Prophylactic effect of a-linolenic acid and a-eleostearic acid against MeHg induced oxidative stress, DNA damage and structural changes in RBC membrane Moumita Pal, M. Ghosh ⇑ Oil Technology Section, Dept. of Chemical Technology, University College of Science & Technology, University of Calcutta, Kolkata 700 009, India article info Article history: Received 9 February 2012 Accepted 23 May 2012 Available online 7 June 2012 Keywords: a-Linolenic acid a-Eleostearic acid DNA damage Oxidative stress Comet Assay abstract The present study was undertaken to evaluate under in vivo condition the effects of a-linolenic acid and a-eleostearic acid against methyl mercury (MeHg) induced oxidative stress. Male albino rats were divided into six groups. Group 1 was under normal control and Group 2 was treated with methyl mercury chloride (MeHgCl; 5 mg/kg BW/day). Groups 3, 4, 5 and 6 were orally treated with different doses of the two fatty acids (0.5% and 1.0% of total lipid given for each kind of linolenic acid isomer) along with MeHgCl (5 mg/kg BW). Comet assay of blood lymphocytes showed that administration of a-linolenic acid reduced DNA damage significantly (P < 0.05). Results also showed that activity of antioxidant enzymes of plasma and brain tissue and total antioxidant capacity in plasma decreased significantly due to oxidative stress generated by MeHgCl. Administration in higher dose of both kind of linolenic acid restored all the activities of the antioxidant enzymes and also reduced lipid peroxidation and increased total antioxidant capacity in plasma. Both kinds of linolenic acid successfully maintained the RBC membrane integrity which was totally disrupted and became flat due to MeHgCl stress. a-Linolenic acid was more efficient antioxidant than a-eleostearic acid against oxidative DNA damage. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction A rise in the industrial activity has gradually redistributed many toxic metals from the earth’s crust to the environment, increasing human exposure to the toxic metals. Among them mercury (Hg); especially its organic form, methylmercury (MeHg), is the most malignant. MeHg exposure has been associated with oxidative stress in vivo (Ascher and Syversen, 2005; Crespo-Lo ´ pez et al., 2007; Franco et al., 2007), in which mercury induces the genera- tion of reactive oxygen species (ROS) (Sarafian, 1999) and alters the antioxidant defense system of cells (Kobal et al., 2007) by inhibiting their sulphydryl groups [-SH] or selenol groups [-SeH] (Mori et al., 2007; Farina et al., 2011). MeHg may also induce DNA damage by produce ROS (Jin et al., 2008) and/or inhibiting the DNA repair system (Cebulska-Wasilewska et al., 2005). It is well recognized that the oxidative stress is directly or indirectly associated with various diseases and aging (Liu and Mori, 1999). The brain is one of the most sensitive tissues to the oxidative stress because of its high contents of polyunsaturated fatty acid and neurotransmitters. Thus the oxidative stress induced neuronal damage and cell death plays critical role in pathogenesis of neuro- degenerative disorders such as Alzheimer (Nunomura et al., 2006; Kidd, 2008) and Parkinson (Ebadi and Sharma, 2006; Danielson and Andersen, 2008) diseases. Again serum contains many different antioxidants that are important to general health and serum TAC has been considered as a suitable parameter for evaluating overall antioxidant status resulting from antioxidant intake, as well as production and consumption in response to oxidative stress (Nemec et al., 2000). In a previous study, antioxidant status in human plasma correlated negatively with the plasma concentra- tion of Hg which in turn was positively correlated to the number of amalgam fillings in human subjects (Pizzichini et al., 2001). A number of studies established that oils containing polyunsaturated fatty acids (PUFA) play an active role in reducing oxidative stress (Watkins et al., 2007; Hassan et al., 2010; Dhar et al., 1999, 2007); as in case of PUFA, lipid peroxidation can be commenced by ROS production and other mechanisms that results in abstrac- tion of an electron from PUFA. 0278-6915/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.fct.2012.05.038 Abbreviations: Hg, mercury; MeHg, methylmercury; MeHgCl, methylmercury chloride; CAT, catalase; PUFA, polyunsaturated fatty acid; ALA, a-linolenic acid; AEA, a-eleostearic acid; CLA, conjugated linoleic acid; EPA, ecosapentaenoic acid; DHA, docosahexaenoic acid; GSH, reduced glutathione; GPx, glutathione peroxidase; MDA, malondialdehyde; RBC, red blood cell; ROS, reactive oxygen species; SH-groups, sulphydryl groups; SOD, superoxide dismutase; TBA, 2-thiobarbituric acid; TCA, trichloro acetic acid; DNA, deoxyribo nucleuc acid; TAC, total antioxidant capacity; -SeH, selenol; -SH, thiol; FRAP, Ferric Reducing Ability of Plasma; AFM, atomic florescence microscope; EGM, erythrocyte ghost membrane. ⇑ Corresponding author. Address: Dept. of Chemical Technology, University College of Science & Technology, University of Calcutta, 92, A.P.C. Road, Kolkata 700 009, India. Tel.: +91 33 23520050x276; fax: +91 33 2351 9755. E-mail address: mahuag@gmail.com (M. Ghosh). Food and Chemical Toxicology 50 (2012) 2811–2818 Contents lists available at SciVerse ScienceDirect Food and Chemical Toxicology journal homepage: www.elsevier.com/locate/foodchemtox