Cobalt complexes in biology and medicine: enzymatic functions, pharmacological applications, and health challenges

Cobalt is an essential trace element in biochemistry that plays a crucial role in the structure and function of several important biomolecules. In this review, vitamin B12 is discussed as one of the best-known examples in this area. Various forms of this vitamin, including methylcobalamin and adenosylcobalamin, play a crucial role in metabolic reactions in mammals and prokaryotes. It also discusses cobalt-containing enzymes that are essential for various biological processes. These enzymes are B12-dependent enzymes, which are well studied, and cobalt-containing enzymes, which are less well known, such as methionine aminopeptidase, nitrile hydratase, glucose isomerase, and prolidase. In addition to the significant role of cobalt complexes in biochemistry, these complexes are considered potent anticancer agents that can exert their antiproliferative effects through the production of ROS, cell cycle arrest, MMP breakdown, and induction of apoptosis in cancer cells. Cobalt complexes are also being explained here for their antimicrobial properties against a variety of pathogens, including bacteria, fungi, and viruses. Furthermore, examples of these complexes are presented as promising agents for the suppression of AD, which could be effective by binding to Aβ-peptides and preventing their aggregation, which is a central feature of the pathogenesis of AD, or by combating the oxidative damage associated with the disease, or even by interfering with the enzyme activities associated with this disease. Finally, the challenges related to the toxicity of cobalt and its compounds in medicine are discussed, and chelation therapy is considered an effective treatment for cobalt poisoning.