Glutamoyl diester of the dietary polyphenol curcumin offers improved protection against peroxynitrite-mediated nitrosative stress and damage of brain mitochondria in vitro: implications for Parkinson’s disease Rajeswara Babu Mythri • G. Harish • Shiv Kumar Dubey • Krishna Misra • M. M. Srinivas Bharath Received: 9 July 2010 / Accepted: 6 October 2010 / Published online: 23 October 2010 Ó Springer Science+Business Media, LLC. 2010 Abstract Oxidative/nitrosative stress plays a crucial role in Parkinson’s disease (PD) by triggering mitochondrial dysfunction. Nitrosative stress is mediated by reactive species such as peroxynitrite (PN) which could damage biomolecules thereby impinging on the cellular machinery. We observed that PN (0–1000 lM) inhibited brain mito- chondrial complex I (CI) activity in a dose-dependent manner with concomitant tyrosine nitration of proteins. We also observed that exposure to PN at low concentrations (62.5–125 lM) significantly decreased the mitochondrial membrane potential and affected the mitochondrial integ- rity at higher doses (500–750 lM) as indicated by the mitochondrial swelling experiment. Therefore, it could be surmised that compounds that prevent such mitochondrial damage might have therapeutic value in neurological conditions such as PD. We previously showed that curcu- min could detoxify PN and protect against CI inhibition and protein nitration. However, the therapeutic potential of curcumin is constrained by limited bioavailability. To address this issue and obtain improved antioxidants, three bioconjugates of curcumin (Di-demethylenated piperoyl, di-valinoyl and di-glutamoyl esters) were generated and tested against PN-mediated nitrosative stress and mito- chondrial damage. We found that among the bioconjugates, the glutamoyl diester of curcumin showed improved pro- tection against PN-dependent CI inhibition and protein nitration compared to other conjugates. Di-glutamoyl cur- cumin protected dopaminergic neurons against 1-methyl-4- phenylpyridinium (MPP ? )-mediated neuronal death. These effects were improved compared to curcumin alone suggesting that di-glutamoyl curcumin could be a better neuroprotective agent in neurodegenerative diseases such as PD. Keywords Neurodegeneration Á Nitrosative stress Á Curcumin Á Mitochondria Á Protein nitration Á Bioconjugates Abbreviations PD Parkinson’s disease SN Substantia nigra NO Nitric oxide PN Peroxynitrite CI Mitochondrial complex I 3-NT 3-nitrotyrosine RNS Reactive nitrogen species GSH Glutathione PTP Permeability transition pore DW m Mitochondrial membrane potential JC-1 5,5 0 ,6,6 0 -Tetrachloro-1,1 0 3,3 0 -tetra ethyl benzimidazolyl carbocyanine iodide D1 Di-demethylenated piperoyl curcumin R. B. Mythri Á G. Harish Á M. M. Srinivas Bharath (&) Department of Neurochemistry, National Institute of Mental Health and Neurosciences, # 2900, Hosur Road, Bangalore 560029, India e-mail: bharath@nimhans.kar.nic.in; thathachar@rediffmail.com S. K. Dubey Center for Biotechnology, University of Allahabad, Allahabad, India K. Misra Indo-Russian Center for Biotechnology, Indian Institute of Information Technology-Allahabad, Jhalwa Campus, Allahabad 211002, India Present Address: S. K. Dubey Division of Hematology & Oncology, University of Michigan Cancer Center, Ann Arbor, MI 48109, USA 123 Mol Cell Biochem (2011) 347:135–143 DOI 10.1007/s11010-010-0621-4