Bioconjugation of Ionophore Antibiotics: A Way to Obtain Hybrids with Potent Biological Activity

Polyether antibiotics (ionophores) represent a large group of lipophilic compounds which are able to form complexes with the metal cations and transport them across the lipid membranes. This process disturbs the intercellular Na+/K+ concentration gradient and intracellular pH and leads to the mitochondrial injuries, cell swelling, vacuolization and finally to apoptosis process. For this reason, ionophores are commonly used in veterinary medicine as the non-hormonal growth-promoting and coccidiostatic agents. In this group, particularly interesting are monensin and salinomycin because of their proved anti-tumour activity, including efficiency against multidrug-resistant cancer cells and cancer stem cells. Prompted by the idea that cancer cells may be individually effectively killed by these compounds, a very interesting direction of research is bioconjugation process of ionophores. This review is focused on the possible role of hybrids of ionophore antibiotics with other biologically active substances in anti-cancer and anti-bacterial treatment and gives an overview of their properties.