Determination of nitecapone and (13C6)nitecapone in human plasma by gas chromatography/mass spectrometry.

A gas chromatographic/mass spectrometric method is developed and validated for simultaneous determination of nitecapone and its 13C6-labelled analogue in human plasma using (2H6,13C6)nitecapone as internal standard. The method involves extraction of the analytes from plasma to ethyl acetate-hexane mixture (20:80) and conversion to bis(trimethylsilyl) ethers prior to determination by gas chromatography/mass spectrometry using selected ion monitoring. The quantification range is 0.5-2000 ng ml-1. Precision ranges from 11.3% (coefficient of variation) at low levels to 2.4% at high levels. Recovery is about 50% in the whole range. The method is applied to a pharmacokinetic study where nitecapone diluted with 14C-labelled nitecapone is given intravenously concomitantly with an oral dose of (13C6)nitecapone.     

Antioxidant activity of active tannoid principles of Emblica officinalis (amla).

The antioxidant activity of tannoid active principles of E. officinalis consisting of emblicanin A (37%), emblicanin B (33%), punigluconin (12%) and pedunculagin (14%), was investigated on the basis of their effects on rat brain frontal cortical and striatal concentrations of the oxidative free radical scavenging enzymes, superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX), and lipid peroxidation, in terms of thiobarbituric acid-reactive products. The results were compared with effects induced by deprenyl, a selective monoamine oxidase (MAO) B inhibitor with well documented antioxidant activity. The active tannoids of E. officinalis (EOT), administered in the doses of 5 and 10 mg/kg, i.p., and deprenyl (2 mg/kg, i.p.), induced an increase in both frontal cortical and striatal SOD, CAT and GPX activity, with concomitant decrease in lipid peroxidation in these brain areas when administered once daily for 7 days. Acute single administration of EOT and deprenyl had insignificant effects. The results also indicate that the antioxidant activity of E. officinalis may reside in the tannoids of the fruits of the plant, which have vitamin C-like properties, rather than vitamin C itself.     

Antioxidant properties of alpha-crystallin

-Crystallin is a major chaperone lens protein to which has been ascribed antioxidant functions. In the present work we have evaluated the antioxidant and free radical scavenging properties of bovine -crystallin in a series of in vitro models: zimosan-induced, luminol-enhanced chemiluminescence response of polymorphonuclear leukocytes, the autoxidation of brain homogenate, bleaching of 2,2-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)-derived radical cations, trapping of peroxyl radicals, and reactivity toward hypochloric acid. In all these systems, the reactivity of -crystallin is higher than or similar to that of bovine serum albumin. It is concluded that, given the high concentrations of -crystallin in the lenses, its capacity to interact with free radicals and to remove hypochlorous acid could contribute to the maintenance of the lens functionality.     

Antioxidant properties of steroids

To determine the relative ranking of antioxidative potential of various steroids the effect of 14 steroid compounds on the fluorescence of phycoerythrin was monitored over time following the addition of a peroxy radical generator 2,2′-azobis (2-amidino-propane) dihydrochloride. The rate of decay of fluorescence in the presence of a 200 nM of 17β-estradiol, 17-estradiol and estriol expressed as percentages of the rate of decay in the absence of these compounds (control curve), were 74.1±6.3, 84.0±5.42 and 64.2±2.53%, respectively (P<0.005). Cortisone and corticosterone appeared to have very mild proxidant properties. Other steroids tested such as esterone, testosterone, progesterone, androstenedione, dehydroepiandrosterone, cortisol, tetrahydrocortisone, deoxycorticosterone and aldosterone had no significant antioxident properties. It is concluded that estrogens especially estriol and 17β-estradiol are naturally occurring antioxidants.     

Antioxidant properties of ganglioside micelles

Antioxidant activity of gangliosides GM1 and GT1b in the Fenton type of reaction was investigated by EPR spectroscopy using DMPO as a spin trap. Hydroxyl radical spin adduct signal intensity was significantly reduced in the presence of gangliosides at their micellar concentrations. Mean micellar hydrodynamic diameter was not changed, whereas significant changes in negative Zeta potential values were observed as evidenced by Zetasizer Nano ZS. This study showed that the primary mode of ganglioside action was not due to direct scavenging of OH·, but rather to the inhibition of hydroxyl radical formation. This phenomenon is related to the ability of ganglioside micelles to bind oppositely charged ferrous ions, thus reducing their concentration and consequently inhibiting OH· formation.     

Antioxidant properties of essential oils

By the method of capillary gas-liquid chromatography, we studied the antioxidant properties and stability during the storage of hexane solutions of 14 individual essential oils from black and white pepper (Piper nigrum L.), cardamom (Elettaria cardamomum L.), nutmeg (Myristica fragrans Houtt.), mace (Myristica fragrans Houtt), juniper berry (Juniperus communis L.), fennel seed (Foeniculum vulgare Mill., var. dulce Thelling), caraway (Carvum carvi L.), dry cinnamon leaves (Cinnamomum zeylanicum Bl.), marjoram (Origanum majorana L.), laurel (Laurus nobilis L.), ginger (Zingiber officinale L.), garlic (Allium sativum L.), and clove bud (Caryophyllus aromaticus L.). We assessed the antioxidant properties by the oxidation of aliphatic aldehyde (trans-2-hexenal) into the corresponding carbonic acid. We established that essential oils of garlic, clove bud, ginger and leaves of cinnamon have the maximal efficiency of inhibiting hexenal oxidation (80!–93%), while black pepper oil has the minimal (49%). Antioxidant properties of essential oils with a high content of substituted phenols depended poorly on their concentrations in model systems. We studied the changes in the composition of essential oils during the storage of their hexane solutions for 40 days in light and compared it with the stability of essential oils stored for a year in darkness.     

Antioxidant properties of myocardial fuels

Oxidative metabolism of blood-borne fuels provides myocardium the energy required to sustain its contractile performance. Recent research has revealed that, in addition to supplying energy, certain fuels are able to detoxify harmful oxidants and bolster the myocardium's endogenous antioxidant defenses. These antioxidant capabilities could potentially protect the myocardium from the ravages of reactive oxygen and nitrogen intermediates generated upon reperfusion of ischemic myocardium. This article reviews experimental evidence that two fuels, pyruvate and acetoacetate, provide such antioxidant protection. Pyruvate's antioxidant properties stem in part from its -keto carboxylate structure, which enables it to directly, non-enzymatically neutralize peroxides and peroxynitrite. Also, citrate, which accumulates in pyruvate-perfused myocardium following anaplerotic pyruvate carboxylation, supports NADPH production to maintain glutathione:glutathione disulfide (GSH/GSSG) redox potential, the central component of the myocardial antioxidant system. Like pyruvate, acetoacetate restores GSH/GSSG and increases contractile function of post-ischemic stunned myocardium, although some of its antioxidant mechanisms may differ from pyruvate's. Both compounds restore -adrenergic signaling and inotropism, which are compromised in stunned myocardium. N-acetylcysteine, a pharmacological antioxidant that does not provide energy, duplicated the salutary effects of pyruvate and acetoacetate on post-ischemic -adrenergic signaling and GSH/GSSG. These findings reveal novel, energy-independent mechanisms for enhancement of post-ischemic cardiac performance by metabolic fuels.     

Antioxidant properties of Mannich bases

The biological importance of antioxidants influenced to synthesize some curcumin-related compounds as potential antioxidants. Accordingly, a series of 2,4-diaryl-3-azabicyco[3.3.1]nonan-9-ones were synthesized with polyphenolic and/or polymethoxyphenyl groups by modified Mannich condensations. The yield was significantly improved using BF₃·SiO₂ as heterogeneous catalyst under mild conditions. Stereochemistry of all the synthesized compounds was established as twin-chair with an equatorial disposition of the aryl groups, through their NMR and XRD interpretations. The ABNs 8 (curcumin analog) and 10 (bis-demethoxycurcumin analog) showed an effective profile over curcumin, α-tocopherol, and vitamin C by chemical methods. Further, the efficiency of one of the active molecules, ABN 10, was demonstrated by its intracellular ROS inhibition activity on RAW 264.7 macrophage cells by FACS analysis in dose-dependent manner.     

Antioxidant properties of galantamine hydrobromide

The antioxidant properties of galantamine hydrobromide ((4alpha,6beta)-4a,5,9,10,11,12-hexahydro-3-methoxy-11-methyl-6H-benzofuro[3a,3,2-ef][2]benzazepin-6-ol hydrobromide) were studied in vitro, using luminol-dependent chemiluminescence and spectrophotometry. It was found that this compound was a scavenger of reactive oxygen species (ROS). By comparing the antioxidant effects of galantamine ((4alpha,6beta)-4a,5,9,10,11,12-hexahydro-3-methoxy-11-methyl-6H-benzofuro[3a,3,2-ef][2]benzazepin-6-ol), galantamine hydrobromide, narwedine (4a,5,9,10,11,12-hexahydro-3-methoxy-11-methyl-6H-benzofuro[3a,3,2-ef][2]benzazepin-6-one), and narwedine hydrobromide it was found that the antioxidant activity depended on the enolic OH group in the molecule. The presence of a quaternary nitrogen in the compound increased the strength of the scavenging effect. It is proposed that the antioxidant properties observed in vitro may contribute to the therapeutical effect of galantamine hydrobromide on patients with brain degeneration.     

Antioxidant properties of di-tert-butylhydroxylated flavonoids

Epidemiological evidence suggests an inverse relationship between dietary intake of flavonoids and cardiovascular risk. The biological activities of flavonoids are related to their antioxidative effects, but they also can be mutagenic, due to the prooxidant activity of the catechol pattern. To prevent these problems, we synthesized new flavonoids where one or two di-tert-butylhydroxyphenyl (DBHP) groups replaced catechol moiety at position 2 of the benzopyrane heterocycle. Two DBHP moieties can also be arranged in an arylidene structure or one DBHP fixed on a chalcone structure. Position 7 on the flavone and arylidene or position 4 on the chalcone was substituted by H, OCH(3), or OH. New structures were compared with quercetin and BHT in an LDL oxidation system induced by Cu(II) ions. Arylidenes and chalcones had the best activities (ED(50) = 0.86 and 0.21) compared with vitamin E, BHT, and quercetin (ED(50) = 10.0, 7. 4, and 2.3 microM). Activity towards stable free radical 1, 1-diphenyl-2-picryl-hydrazyl (DPPH) was measured by log Z and ECR(50) parameters. Synthesized flavones proved to be poor DPPH radical scavengers, the activity increasing with the number of DBHP units. In contrast, arylidenes and chalcones were stronger DPPH radical scavengers (log Z > 3, 0.3 < ECR(50) < 2.12) than BHT (log Z = 0.75, ECR(50) = 12.56) or quercetin (log Z = 2.76, ECR(50) = 0.43). Unlike quercetin, synthesized compounds neither chelated nor reduced copper, proving that these new flavonoids had no prooxidant activity in vitro.     

Antioxidant properties of ganglioside micelles

Antioxidant activity of gangliosides GM1 and GT1b in the Fenton type of reaction was investigated by EPR spectroscopy using DMPO as a spin trap. Hydroxyl radical spin adduct signal intensity was significantly reduced in the presence of gangliosides at their micellar concentrations. Mean micellar hydrodynamic diameter was not changed, whereas significant changes in negative Zeta potential values were observed as evidenced by Zetasizer Nano ZS. This study showed that the primary mode of ganglioside action was not due to direct scavenging of OH·, but rather to the inhibition of hydroxyl radical formation. This phenomenon is related to the ability of ganglioside micelles to bind oppositely charged ferrous ions, thus reducing their concentration and consequently inhibiting OH· formation.     

Antioxidant properties of S-adenosyl-L-methionine in Fe(2+)-initiated oxidations

S-Adenosylmethionine (SAM) is protective against a variety of toxic agents that promote oxidative stress. One mechanism for this protective effect of SAM is increased synthesis of glutathione. We evaluated whether SAM is protective via possible antioxidant-like activities. Aerobic Hepes-buffered solutions of Fe2+ spontaneously oxidize and consume O2 with concomitant production of reactive oxygen species and oxidation of substrates to radical products, e.g., ethanol to hydroxyethyl radical. SAM inhibited this oxidation of ethanol and inhibited aerobic Fe2+ oxidation and consumption of O2. SAM did not regenerate Fe2+ from Fe3+ and was not consumed after incubation with Fe2+. SAM less effectively inhibited aerobic Fe2+ oxidation in the presence of competing chelating agents such as EDTA, citrate, and ADP. The effects of SAM were mimicked by S-adenosylhomocysteine, but not by methionine or methylthioadenosine. SAM did not inhibit Fe2+ oxidation by H2O2 and was a relatively poor inhibitor of the Fenton reaction. Lipid peroxidation initiated by Fe2+ in liposomes was associated with Fe2+ oxidation; these two processes were inhibited by SAM. However, SAM did not show significant peroxyl radical scavenging activity. SAM also inhibited the nonenzymatic lipid peroxidation initiated by Fe2+ + ascorbate in rat liver microsomes. These results suggest that SAM inhibits alcohol and lipid oxidation mainly by Fe2+ chelation and inhibition of Fe2+ autoxidation. This could represent an important mechanism by which SAM exerts cellular protective actions and reduces oxidative stress in biological systems.     

Relationship between genetic polymorphism of CYP1A1 at codon 462 (Ile462Val) in colorectal cancer

AIMS AND BACKGROUND: The enzyme cytochrome P450 plays an important role in the metabolization and detoxification of various compounds. CYP1A1 is a polymorphic enzyme and some of its alleles have been correlated with an increased risk of developing various types of cancer. The aim of this study was to investigate the incidence of the polymorphism A-->G (Ile462Val, exon 7) in colorectal cancer patients and the correlation of this polymorphism with others risk factors. PATIENTS AND METHODS: 114 Brazilian patients with colorectal cancer were matched by age and sex to 114 healthy individuals. DNA was extracted from peripheral blood and the genotypes of the polymorphisms were assessed by PCR-restriction fragment length polymorphism. RESULTS: In the case group 64 subjects were male, 53 were alcohol users and 68 were smokers. In the control group 61 were male, 67 were alcohol users and 53 smokers. There were 14 subjects with wild-type homozygous A/A, 97 with heterozygous A/G, and 3 with homozygous mutated G/G in the cancer group versus 81 subjects with wild-type homozygous A/A and 33 with heterozygous A/G in the control group. The presence of the G allele (OR 5.14, 95%CI 3.15-10.80) was associated with an increased risk of colorectal cancer (p=0.001). The prevalence of smokers was higher in the cancer group (p=0.047, OR 1.71, 95%CI 1.03-3.11). CONCLUSION: These results suggest a positive association between the A-->G polymorphism and the risk of colorectal cancer. In addition, smoking was also a colorectal cancer risk. We did not find any correlation between this polymorphism and sex, grade of differentiation, stage, or evolution of the disease.     

Antioxidant,Antibacterial and Antischistosomal Activities of Extracts from Grateloupia livida (Harv). Yamada

The present study was designated to evaluate the antioxidant, antibacterial and antischistosomal activities of Grateloupia livida (GL) extracts in vitro. A GL Ethanol extract (EE) was separated into petroleum ether (PE), ethyl acetate (EA), n-butyl alcohol (BuOH) and aqueous (AQ) fractions to fractionate the polar and non-polar compounds in the EE. Extracts antioxidant activities were evaluated in vitro by DPPH radical-scavenging, deoxyribose radical scavenging, and β-carotene bleaching assays, all using butylated hydroxytoluene (BHT) as the reference antioxidant compound. The most effective antioxidant properties were observed in the PE fraction in all three assays. Antimicrobial testing showed that the PE fraction exhibited broad-spectrum antimicrobial activity, with the PE fraction also exhibiting strong activity against the human pathogenic trematode S. japonicum adult worm. In order to investigate the relationships between bioactivity and chemical composition, the chemical composition of the PE fraction was analyzed by gas chromatography-mass spectrometry (GC-MS). In total, 25 components were identified in the PE fraction, most of which have known antioxidant and antimicrobial activities. However, none of the compounds have reported activity against Schistosoma, suggesting that the schistosomicidal activity of the PE fraction may be related to minor constituents present in the extract, or governed by more intricate synergistic or additive relationships. Finally, fractions with the greatest biological activity displayed neither cellular cytotoxicity, at concentrations up to 100 ug/ml, or acute oral toxicity in mice, at doses up to 2000 mg/kg. Based on antioxidant, antimicrobial, antischistosomal activities, and low toxicity, the PE fraction possesses properties useful for food preservation and overall improvement of human health.     

Characteristic morphology of intracellular microcolonies of Legionella oakridgensis OR-10

Legionella oakridgensis occasionally causes pneumonia in humans. We report here the characteristic morphology of intracellular microcolonies of L. oakridgensis OR-10 in infected epithelial cells. By light microscopy after Gimenez staining, the bacteria showed serpentine-like chain, disk-like conglomerate, and granular forms when they grew intracellularly in Vero cells, HeLa cells, and A549 cells. In a time-lapse study, we observed the progressive change from a serpentine-like chain form to a conglomerate form in Vero cells. Transmission electron microscopy showed that L. oakridgensis OR-10 proliferated both inside membrane structures and in the cytoplasm. Such highly serpentine chain growth has not been reported in any intracellular bacteria. Furthermore, these results imply that L. oakridgensis OR-10 may be proliferating inside the endoplasmic reticulum.     

Antioxidant properties of 2-O-beta-D-glucopyranosyl-L-ascorbic acid

The antioxidant activity of a provitamin C agent, 2-O-beta-D-glucopyranosyl-L-ascorbic acid (AA-2betaG), was compared to that of 2-O-alpha-D-glucopyranosyl-L-ascorbic acid (AA-2G) and ascorbic acid (AA) using four in vitro methods, 1,1-diphenyl-picrylhydrazyl (DPPH) radical-scavenging assay, 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS(*+))-scavenging assay, oxygen radical absorbance capacity (ORAC) assay, and 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH)-induced erythrocyte hemolysis inhibition assay. AA-2betaG slowly and continuously scavenged DPPH radicals and ABTS(*+) in roughly the same reaction profiles as AA-2G, whereas AA quenched these radicals immediately. In the ORAC assay and the hemolysis inhibition assay, AA-2betaG showed similar overall activities to AA-2G and to AA, although the reactivity of AA-2betaG against the peroxyl radical generated in both assays was lower than that of AA-2G and AA. These data indicate that AA-2betaG had roughly the same radical-scavenging properties as AA-2G, and a comprehensive in vitro antioxidant activity of AA-2betaG appeared to be comparable not only to that of AA-2G but also to that of AA.     

Antioxidant properties of 3-hydroxycoumarin derivatives

A series of hydroxylated 3-hydroxycoumarins was synthesised by the reaction of 3-aryl-2-hydroxypropenoic derivatives with boron tribromide. They were evaluated for their ability to scavenge the 2,2-diphenyl-1-picrylhydrazyl radical, the superoxide anion radical, the hydroxyl radical and the peroxynitrite anion and to inhibit copper-induced human LDL peroxidation. The physicochemical results were in accordance to establish the compounds hydroxylated on C-6 and C-7 positions as the most active of the series with antioxidant potencies comparable to those of quercetin and vitamin C. These compounds form o- and p-quinonoid derivatives upon radical scavenging and may serve as new lead compounds for pharmacological investigations.     

Antioxidant and prooxidant properties of carotenoids

The ability of dietary carotenoids such as beta-carotene and lycopene to act as antioxidants in biological systems is dependent upon a number of factors. While the structure of carotenoids, especially the conjugated double bond system, gives rise to many of the fundamental properties of these molecules, it also affects how these molecules are incorporated into biological membranes. This, in turn, alters the way these molecules interact with reactive oxygen species, so that the in vivo behavior may be quite different from that seen in solution. The effectiveness of carotenoids as antioxidants is also dependent upon their interaction with other coantioxidants, especially vitamins E and C. Carotenoids may, however, lose their effectiveness as antioxidants at high concentrations or at high partial pressures of oxygen. It is unlikely that carotenoids actually act as prooxidants in biological systems; rather they exhibit a tendency to lose their effectiveness as antioxidants.