Synthesis of catecholamide spiroarsoranes and their in vitro anthelmintic properties against Molinema dessetae and Nippostrongylus brasiliensis infective larvae.

Catecholamide spiroarsoranes were synthesized and evaluated for anthelmintic properties on two in vitro models, infective larvae of the filaria Molinema dessetae and infective larvae of an intestinal nematode. Nippostrongylus brasiliensis. On the N dessetae model, the most active compound after 24 h incubation time had an EC50 of 0.1 mumol/l. Eleven compounds had EC50 's in a range from 2 to 200 mumol/l. After 7 days incubation time, the two most active compounds had EC50 's of 0.03 and 0.07 mumol/l, respectively. On the N brasiliensis model, only three compounds were slightly active after 4 days incubation time. The ligands used for the spiroarsoranes synthesis were also evaluated for anthelmintic activity in order to know the contribution of these structures in the spiroarsoranes activity. Spiroarsoranes as prodrugs of arsonic acids were very active on the filaria, nematode having predominantly transcuticular uptake of nutrients while the activity on the intestinal nematode having both the types, transcuticular and intestinal uptake was low. The high sensitivity of filarial infective larvae is probably in relation to their location in the mosquito whereas N. brasiliensis infective larvae are telluric and should be more unsensitive to survive in a variable environment.

Design, synthesis and biological study of new antiparasitic spiroarsoranes.

Thirty-eight new spiroarsoranes were synthesized after structure-activity relationship studies from the first series. These compounds were predicted to cross more easily the membrane of protozoae or the cuticle of Nematodes and to reach their biological target with efficiency. The spiroarsoranes were evaluated for their antiparasitic properties, on helminths and protozoa models in regard of their parent arsonic acids. The following parasite models were used: Entamoeba histolytica and Trichomonas vaginalis in vitro; Molinema dessetae infective larvae in vitro, adults and microfilariae in vivo; Nippostrongylus brasiliensis infective larvae in vitro. The results obtained on these models indicated that the "spiranization" of arsonic acids produced new compounds with a biological activity 10-fold superior to those of arsonic acids. Nevertheless, each parasite had its own sensitivity to spiroarsoranes. Moreover, in vivo results showed that the lipophilicity of the molecules should be optimal to avoid high toxicity in host such as arsenical encephalopathy.