48 Introduction Cell metabolism continuously produces reactive oxygen species (ROS) as by-products of respiration and other metabolic activities (Azbill et al., 1997; Halliwell, 1994; Park et al., 2004). Tese reactive species (RS) can normally be handled by nonenzymatic and enzymatic antioxidant defenses (Rodriguez-Martinez et al., 2000; Santamaria et al., 2003). However, the imbalance between the anti- oxidant system and the overproduction of ROS has been associated with a variety of human diseases, such as atherosclerosis, cancer, and neurodegenerative diseases (Lohr, 1991; Ames et al., 1993; Johnson, 2004). It is known that oxidative damage of biological molecules, such as lipoproteins, proteins, and nucleotides by ROS, can be associated with the development of diseases and degener- ative processes, including infammation, brain ischemia, mutagenesis, cancer, dementia, and physiological aging (Ren et al., 2001a). Moreover, oxidative stress also plays a central role in liver pathologies (Vitaglione et al., 2004). In view of the apparent role of RS in several acute and chronic human diseases, the development of new compounds that improve the antioxidant systems is of interest (Urso and Clarkson, 2003; Nogueira et al., 2004; Halliwell, 2006). Reports have shown that selenium-containing organic molecules are generally more potent antioxidants than “classical” antioxidants, and this fact serves as an impetus for an increased interest in the rational design of synthetic RESEARCH ARTICLE Fe(II) and sodium nitroprusside induce oxidative stress: a comparative study of diphenyl diselenide and diphenyl ditelluride with their napthyl analog Mohammad Ibrahim 1,2 , Waseem Hassan 1,3 , Javed Anwar 1 , Cristina W. Nogueira 1 , and Joao Batista Teixeira Rocha 1 1 Departamento de Química, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil, 2 Department of Chemistry, Abdul Wali Khan University Mardan (AWKUM) KPK, Mardan, Pakistan, and 3 Institute of Chemical Sciences, University of Peshawar, KPK, Peshawar, Pakistan Abstract Here, we compare the infuence of molecular structural modifcations of diphenyl diselenide (DPDS) and diphenyl ditelluride (DPDT) with their naphthalene analogs, 1-dinapthyl diselenide (1-NapSe)2, 2-dinapthyl diselenide (2-NapSe)2, 1-dinapthyl distelluride (1-NapTe)2, and 2-dinapthyl ditelluride (2-NapTe)2. Fe(II)-induced hepatic thiobarbituric acid reactive species (TBARS) was in the order [(2-NapTe)2] > [(2-NapSe)2] > [(DPDS)] > [(1-NapSe)2] > [(1-NapTe)2]> [(DPDT)]. For sodium nitroprusside (SNP)-induced hepatic TBARS, the order was [(2-NapTe)2] > [(DPDT)] > [(1-NapSe)2] > [(2-NapSe)2] > [(1-NapTe)2] > [(DPDS)]. For Fe(II) and SNP-induced renal TBARS, the orders were [(2-NapTe)2] > [(1-NapTe)2] = [(DPDT)] > [(1-NapSe)2] > [(2-NapSe)2] > [(DPDS)] and [(2-NapTe)2] > [(1-NapTe)2] > [(1-NapSe)2] > [(2-NapSe)2] > [(DPDS)] > [(DPDS)], respectively. The present investigation shows that DPDS was less potent and the change in the organic moiety from an aryl to napthyl group dramatically changed the potency of diselenides. These results suggest that minor changes in the organic moiety of aromatic diselenides can profoundly modify their antioxidant properties. In view of the fact that the pharmacological properties of organochalcogens are linked, at least in part, to their antioxidant properties, it becomes important to explore the pharmacological properties of dinaphtyl diselenides and ditellurides. Keywords: Antioxidants, organochalcogenides, lipid peroxidation, iron, sodium nitroprusside Address for Correspondence: Mohammad Ibrahim, Departamento de Química, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, 97105-900, Santa Maria, RS, Brazil; Fax: 55-55-3220-8978; E-mail: Ibrahim189@yahoo.com (Received 14 December 2010; revised 25 January 2011; accepted 28 March 2011) Drug and Chemical Toxicology, 2012; 35(1): 48–56 © 2012 Informa Healthcare USA, Inc. ISSN 0148-0545 print/ISSN 1525-6014 online DOI: 10.3109/01480545.2011.588711