Gold complexes as antimicrobial agents: an overview of different biological activities in relation to the oxidation state of the gold ion and the ligand structure

Abstract

Interest in antimicrobial gold complexes originated from the work of Robert Koch at the end of 19th century, who demonstrated that potassium dicyanidoaurate(I), K[Au(CN)2], showed activity against Mycobacterium tuberculosis, a causative agent of tuberculosis. Subsequently, a large number of gold(I) and gold(III) complexes have been evaluated as possible antimicrobial agents against a broad spectrum of bacteria, fungi and parasites. The first part of the present review article summarizes the results achieved in the field of antibacterial and antifungal activity of gold(I) and gold(III) complexes. The represented gold(I) complexes have been divided into three distinct classes based on the type of coordinated ligand: (i) complexes with phosphine-type ligands, (ii) complexes with N-heterocyclic carbene ligands and (iii) various other gold(I) complexes, while the results related to the antibacterial and antifungal gold(III) complexes have been mainly focused on the organometallic-type of complexes. The second section of this article represents findings obtained from the evaluation of antimalarial activity of gold complexes against chloroquine-sensitive and chloroquine-resistant strains of Plasmodium falciparum parasite. Antimalarial gold(I) and gold(III) complexes have been divided into the following classes, based on the nature of the coordinated ligand: (i) complexes with chloroquine and its derivatives, (ii) complexes with N-heterocyclic carbene ligands, (iii) complexes containing functionalised alkynes and (iv) thiosemicarbazonato ligands, as well as (v) other gold(I) and gold(III) complexes. In the last section of the review, gold(I) and gold(III) complexes have been reported to be potential agents against parasites that cause amoebiasis, leishmaniasis and trypanosomiasis. A systematic summary of these results could contribute to the future design of new gold(I) and gold(III) complexes as potential antimicrobial agents.

First Crystal Structure for a Gold Carbene–Protein Adduct

“…Thanks to their favorable and peculiar chemical and biological properties, gold(I) Nheterocyclic carbene compounds have been tested extensively in recent years as antiarthritic 15 , antibacterial 16 and anticancer agents 2,[11][12][13][14][18][19][20][21][22][23][24][25][26] .…”

In vitro antibacterial and time-kill evaluation of phosphanegold(I) dithiocarbamates, R3PAu[S2CN(iPr)CH2CH2OH] for R = Ph, Cy and Et, against a broad range of Gram-positive and Gram-negative bacteria

“…Reflecting the increasing interest in the antimicrobial activity of gold compounds, very recently, a comprehensive review of the developments in this field appeared [16]. While studies have been reported on phosphanegold(I) monofunctional thiolate compounds, none have yet appeared for bi-functional dithiolate analogues, such as dithiocarbamate.…”

Bis(phosphane)copper(I) and silver(I) dithiocarbamates: crystallography and anti-microbial assay

“…The same dithiocarbamate ligands when complexed to bismuth(III) [17] and zinc(II) [18] also provide cytotoxic compounds. Over and above displaying interesting cytotoxicity profiles, phosphanegold(I) dithiocarbamates also display potential as anti-microbial agents; see [19] for a recent review on the utility of gold compounds in this context. Interestingly, for these R3PAu[S2CN(iPr)CH2CH2OH] compounds, activity was found to be dependent on the nature of the phosphanebound R substituent.…”