Introduction: The overproduction of hydrogen peroxide (H2O2) leads to severe oxidative stress. Thus, the detoxification of H2O2, that is catalase activity, is important for therapeutic antioxidant. However, only a few studies on water-soluble catalase mimics have been reported. Native catalase has both a metalloporphyrin and an imidazole group in its active center. The imidazole group in histidine residue acts as acid-base catalyst to accelerate dismutation of H2O2. In this study, as a new approach for catalase mimics, we have designed the complex between Mn-porphyrin and biocompatible polymer carboxymethyl poly (1-vinylimidazole) (CM-PVIm). The relative location between Mn-porphyrin and imidazole is considered to be advantageous for catalase activity because it is similar to that of active center of native catalase. Furthermore, we have investigated antioxidative activity of the resulting complex using cells. Results and Discussion: The resulting Mn-porphyrin/CM-PVIm complex exhibited catalase activity (kCAT=(1.5 0.1) 102 M-1s-1), whereas Mn-porphyrin alone did not. We have discovered that the acid-base catalytic effect of imidazole groups leads to induce catalase activity of Mn-porphyrins. The effect of chemical structure of Mn-porphyrins and molecular weight of the polymer on catalase activity, and in vitro preliminary antioxidative activity will be reported.

190 Reduced Platelet Activity under Induced Oxidative Stress Conditions in Gilbert's Syndrome (Benign Hyperbilirubinemia) Avinash R Kundur1, Abishek B Santhakumar1, Andrew C Bulmer1, and Indu Singh1 1Griffith University, Australia

unconjugated hyperbilirubinemia (UCB), have a reduced risk of cardiovascular disease (CVD) due to increased levels of circulating antioxidants (AOX). Oxidative stress induced platelet activation is central to the risk of developing thrombosis and CVD, in pre-thrombotic conditions such as diabetes and obesity. Severe acute exercise in sedentary individuals induces a significant oxidative stress, increasing platelet activation and aggregation, which is related to processes underpinning thrombosis and CVD. Here, we evaluate if elevated levels of UCB in GS can attenuate thrombotic risk factors in a model of exercise induced oxidative stress. Blood samples, pre and post continuous aerobic exercise on a cycle ergometer (1 hour at 70% VO2Max (measure of

matched GS and control subjects. Platelet surface marker expression of CD42 (binds to resting platelets), PAC-1 (binds to GPIIb/IIIa surface receptor on activated platelets) and CD62P (binds to P-selectin released form activated platelets) was assessed using flow cytometry. Platelet aggregation using (ADP, collagen and arachidonic acid (AA)) and biochemistry profile were also evaluated.A significant reduction in the expression of platelet surface marker P-selectin existed in GS versus control, pre and post exercise (P<0.001). Platelet aggregation induced by exogenous agonists AA and collagen were also significantly inhibited pre and post exercise in GS (P<0.01; P<0.04). Furthermore, significantly increased levels of UCB, HDL along with reduced levels of CRP and LDL pre exercise were found in GS when compared with control (P<0.05 all variables).The results from this novel study indicate possible mechanisms whereby elevated bilirubin neutralizes platelet activation under OS conditions in GS. Reduced P-selectin expression in addition to decreased AA and collagen induced platelet aggregation pre and

post exercise signifies the potential of UCB related AOX capacity in inhibiting platelet activation, aggregation and granule release. Reduced platelet activity, inflammation and improved lipid profile can significantly reduce the CVD risk in GS when compared with normal population under resting and OS conditions.

191 Total Serum Thiols Is a Biomarker of Disease Activity in Patients with Erythematosus Systemic Lupus and Nephritis Emerson S Lima1, Giselle K B B Souza 1, Domingos Savio Nunes de Lima1, Luiz Fernando Souza Passos 1, Antonio Luiz Boechat 1, and Pritesh Lalwani1 1Federal University of Amazonas, Brazil Nephritis develops in more than half of the Systemic Lupus Erythematous (SLE) patients. However, lack of reliable, specific biomarkers for nephritis hampers clinical management of patients and impedes development of new therapeutics for disease. The goal of this study was to investigate whether oxidative stress biomarkers in patients with SLE is predictive of renal pathology. Serum biochemical and oxidative stress markers were measured in inactive lupus (n=30), active lupus with (n=31) and without nephritis (n=21) patients and compared to healthy control group (n=11). To assess the predictive performance of biomarkers, Receiver Operating Characteristic (ROC) curves were constructed and cut-offs were used to identify SLE patients with nephritis. We observed increased oxidative stress biomarkers such as TBARs in all SLE patients compared to healthy controls. Among the several biomarkers tested, serum thiols had a significant inverse association with SLE Disease Activity Index (SLEDAI). Interestingly, thiols could aptly differentiate between SLE patients with and without renal pathology, and was not affected by immunosuppressive drug therapy. The decreased thiols in SLE correlated significantly with serum creatinine and C3 serum levels. Retrospective evaluation using serum creatinine or C3 levels in combination with thiols cutoff values from ROC analysis, could positively predict chronicity of renal pathology in lupus. Serum thiols emerge as an inexpensive and reliable indicator of LN, which may not only help in early identification of renal pathology but also aid in the therapeutic management of the disease, in developing countries with resource poor settings.

192 Nanonization of Melanin by Laser-Induced Photo-Fragmentation for Resolving Structure and Improving Antioxidant Activity Yi-Cheng Liu1,2, Jhong-Han Liu3, Sih-Min Chen4, Hsiang-Wei Hsu3, Hoang-Yan Lin1, and Szu-yuan Chen2,3,4 1Graduate Institute of Photonics and Optoelectronics, and Department of Electrical Engineering, National Taiwan University, Taiwan, 2Institute of Atomic and Molecular Sciences, Academia Sinica, Taiwan, 3Department of Physics, National Central University, Taiwan, 4Graduate Institute of Biophysics, National Central University, Taiwan Melanin is a heterogeneous biological polymer widespread in our body tissue and it plays a role in scavenging free radicals and reactive oxygen species (ROS). However, its complete molecular

SFRBM 2014S84

doi: 10.1016/j.freeradbiomed.2014.10.295

doi: 10.1016/j.freeradbiomed.2014.10.297

doi: 10.1016/j.freeradbiomed.2014.10.296