Antiparasitic activities of novel ruthenium/lapachol complexes

Abstract

The present study describes the synthesis, characterization, antileishmanial and antiplasmodial activities of novel diimine/(2,2′-bipyridine (bipy), 1,10-phenanthroline (phen), 4,4′-methylbipyridine (Me-bipy) and 4,4′-methoxybipyridine (MeO-bipy)/phosphine/ruthenium(II) complexes containing lapachol (Lap, 2-hydroxy-3- The Ru(III) complex, [RuCl 2 (Lap)(dppb)], was also characterized by the EPR technique. The structure of the complexes [Ru(Lap)(PPh 3 ) 2 (bipy)]PF 6 and [RuCl 2 (Lap)(dppb)] was elucidated by X-ray diffraction. The evaluation of the antiparasitic activities of the complexes against Leishmania amazonensis and Plasmodium falciparum demonstrated that lapachol-ruthenium complexes are more potent than the free lapachol. The [RuCl 2 (Lap)(dppb)] complex is the most potent and selective antiparasitic compound among the five new ruthenium complexes studied in this work, exhibiting an activity comparable to the reference drugs.

Nitro/Nitrosyl-Ruthenium Complexes Are Potent and Selective Anti-Trypanosoma cruzi Agents Causing Autophagy and Necrotic Parasite Death

“…The elemental composition (C, H, and N) of the complexes corresponded closely to the calculated values. The 31 P{ 1 H} nuclear magnetic resonance (NMR) spectra of complexes 1 to 4 exhibited a pair of doublets that indicated the magnetic inequivalence of the phosphorus atoms present in the dppb (30). The observed doublets showed chemical shifts different from those of the starting material cis-[RuCl 2 (dppb)(5,5=-mebipy)], suggesting that the presence of the nitro or nitrosyl groups coordinated to the metal shifted the electron density of the phosphorus atoms from the dppb.…”

“…Fixed parasites were then washed 4 times with sodium cacodylate buffer (0.1 M, pH 7.2) and postfixed with a 1% solution of osmium tetroxide (Sigma-Aldrich). The cells were dehydrated in an ascending acetone series (30,50,70,90, and 100%) and embedded in PolyBed resin (PolyScience Family, Warrington, PA, USA). Ultrathin sections were prepared on a Leica UC7 ultramicrotome and collected on 300-mesh copper grids, contrasted with uranyl acetate and lead citrate.…”

Orthometallation in bidentate Schiff base ligands via C–H activation: synthesis of ruthenium(III) organometallic complexes

“…During the reaction of [Ru(PPh 3 ) 3-Cl 2 ] with Schiff base ligands, we observed that bidentate ligands having imine and phenolato functions became tridentate, such that cyclometalated ruthenium complexes were obtained via orthometallation. Coordination of bidentate ligands with [Ru(PPh 3 ) 3 Cl 2 ] is well known in the literature [29][30][31][32][33][34][35]. Bidentate ligands can stabilize Ru(II) or Ru(III) depending upon the nature of the donor atoms [29][30][31][32][33][34][35].…”

Synthesis, characterization and urease inhibition, in vitro anticancer and antileishmanial studies of Ni(II) complexes with N,N,N′-trisubstituted thioureas

“…The complexes of gold(I) and gold(III), palladium(II), rhenium(V), ruthenium(II), vanadium(IV) have shown great potential as inhibitors of different cysteine proteases in American trypanosomiasis and for Leishmaniasis as well [43][44][45]. A variety of gold(I) and gold(III) complexes have shown cytotoxic effects related to the inhibition of mitochondrial thioredoxin reductase and mitochondrial function [46][47][48].…”