Gold complexes with benzimidazole derivatives: synthesis, characterization and biological studies

Abstract

Synthesis, characterization, DFT studies and biological assays of new gold(I) and gold(III) complexes of benzimidazole are reported. Molecular and structural characterizations of the compounds were based on elemental (C, H and N) and thermal (TG-DTA) analyses, and FT-IR and UV-Visible spectroscopic measurements. The structures of complexes were proposed based DFT calculations. The benzimidazole compounds (Lig1 and Lig2) and the gold complexes were tested against three Leishmania species related to cutaneous manifestations of leishmaniasis. The free benzimidazole compounds showed no leishmanicidal activity. On the other hand, the gold(I and III) complexes have shown to possess significant activity against Leishmania in both stages of parasite, and the gold(III) complex with Lig2 exhibited expressive leishmanicidal activity with IC50 values below 5.7 μM. Also, the gold complexes showed high leishmania selectivity. The gold(I) complex with Lig1, for example, is almost 50 times more toxic for the parasite than for macrophages. Besides the leishmanicidal activity, all complexes exhibited toxic effect against SK-Mel 103 and Balb/c 3T3, cancer cells.

Systematic search for benzimidazole compounds and derivatives with antileishmanial effects

“…These gold-based complexes with benzimidazole moieties as the ligands [49] showed antileishmanial antiparasitic activ- S6) and G2 indicated that the substitution of the benzimidazole scaffold at positions 1 and 2 was important.…”

“…These compounds (4 entries) showed significant activities against promastigotes and amastigotes of L. major, L. amazonensis, and L. braziliensis (Supplementary File 2, Fig. S6) [49]. Thirty-one entries relating toL.…”

In vitro Biological Activities of Gold(I) and Gold(III) Bis(N-Heterocyclic Carbene) Complexes

“…Gold(I) and gold(III) complexes are also known to be effective against cutaneous leishmaniasis and malarial parasites . Gold complexes are known to be more effective on parasites than macrophages . Au(III) tetrachloride complexes are also reported to have anti‐HIV activity …”

Three new mononuclear group 12 complexes with benzimidazole

“…Benzimidazoles are a class of organic compounds which possess extensive applications, especially in medicinal chemistry and a number of compounds containing a benzimidazole have been prepared and described with anti-inflammatory [1], anticancer [2], antimicrobial [3][4][5], antifungal [6], antiparasitic [7,8], and antiviral activities [9]. Benzimidazole-based metal complexes with luminescent properties [10][11][12][13] are also known.…”