Hemoglobin-catalyzed Oxidation Research Articles

Sequential biowashing-biopile processes for remediation of crude oil contaminated soil in Kuwait.

The application of biological processes for remediation of the aged crude oil-contaminated soil of Kuwait can be an inefficient way, thus, this study developed 20 d-sequential biowashing and biopile processes where the biowashing step uses an enrichment culture of the indigenous soil bacterial community and the biopile step includes hemoglobin-catalyzed oxidation (HCO). The residual total petroleum hydrocarbons (TPH) concentrations and CO2 generation were measured to determine the removal efficiency, and the bacterial community changes were studied to investigate the effect of the sequential processes on the soil indigenous bacterial community. The enrichment culture grown on hemoglobin showed an increased surface activity, and this promoted desorption and emulsification of crude oil from the soil sample in the biowashing step resulting in 75% TPH removal. Potential surfactant-producing bacterial species were observed in the soil sample after biowashing. The HCO in the beginning of the biopile step removed 21% of the residual TPH, and further TPH removal was observed with a longer biopile period. Overall, the sequential biowashing and biopile processes removed 86% TPH. The results show that the developed sequential biowashing and biopile processes can be used to efficiently remediate the aged crude oil-contaminated soil of Kuwait.

EFFECT OF DIETARY SORGHUM DISTILLERY RESIDUE ON HEMATOLOGICAL CHARACTERISTICS OF CULTURED GREY MULLET (MUGIL CEPHALUS)?AN ANIMAL MODEL FOR PRESCREENING ANTIOXIDANT AND BLOOD THINNING ACTIVITIES

The sorghum distillery residue (SDR) has been an underutilized by-product with estimated production of 150 ton/day in Kinmen, Taiwan. The objective of this study was to test for any physiological effects of SDR, thus to utilize it as a nutraceutical feed ingredient in diets for cultured fish. Hot air-dried, wet, and dehulled-wet sorghum distillery residue showed 63%, 90% and 97% inhibition of the hemoglobin-catalyzed oxidation of linoleic acid compared to soybean (13%) and rice bran (78%). The feed formulated with 20% wet or dehulled-wet sorghum distillery residue both showed an antioxidant activity of 68% being higher than the control diet (53%). Feeding these diets to cultured grey mullet for 60 days in summer (temperature ranged 24–30C), resulted in a lower hydroperoxide content in gill tissue, as shown by a chemiluminesence intensity of 1806 or 1409 mV as opposed to 2666 mV for fish fed a control diet. In winter, when the water temperature decreased to 14C, grey mullet fed a diet consisting of 10% dehulled wet sorghum distillery residue had a blood viscosity of 1.9 mPas and a hematocrit value of 33%, in contrast to 3.6 mPas and 41% for control. The blood of the control group started to aggregate in 6 h and showed hemolysis, while the mullet fed dehulled, wet sorghum distillery residue did not show blood aggregation, maintained normal fluidity and erythrocyte membrane integrity. It seems that cultured fish may have the potential as an animal model for prescreening antioxidant and blood thinning effects of food ingredients.

Inhibition of Bleach-Induced Luminol Chemiluminescence

The luminol chemiluminescence presumptive test for blood is based on the mild peroxidase activity of hemoglobin in basic peroxide solution. However, this test is subject to interference by strong oxidants, certain transition metal ions, and true peroxidases. This paper reports methods for reducing the interference caused by hypochlorite-containing bleaches. Amines such as 1,2-diaminoethane react rapidly with hypochlorite without interfering significantly with the hemoglobin-catalyzed oxidation. Thus, addition of 0.1 mol/L 1,2-diaminoethane to a standard luminol-peroxide spray lead to almost complete inhibition of hypochlorite-induced chemiluminescence while satisfactory chemiluminescence was still observed from bloodstains. If time allows, an alternative method for reducing interference from hypochlorite bleach is to wait several days until the bloodstains have dried thoroughly, by which time the hypochlorite will have decomposed.

Added triacylglycerols do not hasten hemoglobin-mediated lipid oxidation in washed minced cod muscle.

Hemoglobin-mediated lipid oxidation in washed, minced cod muscle was related to the triacylglycerol to membrane lipid ratio. The same rapid development of thiobarbituric acid reactive substances (TBARS) and painty odor occurred with and without the presence of up to 15% menhaden oil. Without hemoglobin, development of TBARS and painty odor was slow, despite a high amount of hydroperoxides in samples with oil added (1135 micromol/kg muscle). This suggested that hemoglobin reacted by cleaving preformed hydroperoxides into secondary oxidation products. Nearly doubling the hemoglobin concentration approximately doubled the extent of lipid oxidation with and without added oil. This indicated that hemoglobin was limiting for the oxidation reaction. The noneffect of added oil suggests that membrane lipids and/or preformed membrane lipid hydroperoxides provided sufficient substrate in hemoglobin-catalyzed oxidation of washed minced cod muscle. Fe(2+-)ADP did not induce any oxidation of washed minced cod with/without added oil. Results suggest that lipid oxidation in fatty fish may be more related to the quantity and type of the aqueous pro-oxidant and the membrane lipids than to variations in total fat contents.

Caseins and casein hydrolysates. 2. Antioxidative properties and relevance to lipoxygenase inhibition.

The antioxidant activity of caseins and casein-derived peptides was evaluated by using three free radical producing reactions-the lipoxygenase- and AAPH-catalyzed oxidation of linoleic acid and the hemoglobin-catalyzed oxidation of linoleic acid hydroperoxide. Caseins and casein-derived peptides were able to inhibit enzymatic and nonenzymatic lipid peroxidation, suggesting they were preferred targets for the free radical intermediates. The antioxidative feature was not lost with the dephosphorylation or the proteolysis of the proteins. The fractionation of the tryptic beta-casein digest yielded peptides with antioxidant activity. A structure-function relationship between the amino acid sequence and the antioxidant capacity and effectiveness is proposed. In addition, indirect evidence suggested that the trapping of free radicals by the proteins/peptides was accompanied by the oxidation of proteins/peptides, according to a sequence-specific mechanism.

Oxidative and Hydrolytic Stability of Synthetic Diacyl Glyceryl Ether.

Diacyl glyceryl ethers (DGEs) as present in marine animals were chemically synthesized and then were assessed for their oxidative and hydrolytic stabilities. CDD and CEE were easily autoxidized but not COO. The autoxidation rate of DGEs followed the unsaturation of constituent fatty acids, while alkyl chains did not affect the autoxidation of DGEs. DGEs were susceptible to hemoglobin-catalyzed oxidation as well as triacylglycerols (TGs). However, the oxidation rate of DGE was lower than that of the corresponding TG. The oxidation rate of DGEs was CEE > CDD > COO, and did not always follow the unsaturation of constituent fatty acids. DGEs with EPA and DHA were easily oxidized by lipoxygenase, and the oxida-tion rate of DGEs comprised of DHA was BDD > CDD > SDD. On the other hand, DEGs were hardly hydrolyzed by porcine pancreatic lipase except for COO. These results suggest the possibility that DGE may be related to the oil quality of marine foods during storage.

The Antioxidative Effect of Protein on the Hemoglobin-Catalyzed Oxidation of Sardine Oil in an Emulsion System.

Various proteins prepared from cereals, milk, fish and meats retarded the oxidation of sardine oil emulsion initiated by hemoglobin. Of all proteins examined, zein from corn and gliadin from wheat showed the most remarkable inhibitory effect. The precipitated fraction of an α-lactalbumin hydrolyzate also exhibited good protection. From a comparsion of the antioxidant activities among the different sources of myosins, the most pronounced effect was observed in squid. In addition to myosin itself, coexistent α-tocopherol and phospholipids were also found to protect against oxidation. The protective effect of myosin against the hemoglobin-catalyzed sardine oil oxidation is different than the ferrous ion-catalyzed oxidation.

Oxidation of Dibenzothiophene Catalyzed by Hemoglobin and Other Hemoproteins in Various Aqueous-Organic Media

Biocatalytic oxidation of dibenzothiophene (a model of organic sulfur in coal) with hydrogen peroxide was investigated. It was found that various hemoproteins, both enzymic (e.g., horseradish peroxidase) and nonenzymic (e.g., bovine blood hemoglobin), readily oxidized dibensothiophene to its S-oxide and, to a minor extent, further to its S-dioxide (sulfone). This process catalyzed by hemoglobin (a slaughterhouse waste protein) was studied in a number of monophasic aqueousorganic mixtures. Although hemoglobin was competent as an oxidation catalyst even in nearly dry organic solvents (with protic, acidic solvents being optimal), the highest conversions were observed in predominantly aqueous media. The hemoglobin-catalyzed oxidation of dibenzothiophene at low concentrations of the protein stopped long before all the substrate was oxidized. This phenomenon was caused by inactivation of hemoglobin by hydrogen peroxide that destroyed the heme moiety. The maximal degree of the hemoglobin-catalyzed dibenzothiophene oxidation was predicted, and found, to be strongly dependent on the reaction medium composition.

Hemoglobin-mediated oxidation of the carcinogen 1,2-dimethylhydrazine to methyl radicals

Oxidation of 1,2-dimethylhydrazine (SDMH) catalyzed by hemoglobin is investigated by oxygen consumption studies, ESR spin-trapping experiments, and gas chromatography. Kinetic analysis and the study of the effects of superoxide dismutase, catalase, and azide on reaction rates indicate that SDMH oxidation is primarily dependent on ferric hemoglobin and autoxidatively formed H 2O 2. SDMH oxidation generates both methyl and hydroxyl radicals as ascertained by spin-trapping experiments with α-(4-pyridyl-1-oxide)- N-tert-butylnitrone, 5,5-dimethyl-1-pyrroline- N-oxide, and tert-nitrosobutane. Quantitative estimates indicate that the yield of the methyl radical trapped by α-(4-pyridyl-1-oxide)- N-tert-butylnitrone is about 8% of the consumed oxygen. Analysis of the gaseous products by gas chromatography shows methane formation at a yield 10 times lower than that obtained for the spin-trap methyl adduct. These results are discussed within the context of the spin-trapping technique. The relative efficiencies of oxyhemoglobin in catalyzing SDMH, 2-phenylethylhydrazine, and phenylhydrazine oxidation, defined as V max K M , are estimated as 1, 13, and 386, respectively. The higher efficiency obtained for the monosubstituted derivatives leads us to suggest that hemoglobin-catalyzed oxidation could be a detoxification route for these compounds. By contrast, SDMH oxidation requires a peroxidase-like activity, a fact that may be related to the efficacy and specificity of this carcinogen.

Covalent binding of acetaminophen to mouse hemoglobin. Identification of major and minor adducts formed in vivo and implications for the nature of the arylating metabolites

When hepatotoxic doses of [ring-U- 14C]acetaminophen ([ring-U- 14C]APAP) were administered to mice, radioactivity became bound irreversibly to hemoglobin as well as to proteins in the liver and kidney. The covalent binding to hemoglobin was dose-dependent, and in phenobarbital-pretreated mice occurred to the extent of approximately 8% of the corresponding binding to liver proteins. Degradation of the modified globin by acid hydrolysis yielded 3-cystein- S-yl-4-hydroxyacetanilide as the major radioactive product, accounting for ∼70% of protein-bound drug residues. This finding is consistent with the view that the majority of covalent binding of APAP to proteins is mediated by N-acetyl- p-benzoquinone imine (NAPQI), a reactive metabolite which preferentially arylates cysteinyl thiol residues. However, after administration of [ acetyl- 3H]APAP to mice, it was found that ∼20% of the drug bound to hemoglobin had lost the N-acetyl side-chain, indicating the existence of a second type of APAP-protein adduct. One minor component of the globin hydrolysate was identified as S-(2,5-dihydroxyphenyl)-cysteine, which most likely arises from binding to hemoglobin of p-benzoquinone, a hydrolysis product of NAPQI. The two adducts reported represent the first identified examples of arylating drugs binding to hemoglobin. Experiments on the influence of different cytochrome P-450 inducing agents on the ratio of drug bound to hemoglobin versus hepatic proteins suggested that the reactive metabolites of APAP are formed in the liver and migrate to the erythrocyte, rather than being produced by hemoglobin-catalyzed oxidation of APAP. These findings imply that the reactive metabolites of APAP escape from hepatocytes in some latent forms, which then participate in the arylation of protein thiols in red blood cells and, possibly, at other remote sites.