Free Radical Reaction Products Research Articles

Assessment of naphazoline effect on erythrocyte superoxide dismutase activity in rats under experimental modeling of acute radiation sickness

Aim to assess the activity of superoxide dismutase in erythrocytes of rats after a single intramuscular injection of naphazoline in radiofrequency dose and in experimental simulation of acute radiation sickness.
 Material and methods. The activity of erythrocytes superoxide dismutase (SOD) after single intramuscular injection of nafazoline in experimental modeling of acute radiation sickness was investigated. The pharmacological properties and mechanisms of radioprotective action of nafazoline were clarified based on the dynamics of activity of erythrocytes SOD in intact and irradiated animals with the dose of 7,4 Gy.
 Results. The superoxide dismutase activity was found to increase significantly 60 min after single intramuscular administration of nafazolin at a dose of 5 mg/kg. Under experimental conditions of acute radiation disease modeling, a decrease in superoxide dismutase activity was observed within the first hour after exposure, evidencing the direct involvement of the antioxidant system components in the inactivation of free-radical reaction products.
 Conclusion. The radioprotective properties of naphazoline may be due not only to reduction of oxygen delivery to the cells of radiosensitive tissues and inhibition of their metabolism by effect on 2-adreno- and imidazoline receptors, but also by activation of antioxidant system links.

Assessment of lipophilic fluorescence products in β-amyloid-induced cognitive decline: A parallel track in hippocampus, CSF, plasma and erythrocytes.

Oxidative stress implicates in Alzheimer's disease (AD) pathophysiology, and associates with the creation of end products of free radical reactions, are known as lipophilic fluorescent products (LFPs). This study aimed to evaluate the probable parallel alterations in the spectral properties of the LFPs in the hippocampus tissues, cerebrospinal fluid (CSF), plasma, and erythrocytes during AD model induction by intra-cerebroventricular (ICV) amyloid β-protein fragment 25-35 (Aβ) injection. Male rats received an intra-ICV injection of Aβ. Hippocampus, CSF, plasma, and erythrocytes were harvested at 5, 14, and 21days after Aβ injection. The fluorescent intensity of LFPs was assessed by spectrofluorimetry using synchronous fluorescence spectra 25 (SYN 25) and 50 (SYN 50) in the range of 250-500nm. Hippocampal tissue malondialdehyde (MDA) and superoxide dismutase (SOD) were also measured. Cognitive alterations were evaluated using Morris water maze (MWM) test. The parallel significant rise in the fluorescence intensity of LFPs was detected in the hippocampus, CSF, plasma, and erythrocytes, 14, and 21days after ICV-Aβ injection. These alterations were found in both types of synchronous spectra 25, and 50, and were coincided with hippocampal cognitive decline, the MDA rise, and decrease of SOD activity. There was a positive correlation between hippocampus homogenate, and plasma or CSF rise in fluorescence intensity. Data showed that the Aβ increased hippocampal MDA, and decreased SOD activity, led to a higher rate of oxidative products and subsequently resulted in an increase in LFPs fluorescence intensity during the development of cognitive decline. LFPs' alterations reflect a comprehensive view of tissue redox status. The fluorescence properties of LFPs indicate their composition, which may pave the way to trace the different pathological states.

Chemiluminescence Detection in the Study of Free-Radical Reactions. Part 1.

The present review, consisting of two parts, considers the application of the chemiluminescence detection method in evaluating free radical reactions in biological model systems. The first part presents a classification of experimental biological model systems. Evidence favoring the use of chemiluminescence detection in the study of free radical reactions, along with similar methods of registering electromagnetic radiation as electron paramagnetic resonance, spectrophotometry, detection of infrared radiation (IR spectrometry), and chemical methods for assessing the end products of free radical reactions, is shown. Chemiluminescence accompanying free radical reactions involving lipids has been the extensively studied reaction. These reactions are one of the key causes of cell death by either apoptosis (activation of the cytochrome c complex with cardiolipin) or ferroptosis (induced by free ferrous ions). The concept of chemiluminescence quantum yield is also discussed in this article. The second part, which is to be published in the next issue, analyzes the application of chemiluminescence detection using luminescent additives that are called activators, a.k.a. chemiluminescence enhancers, and enhance the emission through the triplet–singlet transfer of electron excitation energy from radical reaction products, followed by light emission with a high quantum yield.

Dynamic Solid-State NMR Experiments Reveal Structural Changes for a Methyl Silicate Nanostructure on Deuterium Substitution

Structural characterizations of three different solid–gas reaction products, recently obtained from abraded solid-state silicate free radicals reacting with two isotopically enriched methane gases, 13CH4 and CD4 (a possible sink for methane on MARS) and with 13CO2, are derived from various dynamic solid-state NMR experiments. These include cross-polarization/depolarization zero-cross times (ZCTs), variable temperature (VT) NMR to study 3-site jump CH3/CD3 activation energies (Ea), and 13CO2/13CH3 molecular species as a spy to determine the approximate diameters for the channel structures for some of these structures. Literature Ea data indicate that l-alanine and 4-CH3-phenanthrene exhibit the highest known Ea values (= 20–22.6 kJ/mol) for CH3 3-site jump motions. The ZCTs for these two compounds are 120 and 162 μs, respectively, indicative of the high Ea values for CH3/CD3 groups. Determination of Ea for 4-CD3-phenanthrene by low-temperature 2H MAS NMR experiments supplemented the previously reported liquid-state Ea value (Ea = 21 kJ/mol) for 4-CH3-phenanthrene. Finally, such experiments also revealed the structural difference for the free-radical reaction products with 13CH4 and CD4, i.e, a change from helical to chain structure.

The effect of antioxidants on the formation of free radicals and primary products of the peroxidase reaction

Antioxidants suppress the formation of radicals in peroxidase processes. The chemiluminescence kinetic curves in the horseradish peroxidase/luminol/H2O2 system have been compared with those obtained from the mathematical model of the reaction. It was shown that the effect of trolox, ascorbate, and mexidol is a result of the reaction of the luminol radical with the inhibitor molecule (rate constants, 1.0·1010, 9.0·109, and 2.3·105 mol–1 min–1, respectively). The antiradical action of quercetin has been described by eight reactions that were based on the assumption of two reaction centers in the molecule, each reacting with two radicals. The hypothesis that the antioxidant molecule captures the enzyme intermediate radicals in peroxidase cycle, rather than the radical of the reaction product was not confirmed because the calculated curves differed from the experimental point positions. Apparently, the formation of radicals in the presence of peroxidases in living cells and the subsequent events, such as apoptosis, may be prevented not only by the inhibition of an enzyme but also by antioxidants that capture free-radical reaction products

Oxidative stress and angiogenesis in primary hyperparathyroidism.

SummaryBackgroundThe inappropriate elevation of parathormone (PTH), which regulates the process of angiogenesis in parathyroid tissue, causes the changes of activity of enzymes responsible for the removal of free radicals. Parathyroidectomy (PTX) in patients with primary hyperparathyroidism (PHPT) lowers the level of PTH and leads to the reduction of risk of cardiovascular and all-cause mortality by normalization of the antioxidant status. Therefore, the aims of the study were to assess the activity of antioxidant enzymes and free radical reaction products in patients after parathyroidectomy, and to evaluate the correlation between the systemic oxidative stress and angiogenic parameters.Materials and methodsPatients with PHPT treated surgically were enrolled into the study. Total antioxidant capacity (TAC), total oxidative status (TOS), oxidative stress index (OSI), superoxide dismutase (SOD), ceruloplasmin (CER), lipid hydroperoxides (LHP) and malondialdehyde (MDA) were measured before and after parathyroidectomy. The immunohistological expression of angiogenic factors in parathyroid specimens was assessed by the BrightVision method from ImmunoLogic using murine monoclonal anti-human: anti-VEGF, anti-CD31 and anti-CD106 antibodies.ResultsThe significant increase of TAC, CER, reduction of TOS, MDA, SOD, especially for cytoplasmic form, and significant decrease of OSI, LHP were observed after PTX. There was no significant correlation between changes of oxidative stress markers and angiogenic parameters: VEGF, CD-31, CD-106 in parathyroid tissue. The correlation level was low and medium.ConclusionsParathyroidectomy causes down-regulation of lipid peroxidation processes and leads to reduction of oxidative stress in patients with PHPT. The decrease in the OSI is the results of down-regulation of oxidative stress in the postoperative period. The change of the antioxidant status has no impact on angiogenesis processes in parathyroid tissue.

Serum superoxide dismutase activity in acute and chronic paediatric liver diseases

Background and study aimsMeasuring serum superoxide dismutase (SOD) levels in infants and children having acute or chronic liver disease of different aetiologies, and correlating these levels with disease aetiology in an attempt to clarify the role of SOD as an antioxidant in these diseases. Patients and methodsWe prospectively enrolled 58 infants and children and divided them into four groups: Group I, 24 patients with surgical cholestasis; group II, 11 patients with medical cholestasis; group III, nine patients with autoimmune chronic hepatitis; and group IV, 14 patients with viral hepatitis. Forty healthy age- and sex-matched children served as controls. Serum SOD activity was measured in all patients and controls using spectrophotometry. ResultsThe level of SOD showed a statistically significant increase in patients with medical cholestasis compared to healthy controls (p<0.0001). SOD activity of other groups showed no significant difference compared to controls. ConclusionsSignificantly increased serum SOD in infants and children with medical cholestasis is probably consequent to its increase in liver tissue in response to the liberation of reactive oxygen species. This suggests that products of free radical reactions might be involved in the pathogenesis and/or progression of medical cholestasis, and that SOD might attempt to minimise the liver injury.

Detection of key enzymes, free radical reaction products and activated signaling molecules as biomarkers of cell damage induced by benzo[a]pyrene in human keratinocytes

Benzo[a]pyrene (BaP) is a known carcinogenic and cell damaging agent. The underlying cell damaging pathomechanisms have not been totally revealed. Especially BaP-related induction of oxidative and nitrosative stress has not been previously investigated in detail. The presented study investigated these effects in order to elucidate the pathomechanism and as well to identify potential biological markers that may indicate a BaP exposure. Human immortalized keratinocytes (HaCaT cells) were exposed to BaP (1μM) for either 5min or 6h, respectively. BaP-induced cellular damage was evaluated by immunocytochemistry analysis of multiple signaling cascades (e.g. apoptosis, Akt, MAPK, NOS, nitrotyrosine and 8-isoprostane formation), detection of nitrosative stress using diaminofluorescein (DAF-FM) and oxidative stress using 3′ -(p-aminophenyl)fluorescein (APF).Our results show that BaP exposure significantly enhanced NO and ROS productions in HaCaT cells. BaP led to eNOS-phosphorylation at Ser1177, Thr495 and Ser116 residues. Using specific inhibitors, we found that the Erk1/2 pathways seemed to have strong impact on eNOS phosphorylation. In addition, BaP-induced apoptosis was observed by caspase-3 activation and PARP cleavage.Our results suggest that BaP mediates its toxic effect in keratinocytes through oxidative and nitrosative stress which is accompanied by complex changes of eNOS phosphorylation and changes of Akt and MAPK pathways.

Interconnection of Antitoxic and Antioxidant Systems of the Organism under the Action of Natural Low Molecular Complex – Fungidol

The influence of the natural complex of low molecular weight compounds (fungidol) on antitoxic and antioxidant systems in animals was investigated. It was demonstrated that the introduction to the experimental animals of fungidol in doses a 0.05 ml per 100 g of body weight increases antioxidant enzymes activity in serum and liver, decreases the content of lipids hydroperoxides and other products of free radical reactions. The components of fungidol antioxidant activity correlated with the stability of membranes of erythrocytes in these animals. In the experimental model the toxic effect of copper sulfate was investigated. The increase in the activity of prooxidant system induced by fungidol correlated with its antitoxic effect.

Free Radicals in Chemical Biology: from Chemical Behavior to Biomarker Development

The involvement of free radicals in life sciences has constantly increased with time and has been connected to several physiological and pathological processes. This subject embraces diverse scientific areas, spanning from physical, biological and bioorganic chemistry to biology and medicine, with applications to the amelioration of quality of life, health and aging. Multidisciplinary skills are required for the full investigation of the many facets of radical processes in the biological environment and chemical knowledge plays a crucial role in unveiling basic processes and mechanisms. We developed a chemical biology approach able to connect free radical chemical reactivity with biological processes, providing information on the mechanistic pathways and products. The core of this approach is the design of biomimetic models to study biomolecule behavior (lipids, nucleic acids and proteins) in aqueous systems, obtaining insights of the reaction pathways as well as building up molecular libraries of the free radical reaction products. This context can be successfully used for biomarker discovery and examples are provided with two classes of compounds: mono-trans isomers of cholesteryl esters, which are synthesized and used as references for detection in human plasma, and purine 5',8-cyclo-2'-deoxyribonucleosides, prepared and used as reference in the protocol for detection of such lesions in DNA samples, after ionizing radiations or obtained from different health conditions.

Free Radicals in Chemical Biology: from Chemical Behavior to Biomarker Development

The involvement of free radicals in life sciences has constantly increased with time and has been connected to several physiological and pathological processes. This subject embraces diverse scientific areas, spanning from physical, biological and bioorganic chemistry to biology and medicine, with applications to the amelioration of quality of life, health and aging. Multidisciplinary skills are required for the full investigation of the many facets of radical processes in the biological environment and chemical knowledge plays a crucial role in unveiling basic processes and mechanisms. We developed a chemical biology approach able to connect free radical chemical reactivity with biological processes, providing information on the mechanistic pathways and products. The core of this approach is the design of biomimetic models to study biomolecule behavior (lipids, nucleic acids and proteins) in aqueous systems, obtaining insights of the reaction pathways as well as building up molecular libraries of the free radical reaction products. This context can be successfully used for biomarker discovery and examples are provided with two classes of compounds: mono-trans isomers of cholesteryl esters, which are synthesized and used as references for detection in human plasma, and purine 5',8-cyclo-2'-deoxyribonucleosides, prepared and used as reference in the protocol for detection of such lesions in DNA samples, after ionizing radiations or obtained from different health conditions.

Free radical reaction products and antioxidant capacity in beating heart coronary artery surgery compared to conventional bypass

Oxygen-derived free radicals are important agents of tissue injury during ischemia and reperfusion. The aim of this study was to investigate changes in protein and lipid oxidation and antioxidant status in beating heart coronary artery surgery and conventional bypass and to compare oxidative stress parameters between the two bypass methods. Serum lipid hydroperoxide, nitric oxide, protein carbonyl, nitrotyrosine, vitamin E, and β-carotene levels and total antioxidant capacity were measured in blood of 30 patients undergoing beating heart coronary artery surgery (OPCAB, off-pump coronary artery bypass grafting) and 12 patients undergoing conventional bypass (CABG, on-pump coronary artery bypass grafting). In the OPCAB group, nitric oxide and nitrotyrosine levels decreased after reperfusion. Similarly, β-carotene level and total antioxidant capacity also decreased after anesthesia and reperfusion. In the CABG group, nitric oxide and nitrotyrosine levels decreased after ischemia and reperfusion. However, protein carbonyl levels elevated after ischemia and reperfusion. Vitamin E, β-carotene, and total antioxidant capacity decreased after ischemia and reperfusion. Significantly decreased nitration and impaired antioxidant status were seen after reperfusion in both groups. Moreover, elevated protein carbonyls were found in the CABG group. The off-pump procedure is associated with lower degree of oxidative stress than on-pump coronary surgery.

Preliminary report: Effect of cobaltous ion on cerebral vasospasm in a rabbit subarachnoid hemorrhage model

Experimental studies have suggested what the primary role is of free radical products in the development of vasospasm. It has been suggested that the degradation products of hemolysis trigger free radical reactions leading to lipid peroxidation is subarachnoid hemorrhage (SAH). Therefore, Fe2+, a degradation product of hemoglobin, seems to be the most important substance in the pathogenesis of vasospasm. Cobaltous ion was shown to be a powerful inhibitor of lipid peroxidation in biological membrane. Eleven rabbits were anesthetized and received 5 ml of autologous arterial blood into the cisterna magna. Group 1 (n=6) received 0.1 mg/kg cobalt solution intratecally via the cisterna magna simultaneously with blood. Group 2 (n =5) underwent sham operation as a control group. Forty-eight hours later the rabbits were deeply anesthetized and the brainstem was quickly removed and put under the operating microscope to measure the basilar artery diameter. Afterwards, the upper part of the brainstem was used for lipid peroxidation measurement and the lower part for the histopathological examination. Significant vasospasm was observed in four and moderate vasospasm in one rabbit of group 2; mild vasospasm was seen in five rabbits and moderate vasospasm was seen in one rabbit of group 1. There was no vasospasm in the control group. A statistically significant increase in the levels of lipid peroxide was found in the brainstem of group 2. These data demonstrate that cobaltous ion represents a promising therapeutic tool in vasospasm after SAH.

Polyethylene Glycol–Superoxide Dismutase Prevents Endotoxin-induced Cardiac Dysfunction

Sepsis produces significant mitochondrial and contractile dysfunction in the heart, but the role of superoxide-derived free radicals in the genesis of these abnormalities is not completely understood. The study was designed to test the hypothesis that superoxide scavenger administration prevents endotoxin-induced cardiac mitochondrial and contractile dysfunction. Four groups of rats were studied, and animals were injected with either saline, endotoxin, endotoxin plus polyethylene glycol-adsorbed-superoxide dismutase (PEG-SOD; a free-radical scavenger), or PEG-SOD alone. Animals were killed 48 h after injections. We then measured cardiac mitochondrial generation of reactive oxygen species (ROS), formation of free-radical reaction products (protein carbonyls, lipid aldehydes, nitrotyrosine), mitochondrial function, and cardiac contractile function. Endotoxin elicited increases in cardiac mitochondrial ROS formation (p < 0.001), increases in cardiac levels of free-radical reaction products, reductions in mitochondrial ATP generation (p < 0.001), and decrements in cardiac pressure-generating capacity (p < 0.01). Administration of PEG-SOD blocked formation of free-radical reaction products, prevented mitochondrial dysfunction, and preserved cardiac contractility. For example, mitochondrial ATP generation was 923 +/- 50, 392 +/- 32, 753 +/- 25, and 763 +/- 36 nmol/min/mg, respectively, for control, endotoxin, endotoxin + PEG-SOD, and PEG-SOD groups (p < 0.001). In addition, cardiac systolic pressure generation at a diastolic pressure of 15 mm Hg averaged 110 +/- 11, 66 +/- 7, 129 +/- 10 and 124 +/- 5 mm Hg, respectively, for control, endotoxin, endotoxin + PEG-SOD, and PEG-SOD groups (p < 0.01). These data indicate that superoxide-derived oxidants play a critical role in the development of cardiac mitochondrial and contractile dysfunction in endotoxin-induced sepsis.

Evaluation of tetrahydrobiopterin (BH4) as a potential therapeutic agent to treat erectile dysfunction

Nitric oxide (NO)-mediated smooth muscle relaxation causes penile erections. The endothelial NO synthase (eNOS) coenzyme tetrahydrobiopterin (BH4) converts eNOS-mediated catalytic activity from oxygen radical to NO production, improving endothelial function and vascular smooth muscle relaxation. Using quantitative immunohistochemistry, 8-isoprostane and nitrotyrosine concentrations were compared in cavernosal tissue from 17 potent and 7 impotent men, and the effect of single oral doses of BH4 on penile rigidity and tumescence was investigated. The pharmacodynamic effect of single oral doses of BH4 on penile rigidity and tumescence was investigated in a randomized, placebo-controlled, double-blind cross-over fashion in 18 patients with erectile dysfunction (ED) while receiving visual sexual stimulation. 8-Isoprostane content in endothelium and smooth muscle was significantly higher in impotent patient samples; the level of nitrotyrosine was unchanged in ED patients. Relative to placebo, a single dose of 200 mg BH4 led to a mean increase in duration of > 60% penile rigidity (33.5 min [95% confidence interval (CI): 13.1-49.3] at base and 29.4 min [95% CI: 8.9-42.2] at tip). A 500-mg dose increased the relative duration of > 60% penile rigidity by 36.1 min (95% CI: 16.3-51.8) at the base and 33.7 min (95% CI: 11.4-43.9) at the tip. Treatments were well tolerated. BH4 treatment is suggested to switch eNOS catalytic activity from super-oxide to NO formation, leading to a reduced formation of free radical reaction product 8-isoprostane without alteration of nitrotyrosine. The observed results make BH4 a suitable candidate as an ED treatment through reconstitution of altered catalytic activity of the eNOS.

Application of Single-Cell Gel Electrophoresis (Comet) Assay for Assessing Levels of DNA Damage in Canine and Feline Leukocytes

Increasing evidence suggests involvement of free-radical species in the development of oxidative DNA damage, the consequences of which have been implicated in a number of degenerative disorders associated with the aging process. Here we report the application of a single-cell gel electrophoresis (comet) assay for assessing levels of DNA damage in canine and feline leukocytes. Leukocytes were collected from 24 healthy adult cats and dogs and subjected to DNA damage ex vivo by exposure to a range of hydrogen peroxide (H(2)O(2)) concentrations (0-250 micromol/L). The optimal concentration of H(2)O(2) to induce a significant increase in DNA damage was 100 micromol/L for both canine and feline leukocyte samples. Levels of DNA damage were assessed and quantified by visual and computer image analysis. The results obtained showed high correlations between visual scoring and computer image analysis for feline samples (percentage DNA in tail, R(2) > 0.99; tail moment, R(2) > 0.95; tail length, R(2) > 0.90) and canine samples (percentage DNA in tail, R(2) > 0.97; tail moment, R(2) > 0.95; tail length, R(2) > 0.91). In conclusion, this method provides a way of assessing levels of DNA damage utilizing visual and/or computer image analysis in the feline and canine systems. With the capacity of the comet assay to be able to measure end products of free-radical reactions, it is a useful tool for determining the optimal effects of dietary antioxidants on a reliable biomarker of oxidative stress such as cellular DNA status in cats and dogs.

Antioxidants Reduce Oxidative Stress in Claudicants

Background. Low-grade ischemia–reperfusion in claudicants leads to damage of local tissues and remote organs. Since this damage is partly caused by oxygen-derived free radicals (ODFR), scavenging these ODFR could reduce the local and remote injury.Methods. Using a new method by which a free radical reaction product (ortho-APOH) of the exogenous marker antipyrine is measured to quantify the oxidative stress, 16 stable claudicants performed a standard walking test before and after administration of vitamin E (200 mg) and vitamin C (500 mg) daily for 4 weeks.Findings. Ortho-APOH was significantly increased during the reperfusion period (P = 0.026) before administration of the vitamins. After 4 weeks of vitamin supplementation no rise was found in the reperfusion period. Malondialdehyde showed no changes in either group.Interpretation. These findings indicate that administering extra antioxidants to claudicants reduces oxidative stress in these patients. This may also have an effect on the remote ischemia–reperfusion damage and reduce cardiovascular morbidity in this group.

Exercise training and oxidative stress in the elderly as measured by antipyrine hydroxylation products

Effects of 12 wk exercise training on oxidative stress were examined in elderly humans. We measured oxidative stress during a 45 min cycling test by using antipyrine hydroxylation products. Antipyrine breakdown is independent of blood flow to the liver, which is important during exercise. Furthermore, antipyrine reacts quickly with hydroxyl radicals to form para- and ortho-hydroxyantipyrine. Ortho-hydroxyantipyrine is not formed in man through the mono-oxygenase pathway of cytochrome P450. Twenty subjects (9 women; 60 ± 3 y) participated in the training program. Thirteen subjects (5 women; 64 ± 7 y) served as inactive controls. Subjects trained, twice a week for 1h, at a fitness center. After 12 wk, maximal oxygen uptake (p < .005) and workload capacity (p < .001) were only significantly elevated in the training group. After 12 wk, both groups observed no change in the ratios of antipyrine hydroxylates, para- and ortho-hydroxy-antipyrine, to native antipyrine. Furthermore, no differences were observed within or between groups in the exercise-induced increase in the plasma level of thiobarbituric acid reactive species. In conclusion, 12-wk training had no effect on exercise-induced oxidative stress in elderly humans as measured by free radical reaction products of antipyrine. Despite the fact that training in elderly humans improves functional capacity, it appears not to compromise antioxidant defense mechanisms.

Superoxide dismutase activity in children with chronic liver diseases

Background/Aims: Liver disease in infancy has multiple etiologies. As reactive oxygen intermediates are involved in several types of tissue damage, we have investigated whether different forms of liver disease in infancy are associated with increased free radical generation, using an indirect approach in which superoxide dismutase (a free radical scavenger) activity is determined in the liver tissue. Methods: A total of 48 liver biopsies performed at diagnosis were evaluated retrospectively. Nine infants had biliary atresia, eight Alagille syndrome, seven α1-antitrypsin deficiency and 12 cryptogenic hepatitis. As controls we studied 12 biopsies with normal histology obtained from seven children with portal vein thrombosis and five children who underwent biopsy for management reason but had no liver disease. Superoxide dismutase activity in liver biopsy specimens was measured using the cytochrome C method by spectrophotometry and expressed as U SOD/mg protein. Results: Superoxide dismutase activity was significantly increased in biliary atresia (1.25±0.56 U SOD/mg protein, p<0.0001) and Alagille syndrome (1.31±0.56 U SOD/mg protein, p<0.0001) as compared with α1-antitrypsin deficiency (0.75±0.3 U SOD/mg protein), neonatal hepatitis (0.72±0.37 U. SOD/mg protein) and normal controls (0.4±0.7 U. SOD/mg protein). The highest level of SOD activity was found, however, in control children with portal vein thrombosis (2.09±0.96 U SOD/mg protein; p<0.0001 as compared to the other groups). Conclusion: Superoxide dismutase, a key enzyme in free radical protection, is increased significantly in the liver tissue of infants with cholestatic liver disease due to bile duct damage and in children with portal vein thrombosis, suggesting that products of free radical reactions are involved in the pathogenesis of these disorders.

Chemical and electro-chemical reduction of qinghaosu (artemisinin)

1,2,4-Trioxane is the essential segment of the new antimalarial agent qinghaosu 1, and hence its reduction is an important plausible process related to the bio-activity mode. An overview of its reduction and a careful examination of some reducing systems are presented herewith. Electrochemical reduction is a two-electron reduction, which is confirmed by the isolation of product deoxyqinghaosu. However, in the presence of a catalytic amount of FeII/III electrochemical reduction yields mainly the single-electron-reduction products, which are identified with the products from reduction of qinghaosu with one equivalent ferrous sulfate or a catalytical amount of FeII/III and excess of other reducing agents, such as ascorbic acid, or cysteine. These results mean that qinghaosu is reduced by ferrous ion and the resulting ferric ion is then reduced on the electrode to regenerate ferrous ion. In addition, qinghaosu could be reduced to deoxyqinghao by iodide, but not by bromide, and also could be reduced by the ascorbic acid–CuSO4 system to give free-radical reaction products.