PP06The role of α-tocopherol in mediating anti-proliferativeeffects through mitochondrial targeting in HepG2 cells

Ruth Banks a, Marc Birringer c, Regina Brigelius-Flohè d,Damon Lowes b, John R. Speakman a, Colin Selman e

a Integrative Environmental Physiology, Institute of Biological andEnvironmental Sciences, University of Aberdeen, UKb Medicine and Therapeutics, Institute of Medical Sciences, Universityof Aberdeen, UKc Department of Nutritional, Food and Consumer Studies, Universityof Applied Sciences, Fulda, Germanyd Biochemistry of Micronutrients Department, German Instituteof Human Nutrition, Potsdam- Rehbruecke, Germanye College of Medical, Veterinary and Life Sciences, Universityof Glasgow, UKE-mail address: r.banks@abdn.ac.uk (R. Banks)

Vitamin E comprises a family of eight steroisomeric compounds,including the tocopherols and tocotrienols (α-, β-, δ-, γ-). α-tocopherol has gained considerable interest extending beyond itsantioxidant properties; previously we showed that long-term α-tocopherol supplementation in C57BL/6 mice induced a transientincrease in xenobiotic metabolism, which was associated with a 15%increase in median lifespan. Furthermore, α-tocopherol metabolites,in particular the long-chain α-tocopheryl acid (α-13’-COOH), wererecently shown to possess anti-cancer activity in vitro, highlightingthe potential association of vitamin E metabolism with longevity inmammals. In the present study, we have used the HepG2 cell line asan in vitro model to further understand this growth-preventativeresponse and to elucidate the mechanism through which α-tocopherol may act to promote lifespan extension. Key mitochon-drial signaling pathways governing energy metabolism and biogen-esis were examined in response to ‘physiological’ doses (2 μM) and‘pharmacological’ doses (20 μM) of α-13’-COOH. Exposure to phy-siological levels of α-13’-COOH increased oxygen consumption,proton leak and caused subsequent depletion of the cellular reservecapacity in HepG2 cells. Elevated SIRT-1 and PGC-1α levels impliedadaptive energy metabolism and increased UCP-3 and ANT proteinlevels suggested cellular adaptation to increased substrate oxidationand/or sensitization to apoptosis. Pharmacological doses of α-13’-COOH significantly increased the rate of ROS production and causedcomplete loss of cellular mitochondrial reserve capacity. Further-more, the presence of high levels of tyrosine residue nitration andconsiderably reduced cell viability could indicate damage to bioe-nergetic components. Cell cycle arrest was indicated by increasedlevels of p-P5346 and P21 levels in association with reduced cyclinD1 levels. These results further clarify the anti-proliferative role ofα-tocopherol and highlight the significance of its metabolism as apotential mechanism of longevity assurance in mammals.

http://dx.doi.org/10.1016/j.freeradbiomed.2013.08.015

PP07Characterization and Kinetic Studies of New Hetero-aryl Nitrones as Spin Traps

G.Barriga González a, E. Chamorro a, C. Olea-Azar b,E. Norambuena c, H. Cerecetto d, M. González d, W. Porcal d

a Departamento de Ciencias Químicas, Facultad de Ciencias Exactas,Universidad Andres Bello, Santiago, Chile

b Departamento de Química Inorgánica y Analítica, Facultad deCiencias Químicas y Farmacéuticas, Universidad de Chile, Santiago,Chilec Departamento de Química, Facultad de Ciencias Básicas, Universi-dad Metropolitana de Ciencias de la Educación, Santiago, Chiled Departamento de Química Orgánica, Facultad de Química - Facultadde Ciencias, Universidad de la Republica, Montevideo, UruguayE-mail address: gbarriga@ciq.uchile.cl (G.Barrig. González)

Although nitrones constitute a structural group highly used intrapping of short-life-free radicals some of the currently availablenitrones, used as “Spin Traps” (ST), display problems of solubility inaqueous media, selectivity and bioavailability. There is an extendedvariety of STs designed in the last 15-20 years as DMPO’s or PBN’smodifications, for instance EMPO, DEPMPO, POBN, SPBN. In spite ofthese modifications, STs have some limitations mainly related to theshort half-life of their spin adducts which does not allow a betterstudy of free radicals with short lives and specific phenomena. In thiswork we present three novel nitrones belonging to two structurallydifferent heterocyclic families, these new nitrones have longer spinadducts half-lives than the currently used ST. The first studied nitrone,NT1, presents a spin adduct with a half-life for the �OH radical near to2-hours and 3.4-times better trapping ability than DMPO according tothe competition studies. The second nitrone, NT2, is 4.7 times betterthan DMPO in the competition studies, and finally the third nitrone,NT3, is 5.0 times better than DMPO in the competition studies. Thesenew heteroaryl nitrones are able for trapping free radicals centered onO, N, C and S atoms and are soluble in aqueous media/acetonitrilemixture. These new nitrones have shown a good capacity for trappingfree radicals in different biological media.

AcknowledgementsGermán Barriga González thanks financial support by FONDE-

CYT grant Nº 3120241. Eduardo Chamorro thanks financial supportby FONDECYT N1 1100277 and UNAB NUCLEO DI-219-12/N.

http://dx.doi.org/10.1016/j.freeradbiomed.2013.08.015

PP08Plasma Malondialdehyde and Erythrocyte SuperoxideDismutase Levels in Obesity

Eda Becer, Güldal Mehmetçik

Near East University, Faculty of Pharmacy, Department of Biochem-istry, Nicosia, Cyprus

Obesity may be a state of chronic oxidative stress. Hyperglycemia,elevated plasma lipid levels and inadequate antioxidant defensespromotes oxidative stress in obesity. The aim of this study was todetermine the relationship between anthropometric parameters,plasma lipid levels and markers of oxidant/antioxidant status in obesesubjects compared with non-obese subjects and its relationship withobesity-linked insulin resistance. The study included 110 obese and 90non-obese subjects. Oxidative stress were assessed by measuring theconcentration of plasma malondialdehyde (MDA). The cytoprotecticenzyme, erythrocyte superoxide dismutase (SOD) activities weremeasured as biological markers of antioxidant status. We also eval-uated antropometric parameters and plasma lipid levels. The obesesubjects had significantly higher plasma MDA levels than non-obesesubjects. Erythrocyte SOD activities significantly lower in obese groupcompared ton non-obese group. Non-obese subjects had significantlylower HOMA-IR compared to obese subjects. Plasma MDA levels were

Abstract / Free Radical Biology and Medicine 65 (2013) S23–S56 S25