Hypoxanthine-xanthine Oxidase System Research Articles

Carbon Nanomaterials with SOD-like Activity: The Effect of the Ionic Strength.

Electrogenerated hydrophilic carbon (EHC) nanomaterials emerge as a highly attractive option for mimicking the activity of the superoxide dismutase enzyme (SOD) due to their exceptional water solubility and electron-transfer reversibility. Motivated by these properties, the EHC nanomaterials were utilized to assess the effect of ionic strength on the SOD-like activity. Superoxide anion radicals (O2•-) were generated using the hypoxanthine-xanthine oxidase system, with nitro blue tetrazolium chloride serving as the detecting system. A significant boost in the SOD-like activity was found via the addition of an electrolyte to the as-prepared nanomaterial solution. The effect of the electrolyte cation (Na+ and K+), as well as its counterion (Cl-, CH3COO-, and H2PO4-/HPO42-) were analyzed. Based on these studies, a new formulation for the preparation of the carbon-based nanomaterial was established. It was demonstrated that the SOD-like activity follows an enzyme-type catalytic activity rather than the stoichiometric scavenging of the superoxide anion radical. It was concluded that 12.71 µg/mL of the EHC nanomaterial exhibits catalytic activity comparable to 15.46 µg/mL of the native Cu/Zn-SOD enzyme. This study provides a starting point for the development of a new nanotool to fight the oxidative stress associated with pathophysiological conditions where SOD activity is depleted.

Assessing the antioxidant capacity of Ganoderma-infused white tea via electrochemical sensing techniques

This study presents a novel electrochemical method for assessing the antioxidant capacity of Ganoderma-infused white tea using carbon black-gold nanoparticle (CB-AuNP) modified glassy carbon electrodes and in situ generated superoxide radicals. The CB-AuNP nanocomposite was characterized using scanning electron microscopy and cyclic voltammetry, revealing an increased electrochemical active surface area of 0.158 cm2, which is 2.2 times larger than that of the bare glassy carbon electrode. Optimal conditions for superoxide radical generation were established using the xanthine oxidase-hypoxanthine system (0.10 U/mL XOD, 0.5 mM HX, 10 minutes incubation). The antioxidant capacity of Ganoderma-infused white tea was evaluated using cyclic voltammetry and chronoamperometry, and expressed as Trolox equivalent antioxidant capacity (TEAC). The proposed method demonstrated a strong linear relationship between TEAC values and Ganoderma extract concentration (R2 = 0.9995), with TEAC values ranging from 0.54 ± 0.03–2.85 ± 0.12 mM Trolox/g tea for 0.1–1.0 % w/v Ganoderma-infused white tea. The method exhibited good agreement with conventional spectrophotometric assays (DPPH, ABTS, and FRAP), showing strong correlations (R > 0.997) for all three assays. The practical applicability of the method was validated using commercial tea products, revealing a positive correlation between antioxidant capacity and Ganoderma polysaccharide content (R = 0.9958). The proposed electrochemical method offers a rapid, sensitive, and reliable approach for assessing the antioxidant capacity of functional tea products, with potential applications in quality control and product development.

A novel DPP-4 inhibitor teneligliptin scavenges hydroxyl radicals: In vitro study evaluated by electron spin resonance spectroscopy and in vivo study using DPP-4 deficient rats

AimsRecently various dipeptidyl peptidase-4 (DPP-4) inhibitors have emerged because of their high effectiveness and safety. In spite of their common effect of DPP-4 inhibition, the chemical structures are diverse. Here we show that the structure of teneligliptin, a novel DPP-4 inhibitor, has a scavenging activity on hydroxyl radical (·OH). Methods·OH and superoxide (O2−) were detected by electron spin resonance (ESR) spectroscopy. ·OH and O2− were generated in vitro by the Fenton reaction and a hypoxanthine-xanthine oxidase system, respectively. The level of free radicals was estimated from the ESR signal intensity. The product via teneligliptin and ·OH reaction was identified by thin layer chromatography and mass spectrometry analysis. In vivo effect was also evaluated using DPP-4 deficient rats with streptozotocin-induced diabetes. ResultsESR spectroscopy analysis showed that teneligliptin did not scavenge O2−, but scavenged ·OH in a dose dependent manner. Its activity was greater than that of glutathione. The reaction product appeared to have an oxygen-atom added structure to that of teneligliptin, which was identical to the most abundant metabolite of teneligliptin in human plasma. Furthermore, using DPP-4 deficient rat, teneligliptin did not affect plasma glucose levels or body weight, but normalized increased levels of 8-hydroxy-2′-deoxyguanosine in urine, kidney and aorta of diabetic rats, supporting that teneligliptin may have a ·OH scavenging activity in vivo independently of DPP-4 inhibition. ConclusionsTeneligliptin is not only effective as DPP-4 inhibitor, but may also be beneficial as ·OH scavenger, which may be useful in the prevention of diabetic complications.

EComment. Application of prostaglandin E1 and pentoxyphylline in clinical mesenteric ischaemia

We read with great interest the original article by San Norberto Garcia and colleagues describing the effects of intra-arterial and intravenous prostaglandin E1 (PGE1) in intestinal ischaemia-reperfusion injury [1]. Using a rat model, the study was designed to assess histopathological score following ileal segment resection, polymorphonuclear leukocytes visualized and myeloperoxidase activity following a well-designed protocol of ischaemia time and reperfusion time with variable route administration of PGE1. The ischaemic insult presents a vicious cycle at the molecular and biochemical level. Vasodilatation occurs with increased microvascular permeability and release of lysosomal hydrolases and ultimately increased proteolysis. This cascade is aggravated by reperfusion, where an already oxygen deprived organ territory is now exposed to oxygen free radicals through oxidation of the hypoxanthine-xanthine oxidase system resulting in the superoxide anion [2]. The main determinants of haemodynamic instability, and subsequent mortality, are the generation of oxygen free radicals and the increased capillary permeability [3]. The spectrum of mesenteric ischaemia encompasses either an acute insult or a chronic phase, and can be caused by thrombosis, embolism, non-occlusive mesenteric ischaemia, and significant venous obstruction. Clearly with acute mesenteric ischaemia, mortality is quite high. As pointed out by the authors, thromboembolic acute occlusion of the superior mesenteric artery is usually unpredictable, so pretreatment is not possible or practical. However, in such a case like the critically ill with non-occlusive mesenteric ischaemia, with early diagnosis and detection, the initiation of continuous intravenous PGE1 may increase survival as noted in a study by Mitsuyoshi and colleagues [4]. The 60-minute ischaemia time and 7 days reperfusion portended the best outcome with regard to Chiu classification of intestinal tissue injury as well as myeloperoxidase activity and polymorphonuclear leukocyte infiltration. Another promising vascular drug that has been evaluated experimentally is pentoxyphylline. It has specific antioxidant properties that directly inhibit the superoxide anion and indirectly blocks xanthine-oxidase enzyme activity. It has been shown to reduce histopathological changes secondary to ischaemia-reperfusion in intestinal experimental models [5]. Again, although in acute mesenteric ischaemia it is impossible to pretreat these patients with PGE1 (or even pentoxyphylline), it may be clinically appropriate to consider such pretreatment in elective revascularization of patients with chronic mesenteric ischaemia or the critically ill in whom high-dose vasoactive agents are necessary for haemodynamic control. Further translational studies are necessary to try delineate whether a functional benefit is clinically realized from a histopathological and anatomic amelioration of the ischaemia-reperfusion injury. Conflict of interest: none declared

Comparative study on antioxidative and macrophage-stimulating activities of polyguluronic acid (PG) and polymannuronic acid (PM) prepared from alginate

The antioxidant and macrophage-stimulating activities of polyguluronic acid (PG) and polymannuronic acid (PM) prepared from alginate were examined. A chemiluminescence (CL) method using a luminol analog, L-012, showed that both PM and PG scavenge superoxide produced by hypoxanthine–xanthine oxidase system in a concentration-dependent manner. At 100μg/ml, PG showed slightly stronger superoxide scavenging activity than PM. In an electron spin resonance (ESR)-spin trapping method in which the Fenton reaction was used as hydroxyl radical generation system, we found that both PM and PG showed potent hydroxyl radical scavenging activity to a similar extent. Because PM and PG showed no chelating activity on Fe2+, it was confirmed that PM and PG can directly scavenge hydroxyl radical. No significant scavenging activity of PM and PG toward hydrogen peroxide was observed. Interestingly, the macrophage-stimulation activity of PG as measured by nitric oxide (NO)-production from mouse macrophage cell line RAW264.7 cells was evidently stronger than that of PM. Our results suggest that RAW264.7 cells might be able to distinguish the conformational differences between PM and PG, and respond differently to them, whereas the effects of such structural differences between PM and PG on the radical scavenging activities may not be so significant.

Synthesis and reactive oxygen species scavenging activity of halogenated alkaloids from boldine

Six halogenated alkaloids have been semi-synthesized from natural boldine as starting material. Their antioxidant activity toward reactive oxygen species (ROS) generation by neutrophils stimulated with N-formyl-methionyl-leucyl-phenylalanine and in the hypoxanthine–xanthine oxidase system was evaluated. Most of the alkaloids synthesized inhibited ROS generation in both systems in a concentration-dependent manner. The alkaloids with phenolic substituents displayed more powerful anti-oxidative activity than those containing methoxylated groups. None of the alkaloids assayed had any effect on xanthine oxidase activity. Therefore, halogenated phenanthrene alkaloids can become in promising candidates for the development of novel and potent anti-inflammatory drugs.

Rhein: an anthraquinone that modulates superoxide anion production from human neutrophils.

Rhein (4,5-dihydroxyanthraquinone-2-carboxylic acid), the active metabolite of diacetylrhein, which has been reported as an effective antirheumatic drug in man, inhibited superoxide anion production from human neutrophils challenged with N-formylmethionyl-leucyl-phenylalanine (FMLP: IC50, 2 x 10(-5) M) and A23186 (IC50, 10(-5) M), but not with phorbol myristate acetate. In the same concentration range (10(-6)-10(-3) M), the drug did not affect oxy-radical production by a cell-free hypoxanthine-xanthine oxidase system and exerted weak inhibitory effects on FMLP-evoked lysosomal enzyme release. Rhein inhibitory effects on neutrophil functioning may contribute to the overall therapeutic activity of the parent drug, diacetylrhein.

Aged Garlic Extract Scavenges Superoxide Radicals

There is increasing evidence to suggest that many degenerative or pathological processes, such as aging, cancer, and coronary heart disease, are related to reactive oxygen species and radical-mediated reactions. We examined the effectiveness of aged garlic extract (AGE), a garlic preparation rich in water-soluble cysteinyl moieties, and its component for scavenging of superoxide by using the hypoxanthine-xanthine oxidase and human neutrophils. In the hypoxanthine-xanthine oxidase system, electron spin resonance showed that aged garlic extract scavenged superoxide radicals in a dose-dependent manner up to 54%. The EC(50) value of aged garlic extract for the superoxide radical scavenging effect was 0.80 mg/ml. N-α-(1-deoxy-D-fructos-1-yl)-L-arginine (25.9%) and (1S, 3S)-1-methyl-1,2,3,4-tetrahydro-β-carboline-1,3-dicarboxylic acid (20.8%), water-soluble moieties of AGE, also exerted superoxide scavenging effects. Phorbol 12-myristate 13-acetate-activated human neutrophils produced superoxide radical of 56.6 ± 9.27 nmol/min/10(7) cells. Aged garlic extract (3 mg/ml) significantly inhibited superoxide production in comparison to the control. These data suggest that aged garlic extract may be useful for preventing diseases associated with reactive oxygen species.

Evaluation of Superoxide Anion Radicals Generated from an Aqueous Extract of Particulate Phase Cigarette Smoke by Electron Spin Resonance Using 5,5-Dimethyl-1-pyrroline-N-oxide

The reactive oxygen species generated by an aqueous extract of the particulate phase of cigarette smoke were evaluated by an electron spin resonance (ESR) analysis, using spin-trapping agents, and by comparing with model reaction systems. The ESR signals of DMPO-OH were detected from the extract by using 5,5-dimethyl-1-pyrroline-N-oxide (DMPO). These signals were eliminated by adding superoxide dismutase, but hardly by catalase. These responses of the ESR signals to the scavengers were similar to those of a hypoxanthine-xanthine oxidase system. The results indicate that the signals of DMPO-OH from the extract were derived from a reaction product of DMPO with superoxide anion radicals and clarify the mechanism by which the extract generated superoxide anion radicals.

Kinetic Analysis of Superoxide Anion Radical-Scavenging and Hydroxyl Radical-Scavenging Activities of Platinum Nanoparticles

There are few reports on the physiological effects of metal nanoparticles (nps), especially with respect to their functions as scavengers for superoxide anion radical (O2(.-)) and hydroxyl radical (.OH). We tried to detect the scavenging activity of Pt nps using a hypoxanthine-xanthine oxidase system for O2(.-) and using a Fenton and a UV/H2O2 system for .OH. Electron spin resonance analysis revealed that 2 nm particle size Pt nps have the ability to scavenge O2(.-) and .OH. The calculated rate constant for the O2(.-)-scavenging reaction was 5.03 +/- 0.03 x 10(7) M (-1) s (-1). However, the analysis of the Fenton and UV/H 2O 2 system in the presence of Pt nps suggested that the .OH-scavenging reaction cannot be determined in both systems. Among particle sizes tested from 1 to 5 nm, 1 nm Pt nps showed the highest O2(.-)-scavenging ability. Almost no cytotoxicity was observed even after adherent cells (TIG-1, HeLa, HepG2, WI-38, and MRC-5) were exposed to Pt nps at concentrations as high as 50 mg/L. Pt nps scavenged intrinsically generated reactive oxygen species (ROS) in HeLa cells. Additionally, Pt nps significantly reduced the levels of intracellular O2(.-) generated by UVA irradiation and subsequently protected HeLa cells from ROS damage-induced cell death. These findings suggest that Pt nps may be a new type of antioxidant capable of circumventing the paradoxical effects of conventional antioxidants.

Ciclopirox olamine directly scavenges hydroxyl radical

Introduction Ciclopirox olamine (CPO), a hydroxypyridone derivative, belongsto antifungal agents used for the treatment of superficial fungalinfections. Recently, it has been reported that CPO acts as apotential chelating agent and influences some cellular processesof the fungus by chelating metal irons.

Inhibitory or scavenging action of ketoconazole and ciclopiroxolamine against reactive oxygen species released by primed inflammatory cells

Reactive oxygen species (ROS) released from inflammatory cells constitute one of the critical causative factors in inflammatory skin diseases such as seborrhoeic dermatitis and atopic dermatitis. To investigate inhibitory effects of ketoconazole (KCZ) and ciclopiroxolamine (CPO), both of which have been used for the treatment of seborrhoeic dermatitis, on ROS released from inflammatory cells. The methyl-Cypridina-luciferin analogue-dependent chemiluminescence method was employed for the detection of ROS production by phorbol 12-myristate 13-acetate (PMA)-stimulated inflammatory cells. Moreover, the radical scavenging activities of both agents were examined by using a hypoxanthine-xanthine oxidase system and the stable radical 1,1-diphenyl-2-picrylhydrazyl (DPPH). NADPH oxidase activity was determined in particulate (membrane) fractions prepared from PMA-stimulated RAW 264 x 7 cells, a macrophage-like cell line. Both of these antifungal agents inhibited PMA-stimulated ROS production. However, only CPO significantly scavenged both ROS generated by the hypoxanthine-xanthine oxidase system and DPPH, and the scavenging activity of CPO seemed to act on ROS other than superoxide anions. Although KCZ inhibited PMA-stimulated ROS production, it did not show radical-scavenging activities. The inhibition of ROS production by KCZ is probably attributable to the inhibition of NADPH oxidase activity. The mechanism of the inhibitory action of KCZ against PMA-stimulated ROS production is distinct from that of CPO. Knowledge of the inhibitory or scavenging effects of both antifungal agents on ROS released from inflammatory cells may be useful in developing a therapeutic strategy for dermatitis.

Development of imidazopyrazinone red‐chemiluminescent probes for detecting superoxide anions via a chemiluminescence resonance energy transfer method

During the development of useful probes for detecting superoxide anions via chemiluminescence with longer wavelengths than that of green, chemiluminescent probes that emit red light (lambda(max) 610 nm) when induced by superoxide anions were synthesized and characterized. These red-chemiluminescent probes consist of a 6-(4-methoxyphenyl)imidazo[1,2-a] pyrazin-3(7H)-one moiety, which reacts with superoxide anions to generate energy, and a sulphorhodamine 101 moiety, which accepts the energy and emits red light. Using a hypoxanthine-xanthine oxidase system for the generation of superoxide anions, it was shown that the superoxide anion-induced chemiluminescences of red-chemiluminescent probes (3 and 4) were more intense than those of the blue- and green-chemiluminescent probes 2-methyl-6-(4-methoxyphenyl)imidazo[1,2-a] pyrazin-3(7H)-one (MCLA) and 6-[4-[2-[N'-(5-fluoresceinyl)thioureido]-ethoxy]phenyl]-2-methylimidazo[1,2-a]pyrazin-3(7H)-one (FCLA), respectively, which are generally considered to be the most sensitive chemiluminescent probes. The ratio between the superoxide-dependent and background chemiluminescence intensities for 3 was comparable to those of MCLA and FCLA, but higher than that of 4. Due to its highly intense superoxide anion-induced chemiluminescence at low probe concentrations, red-chemiluminescent probe 3 is superior to MCLA and FCLA for measurement of superoxide anions.

Interaction of rifalazil with oxidant-generating systems of human polymorphonuclear neutrophils.

It is well acknowledged that ansamycins display immunosuppressive and anti-inflammatory properties in vitro and in vivo. Rifalazil, a new ansamycin derivative, has not been studied in the context of inflammation. In particular, there are no data on the possible interference of rifalazil with oxidant production by phagocytes. We have compared the antioxidant properties of rifalazil to those of rifampin, a drug well known in this context, by using cellular and acellular oxidant-generating systems. Oxidant production by polymorphonuclear neutrophils was measured in terms of cytochrome c reduction, lucigenin-amplified chemiluminescence (Lu-ACL), and the 2',7'-dichlorofluorescin diacetate H2 (DCFDA-H2) technique (intracellular oxidant production). Rifalazil impaired O2- production in a concentration-dependent manner, with 50% inhibitory concentrations (IC50) (concentrations which inhibit 50% of the response) of 5.4 (30 and 60 min of incubation) and 6.4 (30 min) mg/liter, respectively, for phorbol myristate acetate (PMA) and formyl-methionyl-leucyl-phenylalanine (fMLP) stimulation. In agreement with the published fMLP-like activity of rifampin, the inhibitory effect of rifampin was significantly greater for fMLP (IC50 of 5.6 mg/liter) than for PMA (IC50 of 58 mg/liter) stimulation. Alteration of intracellular oxidant production was also observed with IC50 values similar to those obtained by the cytochrome assay. In addition, rifalazil and rifampin (> or = 25 mg/liter) scavenged O2-, as demonstrated by the acellular (hypoxanthine-xanthine oxidase) system. Interference with light detection systems was evidenced for both drugs by Lu-ACL. The clinical relevance of the antioxidant effect of rifalazil demonstrated in vitro, in particular its potential anti-inflammatory activity, requires further investigation.

Superoxide Inhibits ADAMTS-13 Activity and Regulates Sickle Cell Adhesion.

The major clinical manifestations of sickle cell anemia are due to a vaso-occlusive process that leads to severe pain crises, tissue infarction, and in some instances, death. The pathophysiology of vaso-occlusion is extremely complex, the proximate cause appearing to be an increase in the adhesive interaction between sickle erythrocytes and vascular endothelium. There is ample evidence that it is the highest molecular weight forms of VWF, the ultra-large multimers (ULVWF), expressed on endothelium support sickle erythrocyte adhesion most potently. We postulate that variation in the activity of the plasma metalloprotease, ADAMTS-13, which processes ULVWF to the VWF form normally found in plasma will be an important determinant of the propensity for individuals with sickle cell anemia to develop vaso-occlusive crises. It has also been postulated that increased production of reactive oxygen species (ROS) also contributes to the pathology of sickle cell disease. ROS have been implicated in diverse cellular processes, acting through oxidation of cysteine residues. ADAMTS-13 is a cysteine-rich protein; we therefore hypothesized that its function could be affected by ROS. We measured ADAMTS-13 activity in the plasmas of sickle cell disease patients, both in the “steady state” and at various times during vaso-occlusive crises. We used three assays: a static assay that measures the ability of patient plasma to reduce the size of endothelial-derived ULVWF, a static assay that assesses the ability of patient plasma to cleave a recombinant VWF A2 fragment, and an assay performed under flow that evaluates the ability of patient plasma to cleave ULVWF attached to the surfaces of histamine-stimulated human umbilical vein endothelial cells (HUVECs). Five of nine patients with sickle cell anemia had significantly lower ADAMTS-13 activity than measured in normal controls during the chronic phase of the illness, some with activity measuring below 50% of normal levels. We also evaluated activity in two patients during acute vaso-occlusive crisis. Both patients had levels on the day of hospitalization that were indistinguishable from the levels found in patients with thrombotic thrombocytopenic purpura. Recovery of activity correlated with clinical recovery, to the point that in both cases activity was normal upon hospital discharge. We then compared superoxide generation facilitated by sickle erythrocytes with that generated by normal erythrocytes and found, as others have a significantly higher generation by sickle erythrocytes. We also found that superoxide (produced using a hypoxanthine-xanthine oxidase system) significantly decreased the activity of both plasma and recombinant ADAMTS-13 in vitro. Superoxide was also able to stimulate release of ULVWF and cell-membrane expression from cultured HUVEC. These results suggest that the enhanced production of superoxide in patients with sickle cell disease plays an important role in promoting erythrocyte adhesion to the endothelium by both stimulating release of ULVWF and inhibiting its cleavage by ADAMTS-13.

Acute and chronic effects of free radicals on α1-adrenergic-induced vasoconstriction in mesenteric beds of spontaneously hypertensive rats

To determine whether free radicals participate in the increased sensitivity of the alpha-adrenergic pathway in mesenteric arteries from spontaneously hypertensive rats (SHRs). SHRs are characterized by a greater vasoconstriction (P < 0.001) in response to phenylephrine in isolated and perfused mesenteric arteries. Deferoxamine (DFX) produced a significant increase in the phenylephrine-induced vasoconstriction in isolated mesenteric beds from both SHRs (P < 0.001) and Wistar-Kyoto (WKY) rats (P < 0.05), but with a greater magnitude in SHRs (P < 0.01). Acutely, activation of the hypoxanthine-xanthine oxidase (HX-XO) system produced an endothelium- and NO-dependent vasoconstriction at low concentration (P < 0.01), followed by an endothelium-independent vasorelaxation at greater concentrations in phenylephrine-preconstricted mesenteric beds (P < 0.01). Catalase and SOD (P < 0.01) prevented this endothelium-dependent response, whereas the endothelium-independent vasorelaxation induced by HX-XO was blocked by catalase, SOD and DFX (P < 0.01). Chronic administration of a diet deficient in selenium and vitamin E decreased the glutathione peroxidase activity in erythrocytes and plasma from SHRs and WKY rats (P < 0.001). Moreover, the deficient diet significantly increased the sensitivity of mesenteric arteries to phenylephrine in SHRs (P < 0.001) and WKY rats (P < 0.05), whereas it decreased acetylcholine-induced vasodilatation in SHRs only (P < 0.05). The KCl-induced vasoconstriction in response to oxygen radicals was enhanced only in mesenteric bed from SHRs. Free radicals seem to potentiate the alpha-adrenergic pathway acutely in low concentrations and to sensitize this pathway chronically in SHRs. These observations may explain the potentiated response to alpha-adrenergic agonists observed in SHRs.

Superoxide radical production in chicken skeletal muscle induced by acute heat stress

Heat stress is of major concern for poultry, especially in the hot regions of the world because of the resulting poor growth performance, immunosuppression, and high mortality. To assess superoxide (O2*-) production in mitochondria isolated from skeletal muscle of chickens (n = 4 to 8) exposed to acute heat stress, electron spin resonance (ESR) spectroscopy using 5,5-dimethyl-1-pyrroline N-oxide (DMPO) as a spin trap agent and lucigenin-derived chemiluminescence (LDCL) method were applied. ESR spectra of suspensions containing mitochondria from control and acute heat-treated meat-type chickens showed similar hyperfine coupling constants (aN = 1.44 mT, aHbeta = 0.12 mT, and aHbeta = 0.11 mT) to those of DMPO-O2*- adducts observed in a hypoxanthine-xanthine oxidase system. Heat exposure resulted in enhancement of the DMPO-O2*- signal. The results using LDCL showed significantly enhanced superoxide production in heat stress-treated skeletal muscle mitochondria of meat-type chickens, whereas no such increase was observed in laying chickens. The enhancement of superoxide production in the former case was associated with heat-induced increments in rectal and muscle temperatures, leading to significant body weight loss. In contrast, the latter case showed no increase in temperatures, although there was a slight decrease in body weight gain. Percentage increases of superoxide production in the presence of carboxyatractylate, a specific inhibitor of adenine nucleotide translocator (ANT), were the same for skeletal muscle mitochondria from meat- and laying-type chickens from the control or heat stress-treated group. This finding suggests the irrelevance of ANT in the regulation of reactive oxygen species flux under heat stress conditions. The study provides the first evidence of superoxide anion production in the skeletal muscle mitochondria of meat-type chickens in response to acute heat stress.

Salviae miltiorrhizae Radix Inhibits Superoxide Generation by Activated Rat Microglias and Mimics the Action of Amphetamine on in vitro Rat Striatal Dopamine Release

Salviae miltiorrhizae Radix (SMR), an eminent herb in the treatment of cardiovascular disorder (called blood stasis in traditional Chinese medicine), is widely used in China, Japan, Taiwan and Korea. SMR is also herbal medicines used in the treatment of drug addiction without scientific support for their mechanism of action. We evaluated the effect of SMR on superoxide production by rat microglias using a 2-methyl-6-(p-methoxyphenyl)-3,7-dihydroimidazo[1,2-a]pyrazin-3-one-dependent chemiluminescence assay. SMR dose-dependently inhibited superoxide production by microglias stimulated with phorbol myristate acetate or opsonized zymosan, while it had no effect on superoxide production by a hypoxanthinexanthine oxidase system. These results indicate that SMR does not have a scavenging effect, but has an inhibitory effect on superoxide generation by microglias. Although SMR is commonly used for treating chronic cerebral infarction, it may also have a protective effect on progression of Parkinson's disease or Alzheimer's disease. On the other hand, the present study investigated the effect of the medicinal plant on dopaminergic neurotransmission in comparison with amphetamine. The effect of crude water extracts (0.1 g/ml) of SMR on K+ (20 mM)-stimulated dopamine release from rat striatal slices was compared with amphetamine (10(-4) M) using high-performance liquid chromatography with electrochemical detection to measure endogenous dopamine. Amphetamine and SMR significantly increased K+-stimulated dopamine release (P<0.001) from rat striatal slices when compared with K+-stimulated alone. SMR potentiated the effect of amphetamine on K+-stimulated dopamine release (P<0.001) when compared with amphetamine alone. The results indicate that SMR may stimulate dopamine release in the same manner as amphetamine. It remains to be determined whether the effect of this extract on dopamine function is important in its therapeutic use in the treatment of drug addiction.

Reactive oxygen species scavenging ability of a new compound derived from weathered coal

The scavenging activity of three fulvic acids (named XWCS-1, XWCS-4, and XWCS-8 according to time taken for ozonolysis) obtained by ozonolysis of humic acid extracted from Xinjiang (China) weathered coal and a fulvic acid (named XWCFA) extracted from the same coal towards reactive oxygen species such as superoxide radical (O 2 −) and hydroxyl radical ( OH) was investigated with an electron spin resonance (ESR)-spin trapping method using 5,5-dimethyl-1-pyrroline N-oxide (DMPO) as a spin trap. O 2 − was generated with a hypoxanthine–xanthine oxidase system. OH was generated by three different methods; (i) FeSO 4–hydrogen peroxide (H 2O 2) system, (ii) Cu(en) 2–H 2O 2 system, and (iii) UVB photolysis of H 2O 2. At physiological pH, XWCS-1 had the greatest O 2 − scavenging activity, followed by XWCS-4, XWCS-8 and XWCFA. XWCFA had the greatest OH scavenging activity among the four fulvic acids, whereas XWCS-1 and XWCS-4 enhanced the production of OH from a metal-catalyzed hydroxyl radical generating system, suggesting that these molecules act as prooxidants in the presence of metal ion.

Cyclodextrin-bound 6-(4-methoxyphenyl)imidazo[1,2-α]pyrazin-3( 7H)-ones with fluorescein as green chemiluminescent probes for superoxide anions

In providing chemiluminescent probes that have high chemiluminescence intensity and high specificity to superoxide anions, novel chemiluminescent probes involving cyclodextrins covalently bound to 6-(4-methoxyphenyl)imidazo[1,2-α]pyrazin-3( 7H)-one with fluorescein were synthesized and characterized. Using the hypoxanthine–xanthine oxidase system for the generation of the superoxide anions, these novel chemiluminescent probes showed higher superoxide-induced chemiluminescence intensity than that of 6-[4-[2-[ N ′-(5-fluoresceinyl)thioureido]-ethoxy]phenyl]-2-methylimidazo[1,2-α]pyrazin-3( 7H)-one (FCLA). When tested at a probe concentration of 1.0 μM, compound 6, in which 6-(4-methoxyphenyl)imidazo[1,2-α]pyrazin-3( 7H)-one and fluorescein are covalently attached on the secondary and primary hydroxyl faces of γ-cyclodextrin, respectively, showed green luminescence intensity that was 26 times that of FCLA, which was also the highest luminescence intensity in this present study. At probe concentrations of less than 1.0 μM, the ratio of the superoxide-dependent chemiluminescence intensity to the background chemiluminescence intensity for compound 6 was higher than that of FCLA. This high superoxide-induced chemiluminescence intensity and superoxide specificity in low probe concentrations indicates that 6 can be more effective than FCLA toward the measurement of superoxide anions.