The processes for the preparation of alkyl derivatives of N-[4-(2,4-diaminopteridin-6-ylmethylamino)benzoyl]-N-piperidin-2-carboxylic acid and N-[4-(2,4-diaminopteridin-6-ylmethylamino)benzoyl]-N-piperidin-4-carboxylic acid and of N-[4-(2,4-diaminopteridin-6-ylmethylamino)benzoyl]-N-pyrrolidin-2-carboxylic acid and N-[4-(2,4-diaminopteridin-6-ylmethylamino)benzoyl]-N-pyrrolidin-4-carboxylic acid. Their specific properties of inhibition versus Pteridine reductase of parasitic species. The processes for the preparation of alkyl derivatives of 1[4-(quinoxalin-2-ylamino)benzoyl]piperidin-mono and di-carboxylic acid and alkyl derivatives of 1-[4-(quinoxalin-2-ylamino)benzoyl]pyrrolidin-mono and di-carboxylic acid. The specific properties of inhibition versus Pteridine reductase of parasitic species. The processes for the preparation of alkyl derivatives of 4-(6,7-dimethoxy-quinoxalin-2-ylmethoxy)benzoic acid and alkyl derivatives of 2-(phenylsulfanil)-quinoxalin-5,7-diamine and their specific properties of inhibition versus Pteridine reductase of bacterial species. The pharmaceutical composition and their use in the treatment and prevention of parasitic infections caused by Leishmania and Tripanosoma and their antiparasitic action in combination with Pyrimetamine.
