Research Article Modulation of Erythrocyte Plasma Membrane Redox System Activity by Curcumin Prabhakar Singh, 1 Rajesh Kumar Kesharwani, 2 Krishna Misra, 2 and Syed Ibrahim Rizvi 1 1 Department of Biochemistry, University of Allahabad, Allahabad 211002, India 2 Division of Applied Science & Indo-Russian Center For Biotechnology (IRCB), Indian Institute of Information Technology, Allahabad 211012, India Correspondence should be addressed to Syed Ibrahim Rizvi; sirizvi@gmail.com Received 17 October 2015; Revised 30 December 2015; Accepted 31 December 2015 Academic Editor: David L. Daleke Copyright © 2016 Prabhakar Singh et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Plasma membrane redox system (PMRS) is an electron transport chain system ubiquitously present throughout all cell types. It transfers electron from intracellular substrates to extracellular acceptors for regulation of redox status. Curcumin, isolated from Curcuma longa, has modulatory efects on cellular physiology due to its membrane interaction ability and antioxidant potential. Te present study investigates the efect of curcumin on PMRS activity of erythrocytes isolated from Wistar rats in vitro and in vivo and validated through an in silico docking simulation study using Molegro Virtual Docker (MVD). Efects of curcumin were also evaluated on level of glutathione (GSH) and the oxidant potential of plasma measured in terms of plasma ferric equivalent oxidative potentials (PFEOP). Results show that curcumin signifcantly ( < 0.01) downregulated the PMRS activity in a dose-dependent manner. Molecular docking results suggest that curcumin interacts with amino acids at the active site cavity of cytochrome  5 reductase, a key constituent of PMRS. Curcumin also increased the GSH level in erythrocytes and plasma while simultaneously decreasing the oxidant potential (PFEOP) of plasma. Altered PMRS activity and redox status are associated with the pathophysiology of several health complications including aging and diabetes; hence, the above fnding may explain part of the role of curcumin in health benefcial efects. 1. Introduction Plasma membrane redox system (PMRS) is an electron trans- port chain system ubiquitously present in all cell types that transfers electrons from intracellular substrates to extracellu- lar acceptors maintaining redox homeostasis for a successful cell physiology [1]. PMRS has been suggested to play a vital role in reducing oxidative stress; this property has been hypothesized to control the rate of aging, lifespan, and many pathological conditions associated with increased oxidative stress [2, 3]. Proposed functions of PMRS include mainte- nance of redox state in proteins, stimulation of cell growth, reduction of lipid hydroperoxides, recycling of -tocopherol, reduction of ferric ion prior to iron uptake by a transferring- independent pathway, and the maintenance of the extracellu- lar concentration of ascorbic acid [2–6]. In addition, PMRS also regulates physiological functions like cell metabolism, cellular growth, activity of ion channels, and cell death against changes in redox potential [7, 8]. PMRS activity also plays an important role afecting recycling of extracellular ascorbic acid, thus preventing its depletion [9]. PMRS donates elec- trons to extracellular ascorbate free radical (AFR) derived from intracellular redox molecules like glutathione (GSH), L- ascorbic acid, nicotinamide adenine dinucleotide (NADH), and other reduced equivalents [9, 10]. Cellular physiology is modulated by oxidative stress mediated changes in redox status specially reduced GSH [11]. GSH is a hydrophilic antioxidant with nucleophilic thiol group and has been reported to participate in regulation of gene expression, protein synthesis, cell proliferation, sig- nal transduction, cytokine production, apoptosis, immune response, and protein glutathionylation [11]. GSH protects the cell and biomolecules against oxidative injury, thus providing a powerful antioxidant defense mechanism against reactive Hindawi Publishing Corporation Biochemistry Research International Volume 2016, Article ID 6025245, 8 pages http://dx.doi.org/10.1155/2016/6025245