Binding Kinetics of Ruthenium Pyrithione Chemotherapeutic Candidates to Human Serum Proteins Studied by HPLC-ICP-MS.

Katarina Marković,Janez Ščančar,Iztok Turel,Stefan Marković,Radmila Milačič,Jerneja Kladnik

doi:10.3390/molecules25071512

Abstract

The development of ruthenium-based complexes for cancer treatment requires a variety of pharmacological studies, one of them being a drug’s binding kinetics to serum proteins. In this work, speciation analysis was used to study kinetics of ruthenium-based drug candidates with human serum proteins. Two ruthenium (Ru) complexes, namely [(η6-p-cymene)Ru(1-hydroxypyridine-2(1H)-thionato)Cl] (1) and [(η6-p-cymene)Ru(1-hydroxypyridine-2(1H)-thionato)pta]PF6 (2) (where pta = 1,3,5-triaza-7-phosphaadamantane), were selected. Before a kinetics study, their stability in relevant media was confirmed by nuclear magnetic resonance (NMR). Conjoint liquid chromatography (CLC) monolithic column, assembling convective interaction media (CIM) protein G and diethylamino (DEAE) disks, was used for separation of unbound Ru species from those bound to human serum transferrin (Tf), albumin (HSA) and immunoglobulins G (IgG). Eluted proteins were monitored by UV spectrometry (278 nm), while Ru species were quantified by post-column isotope dilution inductively coupled plasma mass spectrometry (ID-ICP-MS). Binding kinetics of chlorido (1) and pta complex (2) to serum proteins was followed from 5 min up to 48 h after incubation with human serum. Both Ru complexes interacted mainly with HSA. Complex (1) exhibited faster and more extensive interaction with HSA than complex (2). The equilibrium concentration for complex (1) was obtained 6 h after incubation, when about 70% of compound was bound to HSA, 5% was associated with IgG, whereas 25% remained unbound. In contrast, the rate of interaction of complex (2) with HSA was much slower and less extensive and the equilibrium concentration was obtained 24 h after incubation, when about 50% of complex (2) was bound to HSA and 50% remained unbound.

Highlights

Cancer is a noncommunicable disease, which is, due to an increase in life expectancy, the leading cause of morbidity worldwide
Isolated chlorido complex (1) is a neutral Ru(II) species, where positive charge of the metal ion is compensated by negative charges of the ligand pyrithione and chloride anion
The conjoint liquid chromatography (CLC) monolithic column assembled from one affinity convective interaction media (CIM) Protein G and one weak anion-exchange CIM DEAE disks was used for separation of Ru complexes (1) and (2) in human serum

Summary

Introduction

Cancer is a noncommunicable disease, which is, due to an increase in life expectancy, the leading cause of morbidity worldwide. In 2018, there were approximately 18.1 million new cancer cases worldwide. Cancer was the cause of death for 9.6 million people [1]. Chemotherapy is the most common cancer treatment in which platinum-based chemotherapeutics are widely used. Cisplatin, carboplatin and oxaliplatin have been approved by relevant regulatory. Molecules 2020, 25, x FOR PEER REVIEW them, cisplatin, carboplatin and Food oxaliplatin haveAdministration been approved(FDA), by relevant institutions like the United States and Drug for theregulatory treatment institutions of various like the[2,3,4,5].

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