New Nitroimidazoles with a Chemotherapeutic Activity
The nitroimidazole preparation >Tinidazole< (Pfizer), compound I, used for combating trichomoniasis is substituted at the imidazole ring in the 1-position by an ethylsulfonylethyl group. If this is replaced by an ethylthioethyl group, compound II, an intermediate of >Tinidazole<, a practically ineffective compound is obtained. Our studies have shown, this structure-activity relation is almost reversed when changing from the corresponding alkyl to aryl sulfur compounds, especially with electronegative radicals. For example, the 1-(4-nitrophenylsulfonylethyl) compound III is practically ineffective, the l-(4-nitrophenylthioethyl) compound IV exhibits a pronounced action against trichomonads. This effect is increased when heterocyclic radicals are introduced. Thus the 1-(4-pyridylsulfonylethyl) compound V also has a weak effect, whilst the 1-(4-pyridylthioethyl) compound VI has a comparable effect to > Metronidazole <. These results promted us to extend the studies also to the 2-position of the 5-nitroimidazoles.