sar-97276 and Malaria

We report herein the design, synthesis, and biological screening of a series of 15 disulfide prodrugs as precursors of albitiazolium bromide (T3/SAR97276, compound 1), a choline analogue which is currently being evaluated in clinical trials (phase II) for severe malaria. The corresponding prodrugs are expected to revert back to the active bis-thiazolium salt through an enzymatic reduction of the disulfide bond. To enhance aqueous solubility of these prodrugs, an amino acid residue (valine or lysine) or a phosphate group was introduced on the thiazolium side chain. Most of the novel derivatives exhibited potent in vitro antimalarial activity against P. falciparum. After oral administration, the cyclic disulfide prodrug 8 showed the best improvement of oral efficacy in comparison to the parent drug.

Topics: Animals; Antimalarials; Disulfides; Malaria; Mice; Plasmodium falciparum; Prodrugs; Stereoisomerism; Structure-Activity Relationship; Thiazoles

We report here the synthesis and biological evaluation of a series of 37 compounds as precursors of potent antimalarial bis-thiazolium salts (T3 and T4). These prodrugs were either thioester, thiocarbonate or thiocarbamate type and were synthesized in one step by reaction of an alkaline solution of the parent drug with the appropriate activated acyl group. Structural variations affecting physicochemical properties were made in order to improve oral activity. Twenty-five of them exhibited potent antimalarial activity with IC(50) lower than 7nM against Plasmodium falciparum in vitro. Notably, 3 and 22 showed IC(50)=2.2 and 1.8nM, respectively. After oral administration 22 was the most potent compound clearing the parasitemia in Plasmodium vinckei infected mice with a dose of 1.3mg/kg.

Topics: Animals; Antimalarials; Dose-Response Relationship, Drug; Malaria; Mice; Molecular Structure; Parasitic Sensitivity Tests; Plasmodium; Prodrugs; Salts; Stereoisomerism; Structure-Activity Relationship; Thiazoles

Within the frame of the design of prodrug candidates to deliver a C-alkylamidine antimalarial agent, we showed that specific O-substitutions were needed on the alkylamidoxime structure. Among the newly synthesized molecules, bis-oxadiazolone and bis-O-methylsulfonylamidoxime derivatives induced a complete clearance of parasitemia in mice after oral administration.

Topics: Administration, Oral; Animals; Antimalarials; Antioxidants; Chemistry, Pharmaceutical; Dose-Response Relationship, Drug; Drug Design; Humans; Malaria; Mice; Models, Chemical; Parasitemia; Plasmodium falciparum; Prodrugs