Antimalarial in-vivo activity of bis(9-amino-6-chloro-2-methoxyacridines).

In the fight against malaria, chemotherapy using bisacridines may represent an alternative method to overcoming chloroquine-resistance. Eight bis(9-amino-6-chloro-2-methoxyacridines), in which acridine moieties were linked by polyamines substituted with a side chain, were tested for their in-vivo activity upon mice infected by Plasmodium berghei. Three of the compounds revealed antimalarial activity but no relationship could be deduced from a comparison of in-vitro and in-vivo activities. N-alkylation of the central amino group generated toxicity and, therefore, only compounds N-acylated in this position can be selected as leads.

Antiplasmodial activity and cytotoxicity of bis-, tris-, and tetraquinolines with linear or cyclic amino linkers.

Bisquinoline heteroalkanediamines were structurally modified in order to study the effects of enhanced bulkiness and rigidity on both their activity on strains of Plasmodium falciparum expressing different degrees of chloroquine (CQ) resistance and their cytotoxicity toward mammalian cells. While cyclization yielded molecules of greater rigidity that were not more active than their linear counterparts, they were characterized by an absence of cytotoxicity. Alternatively, dimerization of these compounds led to tetraquinolines that are very potent for CQ-resistant strains and noncytotoxic.

Antimalarial, antitrypanosomal, and antileishmanial activities and cytotoxicity of bis(9-amino-6-chloro-2-methoxyacridines): influence of the linker.

Forty bis(9-amino-6-chloro-2-methoxyacridines), in which acridine moieties are joined by alkanediamines, polyamines, or polyamines substituted by a side chain, were synthesized and tested for their in vitro activity upon the erythrocytic stage of Plasmodium falciparum, trypomastigote stage of Trypanosoma brucei, and amastigote stage of Trypanosoma cruzi and Leishmania infantum as well as for their cytotoxic effects upon MRC-5 cells. Results clearly showed the importance of the nature of the linker and of its side chain for antiparasitic activity, cytotoxicity, and cellular localization. Among several compounds devoid of cytotoxic effects at 25 microM upon MRC-5 cells, one displayed IC(50) values ranging from 8 to 18 nM against different P. falciparum strains while three others totally inhibited T. brucei at 1.56 microM.

Synthesis of polyamine derivatives for the preparation of affinity chromatography columns for the search of new Trypanosoma cruzi targets.

The most potent trypanocidal compound of a series of symmetrically substituted 1,4-bis(3-aminopropylpiperazines) which displayed an IC50 value of 5 microM on Trypanosoma cruzi trypomastigotes, was inactive on trypanothione reductase. Two derivatives 6 and 12 of this compound, one symmetrical and one dissymmetrical, were synthesized via a reductive amination reaction, to prepare affinity chromatography columns, which allowed us to isolate three parasitic proteins. Among these, the major ligand 6- and 12-binding protein having an apparent molecular weight of 52 kDa has been identified as the thiol-disulfide oxido-reductase Tc52, previously characterized in Trypanosoma cruzi.

Structure-activity relationships in 2-aminodiphenylsulfides against trypanothione reductase from Trypanosoma cruzi.

In order to establish structural elements responsible for inhibition of trypanothione reductase (TR) from Trypanosoma cruzi by 2-aminodiphenylsulfides, a series of dissymmetrical derivatives, corresponding to the replacement of one aromatic moiety by different amines, was synthesized. TR inhibition studies revealed the importance of the aromatic rings and of the amino groups in the side chains for potent inhibition. Quinonic moities were also introduced with the aim of acting as TR redox-cycling substrates.