Metal Complexes, an Untapped Source of Antibiotic Potential?

Abstract

With the widespread rise of antimicrobial resistance, most traditional sources for new drug compounds have been explored intensively for new classes of antibiotics. Meanwhile, metal complexes have long had only a niche presence in the medicinal chemistry landscape, despite some compounds, such as the anticancer drug cisplatin, having had a profound impact and still being used extensively in cancer treatments today. Indeed, metal complexes have been largely ignored for antibiotic development. This is surprising as metal compounds have access to unique modes of action and exist in a wider range of three-dimensional geometries than purely organic compounds. These properties make them interesting starting points for the development of new drugs. In this perspective article, the encouraging work that has been done on antimicrobial metal complexes, mainly over the last decade, is highlighted. Promising metal complexes, their activity profiles, and possible modes of action are discussed and issues that remain to be addressed are emphasized.Antibiotics 2020, 9, 90 2 of 24 Metal-containing compounds have played a small but seminal role in medicinal chemistry of throughout the 20th century. An arsenic-containing compound, Salvarsan, was discovered at the beginning of the century and became the first effective treatment of syphilis [9]. It was however the discovery of the anticancer drug cisplatin and its successors that really kickstarted the field of inorganic medicinal chemistry. Even today, platinum-based chemotherapeutics are still used in the majority of cancer treatments [10]. The gold-containing auranofin is an approved drug for the treatment of rheumatoid arthritis and is currently under investigation for its anticancer as well as antimicrobial properties [11][12][13][14][15][16]. Invigorated by these breakthrough successes, the field has expanded to many other elements in the last few decades, with complexes of titanium, iron, ruthenium, gallium, palladium, silver, gold, bismuth, and copper entering clinical trials [17][18][19][20][21][22]. The medicinal applications of these metal complexes range from anticancer to antimalaria over to neurodegenerative diseases. Strangely, antibacterial applications are remarkably sparse in this list and the number of literature reports on metal-based antimicrobials is dwarfed by the much more frequent publications on metal-based anticancer compounds. This is surprising as metals such as bismuth and silver have long been known to possess antibacterial properties. Some medicinal products are currently available. There are however a variety of products, such as silver-coated underwear, with a more dubious scientific basis. Nevertheless, the systematic evaluation of the antimicrobial properties of metal complexes has increased in pace over the last decade, with several reports highlighting the activity and potential modes of action of metal-based antibiotics. This perspective article will discuss the major discoveries in the non-traditional field of metal complex-based antibiotic co...

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Synthesis, characterization, antifungal and antibacterial activities evaluation of copper (II), zinc (II) and cadmium (II) chloride and bromide complexes with new (E)‐1‐(3,4‐dimethoxybenzylidene)‐4‐methylthiosemicarbazone ligand

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