Oxidative damage and redox metal homeostasis loss are two contributing factors in brain aging and widely distributed neurodegenerative diseases. Oxidative species in company with excessive amounts of intracellular free iron result in Fenton-type reaction with subsequent production of highly reactive hydroxyl radicals which initiate peroxidation of biomolecules and further formation of non-degradable toxic pigments called lipofuscin that amasses in long-lived postmitotic cells such as neurons. Dietary flavonoid baicalein can counteract the detrimental consequences through exertion of a multiplicity of protective actions within the brain including direct ROS scavenging activity and iron chelation. In this study, we evaluated the neuroprotective effects of baicalein in menadione (superoxide radical generator)-treated SK-N-MC neuroblastoma cell line. Our results showed that treatment of cells with menadione led to lipofuscin formation due to elevated intracellular iron contents and accumulation of oxidative products such as MDA and PCO. Also, menadione caused apoptotic cell death in SK-N-MC cells. However, pretreatment with baicalein (40 μM) reversed the harmful effects by chelating free iron and preventing biomolecules peroxidations. Moreover, baicalein prevented cell death through modulation of key molecules in apoptotic pathways including suppression of Bax and caspase-9 activities and induction of bcl2 expression. Key structural features such as presence of hydroxyl groups and iron-binding motifs in baicalein make it the appropriate candidate in antioxidant-based therapy in age-related neurodegenerative diseases.
 L. Rossi, S. Mazzitelli, M. Arciello, C. R. Capo and G. Rotilio, “Benefits from Dietary Polyphenols for Brain Aging and Alzheimer’s Disease,” Neurochemical Research, Vol. 33, No. 12, 2008, pp. 2390-2400. doi:10.1007/s11064-008-9696-7
 J. L. Martindale and N. J. Holbrook, “Cellular Response to Oxidative Stress: Signaling for Suicide and Survival,” Journal of Cell Physiology, Vol. 192, No. 1, 2002, pp. 1-15. doi:10.1002/jcp.10119
 D. Harman, “Free Radical Theory of Aging: Effect of Free Radical Reaction Inhibitors on the Mortality Rate Male LAF Mice,” Journal of Gerontology, Vol. 23, No. 4, 1968, pp. 476-482. doi:10.1093/geronj/23.4.476
 T. Jung, N. Bader and T. Grune, “Lipofuscin: Formation, Distribution and Metabolic Consequences,” Annals of the New York Academy of Science, Vol. 1119, 2007, pp. 97-111. doi:10.1196/annals.1404.008
 U. T. Brunk and A. Terman, “Lipofuscin: Mechanisms of Age-Related Accumulation and Influence on Cell Function,” Free Radical Biology and Medicine, Vol. 33, No. 5, 2002, pp. 611-619. doi:10.1016/S0891-5849(02)00959-0
 T. Kurz, A. Terman and U. T. Brunk, “Autophagy, Aging and Apoptosis: The Role of Oxidative Stress and Lysosomal Iron,” Archieves of Biochemistry and Biophysics, Vol. 462, No. 2, 2007, pp. 220-230. doi:10.1016/j.abb.2007.01.013
 A. Terman and U. T. Brunk, “Lipofuscin: Mechanisms of Formation and Increase with Age,” Acta Pathologica, Microbiologica et Immunologica Scandinavica, Vol. 106, No. 2, 1998, pp. 265-276. doi:10.1111/j.1699-0463.1998.tb01346.x
 M. Giorgio, M. Trinei, E. Migliaccio and P. G. Pelicci, “Hydrogen Peroxide: A Metabolic By-Product or a Common Mediator of Ageing Signals?” Nature Reviews: Molecular Cell Biology, Vol. 8, No. 9, 2007, pp. 722-728. doi:10.1038/nrm2240
 D. Vauzour, K. Vafeiadou, A. Rodriguez-Mateas, C. Rendeiro and J. P. E. Spencer, “The Neuroprotective Potential of Flavonoids: A Multiplicity of Effects,” Genes and Nutrition, Vol. 3, No. 3-4, 2008, pp. 115-126. doi:10.1007/s12263-008-0091-4
 D. Vauzour, “Dietary Polyphenols as Modulators of Brain Functions: Biological Actions and Molecular Mechanisms Underlying Their Beneficial Effects,” Oxidative Medicine and Cellular Longevity, Vol. 2012, Article ID: 914273, pp. 1-16.
 E. Middleton, C. Kandaswami and T. C. Theoharides, “The Effects of Plant Flavonoids on Mammalian Cells: Implications for Inflammation, Heart Disease and Cancer,” Pharmacological Reviews, Vol. 52, No. 4, 2000, pp. 673-751.
 D. Atmani, N. Chaher, D. Atmani, M. Berboucha, N. Debbache and H. Boudaoud, “Flavonoids in Human Health: From Structure to Biological Activity,” Current Nutrition and Food Science, Vol. 5, No. 4, 2009, pp. 225-237. doi:10.2174/157340109790218049
 Z. S. Markovic, M. Dimitric-Markovic, D. Milenkovic and N. Filipovic, “Structural and Electronic Features of Baicalein and Its Radicals,” Monatsh Chemistry, Vol. 142, No. 2, 2011, pp. 145-152. doi:10.1007/s00706-010-0426-x
 O. Firuzi, A. Lacanna, R. Petrucci, G. Marrosu and L. Saso, “Evaluation of the Antioxidant Activity of Flavonoids by ‘Ferric Reducing Antioxidant Power’ Assay and Cyclic Voltammetry,” Biochemica et Biophysica Acta, Vol. 1721, No. 1-3, 2005, pp. 174-184. doi:10.1016/j.bbagen.2004.11.001
 S. H. Zhang, J. Ye and G. Dong, “Neuroprotective Effects of Baicalein on Hydrogen Peroxide-Mediated Oxidative Stress and Mitochondrial Dysfunction in PC12 Cells,” Journal of Molecular Neuroscience, Vol. 40, No. 3, 2010, pp. 311-320. doi:10.1007/s12031-009-9285-5
 C. A. Perez, Y. Wei and M. Guo, “Iron-Binding and Anti-Fenton Properties of Baicalein and Baicalein,” Journal of Inorganic Biochemistry, Vol. 103, No. 3, 2009, pp. 326-332. doi:10.1016/j.jinorgbio.2008.11.003
 C. P. LeBel, H. Ischiropoulos and S. C. Bondy, “Evaluation of the Probe 2', 7'-Dichlorofluorescein as an Indicator of Reactive Oxygen Species Formation and Oxidative Stress,” Chemical Research in Toxicology, Vo. 5, No. 2, 1992, pp. 227-231. doi:10.1021/tx00026a012
 S. Emig, D. Schmalz, M. Shakibaei and K. Buchner, “The Nuclear Pore Complex Protein p62 Is One of Several Sialic Acid-Containing Proteins of the Nuclear Envelope,” Journal of Biological Chemistry, Vol. 270, No. 23, 1995, pp. 13787-13793. doi:10.1074/jbc.270.23.13787
 Y. Mochizuki, M. K. Park, T. Mori and S. Kawashima, “The Difference in Autofluorescence Features of Lipofuscin between Brain and Adrenal,” Zoological Science, Vol. 12, No. 3, 1995, pp. 283-288. doi:10.2108/zsj.12.283
 J. Riemer, H. H. Hoepken, H. Czerwinska, S. R. Robinson and R. Dringen, “Colorimetric Ferrozine-Based Assay for the Quantitation of Iron in Cultured Cells,” Analytical Biochemistry, Vol. 33, No. 2, 2004, pp. 370-375. doi:10.1016/j.ab.2004.03.049
 M. J. Czaja, H. Liu and Y. Wong, “Oxidant-Induced Hepatocytes Injury from Menadione is Regulated by ERK and AP-1 Signaling,” Hepatology, Vol. 37, No. 6, 2003, pp. 1405-1413. doi:10.1053/jhep.2003.50233
 M. Moslehi, A. Meshkini and R. Yazdanparast, “Flavonoid Baicalein Modulates H2O2-Induced Mitogen-Activated Protein Kinases Activation and Cell Death in SK-N-MC Cells,” Cellular and Molecular Neurobiology, Vol. 32, No. 4, 2012, pp. 549-560. doi:10.1007/s10571-011-9795-x
 R. R. Crichton, S. Wilmet, R. Legssyer and R. J. Ward, “Molecular and Cellular Mechanisms of Iron Homeostasis and Toxicity in Mammalian Cells,” Journal of Inorganic Biochemistry, Vol. 91, No. 1, 2002, pp. 9-18. doi:10.1016/S0162-0134(02)00461-0
 J. E. Chipuk and D. R. Green, “How Do Bcl2 Proteins Induce Mitochondrial Outer Membrane Permeabilization?” Trends in Cell Biology, Vol. 18, No. 4, 2008, pp. 157-164. doi:10.1016/j.tcb.2008.01.007
 M. R. D’Andrea, R. G. Nagele, N. A. Gumula, P. A. Reiser, D. A. Polkovitch, B. M. Hertzog and P. Andrade-Gordon, “Lipofuscin and Abeta42 Exhibit Distinct Distribution Patterns in Normal and Alzheimer’s Disease Brain,” Neuroscience Letters, Vol. 323, No. 1, 2002, pp. 45-49. doi:10.1016/S0304-3940(01)02444-2
 L. M. Drach, J. Bohl and H. H. Goebel, “The Lipofuscin Content of Nerve Cells of the Inferior Olivary Nucleus in Alzheimer’s Disease,” Dementia, Vol. 5, No. 5, 1994, pp. 234-239. doi:10.1073/pnas.97.2.611
 H. H. F. Refsgaard, L. Tsai and E. R. Stadtman, “Modifications of Proteins by Polyunsaturated Fatty Acid Peroxidation Products,” Proceedings of the National Academy of Sciences of the United States of America, Vol. 97, No. 2, 2000, pp. 611-616.
 K. L. Seanor, J. V. Cross, S. M. Nguyen, M. Yan and D. J. Templeton, “Reactive Quinines Differentially Regulates SAPK/JNK and p38/mHOG Stress Kinases,” Antioxidants and Redox Signaling, Vol. 5, No. 1, 2003, pp. 103-113.
 K. Keyer and J. A. Imlay, “Superoxide Accelerates DNA Damage by Elevating Free-Iron Levels,” Proceedings of the National Academy of Sciences of the United States of America, Vol. 93, No. 24, 1996, pp. 13635-13640. doi:10.1073/pnas.93.24.13635