Comparative studies on drug binding to the purified and pharmaceutical-grade human serum albumins: Bridging between basic research and clinical applications of albumin Mohammad Reza Ashrafi-Kooshk a , Farangis Ebrahimi a , Samira Ranjbar a , Sirous Ghobadi b , Nastaran Moradi a, c , Reza Khodarahmi a, d, * a Medical Biology Research Center, Kermanshah University of Medical Sciences, Kermanshah, Iran b Department of Biology, Faculty of Science, Razi University, Kermanshah, Iran c Students' Research Committee, Kermanshah University of Medical Sciences, Kermanshah, Iran d Department of Pharmacognosy and Biotechnology, Faculty of Pharmacy, Kermanshah University of Medical Sciences, Kermanshah, Iran article info Article history: Received 19 November 2014 Received in revised form 4 July 2015 Accepted 9 July 2015 Available online xxx Keywords: Albumin Infusion Drug binding constant Esterase activity abstract Human serum albumin (HSA), the most abundant protein in blood plasma, is a monomeric multidomain protein that possesses an extraordinary capacity for binding, so that serves as a circulating depot for endogenous and exogenous compounds. During the heat sterilization process, the structure of pharmaceutical-grade HSA may change and some of its activities may be lost. In this study, to provide deeper insight on this issue, we investigated drug-binding and some physicochemical properties of purified albumin (PA) and pharmaceutical-grade albumin (PGA) using two known drugs (indomethacin and ibuprofen). PGA displayed significantly lower drug binding capacity compared to PA. Analysis of the quenching and thermodynamic parameters indicated that intermolecular interactions between the drugs and the proteins are different from each other. Surface hydrophobicity as well as the stability of PGA decreased compared to PA, also surface hydrophobicity of PA and PGA increased upon drugs binding. Also, kinetic analysis of pseudo-esterase activities indicated that K m and V max parameters for PGA enzymatic activity are more and less than those of PA, respectively. This in vitro study demonstrates that the specific drug binding of PGA is significantly reduced. Such studies can act as connecting bridge between basic research discoveries and clinical applications. © 2015 The International Alliance for Biological Standardization. Published by Elsevier Ltd. All rights reserved. 1. Introduction The name “albumin” originates from the Latin word “albus” (white) or “albumen” (whiteness) [1]. Albumin is the most abun- dant plasma protein, with a normal concentration in the range of 35e45 g/L. Structurally; it comprises a single peptide chain with 585 amino acids held in three homologous domains by 17 disulfide bonds, forming a heart-shaped molecule (Fig. 1A) [2,3]. Albumin which is produced in the liver has several physiological functions including: contributing to the colloid osmotic pressure and facili- tates the transport, distribution, and metabolism of many endogenous substances, such as fatty acids, amino acids, bile acids/ salts, and hormones, and exogenous substances such as drugs [4]. Moreover, for many hormones and vitamins, albumin acts not only as a carrier, but also as a reservoir and for a number of endogenous and exogenous toxins are sequestered by albumin and, in that way, rendered harmless in the circulation. Human albumin solutions (pharmaceutical-grade albumins) were developed in the United States during the Second World War [5]. The traditional method for its isolation, first described by Cohn and col- leagues in 1946 [6]. Some manufacturers employed chromatographic processing of plasma, a process that provides both a purer product and a higher yield. However, during the heat sterilization process [7], oxidative quality and some of physiological activities and hence the drug binding characteristics of the protein may changed [8,9]. The drug-binding properties of human serum albumin (HSA) have been extensively studied. The binding of drugs to plasma * Corresponding author. Medical Biology Research Center, Kermanshah Univer- sity of Medical Sciences, Kermanshah, Iran. E-mail addresses: rkhodarahmi@mbrc.ac.ir, rkhodarahmi@kums.ac.ir (R. Khodarahmi). Contents lists available at ScienceDirect Biologicals journal homepage: www.elsevier.com/locate/biologicals http://dx.doi.org/10.1016/j.biologicals.2015.07.003 1045-1056/© 2015 The International Alliance for Biological Standardization. Published by Elsevier Ltd. All rights reserved. Biologicals xxx (2015) 1e11 Please cite this article in press as: Ashrafi-Kooshk MR, et al., Comparative studies on drug binding to the purified and pharmaceutical-grade human serum albumins: Bridging between basic research and clinical applications of albumin, Biologicals (2015), http://dx.doi.org/10.1016/ j.biologicals.2015.07.003