[A new series of antiparasitic organic arsenicals: the spiroarsoranes. Experimental trypanocidal activity].

Arsenical compounds are the main therapeutic way, effective in the neurological phase of trypanosomiasis. Unfortunately, their important toxicity prevents their easy administration. Structural cyclization of arsonic acid derivatives has led to a class of non-toxic compounds: spiroarsoranes. A 47 compound primary screening on an in vivo murine model of Trypanosoma brucei brucei resulted in the isolation of a very effective derivative after a single subcutaneous injection of 30 mg.kg-1 body weight (Chemotherapeutic Index = 21). In this study, trypanocidal activity of this compound was evaluated on an in vivo sheep model of trypanosomiasis by T. brucei brucei, according to experimental model of the Institute of Neurological Epidemiology and Tropical Neurology of Limoges (France). A single subcutaneous injection of 30 and 100 mg.kg-1 b.w., and 30 and 60 mg.kg-1 b.w. was given respectively during first and second phase of trypanosomiasis. Ovine pharmacokinetics of this compound will be evaluated in a further study.