner C. With the FapyA lesion, Fpg and Ntg1 catalyze its removal more readily than OG opposite all four natural bases. In contrast, the removal of FapyA by hOGG1 was not as robust as FapyG or OG, and was only significant when the lesion was paired with C. The discrimination by the various glycosylases with respect to the opposing base was highly dependent on the identity of the lesion. OG induced the greatest selectivity against its removal when part of a promutagenic base pair. The superb activity of the various OG glycosylases toward removal of FapyG and FapyA in vitro suggests that these enzymes may act upon these oxidized lesions in vivo. The differences in the activity of the various glycosylases for removal of FapyG and FapyA compared to OG in nonmutagenic versus promutagenic base pair contexts may serve to alter the mutagenic profiles of these lesions in vivo.

Anti-Human Immunodeficiency Virus Type 1 Activity and Resistance Profile of 2′,3′-Didehydro-3′-Deoxy-4′-Ethynylthymidine In Vitro

Abstract: 2′,3′-Didehydro-3′-deoxy-4′-ethynylthymidine (4′-Ed4T) has been identified as a novel nucleoside analog with potent and selective anti-human immunodeficiency virus type 1 (HIV-1) activity and weak cytotoxicity in cell cultures. 4′-Ed4T proved to be 5- to 10-fold more active than its structurally related compound, stavudine (d4T). However, the drug resistance profile of 4′-Ed4T was different from those of d4T and other existing HIV-1 nucleoside reverse transcriptase inhibitors (NRTIs). Approximately 6- to 11-fold decreases in susceptibility to 4′-Ed4T were observed for HIV-1 carrying NRTI-associated mutations (D67N, K70R, T215F, and K219Q) or the lamivudine (3TC)-resistant mutation M184V. In contrast, the susceptibility of the virus carrying the K65R mutation or the multidrug-resistant mutation with the Q151M complex (A62V, V75I, F77L, F116Y, and Q151M) was not altered. Furthermore, the activity of 4′-Ed4T appeared to be enhanced in the presence of K103N, a major nonnucleoside reverse transcriptase inhibitor-resistant mutation. Although 4′-Ed4T was 4.5- to 17.5-fold less active against multidrug-resistant clinical isolates than against a reference strain isolated from a treatment-naive patient, it was still inhibitory to these isolates at low concentrations. Analysis of 4′-Ed4T-resistant HIV-1 obtained through in vitro selection revealed that the virus was also resistant to 3TC and had two amino acid mutations (P119S and T165A) in addition to the M184V mutation. Since 4′-Ed4T has increased anti-HIV-1 activity, decreased cytotoxicity, and a different resistance profile, it should be considered for further development as a new member of NRTIs.

Advances in the development of nucleoside and nucleotide analogues for cancer and viral diseases

Abstract: Nucleoside analogues have been in clinical use for almost 50 years and have become cornerstones of treatment for patients with cancer or viral infections. The approval of several additional drugs over the past decade demonstrates that this family still possesses strong potential. Here, we review new nucleoside analogues and associated compounds that are currently in preclinical or clinical development for the treatment of cancer and viral infections, and that aim to provide increased response rates and reduced side effects. We also highlight the different approaches used in the development of these drugs and the potential of personalized therapy.

Substituted purines and oligonucleotide cross-linking

Abstract: This invention is directed to novel purine-based compounds for inclusion into oligonucleotides. The compounds of the invention, when incorporated into oligonucleotides are especially useful as 'antisense' agents -- agents that are capable of specific hybridization with a nucleotide sequence of an RNA. The compounds of the invention may also be used for cross-linking oligonucleotides. Oligonucleotides are used for a variety of therapeutic and diagnostic purposes, such as treating deseases, regulating gene expression in experimental systems, assaying for RNA and for RNA products through the employment of antisense interactions with such RNA, diagnosing diseases, modulating the production of proteins, and cleaving RNA in site specific fashions. The compounds of the invention include novel heterocyclic bases, nucleosides, and nucleotides. When incorporated into oligonucleotides, the compounds of the invention can be useful for modulating the activity of RNA.

Kinetics of RNA Degradation by Specific Base Catalysis of Transesterification Involving the 2‘-Hydroxyl Group

Abstract: A detailed understanding of the susceptibility of RNA phosphodiesters to specific base-catalyzed cleavage is necessary to approximate the stability of RNA under various conditions. In addition, qua...

Pyrimidine as constituent of natural biologically active compounds.

Abstract: This review describes the various manifestations of the pyrimidine system (alkylated, glycosylated, benzo-annelated.). These comprise pyrimidine nucleosides as well as alkaloids and antibiotics – some of them have been discovered and isolated from natural sources already long time ago, others have been reported very recently. A short overview on pyrimidine syntheses (prebiotic synthesis, biosynthesis, and metabolism) is given. The biological activities of most of the pyrimidine analogs are briefly described, and, in some cases, syntheses are formulated.