Molecular structure and spectroscopic studies of the product of acidic degradation of salinomycin and its potassium salt

Abstract

Salinomycin (SAL), a monocarboxylic polyether antibiotic isolated from Streptomyces albus is widely used in veterinary medicine as a growth promoter and as a supplement in poultry feed to control infection with coccidia. SAL exhibits also potent activity against the proliferation of various cancer cells, including those that display multidrug resistance (MDR), and can precisely kill cancer stem cells (CSCs). The compound 2 – a product of the acidic degradation of SAL has been isolated and structurally characterized by X-ray, FT-IR, NMR, and DFT methods. Additionally, to check the ionophoretic properties of this compound its potassium salt (2-K) has been also obtained and the crystal structures of these two compounds as well as their structures in solution were studied in detail. It was found that the structures of 2 and 2-K salt were different in the solid and in the solution. Using ESI MS method it was demonstrated that that compound 2 was also able to form 1:1 and 2:1 complexes with Na+, K+, and Rb+ cations. For the first time we have demonstrated that the product of salinomycin degradation still shows ionophoretic properties.