Imidazole and benzimidazole systems are presented in a large number of common therapeutics agents. They were widely used in organic and medicinal chemistry, but recently the development of N-oxide derivatives got an improvement from the point of view of its chemical and biological activity. Though we will review recent developments in chemical and biological profiles (as antitumoral, antiparasitic, antiviral and antimicrobial agents) of these heterocycle systems and the corresponding N-oxides.

In the search for new therapeutic tools against American Trypanosomiasis palladium complexes with bioactive nitrofuran-containing thiosemicarbazones as ligands were obtained. Sixteen novel palladium (II) complexes with the formulas [PdCl2(HL)] and [Pd(L)2] were synthesized, and the crystal structure of [Pd(5-nitrofuryl-3-acroleine thiosemicarbazone)2] x 3DMSO was solved by X-ray diffraction methods. Most complexes showed higher in vitro growth inhibition activity against Trypanosoma cruzi than the standard drug Nifurtimox. In most cases, the activity of the ligand was maintained or even increased as a result of palladium complexation. In addition, the complexes' mode of antitrypanosomal action was investigated. Although the complexes showed strong DNA binding, all data strongly suggest that the main trypanocidal mechanism of action is the production of oxidative stress as a result of their bioreduction and extensive redox cycling. Moreover, the complexes were found to be irreversible inhibitors of trypanothione reductase.

No abstract

The chemistry of furoxans (1, 2, 5-oxadiazole-2-oxides) and benzofuroxans (benzo[1, 2-c]1, 2, 5-oxadiazole-1-oxides) is very well known. These systems are widely used in organic chemistry as intermediate compounds for the synthesis of numerous heterocycles. In the other hand, furoxan and benzofuroxan derivatives were extensively studied as bioactive compounds. They possess remarkable biological activities, such as anti-microbial and anti-parasitic properties, mutagenic, immunosuppressive and anticancer effects, anti-aggregating and vasorelaxant activity, among others. In some cases, molecular mode of action was proposed. Recently, the research and development in the medicinal chemistry of these systems have produced hybrid compounds in which furoxan or benzofuroxan moieties together with a classical drug moieties are present in a single molecule. So, new anti-ulcer drugs, calcium channel modulators and vasodilator derivatives were described and they are currently in study. In this presentation recent developments in the medicinal chemistry of furoxans and benzofuroxans will be reviewed.

No abstract

No abstract

No abstract

The syntheses of a new series of derivatives of 1,2,5-oxadiazole N-oxide, benzo[1,2-c]1,2,5-oxadiazole N-oxide, and quinoxaline di-N-oxide are described. In vitro antitrypanosomal activity of these compounds was tested against epimastigote forms of Trypanosoma cruzi. For the most effective drugs, derivatives IIIe and IIIf, the 50% inhibitory dose (ID50) was determined as well as their cytotoxicity against mammalian fibroblasts. Electrochemical studies and ESR spectroscopy show that the highest activities observed are associated with the facile monoelectronation of the N-oxide moiety. Lipophilic-hydrophilic balance of the compounds could also play an important role in their effectiveness as antichagasic drugs.