Chelation is the rational treatment modality in metal overload conditions, but chelators are often non-selective and can, hence, cause an imbalance in the homeostasis of physiological metals including calcium and magnesium. The aim of this study was to develop an affordable, rapid but sensitive and precise method for determining the degree of chelation of calcium and magnesium ions and to employ this method for comparison on a panel of known metal chelators. Spectrophotometric method using o-cresolphthalein complexone (o-CC) was developed and its biological relevance was confirmed in human platelets by impedance aggregometry. The lowest detectable concentration of calcium and magnesium ions by o-CC was 2.5 μM and 2 μM, respectively. The indicator was stable for at least 110 days. Four and seven out of twenty-one chelators strongly chelated calcium and magnesium ions, respectively. Importantly, the chelation effect of clinically used chelators was not negligible. Structure-activity relationships for eight quinolin-8-ols showed improvements in chelation particularly in the cases of dihalogen substitution, and a negative linear relationship between pKa and magnesium chelation was observed. Calcium chelation led to inhibition of platelet aggregation in concentrations corresponding to the complex formation. A novel method for screening of efficacy and safety of calcium and magnesium ion chelation was developed and validated.

• Keywords
• Chelator, Depletion, Methodology, Platelet, Selectivity,
• MeSH
• Platelet Aggregation drug effects   MeSH
• Chelating Agents * chemistry   MeSH
• Magnesium * chemistry   MeSH
• Humans MeSH
• Drug Evaluation, Preclinical methods   MeSH
• Blood Platelets drug effects   metabolism   MeSH
• Calcium * analysis   metabolism   MeSH
• Structure-Activity Relationship MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Comparative Study MeSH
• Names of Substances
• Chelating Agents * MeSH
• Magnesium * MeSH
• Calcium * MeSH

The bisdioxopiperazine topoisomerase IIβ inhibitor ICRF-193 has been previously identified as a more potent analog of dexrazoxane (ICRF-187), a drug used in clinical practice against anthracycline cardiotoxicity. However, the poor aqueous solubility of ICRF-193 has precluded its further in vivo development as a cardioprotective agent. To overcome this issue, water-soluble prodrugs of ICRF-193 were prepared, their abilities to release ICRF-193 were investigated using a novel UHPLC-MS/MS assay, and their cytoprotective effects against anthracycline cardiotoxicity were tested in vitro in neonatal ventricular cardiomyocytes (NVCMs). Based on the obtained results, the bis(2-aminoacetoxymethyl)-type prodrug GK-667 was selected for advanced investigations due to its straightforward synthesis, sufficient solubility, low cytotoxicity and favorable ICRF-193 release. Upon administration of GK-667 to NVCMs, the released ICRF-193 penetrated well into the cells, reached sufficient intracellular concentrations and provided effective cytoprotection against anthracycline toxicity. The pharmacokinetics of the prodrug, ICRF-193 and its rings-opened metabolite was estimated in vivo after administration of GK-667 to rabbits. The plasma concentrations of ICRF-193 reached were found to be adequate to achieve cardioprotective effects in vivo. Hence, GK-667 was demonstrated to be a pharmaceutically acceptable prodrug of ICRF-193 and a promising drug candidate for further evaluation as a potential cardioprotectant against chronic anthracycline toxicity.

• MeSH
• Anthracyclines adverse effects   MeSH
• Dexrazoxane chemistry   pharmacology   MeSH
• Diketopiperazines chemistry   pharmacology   MeSH
• DNA Topoisomerases, Type II metabolism   MeSH
• Topoisomerase II Inhibitors chemistry   pharmacology   MeSH
• Myocytes, Cardiac drug effects   metabolism   MeSH
• Cardiotonic Agents chemistry   pharmacology   MeSH
• Cardiotoxicity drug therapy   metabolism   MeSH
• Rabbits MeSH
• Piperazine chemistry   pharmacology   MeSH
• Prodrugs chemistry   pharmacology   MeSH
• Razoxane chemistry   pharmacology   MeSH
• Water chemistry   MeSH
• Animals MeSH
• Check Tag
• Rabbits MeSH
• Male MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• 4,4'-(1,2-dimethyl-1,2-ethanediyl)bis-2,6-piperazinedione MeSH Browser
• Anthracyclines MeSH
• Dexrazoxane MeSH
• Diketopiperazines MeSH
• DNA Topoisomerases, Type II MeSH
• Topoisomerase II Inhibitors MeSH
• Cardiotonic Agents MeSH
• Piperazine MeSH
• Prodrugs MeSH
• Razoxane MeSH
• Water MeSH

Sobuzoxane (MST-16) is an approved anticancer agent, a pro-drug of bisdioxopiperazine analog ICRF-154. Due to the structural similarity of ICRF-154 to dexrazoxane (ICRF-187), MST-16 deserves attention as a cardioprotective drug. This study presents for the first time UHPLC-MS/MS assay of MST-16, ICRF-154 and its metabolite (EDTA-diamide) in cell culture medium, buffer, plasma and cardiac cells and provides data on MST-16 bioactivation under conditions relevant to investigation of cardioprotection of this drug. The analysis of these compounds that differ considerably in their lipophilicity was achieved on the Zorbax SB-Aq column using a mixture of aqueous ammonium formate and methanol as a mobile phase. The biological samples were either diluted or precipitated with methanol, which was followed by acidification for the assay of MST-16. The method was validated for determination of all compounds in the biological materials. The application of the method for analysis of samples from in vitro experiments provided important findings, namely, that (1) MST-16 is quickly decomposed in biological environments, (2) the cardiac cells actively metabolize MST-16, and (3) MST-16 readily penetrates into the cardiac cells and is converted into ICRF-154 and EDTA-diamide. These data are useful for the in-depth examination of the cardioprotective potential of this drug.

• MeSH
• Edetic Acid chemistry   MeSH
• Myocytes, Cardiac cytology   metabolism   MeSH
• Rats MeSH
• Cells, Cultured MeSH
• Piperazines analysis   MeSH
• Rats, Wistar MeSH
• Antineoplastic Agents analysis   metabolism   MeSH
• Razoxane analogs & derivatives   chemistry   metabolism   MeSH
• Tandem Mass Spectrometry MeSH
• Chromatography, High Pressure Liquid MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• 1,2-bis(3,5-dioxopiperazin-1-yl)ethane MeSH Browser
• Edetic Acid MeSH
• Piperazines MeSH
• Antineoplastic Agents MeSH
• Razoxane MeSH
• sobuzoxane MeSH Browser