A method for detecting carbonylated proteins in two-dimensional electrophoresis (2-DE) was developed using biotinylation and avidin-fluorescein isothiocyanate (FITC) affinity staining. The method was used to examine oxidatively modified proteins associated with oxidative stress. Carbonyl formation in proteins was first examined in a model system by subjecting bovine serum albumin (BSA) and ribonuclease A (RNase A) to metal-catalyzed oxidation (MCO). Carbonyl group formation was found to occur at multiple sites along with a small amount of polypeptide chain cleavage. In vivo studies were conducted in yeast cell cultures using 5 mM hydrogen peroxide to induce oxidative stress. Biotinylation of yeast protein was accomplished during extraction at 4 degrees C in a lysis buffer containing 5 mM biotin-hydrazide. Biotin-hydrazide forms a Schiff base with a carbonyl group on an oxidized protein that is subsequently reduced before electrophoresis. Proteins were separated by either 2-DE or sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Biotinylated species were detected using avidin-FITC affinity staining. Detection sensitivity with biotinylated proteins was five times higher than achieved by silver staining. The limit of detection with avidin-FITC staining approached 0.64 pmol of protein-associated carbonyls. Twenty carbonylated proteins were identified in the proteome of yeast following oxidative stress with hydrogen peroxide. Matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) analysis of tryptic peptides was used to identify peptides extracted from gels. Aconitase, heat shock protein SSA1 and SSC1, pyruvate decarboxylase isozyme 1, pyruvate kinase 1, enolase 1 and 2, phosphoglycerate kinase, fructose-bisphosphate aldorase, and glyceraldehyde-3-phosphate dehydrogenase were among the major targets of oxidative stress.

Despite its beneficial role in host defense mechanisms, excessive nitric oxide (NO) production by activated macrophages has been implicated in several inflammatory diseases. To clarify the mechanisms of the anti-inflammatory activities of Sargassum micracanthum, we evaluated whether extracts of S. micracanthum could modulate the production of NO by activated macrophages. S. micracanthum were extracted with 80% EtOH. The extract was then successively partitioned with hexane, CH 2 Cl 2 , EtOAc, BuOH, and water. The results indicate that the hexane and CH 2 Cl 2 fractions of S. micracanthum extract were effective inhibitors of LPS-induced NO and prostaglandin E 2 (PGE 2 ) production in RAW 264.7 cells. The inhibitory effects of the hexane and CH 2 Cl 2 fractions of S. micracanthum were accompanied by dosedependent decreases in the production of iNOS and COX-2 proteins and iNOS and COX-2 mRNA expression. To test the inhibitory effects of S. micracanthum fractions on other cytokines, we also performed ELISA and RT-PCR assays for TNF-, IL-1ß, and IL-6 in LPSstimulated RAW 264.7 macrophage cells. In these assays, the hexane and CH 2 Cl 2 fractions of S. micracanthum produced dose-dependent decreases in the production and mRNA expression of TNF-, IL-1ß, and IL-6. To test the potential application of S. micracanthum extract as a cosmetic material, we also performed MTT assays on human dermal fibroblast cells, as well as primary skin irritation tests. In these assays, S. micracanthum extracts did not induce any adverse reactions. Based on these results, we suggest that S. micracanthum extracts may be considered potential anti-inflammatory candidates for topical application.

In the present study, triphlorethol-A, a phlorotannin, was isolated from Ecklonia cava and its antioxidant properties were investigated. Triphlorethol-A was found to scavenge intracellular reactive oxygen species (ROS) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, and thus prevented lipid peroxidation. The radical scavenging activity of triphlorethol-A protected the Chinese hamster lung fibroblast (V79-4) cells exposed to hydrogen peroxide (H2O2) against cell death, via the activation of ERK protein. Furthermore, triphlorethol-A reduced the apoptotic cells formation induced by H2O2. Triphlorethol-A increased the activities of cellular antioxidant enzymes like, superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx). Hence, from the present study, it is suggestive that triphlorethol-A protects V79-4 cells against H2O2 damage by enhancing the cellular antioxidative activity.

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