Adam Huczyński

Salinomycin: a new cancer drug candidate.

Very recently, it has been shown that it is possible to selectively kill breast cancer stem cells using the ionophore antibiotic, salinomycin. Its ability to kill cancer stem cells and apoptosis‐resistant cancer cells may define salinomycin as a novel anticancer drug.

Polyether ionophores—promising bioactive molecules for cancer therapy

The natural polyether ionophore antibiotics might be important chemotherapeutic agents for the treatment of cancer. In this article, the pharmacology and anticancer activity of the polyether ionophores undergoing pre-clinical evaluation are reviewed. Most of polyether ionophores have shown potent activity against the proliferation of various cancer cells, including those that display multidrug resistance (MDR) and cancer stem cells (CSC). The mechanism underlying the anticancer activity of ionophore agents can be related to their ability to form complexes with metal cations and transport them across cellular and subcellular membranes. Increasing evidence shows that the anticancer activity of polyether ionophores may be a consequence of the induction of apoptosis leading to apoptotic cell death, arresting cell cycle progression, induction of the cell oxidative stress, loss of mitochondrial membrane potential, reversion of MDR, synergistic anticancer effect with other anticancer drugs, etc. Continued investigation of the mechanisms of action and development of new polyether ionophores and their derivatives may provide more effective therapeutic drugs for cancer treatments.

Synthesis, cytotoxicity and antibacterial activity of new esters of polyether antibiotic – salinomycin

A series of 12 novel ester derivatives of naturally occurring polyether antibiotic - salinomycin were synthesized, characterised by spectroscopic method and evaluated for their in vitro antibacterial activity and cytotoxicity. The new esters were demonstrated to form complexes with monovalent and divalent metal cation of 1:1 stoichiometry in contrast to the salinomycin which forms only complexes with monovalent cations. All the obtained compounds show potent antiproliferative activity against human cancer cell lines and a good selectivity index for cancer versus mammalian cells. Additionally, 3 compounds showed higher antiproliferative activity against the drug-resistant cancer cells and lower toxicity towards normal cells than those of unmodified salinomycin and standard anticancer drugs such as cisplatin and doxorubicin. Some of the synthesized compounds showed good inhibitory activity against Staphylococcus strains and clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus epidermidis (MRSE). These studies show that salinomycin esters are interesting scaffolds for the development of novel anticancer and Gram-positive antibacterial agents.

Synthesis and antimicrobial properties of monensin A esters.

The esters (2-10) of the ionophore antibiotic Monensin (1) were synthesized by four different methods, which are discussed in detail. These new esters were characterized by various spectroscopic techniques and subsequently tested in the face of their antimicrobial properties. Three derivatives (3, 8 and 10) showed activity against Gram-positive bacteria. Additionally derivative (10) exhibited a relatively low antifungal activity against Candida in contrast to Monensin A.

Antiproliferative activity of salinomycin and its derivatives.

Antiproliferative activity of seven amides and one benzotriazole ester derivative of salinomycin, a polyether ionophore antibiotic, with recently reported antibacterial activity, are herein described. Salinomycin and the majority of derivatives exhibit potent antiproliferative activity against the drug-resistant cancer cell lines. Moreover almost all derivatives show stronger activity against LoVo/DX cell line than that of unmodified salinomycin.

Synthesis and antimicrobial activity of amide derivatives of polyether antibiotic-salinomycin.

For the first time a direct and practical approach to the synthesis of eight amide derivatives of polyether antibiotic-salinomycin is described. The structure of allyl amide (3a) has been determined using X-ray diffraction. Salinomycin and its amide derivatives have been screened for their in vitro antimicrobial activity against the typical gram-positive cocci, gram-negative rods and yeast-like organisms, as well as against a series of clinical isolates of methicillin-resistant Staphylococcus aureus and methicillin-sensitive S. aureus. Amides of salinomycin have been found to show a wide range of activities, from inactive at 256 μg/mL to active with MIC of 2 μg/mL, comparable with salinomycin. As a result, phenyl amide (3b) was found to be the most active salinomycin derivative against gram-positive bacteria, MRSA and MSSA.

Synthesis, antiproliferative and antibacterial activity of new amides of salinomycin.

A series of 11 novel amides of salinomycin were synthesized for the first time. All the obtained compounds were found to show potent antiproliferative activity against human cancer cell lines including the drug-resistant cancer cells. Four new salinomycin derivatives revealed good antibacterial activity against clinical isolates of methicillin-resistant Staphylococcus epidermidis (MRSE).

Structure and Antimicrobial Properties of Monensin A and Its Derivatives: Summary of the Achievements

In this paper structural and microbiological studies on the ionophorous antibiotic monensin A and its derivatives have been collected. Monensin A is an ionophore which selectively complexes and transports sodium cation across lipid membranes, and therefore it shows a variety of biological properties. This antibiotic is commonly used as coccidiostat and nonhormonal growth promoter. The paper focuses on both the latest and earlier achievements concerning monensin A antimicrobial activity. The activities of monensin derivatives, including modifications of hydroxyl groups and carboxyl group, are also presented.

Monensin A acid complexes as a model of electrogenic transport of sodium cation.

New Monensin A acid complexes with water molecule, sodium chloride and sodium perchlorate were obtained and studied by X-ray and (1)H, (13)C NMR and FT-IR methods as well as ab initio calculations. The crystal structure of the complexes indicates the complexation of the water molecule and Na(+) cation in the pseudo-cycle conformation of the Monensin acid molecule stabilised by intramolecular hydrogen bonds. Important for stabilisation of this structure is also the intermolecular hydrogen bonds with water molecule or the coordination bonds with Na(+) cation. It is demonstrated that the counterions forming intermolecular hydrogen bonds with OH groups influence the strength of the intramolecular hydrogen bonds, but they have no influence on the formation of pseudo-cyclic structure. Spectroscopic studies of the complexes in dichloromethane solution have shown that the pseudo-cyclic structure of the compounds is conserved. As follows from the ab initio calculations, the interactions between the Na(+) cation and the electronegative oxygen atoms of Monensin acid totally change the molecular electrostatic potential around the supramolecular Monensin acid-Na(+) cationic complex relative to that of the neutral Monensin acid molecule.

Synthesis, Anticancer and Antibacterial Activity of Salinomycin N-Benzyl Amides

A series of 12 novel monosubstituted N-benzyl amides of salinomycin (SAL) was synthesized for the first time and characterized by NMR and FT-IR spectroscopic methods. Molecular structures of three salinomycin derivatives in the solid state were determined using single crystal X-ray method. All compounds obtained were screened for their antiproliferative activity against various human cancer cell lines as well as against the most problematic bacteria strains such as methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus epidermidis (MRSE), and Mycobacterium tuberculosis. Novel salinomycin derivatives exhibited potent anticancer activity against drug-resistant cell lines. Additionally, two N-benzyl amides of salinomycin revealed interesting antibacterial activity. The most active were N-benzyl amides of SAL substituted at -ortho position and the least anticancer active derivatives were those substituted at the -para position.