Synthesis of N-benzyl- and N-phenyl-2-amino-4,5-dihydrothiazoles and thioureas and evaluation as modulators of the isoforms of nitric oxide synthase

Claire L M Goodyer, Edwin C. Chinje, Mohammed Jaffar, Ian J. Stratford, Michael D. Threadgill

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Inhibition of the isoforms of nitric oxide synthase (NOS) has important applications in therapy of several diseases, including cancer. Using 1400W [N-(3-aminomethylbenzyl)acetamidine], thiocitrulline and N δ-(4,5-dihydrothiazol-2-yl)ornithine as lead compounds, series of N-benzyl- and N-phenyl-2-amino-4,5-dihydrothiazoles and thioureas were designed as inhibitors of NOS. Ring-substituted benzyl and phenyl isothiocyanates were synthesised by condensation of the corresponding amines with thiophosgene and addition of ammonia gave the corresponding thioureas in high yields. The substituted 2-amino-4,5-dihydrothiazoles were approached by two routes. Treatment of simple benzylamines with 2-methylthio-4,5-dihydrothiazole at 180 °C afforded the corresponding 2-benzylamino-4,5-dihydrothiazoles. For less nucleophilic amines and those carrying more thermally labile substituents, the 4,5-dihydrothiazoles were approached by acid-catalysed cyclisation of N-(2-hydroxyethyl)thioureas. This cyclisation was shown to proceed by an SN2-like process. Modest inhibitory activity was shown by most of the thioureas and 4,5-dihydrothiazoles, with N-(3-aminomethylphenyl)thiourea (IC50=13 μM vs rat neuronal NOS and IC50=23 μM vs rat inducible NOS) and 2-(3-aminomethylphenylamino)-4,5-dihydrothiazole (IC50=13 μM vs rat neuronal NOS and IC50=19 μM vs human inducible NOS) being the most potent. Several thioureas and 4,5-dihydrothiazoles were found to stimulate the activity of human inducible NOS in a time-dependent manner. © 2003 Elsevier Ltd. All rights reserved.
    Original languageEnglish
    Pages (from-to)4189-4206
    Number of pages17
    JournalBioorganic and Medicinal Chemistry
    Volume11
    Issue number19
    DOIs
    Publication statusPublished - 15 Sept 2003

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