Evaluation of the antiparasitic activities of imidazol‐2‐ylidene–gold(I) complexes

Abstract

A series of cationic gold(I)-carbene complexes with various 4,5-diarylimidazolylidene ligands were either newly prepared or repurposed for testing against protozoal Leishmania major, Toxoplasma gondii, and Trypanosoma brucei parasites. The syntheses of the new complexes 1b and 1c were described. Ferrocene compound 1a showed the highest activities against L. major amastigotes and T. gondii and distinct selectivity for T.gondii cells when compared with the activity against nonmalignant Vero cells. The ferrocene derivatives 1a-c are generally more active against the L. major amastigotes and the T. gondii tachyzoites than the other tested anisyl gold complexes and the approved drugs atovaquone and amphotericin B. Compounds 1a and 1e showed the highest selectivities for L. major amastigotes. Compounds 1d and 1f showed the highest selectivities for L. major promastigotes; 1f was the most active compound against L.major promastigotes of this series of compounds. The 3,4,5-trimethoxyphenyl analog 1b also exhibited a much greater selectivity for T. b. brucei cells when compared with its activity against human HeLa cells.

Comparing the Antileishmanial Activity of Gold(I) and Gold(III) Compounds in L. amazonensis and L. braziliensis in Vitro

“…[18,19] Interestingly, a heteronuclear complex featuring both Au I NHC and ferrocene moieties showed the highest activities (nM level) against Leishmania major amastigotes. [20] Recently, Monte-Neto and co-workers reported on the effects on promastigote and amastigote proliferation from L. infantum and L. braziliensis of a series of Au I phosphane complexes with thiol-containing ligands. [21,22] Moreover, some of the reported derivatives were effective for experimental cutaneous leishmaniasis in animal models.…”

New Pyrano‐4H‐benzo[g]chromene‐5,10‐diones with Antiparasitic and Antioxidant Activities

“…Cell assays with L. major promastigotes and amastigotes were carried out as described previously [41–48] …”

“…Fluorescence (extinction at 544 nm, emission at 590 nm) was determined on an Omega FLUOstar (BMG Labtech) fluorescence plate reader. The IC 50 values were determined with the Quest Graph TM IC 50 Calculator (AAT Bioquest Inc.) [47] …”

“…MTT assay with Vero cells was carried out for cytotoxicity evaluation of compounds. The assay was carried out as reported previously [47,48] …”

“…After 30 min the absorbance was measured with a double beam spectrophotometer (JASCO V‐630) at 517 nm. IC 50 values were calculated from the plot of inhibition (In %) vs. concentration (in μM) [46,47] . The free radical scavenging kinetics for standard antioxidant viz.…”