Antimicrobial resistance (including antibiotics, antivirals, antifungals, and antiparasitics) is a very serious global problem that has arisen due to the misuse and overuse of drugs in modern medicine, veterinary medicine, and food production. It is estimated that around 5 million people die annually due to drug resistance. The WHO has listed this as one of the ten most critical problems facing humanity. You can find more information in the WHO fact sheets on antimicrobial and antibiotic resistance.
Many of the used antibiotics are synthetically prepared small organic molecules with an inhibitory mechanism of action. For example, sulfonamides (e.g. Sulfamethoxazole, Figure 1) were among the first drugs broadly used as antibiotics. They work as competitive inhibitors of a bacterial enzyme responsible for folate biosynthesis and therefore, disrupt the protein production in bacteria. This means that sulfonamides are bacteriostatic drugs but do not kill bacteria. Another antibiotic class are Oxazolidones (e.g. Linezolid). They bind into the catalytic center of bacterial ribosome subunit 50s and inhibit translation by preventing the amide bond formation between the respective amino acids. Quinolones and more specifically fluoroquinolones (e.g. Ciprofloxacin) work through the inhibition of bacterial type II topoisomerases (gyrase and Topo IV) which results in bactericidal DNA fragmentation. Practically all bioisosteres published so far use BC as substituents for various cyclic groups, most often benzene. We will also focus on the replacement of benzene with carborane (and other BC as well), but most importantly, we will aim for the incorporation of the cluster in the very center of the targeted molecules. Therefore, this approach is more alike to the total synthesis of various drugs with carboranes attached, something not yet previously performed. I strongly believe we can control solubility requirements and increase the number of bonding interactions via dihydrogen bond formation with amino acids inside the active sites. Furthermore, electron distribution over the carborane cluster will result in different Lewis’s acidity/basicity and therefore stronger or weaker hydrogen bonding inside the enzymatic cavities. This difference can be further improved by switching the substitution (boron vs. carbon) sites of carboranes.
 Murray C. J. L. ; Ikuta, K. S.; Sharara, F.; Swetschinski, L. et al. Global burden of bacterial antimicrobial resistance in 2019: a systematic analysis. The Lancet, 2022, 399, 629.
 Madigan, M. T., et al., Brock Biology of Microorganisms, Global Edition, Pearson Education Limited, 2018.
 Schifano, J. M., et al., Proc. Natl. Acad. Sci. U.S.A. 2013, 110, 8501.
 a) Drlica, K., et al., Microbiol Mol Biol Rev 1997, 61, 377; b) Pommier, Y., et al., Chem Biol 2010, 17, 421.
 a) Scholz, M., et al., Chem. Rev. 2011, 111, 7035; b) Stockmann, P., et al., Chem. Soc. Rev. 2019, 48, 3497; c) Issa, F., et al., Chem. Rev. 2011, 111, 5701; e) Chen, Y., et al., Mol. Ther. Oncolytics 2022, 24, 400.