Study design:In vitro studies using isolated guinea pig spinal cord. Objectives: To develop an alternative model using isolated guinea pig spinal cord, which can be used to screen antioxidants for in vivo SCI treatment. Setting: Department of Basic Medical Sciences, Purdue University, West Lafayette, Indiana, USA. Methods: The compression injury was induced by a constant-displacement of 5-s compression of spinal cord using a modi®ed forceps possessing a spacer. Reactive oxygen species (ROS) were evaluated using three distinct methods:¯uorescence microscopy, lipid peroxidation assay, and¯ow cytometry. Results: The injury-mediated ROS increases are comparable with other in vivo studies and consistent with our previous observation using a similar injury model and measured with electrophysiological and anatomical technique. Further, ascorbic acid, hypothermia, or the combination of both signi®cantly suppressed superoxide and lipid peroxidation. The combination treatment was the most e ective when compared with ascorbic acid or hypothermia alone. Conclusion: This in vitro model has the advantage of replicating some of the in vivo conditions while gaining the ability to control the experimental conditions. This in vitro model is suitable to study the mechanisms of ROS generation and degradation and can also be used to critically evaluate the e ective suppressor of ROS in the contents of spinal cord traumatic injury.
Various vegetables were investigated for antioxidant activities in two assays, namely, inhibition of lysis of erythrocytes induced by peroxyl radicals and inhibition of lipid peroxidation. The lotus (Nelumbo nucifera Gaertn) rhizome showed the strongest antioxidant activity in both assays. The crude extract (L) of lotus rhizome was chromatographed on a macroporous adsorption resin named NKA. The resulting three fractions were designated L1, L2 and L3, respectively. L2 showed the highest antioxidant activity and was further fractionated by Sephadex LH-20 chromatography. Eight fractions were obtained and named from L2a to L2h, respectively. L2c showed the strongest activity in inhibiting hemolysis of erythrocytes and was further purified by high-performance liquid chromatography. L2c-3 was identified as tryptophan. Its inhibitory concentration of 50% (IC(50)) value in inhibiting hemolysis of erythrocytes was 156.3 microg/ml (i.e. 765.4 microM). This is the first report on isolation of tryptophan from the aqueous extract of lotus rhizome and demonstration of their antioxidant activities.
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