Presence Of Antioxidant Molecules Research Articles

Green Recovery and Identification of Antioxidant and Enzyme Inhibitor Molecules from Pisco Grape Pomace by Targeted Effects Analysis Using Thin-Layer Chromatography, Bioassay, and Mass Spectrometry.

The search and identification of inhibitory molecules from novel natural sources, such as pisco grape pomace extract obtained by green techniques, may help to develop agents with therapeutic potential that are beneficial to health with fewer adverse effects than drugs. Many drugs act as enzyme inhibitors, decreasing their activity and thus correcting a metabolic imbalance. This study aims to identify bioactive molecules with antioxidant and inhibitory activity over acetylcholinesterase and cyclooxygenase enzymes present in pisco grape pomace green extracts. Bioactive molecules were detected and identified applying directed effect analysis on planar chromatography coupled to mass spectrometry. For the first time, the presence of antioxidant molecules (quercetin-3-O-glucuronide, quercetin-3-O-glucoside, and gallic acid) and inhibitors of acetylcholinesterase (kaempferol-3-O-glucoside) and cyclooxygenase (gallic acid) enzymes are reported in pisco grape pomace. According to the results, grape pomace could be an alternative to develop novel functional foods and nutraceuticals that provide health benefits and, at the same time, generate a circular economy in the industry.

Validation of circular dichroic spectroscopy of synthetic oligonucleotide PS2.M for {hbox {K}}^{+} concentration measurements

The single-stranded synthetic oligonucleotide PS2.M is known to provide a basis for developing sensors since it tends to fold into structures called G-quadruplexes (G4) having characteristic topology and orientation with probabilities that depend on the chemical environment. The presence and concentration of cation species are among the key factors that determine the outcome of such a process. PS2.M and other aptamers have been used in several applications in conjunction with various probes, such as hemin, at the cost of increased technical complexity and applicability limitations. We instead validated the application limits of Circular Dichroic spectroscopy (CD) as only measurement method to assay PS2.M as {hbox {K}}^{+} sensor in a variety of solutions having different chemical complexity. The tested solutions range from simple hbox {NaCl} and hbox {KCl} solutions to chemically complex solutions like DMEM—Dulbecco’s Modified Eagle Medium—which is widely used in a biological laboratory. PS2.M was also evaluated in solutions of {hbox {KHCO}}_{3}and D-ribose (K:D-rib), an antioxidant potassium compound, to compare its response to the simple hbox {KCl} solution case. Our findings show that, within specific concentration applicability ranges, CD spectra can estimate the {hbox {K}}^{+} concentration in the examined water solutions even at high {hbox {Na}}{+} concentrations with respect to {hbox {K}}^{+}and in the presence of antioxidant molecules.

Hemozoin is a potential threat in cerebral malaria pathology through the induction of RBC-EC cytoadherence

Cerebral malaria is an outcome of multifaceted and complicated condition. Cytoadherence is one critical factor in cerebral malaria pathology as high order cytoadherence complexes result in vascular congestion and cell apoptosis. Morphological abnormalities in uninfected RBCs can be a contributing factor to aggravate cytoadherence. Malaria pigment hemozoin is a potential bioactive molecule and the role of this pigment in cerebral malaria pathology is not completely understood. To understand this, primarily we investigated the impact of hemozoin pigment on uninfected RBCs. Secondarily, we investigated the role of this pigment in formation of endothelial cells-RBCs (EC-RBC) cytoadherence complex. We first observed that a dose dependent hemozoin exposure to uninfected RBCs induced structural abnormalities. Differential counting of these abnormal RBCs indicated population of acanthocytes, spherocytes and microcytes. The formation of abnormal RBCs was observed with phosphatidylserine externalization. Lipid peroxidation, reduced glutathione and reactive oxygen species (ROS) levels indicated an increase in hemozoin exposure mediated oxidative stress. Our in-vitro cytoadherence assay indicated formation of endothelial EC-RBC cytoadherence complex. The dose dependent hemozoin exposure to uninfected RBCs resulted in oxidative stress mediated high order cytoadherence complex formation. This effect was reversed in presence of antioxidant molecules. The inhibitory effect of antioxidant molecules indicates that oxidative stress can be a regulatory factor to control cerebral malaria pathology. Being the first report to highlight the impact of malaria pigment hemozoin on uninfected RBCs, this study brings attention to the role of abnormal RBCs in worsening of cerebral malaria pathology.

Stability of Plasma Treated Non-vulcanized Polybutadiene Surfaces: Role of Plasma Parameters and Influence of Additives

Surface modification studies of non-vulcanized BR elastomers (butadiene rubber) by low-pressure air plasma treatment and the effect on ageing and adhesion performances are presented in this paper. In particular, the influence of discharge power and distance from the glow discharge, and impact of antioxidant molecules in the BR formulation were examined. To characterize the changes to the BR surface, XPS spectroscopy, contact angle measurements, AFM nanoindentation experiments and tack measurements were utilized. Oxidation and crosslinking were the main mechanisms observed on the polymer chains regardless of the plasma conditions used. Beyond a certain threshold of plasma energy (in our case, discharge power of ~60 W and exposure time of ~30 s), a steady state was reached irrespective of the distance from the glow discharge. The presence of antioxidant molecules considerably reduced crosslinking phenomena while maintaining oxidation processes on polymer chains and increasing the nitrogen content in the near surface region. The mechanisms responsible for these differences have been identified. Interestingly, the COOH/C=O ratio changed according to the balance between oxidation and crosslinking. The hydrophobic recovery rate was mainly driven by temperature-dependent dynamics and varied according to the degree of crosslinking in the surface region. It was found to be lower in air atmosphere in the presence of antioxidant molecules. Finally, the presence of antioxidant molecules in the BR formulation allowed the adhesion performances after plasma exposure to significantly increase.

CHEMICAL COMPOSITION AND ANTI-INFLAMMATORY ACTIVITIES OF AN UNSAPONIFIABLE FRACTION OF PULP OIL FROM AWARA (ASTROCARYUM VULGARE M.)

Awara is a palm tree common in the French Guyana, used for the nutritional properties of the fruit and in the traditional pharmacopoeia of the country. The pulp of this fruit is rich in oil of which the unsaponitiable fraction contains a lot of antioxidant and anti-inflammatory molecules. The aim of this study was to characterize the chemical composition of the unsaponitiable fraction of awara pulp oil and to evaluate the in vitro anti-inflammatory activities. In a first part, chemical analyses of the unsaponitiable fraction allowed us to determined for 1 mg of unsaponitiable fraction: 6.8 11g of a-tocopherol, 125.7 11g of carotenoids (mainly p-carotene), and 152.6 11g of phytosterols (mainly P-sitosterol). In a second part, the unsaponitiable fraction has shown a significant inhibition of the cyclooxygenase I and 2 activities (COX-I and -2 respectively). On LPS/1 F'Ny-stimulated J774 macrophages, it strongly inhibited the PGE2 production in a dose dependent manner. The unsaponitiable fraction produced a decrease of an important proinflammatory mediator, which might be due by the inhibition of the corresponding enzyme activity showing potential anti-inflammatory properties. These effects could be explained by the presence of antioxidant molecules like tocopherols and carotenoids, and anti-inflammatory molecules like sterols. (Resume d'auteur)

Impact of oxygen on the accuracy and precision of normoxic polymer gel dosimeters

Diffusion of oxygen in normoxic polymer gel dosimeters was studied. Gel samples in glass tubes were exposed to oxygen for different periods and then irradiated. Oxygen inhibited polymerization at the surface and polymerization occurred at larger depths. However the interface between these two regions revealed a local increase of polymerization. R2 values in these distinct regions are analyzed in terms of the concentration of oxygen and of antioxidant. Perhaps counter-intuitively, a small concentration of oxygen increases the sensitivity of the gel by consuming antioxidant molecules. The presence of antioxidant molecules is shown to cause a decrease of sensitivity, presumably through interactions with water free radicals and/or polymer radicals. Mixing and filling procedures as well as oxygen penetration from plastic caps or walls of gel containers are potential sources of oxygen-related discrepancies in normoxic polymer gel dosimeters. This effect may cause dosimetric inaccuracies of up to 60%.

Generation of OH radicals at palladium oxide nanoparticle modified electrodes, and scavenging by fluorescent probes and antioxidants

The reduction of palladium oxide nanoparticles in the presence of hydrogen peroxide or dissolved oxygen gives rise to a catalytic reduction current dependent on the hydrogen peroxide concentration or the oxygen concentration. Using terephthalic acid as an OH radical scavenger yielding the fluorescent 2-hydroxyterephthalic acid, we demonstrate that the catalytic current stems from the freshly exposed palladium metal re-oxidation by OH radicals. A kinetic model is presented to account for these catalytic reactions. We also demonstrate that the measurement of the catalytic reduction current in the presence of antioxidant molecules can be used to measure the OH scavenging properties of antioxidants.

Pivotal role of superoxide anion and beneficial effect of antioxidant molecules in murine steatohepatitis.

Nonalcoholic fatty liver disease, frequently associated with obesity, can lead to nonalcoholic steatohepatitis (NASH) and cirrhosis. The pathophysiology of NASH is poorly understood, and no effective treatment is available. In view of a potential deleterious role for reactive oxygen species (ROS), we investigated the origin of ROS overproduction in NASH. Mitochondrial production of ROS and its alterations in the presence of antioxidant molecules were studied in livers from ob/ob mice that bear a mutation of the leptin gene and develop experimental NASH. N-acetyl-cysteine and the superoxide dismutase (SOD) mimics ambroxol, manganese [III] tetrakis (5,10,15,20 benzoic acid) (MnTBAP), and copper [II] diisopropyl salicylate (CuDIPS) were used to target different checkpoints of the oxidative cascade to determine the pathways involved in ROS production. Liver mitochondria from ob/ob mice generated more O(2)*- than those of lean littermates (P <.01). Ex vivo, all three SOD mimics decreased O(2)*- generation (P <.001) and totally inhibited lipid peroxidation (P <.001) versus untreated ob/ob mice. Those modifications were associated with in vivo improvements: MnTBAP and CuDIPS reduced weight (P <.02) and limited the extension of histological liver steatosis by 30% and 52%, respectively, versus untreated ob/ob mice. In conclusion, these data demonstrate deleterious effects of superoxide anions in NASH and point at the potential interest of nonpeptidyl mimics of SOD in the treatment of NASH in humans.

Apoptotic Neuronal Cell Death Induced by the Non-fibrillar Amyloid-β Peptide Proceeds through an Early Reactive Oxygen Species-dependent Cytoskeleton Perturbation

In the present study, we have determined the nature and the kinetics of the cellular events triggered by the exposure of cells to non-fibrillar amyloid-beta peptide (A beta). When cortical neurons were treated with low concentrations of soluble A beta (1-40), an early reactive oxygen species (ROS)-dependent cytoskeleton disruption precedes caspase activation. Indeed, caspase activation and neuronal cell death were prevented by the microtubule-stabilizing drug taxol. A perturbation of the microtubule network was noticeable after being exposed to A beta for 1 h, as revealed by electron microscopy and immunocytochemistry. Microtubule disruption and neuronal cell death induced by A beta were inhibited in the presence of antioxidant molecules, such as probucol. These data highlight the critical role of ROS production in A beta-mediated cytoskeleton disruption and neuronal cell death. Finally, using FRAP (fluorescence recovery after photo bleaching) analysis, we observed a time-dependent biphasic modification of plasma membrane fluidity, as early as microtubule disorganization. Interestingly, molecules that inhibited neurotubule perturbation and cell death did not affect the membrane destabilizing properties of A beta, suggesting that the lipid phase of the plasma membrane might represent the earliest target for A beta. Altogether our results convey the idea that upon interaction with the plasma membrane, the non-fibrillar A beta induces a rapid ROS-dependent disorganization of the cytoskeleton, which results in apoptosis.