• Journal of Plant Biotechnology
• /
• v.41 no.4
• /
• pp.169-179
• /
• 2014

Intracellular antioxidants include low molecular weight scavengers of oxidizing species, and enzymes which degrade superoxide and hydroperoxides. Such antioxidants systems prevent oxidative damage to cellular component by scavenging free radicals and activated oxygen species. Hydrophobic scavengers are found in cell membrane where they interrupt chain reactions of lipid peroxidation. The three major lipophilic antioxidant classes for human health are carotenoids, vitamin E and coenzyme Q10. The biofortification of staple crops with these lipid soluble antioxidants is an attractive strategy to increase the nutritional quality of human food. Here, we have summarized the biosynthetic pathways of three lipid soluble antioxidants in plants and current status of genetic engineered plants for elevated levels of each lipophilic antioxidant.

• Molecules and Cells
• /
• v.21 no.2
• /
• pp.276-283
• /
• 2006

The potent environmental contaminant, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), induces thymus atrophy in experimental animals. However, its mechanism of action is not fully understood. To gain insight into its immunosuppressive effect, Balb/c mice were intraperitoneally injected with TCDD ($30{\mu}g/kg$ body weight) and genes regulated by TCDD were identified using cDNA arrays [Park and Lee (2002)]. One of the regulated genes was that for plasma glutathione peroxidase (pGPx). Upon TCDD injection, pGPx mRNA levels in the thymus increased, in parallel with increases in GPx activity and the frequency of anti-human pGPx antibody-reactive cells. pGPX mRNA levels were also moderately up-regulated in the testis and spleen. This is the first report that a particular isotype of the glutathione peroxidase family is regulated by TCDD at both mRNA and protein levels. pGPx is expressed in various tissues in contact with body fluids, and detoxifies hydrogen peroxides and lipid hydroperoxides. It will be of interest to assess the role of pGPx in TCDD-induced thymic atrophy.

• Applied Biological Chemistry
• /
• v.47 no.1
• /
• pp.72-77
• /
• 2004

The purpose of this research was to determine the effect of phenol compounds from green tea leaves and surfactant micelles on lipid oxidation in com oil-in-water emulsion (O/W). The concentration of phenol and surfactant in continuous phase of the O/W with exceed Brij 700 and phenol compounds was measured. The particle size of O/W with phenol (100 ppm) increased with increasing added exceed surfactant $(0{\sim}2.0%)$ and the concentration of surfactant and phenols in the continuous phase higher than these of control. Lipid oxidation rates, as determined by the formation of lipid hydroperoxides and headspace hexanal, in the O/W emulsions containing phenol compounds (100 ppm) and exceed surfactant $(0{\sim}2.0%)$ decreased with increasing concentration of exceed surfactant. The ability of the phenol compounds and exceed surfactant to inhibit hydroperoxide and headspace hexanal producing as lipid oxidation in O/W was BHT>procyanidin B3-3-O-gallate> (+)-gallocatechin > (+)-catechin and 2% > 1 % > 0% of exceed surfactant. These results indicate that phenol compounds and exceed surfactant could alter the physical location of hydroperoxide in O/W.

• Proceedings of the Korean Society of Applied Pharmacology
• /
• 2001.11a
• /
• pp.94-94
• /
• 2001

Prostaglandin endoperoxide H synthase (PGHS) catalyzes the committed step in prostaglandins and thromboxane A$_2$-- oxygenation of arachidonic acid to the hydroperoxy endoperoxide PGG$_2$, followed by reduction PGG$_2$to the alcohol PGH$_2$. The two reactions by PGHS -- cyclooxygenase and peroxidase -- occur at distinct but structurally and functionally interconnected sites. The peroxidase reaction occurs at a heme-containing active site located near the protein surface. The cyclooxygenase reaction occurs in a hydrophobic channel in the core of the enzyme. Initially a peroxide reacts with the heme group, yielding Compound I and an alcohol derived from the oxidizing peroxide. Compound I next undergoes an intramolecular reduction by a single electron traveling from Tyr385 along the peptide chain to the proximal heme ligand, His388, and finally to the heme group. Following the binding of arachidonic acid, Tyr385 tyrosyl radical initiates the cyclooxygenase reaction by abstracting the 13-pro(5) hydrogen atom to give an arachidonyl radical, which sequentially reacts with two molecules of oxygen to yield PGG$_2$. In order to characterize PGHS peroxidase active site, we examined various lipid peroxides with purified recombinant ovine PGHS proteins and determined the rate constants. The results have shown that twenty-carbon unsaturated fatty acid hydroperoxides have similar efficiency in peroxidation by PGHS, irrespective of either the location of hydroperoxy group or the number of double bonds. It was also confirmed by the subsequent study with PGHS peroxidase active site mutants.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.25 no.6
• /
• pp.501-510
• /
• 1992

Lipid prooxidants in sardine skin was characterized. Prooxidants in the sardine skin extract with 0.05M phosphate buffer was purified by successive chromatography on Sephadex G-200, DEAE-Sephadex A-50 and CM-Sephadex A-50. Prooxidants of sardine skin exist mainly in the intermediate molecular weight fractions. Observations of the thermounstability and optimum pH(pH 7.0) suggest that the major prooxidants are enzymes and hemoproteins. They can oxidize well both free and esterified linoleic acid and form conjugated hydroperoxides. From these results, the major prooxidants in sardine skin are assumed to be lipoxygenase-like enzymes.

• BMB Reports
• /
• v.40 no.3
• /
• pp.412-418
• /
• 2007

Phospholipid hydroperoxide glutathione peroxidase (PHGPx) is an unique antioxidant enzyme that directly reduces lipid hydroperoxides in biomembranes. In the present work, the entire encoding region for Oryza sativa PHGPx was expressed in Escherichia coli M15, and the purified fusion protein showed a single band with 21.0 kD and pI = 8.5 on SDS- and IFE-PAGE, respectively. Judging from CD and fluorescence spectroscopy, this protein is considered to have a well-ordered structure with 12.2% $\alpha$-helix, 30.7%$\beta$-sheet, 18.5% $\delta$-turn, and 38.5% random coil. The optimum pH and temperature of the enzyme activity were pH 9.3 and 27$^{\circ}C$. The enzyme exhibited the highest affinity and catalytical efficiency to phospholipid hydroperoxide employing GSH or Trx as electron donor. Moreover, the protein displayed higher GSH-dependent activity towards t-Butyl-OOH and $H_2O_2$. These results show that OsPHGPx is an enzyme with broad specificity for hydroperoxide substrates and yielded significant insight into the physicochemical properties and the dynamics of OsPHGPx.

• Korean Journal of Food Science and Technology
• /
• v.22 no.3
• /
• pp.332-336
• /
• 1990

Antioxidative characteristics of freeze dried soybean sauce powder (SSP) on the oxidation reaction of linoleic acid mixture(LA) were evaluated by the determinations of peroxide formation, synergistic property, hydrogen donation and lipoxygenase activity. SSP was found to possess a considerable potentiality of antioxidant activity on the formation of hydroperoxides in the LA oxidation reaction system at $50^{\circ}C$ for 144hrs. This antioxidative effect was increased by the concentration from 0.02% to 0.5% of SSP in the reaction system. Under the condition of presence of ferric chloride (10 ppm) in the reaction system. appreciable effect of SSP on the synergistic antioxidation were observed. On the other hand, hydrogen donation property of SSP onto ${\alpha},\;{\alpha}'-diphenyl-{\beta}-picrylhydrazyl$ was found and inhibitory ability of SSP on LA oxidation was also shown in the reaction system of lipoxygenase-catalized oxidation.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.36 no.9
• /
• pp.1182-1187
• /
• 2007

Changes in composition of fatty acids and free amino acids in three differently dried Alaska pollack (sun dried, naturally cyclic freeze-thaw dried, and 1-year-aged cyclic freeze-thaw dried Alaska pollack (Hwangtae)) were investigated to correlate them with browning reactions in drying and aging Alaska pollack. Major fatty acids of the sun dried Alaska pollack were palmitic acid, oleic acid, and eicosapentaenoic acid (EPA), and those in the Hwangtae were palmitic acid, oleic acid, and gondoic acid. Hwangtae showed the lowest amount of polyunsaturated fatty acids among the three types of dried Alaska pollack. Free amino acids content of sun dried Alaska pollack was higher than that of the cyclic freeze-thaw dried Alaska pollack and Hwangtae. Lesser amount of histidine in Hwangtae (0.02%) than that in the cyclic freeze-thaw dried Alaska pollack (0.087%) may indicate the degradation of histidine due to the browning reaction in aging the cyclic freeze-thaw dried Alaska pollack. Significant changes in compositions of fatty acids and free amino acids among the dried products revealed the browning reaction resulted from carbonyl compounds produced by decomposition of lipid hydroperoxides and free amino acids. Aging the cyclic freeze-thaw dried Alaska pollack for a year contributed to the development of browning.

• Korean Journal of Food Science and Technology
• /
• v.33 no.1
• /
• pp.1-6
• /
• 2001

Emulsion products with water soluble protein were exposed under light at $5^{\circ}C$ for 8 days. Peroxide value (POV) was increased significantly at the bigining of storage and 2-thiobarbituric acid (TBA) value also increased until 4 days of storage with increase of the production of carbonyl compounds, suggesting that the condition was reacted different from that of the lipid autoxidation. The reaction was similar to the flavor reversion that usually produced from the bigining of soybean oil oxidation. The reason might be the meat pigment, myoglobin, oxidation and it would be due to the singlet oxygen rather than superoxide anion. When the light was excluded general pattern was similar but the production of oxidation products were smaller than that when the sample was exposed under light. The effect of the singlet oxygen was also smaller which meant that the singlet oxygen produced during emulsion process may affect on the flavor reversion at the bigining of storage. The POV of the emulsion without water soluble protein increase gradually by storage and the results indicated that the degradation rate of the peroxides were lower than the sample with water soluble protein. Especially after 4 days of storage, production of carbonyl compounds were decreased. During storage it would be possible to produce the singlet oxygen and the sensitizer from the plants that can be produced during decoloration of soybean oil may be responsible for it. When the light was excluded the production of oxidation products were reduced at the begining of storage and the effect of quencher also was not detected. Therefore the results indicated that the light can accelerate the lipid oxidation.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.22 no.2
• /
• pp.132-137
• /
• 1993

These studies were carried out to investigate the effects of ascorbate and $\alpha$-tocopherol administration on the biochemical parameters of liver function and hydroperoxidation in liver of chronically ethanol-treated rats. Forty healthy Sprague-Dawley (SD) rats weighing about 120g were used for this experiment and divided into the following 5 groups: control group (CON), ethanol control group (ECON), ascorbate treated group (EASC), $\alpha$-tocopherol treated group (ETOC) and ascorbate.$\alpha$-tocopherol mixture treated group(EASC + ETOC). Ethanol was administered orally by 5ml per kg, body weight per day for 8weeks. Antioxidants treated groups were administered orally by 5mg per kg body weight per day in saline solution for 3 weeks. Lipid hydroperoxides were analyzed by using chemiluminescense-high performance liquid chromatography (CL-HPLC) method phosphatidylcholine hydroperoxide value (PCOOH) in liver tissues. Ethanol treatment significantly (p<0.05) resulted in an increase in GPT and GOT activities and liver hydroperoxide values comparing with the untreated control, while administration of $\alpha$-tocopherol and ascorbate+$\alpha$-tocopherol to the chronically ethanol-treated rats significantly (p<0.001) decreased GPT and GOT activities and liver hydroperoxide value. These results indicate that dietary $\alpha$-tocopherol and $\alpha$-tocopherol combined with ascorbate administration may inhibit the formation of liver lipid hydroperoxidation in vivo and were very effective in recovering the liver function in chronically ethanol-treated rats.