Sulphimidazole (1-methyl-2((4-aminophenyl)-sulphonyl)-amino-5-nitroimidazole) is a new compound in which a p-aminobenzenesulphonamide radical has been attached at position 2 of the 5-nitroimidazole ring. It possesses a useful spectrum of activity in vitro against various anaerobic microorganisms and its action against aerobic and facultative bacteria is synergically enhanced in association with trimethoprim. In the present study, we determined the cytotoxicity in vitro of sulphimidazole and trimethoprim, both alone and in combination, and analysed the viability of Vero cells and the protein content of their cell lysate in the presence of increasing concentrations of these drugs. Also, in order to verify the hypothesis that the action of sulphimidazole against aerobic and facultative bacteria is mediated by the sulphonamide component of the molecule, while that against anaerobic bacteria depends on the action of the nitro group of the 5-nitroimidazole ring, we studied the mechanism of action of the new compound both indirectly, by means of microbiological techniques, and directly, by determining its oxidoreduction potential with respect to that of metronidazole. The results show that sulphimidazole is only slightly toxic in vitro for Vero cells, either alone or in association with trimethoprim, and that the combination of the two functional groups in a single molecule not only maintains its structure-activity relationship intact but also broadens its antibacterial spectrum.

Abstract:The antiviral and antiproliferative activity of new compounds having n-benzenesulphony 1-2 (2 or 3-pyridylethyl) benzimidazole as a base structure were studied in vitro. Their antitumour activity against human chronic myeloid leukaemia cells was evaluated and compared with that of equimolar doses of daunorubicin. Only compound 7a, with the presence of both the pyridyl moiety bound at the ethylenic bridge in C-2 of benzimidazole and the nitro-group in the benzene ring, displays a selective antiproliferative effect against certain leukaemia cells and a good antiviral activity especially towards the Coxsackie B5 virus. However, it should be noted that, in the case of hydroxybenzyl-benzimidazole, resistance also builds up to compound 7a, the Coxsackie B5 virus developing resistance to it after about ten runs. Cytotoxicity tests show that many of these substances are well tolerated by the VERO cells. The mechanism of action is still unclear.

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The antiviral and antiproliferative activity of new compounds having n-benzenesulphony 1-2 (2 or 3-pyridylethyl) benzimidazole as a base structure were studied in vitro. Their antitumour activity against human chronic myeloid leukaemia cells was evaluated and compared with that of equimolar doses of daunorubicin. Only compound 7a, with the presence of both the pyridyl moiety bound at the ethylenic bridge in C-2 of benzimidazole and the nitro-group in the benzene ring, displays a selective antiproliferative effect against certain leukaemia cells and a good antiviral activity especially towards the Coxsackie B5 virus. However, it should be noted that, in the case of hydroxybenzyl-benzimidazole, resistance also builds up to compound 7a, the Coxsackie B5 virus developing resistance to it after about ten runs. Cytotoxicity tests show that many of these substances are well tolerated by the VERO cells. The mechanism of action is still unclear.

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