Extracellular thermostable proteolytic activity of the milk spoilage bacterium Pseudomonas fluorescens PS19 on bovine caseins.

We studied the thermostable proteolytic activity of Pseudomonas fluorescens PS19 isolated from raw bovine milk. The heat-treated cell-free supernatant (HT-CFS) contained a thermostable protease of approximately 45 kDa, as revealed by casein zymography. We assigned this enzyme to P. fluorescens AprX metalloprotease (UniProtKB Acc. No. C9WKP6). After concentration by ultrafiltration at 10 kDa, the HT-CFS showed 2 other thermostable proteolytic bands on zymogram, with molecular masses of approximately 15 and 25 kDa. The former resulted a fragment of the AprX protease, whereas the 25-kDa protease was not homologous to any known protein of Pseudomonas spp. Subsequently, we assessed the proteolytic activity of the HT-CFS on bovine αS-, ß-, and κ-casein during in vitro incubation at 7 or 22°C. By means of ultra-performance liquid chromatography-tandem mass spectrometry we identified the released peptides (n=591). Some of them resisted proteolysis during the whole incubation period at both incubation temperatures and, therefore, they could be assumed as indicators of the proteolytic action of P. fluorescens PS19 on bovine caseins.

Unraveling the parahormetic mechanism underlying the health-protecting effects of grapeseed procyanidins.

Proanthocyanidins (PACs), the predominant constituents within Grape Seed Extract (GSE), are intricate compounds composed of interconnected flavan-3-ol units. Renowned for their health-affirming properties, PACs offer a shield against a spectrum of inflammation associated diseases, such as diabetes, obesity, degenerations and possibly cancer. While monomeric and dimeric PACs undergo some absorption within the gastrointestinal tract, their larger oligomeric and polymeric counterparts are not bioavailable. However, higher molecular weight PACs engage with the colonic microbiota, fostering the production of bioavailable metabolites that undergo metabolic processes, culminating in the emergence of bioactive agents capable of modulating physiological processes. Within this investigation, a GSE enriched with polymeric PACs was employed to explore in detail their impact. Through comprehensive analysis, the present study unequivocally verified the gastrointestinal-mediated transformation of medium to high molecular weight polymeric PACs, thereby establishing the bioaccessibility of a principal catabolite termed 5-(3',4'-dihydroxyphenyl)-γ-valerolactone (VL). Notably, our findings, encompassing cell biology, chemistry and proteomics, converge to the proposal of the notion of the capacity of VL to activate, upon oxidation to the corresponding quinone, the nuclear factor E2-related factor 2 (Nrf2) pathway-an intricate process that incites cellular defenses and mitigates stress-induced responses, such as a challenge brought by TNFα. This mechanistic paradigm seamlessly aligns with the concept of para-hormesis, ultimately orchestrating the resilience to stress and the preservation of cellular redox equilibrium and homeostasis as benchmarks of health.

Supplementation-induced change in muscle carnosine is paralleled by changes in muscle metabolism, protein glycation and reactive carbonyl species sequestering.

Carnosine is a performance-enhancing food supplement with a potential to modulate muscle energy metabolism and toxic metabolites disposal. In this study we explored interrelations between carnosine supplementation (2 g/day, 12 weeks) induced effects on carnosine muscle loading and parallel changes in (i) muscle energy metabolism, (ii) serum albumin glycation and (iii) reactive carbonyl species sequestering in twelve (M/F=10/2) sedentary, overweight-to-obese (BMI: 30.0+/-2.7 kg/m2) adults (40.1+/-6.2 years). Muscle carnosine concentration (Proton Magnetic Resonance Spectroscopy; 1H-MRS), dynamics of muscle energy metabolism (Phosphorus Magnetic Resonance Spectroscopy; 31P-MRS), body composition (Magnetic Resonance Imaging; MRI), resting energy expenditure (indirect calorimetry), glucose tolerance (oGTT), habitual physical activity (accelerometers), serum carnosine and carnosinase-1 content/activity (ELISA), albumin glycation, urinary carnosine and carnosine-propanal concentration (mass spectrometry) were measured. Supplementation-induced increase in muscle carnosine was paralleled by improved dynamics of muscle post-exercise phosphocreatine recovery, decreased serum albumin glycation and enhanced urinary carnosine-propanal excretion (all p<0.05). Magnitude of supplementation-induced muscle carnosine accumulation was higher in individuals with lower baseline muscle carnosine, who had lower BMI, higher physical activity level, lower resting intramuscular pH, but similar muscle mass and dietary protein preference. Level of supplementation-induced increase in muscle carnosine correlated with reduction of protein glycation, increase in reactive carbonyl species sequestering, and acceleration of muscle post-exercise phosphocreatine recovery.

Acute preexercise supplementation of combined carnosine and anserine enhances initial maximal power of Wingate tests in humans.

Classic in vitro experiments (Severin's phenomenon) demonstrated that acute carnosine supplementation may potentiate muscle contractility. However, upon oral ingestion, carnosine is readily degraded in human plasma by the highly active serum carnosinase-1 (CN1). We developed a novel strategy to circumvent CN1 by preexercise ingestion of combined carnosine (CARN) and anserine (ANS), the methylated analog with similar biochemical properties but more resistant to CN1. First, in vitro hydrolysis was tested by adding carnosine and anserine to human plasma, alone or in combination. Second, five subjects were supplemented with 25 mg/kg anserine or 25 mg/kg of each anserine and carnosine to test in vivo bioavailability. Third, two double-blind, placebo-controlled, crossover studies investigated the effect of preexercise ANS + CARN (20 mg/kg body wt of each) supplementation on performance during a single all-out Wingate test following 6-min high-intensity cycling (study A) or three repeated Wingate tests (study B). In vitro experiments demonstrated slower degradation of anserine versus carnosine, which was further slowed by simultaneously adding carnosine. In vivo bioavailability of plasma anserine was more prominent [2.5-fold increased area under the curve (AUC)] when ANS + CARN versus ANS was ingested. Study A showed significantly higher (+6% ± 11%; P = 0.04) power in the first 5 s of the Wingate test following ANS + CARN (12.8 ± 2.4 W/kg) versus placebo (12.1 ± 2.2 W/kg). Study B demonstrated increased peak power (+3%) throughout three consecutive Wingate tests (ANS + CARN 10.5 ± 0.6 W/kg vs. placebo 10.2 ± 9.9 W/kg). These experiments reveal a novel acute nutritional method to effectively raise plasma anserine and carnosine by high-dose combined supplementation. This approach led to improved initial cycling power, revealing a new nutritional strategy to increase exercise performance.NEW & NOTEWORTHY Current results reveal that carnosine and anserine competitively bind to the highly active carnosinase enzyme in human plasma. Acute combined carnosine and anserine supplementation is therefore described as novel strategy to raise plasma anserine and carnosine. We report that indices of maximal exercise/muscle power during the initial stage of a Wingate test were significantly improved by preexercise 20-25mg/kg body wt anserine and carnosine supplementation, pointing toward a novel acute nutritional strategy to improve high-intensity exercise performance.

Pharmacokinetic profile of bilberry anthocyanins in rats and the role of glucose transporters: LC-MS/MS and computational studies.

The aim of the present investigation was to better understand the pharmacokinetic profile of bilberry (Vaccinium Myrtillus) anthocyanins and the role of glucose transporters (sGLT1 and GLUT2) on their absorption. In particular, the absorption of 15 different anthocyanins contained in a standardized bilberry extract (Mirtoselect®) was measured in rats by a validated LC-ESI-MS/MS approach. The plasma concentration peak (Cmax) of 11.1ng/mL was reached after 30min and fasting condition significantly increased the bioavailability of anthocyanins by more than 7 fold in respect to fed rats. Glucose co-administration did not interfere with the overall anthocyanin uptake. Bioavailability of each anthocyanin was then estimated by comparing the relative content in plasma vs extract. The 15 anthocyanins behaved differently in term of bioavailability and both the aglycone and the sugar moiety were found to affect the absorption. For instance, arabinoside moiety was detrimental while cyanidin enhanced bioavailability. Computational studies permitted to rationalize such results, highlighting the role of glucose transporters (sGLT1 and GLUT2) in anthocyanins absorption. In particular a significant correlation was found for the 15 anthocyanins between sGLT1 and GLUT2 recognition and absorption.

Antioxidant activity of polyphenols from solid olive residues of c.v. Coratina.

The antioxidant profile of extracts from solid olive residue (SOR) of c.v. Coratina, a cultivar widely diffused in the south of Italy, using both cell-free and cell-based experimental models, was investigated. A total hydroalcoholic extract (polyphenols content 19.7%) and a purified extract (Oleaselecttrade mark) (polyphenols content 35.1%) were tested for their ability to quench the stable free radical DPPH, the peroxyl radicals (ORAC assay), by monitoring the loss in fluorescence of R-phycoerythrin induced by the peroxyl radical generator AAPH and their ability to inhibit the cumene hydroperoxide-induced lysis of rat red blood cells (RBC). The total hydroalcoholic extract showed IC(50) 26.96+/-1.53 microg/ml in the DPPH assay, that 10 microg/ml were equivalent to 2.11+/-0.12 microg/ml Trolox (ORAC assay) and IC(50) 1.7+/-0.20 microg/ml in the RBC hemolysis. The Oleaselect extract was 4 to 5 folds more active than the hydroalcoholic extract in all the experimental models, with IC(50) values of 7.36+/-0.38 microg/ml in the DPPH test and of 0.38+/-0.03 microg/ml in RBC; the antioxidant activity in the ORAC assay was slightly greater than that of Trolox (10 microg/ml equivalent to 11.45+/-0.40 microg/ml). The scavenging effect of the extract in the ORAC assay was compared to that of verbascoside (the main polyphenol component) and of caffeic acid (the basic constituent of verbascoside): the results indicate that caffeic acid (10 microg/ml equivalent to 35.70+/-2.95 microg/ml Trolox) is more potent than verbascoside (10 microg/ml equivalent to 15.42+/-1.21 microg/ml Trolox) in entrapping peroxyl radicals. Finally the antioxidant activity of the Oleaselect extract was confirmed in human umbilical endothelial cells (EC) exposed to the site-specific peroxyl radical inducer AAPH, where a massive lipid peroxidation process (marker the fluorescence probe BODIPY) takes place, paralleled by a marked loss of cell viability (calcein assay). The purified extract (1-20 microg/ml) pre-incubated with EC for 1 h dose-dependently inhibited both the lipid-peroxidation damage and cell death. Taking into account the total polyphenol content, these results clearly indicate a greater antioxidant activity for the purified extract, due to a cooperative antioxidant interaction among its polyphenol constituents.

A method to measure the oxidizability of both the aqueous and lipid compartments of plasma.

The lipophilic radical initiator (MeO-AMVN) and the fluorescent probe C11BODIPY581/591 (BODIPY) were used to measure the lipid compartment oxidizability of human plasma. Aqueous plasma oxidizability was initiated by the aqueous peroxyl radical generator, AAPH, and 2',7'-dichlorodihydrofluorescein (DCFH) was employed as the marker of the oxidative reaction. The distribution in aqueous and lipid compartments of the two radical initiators was determined by measuring the rate of consumption of the plasma hydrophilic and lipophilic endogenous antioxidants. In the presence of AAPH (20 mM), the order of consumption was: ascorbic acid > alpha-tocopherol > uric acid > beta-carotene, indicating a gradient of peroxyl radicals from the aqueous to the lipid phase. When MeO-AMVN was used (2mM), beta-carotene was consumed earlier than uric acid and almost at the same time as alpha-tocopherol, reflecting the diffusion and activation of MeO-AMVN in the lipophilic phase. The rate of BODIPY oxidation (increase in green fluorescence) significantly increased after the depletion of endogenous alpha-tocopherol and beta-carotene, whereas it was delayed for 180 min when AAPH was used instead of MeO-AMVN. The measurement of lipid oxidation in plasma was validated by adding to plasma the two lipophilic antioxidants, alpha-tocopherol and beta-carotene, whose inhibitory effects on BODIPY oxidation were dependent on the duration of the preincubation period and hence to their lipid diffusion. DCFH oxidation induced by AAPH only began after uric acid, the main hydrophilic plasma antioxidant, was consumed. In contrast, when MeO-AMVN was used, DCFH oxidation was delayed for 120 min, indicating its localization in the aqueous domain. In summary, the selective fluorescence method reported here is capable of distinguishing the lipophilic and hydrophilic components of the total antioxidant capacity of plasma.

Antioxidant activity of nimesulide and its main metabolites.

The antioxidant activity of nimesulide and its main metabolites, 4'-hydroxynimesulide (M1) and 2-(4'-hydroxyphenoxy)-4-N-acetylamino-methansulfonanilide (M2), was investigated using 2 in vitro models: NADPH-supported lipid peroxidation in rat liver microsomes (marker MDA formation) and xanthine/xanthine oxidase, iron-promoted depolymerisation of hyaluronic acid, determined by gel permeation chromatographic analysis (marker molecular weight distribution). In the lipid peroxidation model, all the compounds inhibited MDA formation in a concentration-dependent manner, although with different potencies; the maximum scavenging effect was observed for M1 [50% inhibitory concentration (IC50) = 30 mumol/L; M2 IC50 = 0.5 mmol/L; nimesulide = 0.8 mmol/L]. Nimesulide was more active than its metabolites in preventing OH-induced depolymerisation of hyaluronic acid, with a 50% effective concentration of approximately 230 mumol/L, which was fairly comparable to that of tenoxicam. This protective effect was due to the OH.-entrapping capacity of the drug, which, in the Fenton-driven model, is easily converted, via OH. attack, to M1 and putatively to 2-hydroxy-4-nitro-methansulfonanilide.

UVB-induced hemolysis of rat erythrocytes: protective effect of procyanidins from grape seeds.

Besides erythema and sunburn reactions, UVB stress can promote erythrocyte extravasation from skin capillaries and hemolysis, and photosensitized hemoglobin can in turn lead to an overload of free radicals in dermis which exacerbates photodamage. The objective of this study was to investigate in rat erythrocytes (RBC) the pattern of events leading to membrane peroxidation and hemolysis following UVB insult (1.5-8.5 J/cm2), and the protective action of grape seed procyanidins. UVB causes a dramatic dose-dependent decrease of intracellular glutathione (paralleled by the formation of pro-oxidant ferryl-hemoglobin), of intramembrane vitamin E and of membrane fluidity, then a rise of conjugated dienes (CD), and thiobarbituric acid-reactive substances (TBARS) and finally a strong hemolytic effect. Procyanidins prevent membrane peroxidation (but not intracellular GSH depletion nor ferryl-hemoglobin formation), with a minimal effective concentration of 0.1 microM (IC50 for TBARS and CD after 120 min UVB exposure: 0.71 microM and 0.56 microM) and dose-dependently delay the onset of hemolysis, by 30 min at 0.1 mciroM, by 90 and 120 min at 0.5 and 1.0 microM. Epigallocatechin-3-O-gallate (EGCG) and catechin, typical constituents of the fraction, were significantly less potent. This since procyanidins (1 microM) inhibit the formation of phospholipid hydroperoxides of the inner (phosphatidylserine, phosphatidylethanolamine) and outer (phosphatidylcholine) layers of the RBC membrane (HPLC analysis), suppress the decrease in membrane fluidity due to lipid and protein thiol oxidation and spare vitamin E from consumption in a dose-dependent manner (0.1-1 microM). Hence procyanidins, preserving membrane phospholipids, since their strong antilipoperoxidant activity, may maintain in vivo the integrity of RBC in sub-epidermal capillaries and effectively counteract in dermis the onset/exacerbation of the UVB-induced skin photodamage.

Diet enriched with procyanidins enhances antioxidant activity and reduces myocardial post-ischaemic damage in rats.

Aim of this work was to study the efficacy of procyanidins from Vitis vinifera seeds, a standardized mixture of polyphenol antioxidants, on cardiac mechanics following ischemia/reperfusion stunning in the rat, after 3 weeks supplementation. Young and aged male rats were fed a diet enriched with procyanidins complexed (1:3 w/w) with soybean lecithin (2.4%); control animals (CTR-young and CTR-aged) received an equal amount of lecithin and 2 additional groups of animals the standard diet. At the end of the treatment, the total plasma antioxidant defense (TRAP), vitamin E, ascorbic acid and uric acid were determined in plasma and the hearts from all groups of animals subjected to moderate ischemia (flow reduction to 1 ml/min for 20 min) and reperfusion (15 ml/min for 30 min). In both young and aged rats supplemented with procyanidins the recovery of left ventricular developed pressure (LVDP) at the end of reperfusion was 93% (p < 0.01) and 74% (p < 0.01) of the preischemic values and the values of coronary perfusion pressure (CPP) were maintained close to those of the preischemic period. Also creatine kinase (CK) outflow was restrained to baseline levels, while a 2-fold increase in prostacyclin (6-keto-PGF1alpha) in the perfusate from hearts of young and aged rats was elicited during both ischemia and reperfusion. In parallel, procyanidins significantly increased the total antioxidant plasma capacity (by 40% in young and by 30% in aged rats) and the plasma levels of ascorbic acid, while tend to reduce vitamin E levels; no significant differences were observed in uric acid levels. The results of this study demonstrate that procyanidins supplementation in the rat (young and aged) makes the heart less susceptible to ischemia/reperfusion damage and that this is positively associated to an increase in plasma antioxidant activity.

LC coupled to ion-trap MS for the rapid screening and detection of polyphenol antioxidants from Helichrysum stoechas.

Liquid Chromatography-Ion Trap Mass Spectrometry with an atmospheric pressure chemical ionization (APCI) interface in the negative and positive-ion modes in parallel to UV-diode-array detection (DAD), was applied for the rapid detection/characterization in crude extracts of the water-soluble antioxidant phenolics from Helichrysum stoechas. APCI-MS provides unequivocal molecular weight data of these compounds and useful information about their structures (diagnostic fragments ions), which were confirmed by the UV-DAD fingerprints. This combined approach allows the identification of ten constituents, including the three naturally occurring isomers of caffeoylquinic acid (CGAs), namely neo-chlorogenic acid, chlorogenic acid and crypto-chlorogenic acid, 2 isomeric dicaffeoyl quinic acids, 2 isomeric naringenin glucosides, quercetin, kaempferol and apigenin glucosides and a tetrahydroxychalcone-glucoside. The water-soluble extract from H. stoechas, standardized in both total polyphenol and kaempferol-3-glucoside content, exhibits strong antioxidant activity in vitro when tested in both artificial membrane systems (phosphatidylcholine liposomes) and in a cell model (rat erythrocytes).

Mass spectrometric characterization and HPLC determination of the main urinary metabolites of nimesulide in man.

A study was undertaken for the characterization and quantitative determination of the main urinary metabolites of the non-steroidal anti-inflammatory drug (NSAID) nimesulide (4-nitro-2-phenoxy-methanesulfonanilide) in man following single oral administration (200 mg). Urines were collected from six healthy volunteers at 12, 24, 48, 72 and 96 h post-administration and submitted to liquid liquid extraction before (free metabolites) and after enzymatic hydrolysis (conjugated metabolites). The structure of the metabolites, isolated by TLC separation, was elucidated by mass spectrometry (electron impact ionization) and confirmed by synthesis. Five metabolites were identified: they arise from hydroxylation to the phenoxy nucleus (M1 = hydroxynimesulide); reduction of the nitro group to an amino derivative (M2); concomitant hydroxylation and reduction (M3); N-acetylation of the M2 (M4) and of the M3 (M5) metabolites. Quantitation was by reverse phase high performance liquid chromatography (Supelcosil LC-18 DB column; mobile phase: sodium phosphate buffer (pH 3.0, 50 mM)-acetonitrile (gradient elution); flow rate: 1 ml min(-1); UV detection, 230 nm), procedure which allows in a single chromatographic run the simultaneous determination of the unchanged drug and of its metabolites. The urinary excretion of the drug and metabolites (free + conjugated) in the overall 96 h-interval accounts for approximately 40% of the administered dose: 17.55 +/- 3.6% M1; 0.72 +/- 0.43% M2; 2.45 +/- 1.22% M3; 19.07 +/- 4.3% M5. The bulk of the metabolites was in conjugated form. Percentages excretion of the unchanged drug and of M4 metabolite were below 0.5%. The described method is suited to specifically and quantitatively measure nimesulide and metabolites in human urine with acceptable precision and accuracy.

Nitrosylhemoglobin, an unequivocal index of nitric oxide release from nitroaspirin: in vitro and in vivo studies in the rat by ESR spectroscopy.

Electron spin resonance (ESR) spectroscopy was applied for the unequivocal detection/quantitation of nitric oxide (NO) as nitrosylhemoglobin (HbFe(II)NO) released from nitroaspirin, benzoic acid,2-(acetyloxy)-3-[(nitrooxy)methyl]phenyl ester (NCX-4016; NO-ASA), the lead of a new class of nonsteroidal anti-inflammatory drugs. In both in vitro and in vivo experiments, the paramagnetic complex was detected at 100 K in the venous blood of the rat (microwave power, 20 mW) and characterized by a three-line hyperfine structure with coupling constants (A(x) and A(z)) of 17 G at g(x)=2.066 and g(z)=2.009. The kinetics of NO release from the drug were first determined in vitro by incubating rat blood with 1 mM NO-ASA and confirmed by the two-line hyperfine structure obtained with the labeled compound ((15)N-NO-ASA). In in vivo studies, the hematic levels of HbFe(II)NO were determined after oral (p.o.) and intraperitoneal (i.p.) administration of the drug (100 and 200 mg kg(-1)). In p.o. treated animals, the complex was detectable at 1 h post-dosing and its formation was maximal at 4-6 h, where the antithrombotic activity peaks. In i.p. treated animals, HbFe(II)NO complex peaks at the second hour to decline thereafter: in these animals, the ESR technique was applied to also detect nitrosylmyoglobin as an index of NO diffusion/compartmentalization in myocardial tissue. The results of this study emphasize the great potentiality of ESR spectroscopy for the study of the release, the metabolic fate and distribution of NO from nitrovasodilators.

Hydroxynimesulide, the main metabolite of nimesulide, prevents hydroperoxide/hemoglobin-induced hemolysis of rat erythrocytes.

The protective effect of hydroxynimesulide, the main metabolite of the nonsteroidal antiinflammatory drug nimesulide, on red blood cells (RBCs, 0.2%; 3.5 x 10(7) cell/ml) hemolysis induced by cumene hydroperoxide (CuOOH; 50 microM) was evaluated by turbidimetric and morphological analyses. Hydroxynimesulide inhibits the CuOOH-induced hemolysis in a dose dependent fashion: the protective effect, calculated after 150 min incubation (100% hemolysis in the controls), starts at 1 micron (% hemolysis 85.2 +/- 3.4%) and increases at the higher concentrations (63.5 +/- 3.9% at 5 microM; 43.5 +/- 6.3% at 10 microM; and, 14.5 +/- 4.3% at 20 microM). In addition, in the samples protected with 10 microM and 20 microM, there is a significant delay (30 and 60 min) in the onset of the hemolytic response. Inhibition of hemolysis is the result of protection of RBC membrane integrity, both on lipid (cis-Parinaric acid fluorescence quenching was delayed by 53 +/- 10 sec vs. the controls at 1 micron, by 115 +/- 15 sec at 5 microM, with a lag phase of 240 +/C- 18 sec at 10 microM) and protein constituents, as determined by SDS-PAGE electrophoresis. In hemolysis experiments, the efficacy of hydroxynimesulide is comparable to that of alpha-tocopherol and a cooperative interaction between hydroxynimesulide and alpha-tocopherol (both at 10 microM) has been observed. These results indicate that hydroxynimesulide protects RBC membranes by directly quenching reactive oxygen species generated by hemoglobin/peroxide interaction. Evidence for a direct radical scavenging intervention of the metabolite comes from HPLC studies, which demonstrate a time-dependent consumption of hydroxynimesulide, with the concomitant formation of two main reaction (addition/oxidation) products.

Fluorescent probes as markers of oxidative stress in keratinocyte cell lines following UVB exposure.

In this work we describe the development of specific markers for determination of both the membrane and intracellular damage induced by free radicals generated by UVB radiation (5-150 mJ/cm2) in cultured keratinocytes. This using simple, specific and sensitive fluorescent probes: cis-parinaric acid (PNA) to monitor membrane lipid peroxidation and 2',7'-dichloro-dihydrofluorescein diacetate (DCFH-DA) to evaluate the intracellular redox status, in parallel to the fluorimetric determination of the main intracellular antioxidant glutathione. To validate the methodologies, the changes in the intracellular oxidative status following exposure to low doses UVB were measured in both control and N-acetylcysteine-protected cells, in parallel with morphological analyses. UVB induces an early reduction of GSH inside the cell correlated with an increase in the intracellular peroxide content. The effects were time- and dose-dependent. In addition, using a sensitive fluorescent method, we quantitated the release of proteases, a family of proteolytic enzymes greatly involved in the onset/perpetuation of the free radical-induced skin damage from keratinocytes exposed to suberythemal UVB doses (5-15 mJ/cm2). The use of these fluorescent probes provides a reliable tool to detect the early signs of damage in keratinocyte cultures (when the apoptotic phenomenon has not yet been triggered) useful for future screening of protective molecules.

Antioxidant profile of nimesulide, indomethacin and diclofenac in phosphatidylcholine liposomes (PCL) as membrane model.

An in vitro assay based on the oxidation of phosphatidylcholine liposomes (PCL) with which we can distinguish the anti-HO zero activity from the antilipoperoxidant (R zero, ROO zero, RO zero) has been developed for testing the free-radical-scavenging ability of antiinflammatory drugs. PCL were exposed to a flux of hydroxyl radicals generated by water sonolysis for different periods, and the spontaneous lipid peroxidative phenomenon (propagation and breakdown phases) was followed for the subsequent 24 hours. Lipid peroxidation was assayed by simultaneous measurements of a) conjugated dienes, by UV spectroscopy (absorbance and second derivative at 233 nm), b) loss of lipid substrate (PC), by HPLC, and c) breakdown products (total carbonyl functions as 2,4-dinitrophenylhydrazones). Diclofenac, nimesulide and indomethacin, added to PCL at the starting of the different stages of lipid peroxidation, were tested for their overall and specific anti-radical properties. All the drugs exhibited a remarkable scavenging activity against oxy and lipid radicals, determined as percent inhibition of the formation of conjugated dienes, at concentrations easily attainable in vivo (IC50:diclofenac 2.5 microM, nimesulide 4.92 microM, indomethacin 6.85 microM), diclofenac being the most effective in quenching the R zero and ROO degree species responsible for the propagation phase. By contrast, the antioxidant activity of nimesulide and indomethacin, less potent as alkyl and peroxyl radical scavengers, is due to their ability to restrain the induction phase of the radical chain reaction mediated by hydroxyl radicals (IC50:nimesulide 1.85 microM, indomethacin 3.57 microM).

Direct characterization of caffeoyl esters with antihyaluronidase activity in crude extracts from Echinacea angustifolia roots by fast atom bombardment tandem mass spectrometry.

Fast atom bombardment (FAB-MS) and fast atom bombardment tandem mass spectrometry (FAB-MS/MS) techniques (negative ions) have been successfully applied for identification of the constituents responsible for the antihyaluronidase activity of Echinacea angustifolia roots, whose extracts are widely employed for the adjuvant therapy of chronic inflammatory diseases. Crude extracts from different solvents were tested for antihyaluronidase activity, and those with the greatest inhibitory action (the ethylacetate, butylacetate and chloroform fractions, IC50 0.44, 0.50 e 0.62 mg/ml) were directly analyzed by MS. Full scan mass spectra produced intense molecular anions: collisional activation of these resulted in tandem mass spectra rich in significant product ions. Four main caffeoyl conjugates were detected and identified by tandem mass spectrometry (daughter and parent ion mode): 2,3-O-dicaffeoyltartaric acid (chicoric acid) and 5-O-dicaffeoylquinic acid (cynarine) and 2-O-caffeoyltartaric acid (caffaric acid) in the ethylacetate fraction. Among these caffeoyl conjugates, chicoric and caftaric acids had the greatest antihyaluronidase activity: IC50 = 0.42 and 0.61 mM, while the IC50 of cynarine and chlorogenic acid were 1.85 and 2.25 mM.

Advanced glycoxidation and lipoxidation end products (AGEs and ALEs): an overview of their mechanisms of formation.

Advanced lipoxidation end products (ALEs) and advanced glycation end products (AGEs) have a pathogenetic role in the development and progression of different oxidative-based diseases including diabetes, atherosclerosis, and neurological disorders. AGEs and ALEs represent a quite complex class of compounds that are formed by different mechanisms, by heterogeneous precursors and that can be formed either exogenously or endogenously. There is a wide interest in AGEs and ALEs involving different aspects of research which are essentially focused on set-up and application of analytical strategies (1) to identify, characterize, and quantify AGEs and ALEs in different pathophysiological conditions; (2) to elucidate the molecular basis of their biological effects; and (3) to discover compounds able to inhibit AGEs/ALEs damaging effects not only as biological tools aimed at validating AGEs/ALEs as drug target, but also as promising drugs. All the above-mentioned research stages require a clear picture of the chemical formation of AGEs/ALEs but this is not simple, due to the complex and heterogeneous pathways, involving different precursors and mechanisms. In view of this intricate scenario, the aim of the present review is to group the main AGEs and ALEs and to describe, for each of them, the precursors and mechanisms of formation.

Human serum albumin cysteinylation is increased in end stage renal disease patients and reduced by hemodialysis: mass spectrometry studies.

The aim of the present work was to monitor the covalent modifications of human serum albumin (HSA) in end stage renal diseases (ESRD) non-diabetic patients, before and after hemodialysis (HD), by direct infusion electrospray mass spectrometry (ESI-MS). Human serum samples were collected from healthy subjects (n = 10, 20-60 yr) and age-matched ESRD patients (n = 8) before and after HD, purified by affinity chromatography and analyzed by a triple-quadrupole mass spectrometer. The deconvoluted spectra from healthy subjects were all characterized by three peaks attributed to non-glycated mercaptoalbumin (HSA-SH) and to the corresponding adducts with cysteine (HSA-Cys) and glucose (HSA-Glc); relative contents: mercaptoalbumin in both glycated and non-glycated form, HSA-SHt (74 ± 6%), HSA-Cys (26 ± 5%) and HSA-Glc (24 ± 3%). HSA isolated from ESRD patients before HD was characterized by a significant reduction of HSA-SHt (42 ± 7%), and by a concomitant increase of the HSA-Cys adduct (58 ± 7%). Hemodialysis significantly reduced the cysteinylated form (37 ± 7%) and restored HSA-SHt (63 ± 8%) in all the ESRD patients. The mechanism of thiol oxidation and cysteinylation was then studied by mass spectrometry, using LQQCPF as a model peptide and H(2)O(2) as an oxidizing agent.