Ascorbic acid inhibits visceral obesity and nonalcoholic fatty liver disease by activating peroxisome proliferator-activated receptor α in high-fat-diet-fed C57BL/6J mice.

BACKGROUND/OBJECTIVES: Ascorbic acid is a known cofactor in the biosynthesis of carnitine, a molecule that has an obligatory role in fatty acid oxidation. Our previous studies have demonstrated that obesity is regulated effectively through peroxisome proliferator-activated receptor α (PPARα)-mediated fatty acid ß-oxidation. Thus, this study aimed to determine whether ascorbic acid can inhibit obesity and nonalcoholic fatty liver disease (NAFLD) in part through the actions of PPARα. DESIGN: After C57BL/6J mice received a low-fat diet (LFD, 10% kcal fat), a high-fat diet (HFD, 45% kcal fat), or the same HFD supplemented with ascorbic acid (1% w/w) (HFD-AA) for 15 weeks, variables and determinants of visceral obesity and NAFLD were examined using metabolic measurements, histology, and gene expression. RESULTS: Compared to HFD-fed obese mice, administration of HFD-AA to obese mice reduced body weight gain, visceral adipose tissue mass, and visceral adipocyte size without affecting food consumption profiles. Concomitantly, circulating ascorbic acid concentrations were significantly higher in HFD-AA mice than in HFD mice. Ascorbic acid supplementation increased the mRNA levels of PPARα and its target enzymes involved in fatty acid ß-oxidation in visceral adipose tissues. Consistent with the effects of ascorbic acid on visceral obesity, ascorbic acid not only inhibited hepatic steatosis but also increased the mRNA levels of PPARα-dependent fatty acid ß-oxidation genes in livers. Similarly, hepatic inflammation, fibrosis, and apoptosis were also decreased during ascorbic acid-induced inhibition of visceral obesity. In addition, serum levels of alanine aminotransferase, aspartate aminotransferase, total cholesterol, and LDL cholesterol were lower in HFD-AA-fed mice than in those of HFD-fed mice. CONCLUSIONS: These results suggest that ascorbic acid seems to suppress HFD-induced visceral obesity and NAFLD in part through the activation of PPARα.

Impact of specific inhibitors on metallo-ß-carbapenemases detected in Escherichia coli and Klebsiella pneumoniae isolates.

Carbapenems are widely regarded as the drugs of choice for the treatment of severe infections caused by extended-spectrum beta lactamases producing Enterobacteriaceae. The emergence of carbapenem-resistant organisms is worrisome due to the limited treatment options. Detection of carbapenemase-producing bacteria is critical for the choice of appropriate therapy. However, Inhibition of carbapenemases is an alternative approach to combat resistance to carbapenms. In this study, Escherichia coli and Klebsiella pneumoniae carbapenem resistant isolates were recovered from 300 clinical isolates. They were subjected phenotypically for detection of class B metallo-carbapenemase (MBL) producers (by carbapenem disks with or without EDTA), and were subjected for confirmation genotypically by PCR. In addition, the synergistic activities of MBL-inhibitors in combination with carbapenems were elucidated. Two E. coli and 15 K. pneumoniae isolates were carbapenem resistant. The genes encoding blaNDM-1 carbapenemase were detected in 16/17 isolates solely, or collaboratively with either blaVIM, or blaIMP or both in all carbapenem resistant isolates, by PCR method. The VIM-carbapenemase was encoded by one isolate. In pre-clinical trials for development of MBL-specific inhibitors, Sub-inhibitory concentrations of citric acid, malic acid, ascorbic acid and ciprofloxacin in combination with imipenem or meropenem exerted synergistic activities against metallo-carbapenemases. Their activities are probably attributed to the chelation of zinc ions in the active site of carbapenemase. Conclusively, these promising combined therapies might represent a new strategy for combating such serious infections caused by metallo-B-carbapenemase producers of K. pneumoniae and E. coli isolates.

Mannich-Benzimidazole Derivatives as Antioxidant and Anticholinesterase Inhibitors: Synthesis, Biological Evaluations, and Molecular Docking Study.

A series of Mannich bases of benzimidazole derivatives having a phenolic group were designed to assess their anticholinesterase and antioxidant activities. The acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibitory activities were evaluated in vitro by using Ellman's method. According to the activity results, all of the compounds exhibited moderate to good AChE inhibitory activity (except for 2a), with IC50 values ranging from 0.93 to 10.85 µM, and generally displayed moderate BuChE inhibitory activity. Also, most of the compounds were selective against BuChE. Compound 4b was the most active molecule on the AChE enzyme and also selective. In addition, we investigated the antioxidant effects of the synthesized compounds against FeCl2 /ascorbic acid-induced oxidative stress in the rat brain in vitro, and the activity results showed that most of the compounds are effective as radical scavengers. Molecular docking studies and molecular dynamics simulations were also carried out.

Dose-dependent effects of nicotine on proliferation and differentiation of human bone marrow stromal cells and the antagonistic action of vitamin C.

A range of biological and molecular effects caused by nicotine are considered to effect bone metabolism. Vitamin C functions as a biological antioxidant. This study was to evaluate the in vitro effects of nicotine on human bone marrow stromal cells and whether Vitamin C supplementation show the antagonism action to high concentration nicotine. We used CCK-8, alkaline phosphatase (ALP) activity assay, Von Kossa staining, real-time polymerase chain reaction and Western Blot to evaluate the proliferation and osteogenic differentiation. The results indicated that the proliferation of BMSCs increased at the concentration of 50, 100 ng/ml, got inhibited at 1,000 ng/ml. When Vitamin C was added, the OD for proliferation increased. For ALP staining, we found that BMSCs treated with 50 and 100 ng/ml nicotine showed a higher activity compared with the control, and decreased at the 1,000 ng/ml. Bone morphogenetic protein-2 (BMP-2) expression and the calcium depositions decreased at 100 and 1,000 ng/ml nicotine, while the addition of Vitamin C reversed the down regulation. By real-time PCR, we detected that the mRNA expression of collagen type I (COL-I) and ALP were also increased in 50 and 100 ng/ml nicotine groups (P < 0.05), while reduced at 1,000 ng/ml (P < 0.05). When it came to osteocalcin (OCN), the changes were similar. Taken all together, it is found that nicotine has a two-phase effect on human BMSCs, showing that low level of nicotine could promote the proliferation and osteogenic differentiation while the high level display the opposite effect. Vitamin C could antagonize the inhibitory effect of higher concentration of nicotine partly.

Ascorbic acid enhances adipogenesis of 3T3-L1 murine preadipocyte through differential expression of collagens.

BACKGROUND: Adipogenesis from preadipocytes into mature adipocyte is precisely coordinated by transcription factors such as CCAAT-enhancer-binding proteins (C/EBPs) and peroxisome proliferator-activated receptor γ (PPARγ), cytokines, and hormones, which is accompanied by extracellular matrix remodeling. Besides anti-oxidant activity, ascorbic acid (ASC) is participating in collagen biosynthesis and increase production and processing of collagens. Moreover, several studies demonstrated that ASC enhanced differentiation from preadipocytes into mature adipocytes. METHODS: The adipogenic effect of ascorbic acid was evaluated in chemical induced 3T3-L1 by Oil Red O staining. This effect was elucidated by immunoblotting which detected the expression level of collagens and transcription factors in adipogenesis. The immunocytochemical determination of type I collagen was performed in 3T3-L1 adipocyte to show the change of extracellular matrix during adipogenesis. RESULTS: In this study, Oil Red O staining in 3T3-L1 preadipocytes was increased dose-dependently by addition of ASC. These ASC-treated adipocytes increased collagen processing of α1(I) and α1(V) and expressed α1(VI) and α2(VI) collagens differentially. ASC also stimulated expression of C/EBPα and PPARγ, which is preceded by collagen enhancement. In addition, inhibition of ASC activity by ethyl-3,4-dihydroxybenzoate showed reduction of lipid accumulation by removal of large lipid droplets, not by inhibition of lipid production. This observation went with loss of α1(I) deposition on adipocyte surface, increase of α1(V) and α2(VI) collagens and decrease of C/EBPs. CONCLUSION: Our findings imply that various actions of ASC on adipogenesis through differential collagen expression may provide diverse applications of ASC to adipose tissue technology.

Up-regulation of GLT1 reverses the deficit in cortically evoked striatal ascorbate efflux in the R6/2 mouse model of Huntington's disease.

A corticostriatal-dependent deficit in the release of ascorbate (AA), an antioxidant vitamin and neuromodulator, occurs concurrently in striatum with dysfunctional GLT1-dependent uptake of glutamate in the R6/2 mouse model of Huntington's disease (HD), an autosomal dominant condition characterized by overt corticostriatal dysfunction. To determine if deficient striatal AA release into extracellular fluid is related to altered GLT1 activity in HD, symptomatic R6/2 mice between 6 and 9 weeks of age and age-matched wild-type (WT) mice received single daily injections of 200 mg/kg ceftriaxone, a ß-lactam antibiotic that elevates the functional expression of GLT1, or saline vehicle for five consecutive days. On the following day, in vivo voltammetry was coupled with corticostriatal afferent stimulation to monitor evoked release of AA into striatum. In saline-treated mice, we found a marked decrease in evoked extracellular AA in striatum of R6/2 relative to WT. Ceftriaxone, in contrast, restored striatal AA in R6/2 mice to WT levels. In addition, intra-striatal infusion of either the GLT1 inhibitor dihydrokainic acid or dl-threo-beta-benzyloxyaspartate blocked evoked striatal AA release. Collectively, our results provide compelling evidence for a link between GLT1 activation and release of AA into the striatal extracellular fluid, and suggest that dysfunction of this system is a key component of HD pathophysiology.

Ciprofloxacin-induced antibacterial activity is reversed by vitamin E and vitamin C.

In the present study, we investigated the possible involvement of oxidative stress in ciprofloxacin-induced cytotoxicity against several reference bacteria including Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 29213, and clinical isolate of methicillin-resistant Staphylococcus aureus (MRSA). Oxidative stress was assessed by measurement of hydrogen peroxide generation using a FACScan flow cytometer. The antibacterial activity of ciprofloxacin was assessed using the disk diffusion method and by measuring the minimum inhibitory concentration (MIC). Ciprofloxacin induced a dose-dependent antibacterial activity against all bacteria where the highest tested concentration was 100 ug/ml. Results revealed that E. coli cells were highly sensitive to ciprofloxacin (MIC = 0.21 µg/mL ± 0.087), P. aeruginosa and S. aureus cells were intermediately sensitive (MIC = 5.40 µg/mL ± 0.14; MIC = 3.42 µg/mL ± 0.377, respectively), and MRSA cells were highly resistant (MIC = 16.76 µg/mL ± 2.1). Pretreatment of E. coli cells with either vitamin E or vitamin C has significantly protected cells against ciprofloxacin-induced cytotoxicity. These results indicate the possible antagonistic properties for vitamins C or E when they are used concurrently with ciprofloxacin.

Opposite effects of vitamin C and vitamin E on the antifungal activity of honokiol.

The aim of the present study was to evaluate the effects of two well-known natural antioxidants vitamin C (VC) and vitamin E (VE) on the antifungal activity of honokiol against Candida albicans. The broth microdilution method was employed to test the antifungal activities of honokiol with or without antioxidants in the medium against C. albicans strain. Intracellular reactive oxygen species (ROS) and lipid peroxidation were determined by fluorescence staining assay. Mitochondrial dysfunction was assessed by detecting the mitochondrial DNA and the mitochondrial membrane potential. We observed that VC could significantly potentiate the antifungal activities of honokiol while VE reduced the effectiveness of honokiol against C. albicans. In addition, VC accelerated honokiol-induced mitochondrial dysfunction and inhibited glycolysis leading to a decrease in cellular ATP. However, VE could protect against mitochondrial membrane lipid peroxidation and rescue mitochondrial function after honokiol treatment. Our research provides new insight into the understanding of the action mechanism of honokiol and VC combination against C. albicans.

Antioxidant properties of argpyrimidine.

Argpyrimidine, the product of non-enzymatic protein glycation by methylglyoxal, has been implicated in the pathophysiology of diabetes mellitus and neurodegenerative diseases. Chemically, argpyrimidine is a substituted pyrimidinol with structural features common to known antioxidants. The objective of this study was to investigate the antioxidant properties of argpyrimidine. Argpyrimidine was synthesized by mixing L-arginine with 3-acetoxypentane-2,4-dione under acidic conditions and purified by chromatography. Argpyrimidine inhibited lipid peroxidation of rat brain homogenates catalyzed by hydroxyl radicals, metal ions, and autooxidation in a concentration- and time-dependent manner. In addition, argpyrimidine scavenged superoxide anion, 1,1-diphenyl 2-picryl-hydrazyl-stable free radical, intracellular-hydrogen peroxide, and inhibited free-radical-mediated nicking of plasmid-DNA. Taken together, our data suggest that argpyrimidine has antioxidant properties and may therefore have biological relevance in pathophysiologies associated with diabetes mellitus and neurodegenerative diseases.

Potential pro-oxidative effects of single dose of mephedrone in vital organs of mice.

BACKGROUND: Mephedrone is a recreationally used synthetic cathinone, relatively new abusive substances with molecular structure similar to amphetamine. As there is still lack of scientific data regarding mechanisms of action as well as metabolism of mephedrone, especially in aspects other than neurotoxicity, addiction or behavioral changes, therefore we aimed, for the first time, to investigate potential pro-oxidative actions of a single dose of mephedrone in organs other than brain and its structures, i.e. in liver, kidneys, heart and spleen of Swiss mice. METHODS: The following biomarkers of oxidative stress were measured: concentration of ascorbic acid (AA) and malondialdehyde (MDA) as well as total antioxidant capacity (TAC) of the tissues homogenates. RESULTS: Our study revealed that mephedrone intoxication induces oxidative stress by reducing concentration of AA and TAC and increasing concentration of MDA in these organs. CONCLUSIONS: Such occurred state of antioxidant-oxidant imbalance may be etiopathological factor of a number of severe diseases within cardiovascular, digestive as well as immunological systems.

A novel function of monomeric amyloid beta-protein serving as an antioxidant molecule against metal-induced oxidative damage.

Aggregated and oligomeric amyloid beta-protein (Abeta) is known to exhibit neurotoxicity. However, the action of Abeta monomers on neurons is not fully understood. We have studied aggregation state-dependent actions of Abeta and found an oligomer-specific effect of Abeta on lipid metabolism in neurons (Michikawa et al., 2001). Here, we show a novel function of monomeric Abeta1-40, which is the major species found in physiological fluid, as a natural antioxidant molecule that prevents neuronal death caused by transition metal-induced oxidative damage. Monomeric Abeta1-40, which is demonstrated by SDS-PAGE after treatment with glutaraldehyde, protects neurons cultured in a medium containing 1.5 microm Fe(II) without antioxidant molecules. Metal ion chelators such as EDTA, CDTA (trans-1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid), and DTPA (diethylenetriamine-N,N,N',N",N"-penta-acetic acid, an iron-binding protein, transferrin, and antioxidant scavengers such as catalase, glutathione, and vitamin E also inhibit neuronal death under the same conditions. Monomeric Abeta1-40 inhibits neuronal death caused by Cu(II), Fe(II), and Fe(III) but does not protect neurons against H2O2-induced damage. Monomeric Abeta1-40 inhibits the reduction of Fe(III) induced by vitamin C and the generation of superoxides and prevents lipid peroxidation induced by Fe(II). Abeta1-42 remaining as a monomer also exhibits antioxidant and neuroprotective effects. In contrast, oligomeric and aggregated Abeta1-40 and Abeta1-42 lose their neuroprotective activity. These results indicate that monomeric Abeta protects neurons by quenching metal-inducible oxygen radical generation and thereby inhibiting neurotoxicity. Because aggregated Abeta is known to be an oxygen radical generator, our results provide a novel concept that the aggregation-dependent biological effects of Abeta are dualistic, being either an oxygen radical generator or its inhibitor.

Inhibition of free radical-induced peroxidation of rat liver microsomes by resveratrol and its analogues.

Resveratrol (3,5,4'-trans-trihydroxystilbene) is a natural phytoalexin present in grapes and red wine, which possesses a variety of biological activities including antioxidative activity. To find more efficient antioxidants by structural modification, resveratrol analogues, that is, 3,4-dihydroxy-trans-stilbene (3,4-DHS), 4,4'-dihydroxy-trans-stilbene (4,4'-DHS), 4-hydroxy-trans-stilbene (4-HS) and 3,5-dihydroxy-trans-stilbene (3,5-DHS), were synthesized and their antioxidant activity studied for the free radical-induced peroxidation of rat liver microsomes in vitro. The peroxidation was initiated by either a water-soluble azo compound 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH) or Fe(2+)/ascorbate, and monitored by oxygen uptake and formation of thiobarbituric acid reactive substances (TBARS). It was found that all of these trans-stilbene derivatives are effective antioxidants against both AAPH- and iron-induced peroxidation of rat liver microsomes with an activity sequence of 3,4-DHS>4,4'-DHS>resveratrol>4-HS>3,5-DHS. The remarkably higher antioxidant activity of 3,4-DHS is discussed.

Magnesium reduces free radicals in an in vivo coronary occlusion-reperfusion model.

OBJECTIVE: This study demonstrated that magnesium (Mg) reduces free radicals after a brief coronary occlusion-reperfusion sequence. BACKGROUND: Magnesium has been shown to reduce infarct size in patients with acute myocardial infarction. We hypothesized that this action of Mg occurs through its action on free radicals. METHODS: Eighteen mongrel dogs were studied (nine control, nine receiving Mg). Catheters were placed into the coronary sinus for continuous blood withdrawal. A Varian E-4 electron paramagnetic resonance spectrometer was used to monitor the ascorbate free radical (AFR) signal in the coronary sinus blood; AFR is a measure of total oxidative stress. Occlusion of the left anterior descending coronary artery for 20 min was followed by reperfusion. The study animals received 4 g Mg intravenously starting at 15 min of occlusion (5 min before reperfusion) and continuing during reperfusion. RESULTS: Results are presented as percent change from baseline +/- SEM. Magnesium blunted the peak AFR increase: at 4 min of reperfusion there was a 4.7 +/- 3.3% increase in AFR signal in the dogs receiving Mg versus an 18.2 +/- 3.3% increase in the control animals (p < 0.05). Total radical flux was reduced during reperfusion by 53% in the Mg dogs compared with controls (p < 0.05). CONCLUSIONS: Magnesium attenuates AFR increase after an occlusion-reperfusion sequence. To our knowledge this is the first in vivo real-time demonstration of Mg's impact on free radicals.

U937 cell apoptosis induced by arsenite is prevented by low concentrations of mitochondrial ascorbic acid with hardly any effect mediated by the cytosolic fraction of the vitamin.

Arsenite directly triggers cytochrome c and Smac/DIABLO release in mitochondria isolated from U937 cells. These effects were not observed in mitochondria pre-exposed for 15 min to 10 µM L-ascorbic acid (AA). In other experiments, intact cells treated for 24-72 h with arsenite were found to die by apoptosis through a mechanism involving mitochondrial permeability transition. Pre-exposure (15 min) to low micromolar concentrations of AA and dehydroascorbic acid (DHA), resulting in identical cytosolic levels of the vitamin, had a diverse impact on cell survival, as cytoprotection was only observed after treatment with AA. Also the mitochondrial accumulation of the vitamin was restricted to AA exposure. An additional indication linking cytoprotection to the mitochondrial fraction of the vitamin was obtained in experiments measuring susceptibility to arsenite in parallel with loss of mitochondrial and cytosolic AA at different times after vitamin exposure. Finally, we took advantage of our recent findings that DHA potently inhibits AA transport to demonstrate that DHA abolishes all the protective effects of AA, under the same conditions in which the mitochondrial accumulation of the vitamin is prevented without affecting the overall cellular accumulation of the vitamin.

Ascorbate-mediated electron transfer in protein thiol oxidation in the endoplasmic reticulum.

Addition of, or gulonolactone oxidase-dependent in situ generation of, ascorbate provoked the oxidation of protein thiols, which was accompanied by ascorbate consumption in liver microsomal vesicles. The maximal rate of protein thiol oxidation was similar upon gulonolactone, ascorbate or dehydroascorbate addition. Cytochrome P450 inhibitors (econazole, proadifen, quercetin) decreased ascorbate consumption and the gulonolactone or ascorbate-stimulated thiol oxidation. The results demonstrate that the ascorbate/dehydroascorbate redox couple plays an important role in electron transfer from protein thiols to oxygen in the hepatic endoplasmic reticulum, even in gulonolactone oxidase deficient species.

Intracellular flavonoids as electron donors for extracellular ferricyanide reduction in human erythrocytes.

Reduction of extracellular ferricyanide [Fe(CN)(6)](-3) to ferrocyanide by intact cells reflects the activity of a trans-plasma membrane oxidoreductase that, in human red blood cells, utilizes ascorbic acid as an electron donor. We herein report that the flavonoids quercetin and myricetin, while inhibiting dehydroascorbic acid uptake-and thus the erythrocyte ascorbic acid content-effectively stimulate the extracellular reduction of ferricyanide. Other flavonoids such as rutin, acacetin, apigenin, and genistein do not show the same effect. The notion that quercetin or myricetin may serve as an intracellular donor for a trans-plasma membrane oxidoreductase is supported by the following lines of evidence: (i) they afford direct reduction of ferricyanide; (ii) extracellular reduction of ferricyanide was not mediated by direct effects of the flavonoids released by the cells and was abolished by the sulphydryl reagent parachloromercuribenzenesulfonic acid (pCMBS); (iii) the intracellular concentrations of quercetin or myricetin well correlate with increases in ferricyanide reduction; (iv) the intracellular concentration of the flavonoids dramatically declines after ferricyanide exposure. Taken together, the results presented in this study demonstrate that myricetin and quercetin, which accumulate in large amounts in red blood cells, act as intracellular substrates of a pCMBS-sensitive trans-plasma membrane oxidoreductase. This may represent a novel mechanism whereby these flavonoids exert beneficial effects under oxidative stress conditions.

Tetradecylthioacetic acid and tetradecylselenoacetic acid inhibit lipid peroxidation and interact with superoxide radical.

Reactive oxygen species are thought to induce cellular damage and to play a pathological role in several human diseases. Tetradecylthioacetic acid (TTA) was previously reported to prevent the oxidative modification of low-density lipoprotein (LDL) particles and to act as an antioxidant. In this study we present a new fatty acid analogue, namely tetradecylselenoacetic acid (TSA), in which the sulfur atom of TTA is replaced by a selenium atom. TSA was more potent than TTA in increasing the lag time before the onset of LDL oxidation and this effect was dose dependent. TTA and TSA were shown to reduce the iron-ascorbate-induced microsomal lipid peroxidation, TSA being more efficient than TTA. TTA and TSA, in the presence of iron, interacted with the superoxide radical as assessed by direct and indirect testing methods. TSA like TTA failed to scavenge 1.1-diphenyl-2-picrylhydrazyl radicals. TSA bound copper ions as shown by the wavelength spectra measurement. These results suggest that TTA and TSA exert their antioxidant capacity by interaction with copper or iron ions in radical scavenging, TSA being more potent than TTA. Nevertheless, a chelating effect resulting in chemically inactive metal ions cannot be excluded.

Differences in basal airway antioxidant concentrations are not predictive of individual responsiveness to ozone: a comparison of healthy and mild asthmatic subjects.

The air pollutant ozone induces both airway inflammation and restrictions in lung function. These responses have been proposed to arise as a consequence of the oxidizing nature of ozone, depleting endogenous antioxidant defenses with ensuing tissue injury. In this study we examined the impact of an environmentally relevant ozone challenge on the antioxidant defenses present at the surface of the lung in two groups known to have profound differences in their antioxidant defense network: healthy control (HC) and mild asthmatic (MA) subjects. We hypothesized that baseline differences in antioxidant concentrations within the respiratory tract lining fluid (RTLF), as well as induced responses, would predict the magnitude of individual responsiveness. We observed a significant loss of ascorbate (ASC) from proximal (-45.1%, p <.01) and distal RTLFs (-11.7%, p <.05) in healthy subjects 6 h after the end of the ozone challenge. This was associated (Rs, -0.71, p <.01) with increased glutathione disulphide (GSSG) in these compartments (p =.01 and p <.05). Corresponding responses were not seen in asthmatics, where basal ASC concentrations were significantly lower (p <.01) and associated with elevated concentrations of GSSG (p <.05). In neither group was any evidence of lipid oxidation seen following ozone. Despite differences in antioxidant levels and response, the magnitude of ozone-induced neutrophilia (+20.6%, p <.01 [HC] vs. +15.2%, p =.01 [MA]) and decrements in FEV(1) (-8.0%, p <.01 [HC] vs. -3.2%, p <.05 [MA]) did not differ between the two groups. These data demonstrate significant differences between the interaction of ozone with RTLF antioxidants in MA and HC subjects. These responses and variations in basal antioxidant defense were not, however, useful predictive markers of group or individual responsiveness to ozone.

The natural antioxidant otobaphenol delays the permeability transition of mitochondria and induces their aggregation.

The lignan otobaphenol, (8R,8'R,7R)-4'-hydroxy-5'-methoxy-3,4-methylenedioxy-2',7,8,8'-neolignan, extracted from Virola Aff. Pavonis leaves, completely inhibits at a concentration of 2.5 micro M the Fe(3+)-ascorbate-induced lipoperoxidation of rat liver mitochondria that was determined by oxygen consumption and accumulation of thiobarbituric acid-reactive species. At 25 micro M, it delays the mitochondrial permeability transition induced by tert-butyl hydroperoxide or Ca(2+), substantially inhibits the state 3 respiration, does not affect the state 4 respiration and the ADP/O ratio (with succinate), diminishes the rate of Ca(2+) uptake by mitochondria, and delays the ruthenium red-insensitive uncoupler-induced release of the loaded Ca(2+). Dose-dependent delaying of the calcium-induced swelling of mitochondria in the presence of otobaphenol nonlinearly correlates with its 1,1-diphenyl-2-picrylhydrazyl free radical scavenging activity. At 75 micro M and higher, this lignan causes mitochondrial aggregation and is able to aggregate itself, without mitochondria. The formed aggregates of otobaphenol do not cause an aggregation of subsequently added mitochondria. Thus, otobaphenol seems to be a promising target to prevent the oxidative stress death of cells.

Ascorbic acid uptake by young and aged guinea pig lenses.

The dynamics of in vitro uptake of [14C]-ascorbic acid into intact lenses of young (50 days old) and old (730 days old) guinea pigs was evaluated in this study. Two-dimensional protein gel analysis of [35S]-methionine labeled proteins provided evidence that the isolated lenses were viable throughout the culture period. It was found that the in vitro uptake of ascorbate into these lenses follows similar saturation kinetics for lenses from both age groups. Moreover, the linear uptake rate was identical. Ascorbate transport was inhibited by phloretin, p-chloromercuribenzoate, insulin, glucose and ouabain; however, no inhibition was observed with 2,4-dinitrophenol or NaF. These results suggest that the lenticular ascorbate concentration is regulated by a facilitated diffusion process and it not energy-dependent. Data on ascorbate transport into lenses from aged guinea pigs provide strong evidence that the abnormally low ascorbic acid concentrations in lenses of old mammals is not likely the result of a decreased lenticular uptake ability.