Mechanisms Of Antioxidant Action Research Articles

Polyphenolic compounds of the stilbenoid class: classification, representatives, content in plant raw materials, structural features, use in the food industry and pharmacy

Nowadays, more than 300 representatives of stilbenoids are known - a group of natural, synthetic and semi-synthetic biologic active substances, according to the chemical structure belonging to the group of polyphenolic compounds - phenylpropanoids. Representatives of this group of compounds can be detected in such classes of plants as gymnosperms, angiosperms, bryophytes and pteridophyte. The main food sources are the fruits of grapes, blueberries, blueberries, peanuts, cocoa. The history of their detection is associated with the discovery of the protective functions of plants in response to the action of external stimuli. Further study revealed pronounced antioxidant properties. The mechanism of development of many diseases is associated with the processes of oxidation of free radicals, which can be interrupted by the effect of antioxidants. Possible mechanisms of antioxidant action of stilbenoids and their effect on diseases caused by excessive amounts of free radicals have been studied. Stilbenoids increase the tone and stability of the body to stress factors of the environment, improve the adaptive capacity of the nervous and immune systems, show antitumor, cardio-protective and lipid-lowering activities, inhibit lipid peroxidation. In this regard specialized products, food supplements and drugs containing stilbenoids have been developed. However, representatives of this group of compounds have low consumer properties, are sensitive to environmental factors and have low solubility and absorption. Therefore, solutions of these problems are important when developing new foods and drugs. Nowadays, auxiliary substances (solubilizers) are used, as well as such technological methods as microencapsulation, coacervation, polymerization, and others that can cope with problems of instability, poor solubility, low bioavailability, and unsatisfactory consumer qualities, which improve the effect of stilbenoids on the organism.

DFT Study on Antioxidant Action Mechanisms of Naphthoquinone-Urazole Hybrids

The aim of this study is on the evaluation of the antioxidant activities of the investigated naphthoquinone-urazole hybrids by comparing our theoretical results with experimental results and on the elucidation the antioxidant action mechanisms. For this purpose, quantum chemical calculations were performed at the B3LYP/6-311++G(d,p) level for the investigated naphthoquinone-urazole hybrids and their ionic forms in the gas phase and in water. The solvation effect of water on the antioxidant activity was examined using the conductor–like polarizable continuum model (C-PCM) at the same level of theory. The antioxidant action mechanisms for the investigated naphthoquinone-urazole hybrids were assessed thermodynamically by several physicochemical parameters.

Evaluation of in vitro Antioxidant Potential of Amaranthus caudatus L. Grown in Kashmir Region

Background: Plants have a well-developed defensive machinery for minimizing the reactive oxygen species (ROS) associated damages in the form of enzymatic and nonenzymatic antioxidants. The in-vitro mechanism of antioxidant action of plant extracts may involve direct inhibition of the ROS generation or ROS scavenging. The antioxidant activity of the extracts may be due to active constituents alone or the combination of constituents. However, the amount of constituents are known to vary according to the change in environment. Method: In our study, antioxidant activity of Amaranthus caudatus L. from two different sites (elevation sites) was investigated at three stages, (vegetative, pre flowering and post flowering) using ethanolic extract (EtOH). Result: The phenolic and flavonoid content increased at all stages from site 1 to site 2. The total reducing power, Ferrous reducing antioxidative power (FRAP), diphenyl picryl hydrazine (DPPH) radical scavenging assay, superoxide dismutase scavenging (SOD) assay and hydrogen peroxide (H2O2) scavenging activity increased from site 1 to site 2 at all the three stages. Conclusion: The results reveal that the altitude and the growth stage have a significant effect on antioxidative potential of Amaranthus.

Phenolic compounds can delay the oxidation of polyunsaturated fatty acids and the growth of Listeria monocytogenes: structure-activity relationships.

Phenolic compounds present a potential solution to ensure food quality and safety. Indeed, they can limit oxidation reactions and bacterial growth in food products. Although their antioxidant mechanisms of action are well known, their antibacterial ones are less well understood, especially in light of their chemical structures. The aim of this study was first to quantify both aspects of a series of natural phenolic compounds and then link these activities to their chemical structure. We evaluated antioxidant activity by measuring the capacity of phenolic compounds to delay free linoleic acid oxidation caused by the action of a hydrophilic azo-radical initiator (AAPH). We evaluated antibacterial activity by measuring the growth inhibition of Listeria monocytogenes and determining the non-inhibitory and minimum inhibitory concentrations for each compound. Compounds with ortho-diphenolic structures were the best antioxidants, whereas those belonging to the simple phenol category were the best antibacterial compounds. The physico-chemical properties of the compounds influenced both activities but not in the same way. The chemical environment of the phenolic group and the presence of delocalization structures are the most important parameters for antioxidant activity, whereas the partition coefficient, logP, is one of the most important factors involved in antibacterial activity. © 2018 Society of Chemical Industry.

Pro- and antioxidant characteristics of natural thiols

In aqueous solutions at physiological temperature, the mechanism of antioxidative action of natural thiols (glutathione, cysteine, and homocysteine) mainly involves reactions with reactive oxygen species (ROS), peroxyl radicals and hydrogen peroxide. Reduction of hydrogen peroxide by thiols is accompanied by radical generation. The kinetic characteristics of these processes, including those for the reactions of hydrogen peroxide and glutathione immobilized on solid supports such as sodium montmorillonite (clay) and cellulose were determined. Prooxidative effects of thiols are related with the reactions of thiyl radicals formed in the exchange reactions of thiols with other radicals and in the reactions between thiols and hydroperoxides. Thiyl radicals are known to react easily with double bonds. Resveratrol and caffeic acid, phenolic antioxidants containing double bond in their molecules, were shown to be consumed when reacted with glutathione and the process accelerated in the presence of hydrogen peroxide.

A theoretical study of UV-Vis spectrum and antioxidant activity of chryso-obtusin

The conformation, electron structure, and antioxidant mechanism of chryso-obtusin, extracted from Leguminosae of traditional Chinese herb, have been studied in CH3OH by the density functional theory B3LYP/PCM/6-311[Formula: see text]G(2df,p)//B3LYP/PCM/6-31G([Formula: see text]) method. Three mechanisms of antioxidant actions are examined, which contain hydrogen atom transfer (HAT), single-electron transfer-proton transfer (SET-PT), and sequential proton loss transfer (SPLET), by using the computed corresponding indicators (BDE, IP, and PDE). Still, the spin density is employed to measure the delocalization of the antioxidant and its radical form. The finding suggests that hydrogen bond interaction is the main cause for the antioxidant activity of this antioxidant.

Theoretical studies on anti-oxidant potential of alpinetin

Alpinetin is a natural flavanone which is found abundantly in ginger family and is a well-known traditional Chinese medicinal ingredient. It exhibits broad spectrum of biological properties like anti-inflammatory effect, anti-hemostasis, anti-microbial effects etc. In this work we have attempted to perform a Density functional theory calculation to reveal the electronic and structural information of alpinetin. Several anti-oxidant descriptors like hardness, softness, electronegativity, electrophilicity index, chemical potential etc. were calculated as part of this. From the value of these quantum chemical descriptors, it could be concluded that alpinetin can have significant anti-oxidant activity. Mechanism of antioxidant action was also theoretically studied. It shows that the molecule prefers hydrogen atom transfer mechanism in vaccuo and in non-polar solution but in polar solution it follows sequential proton electron transfer mechanism. Thus the potentiality of alpinetin as an antioxidant molecule is revealed.

Methods to Assess the Antioxidative Properties of Probiotics.

Probiotics prove useful in correcting and preventing numerous health conditions, including those having severe impact on society, e.g., obesity and cancer. Notably, these capabilities of probiotics appear to be associated with their antioxidant properties. The mechanisms of antioxidant action of probiotics range from immediate biochemical scavenging of reactive substances to induction of signaling events leading to increased capacity of the host's cytoprotective systems. Since the antioxidant effects of probiotics significantly vary in types and details, a broad selection of methods of assessment of these properties is required in order to identify, characterize, and develop novel probiotics for medical purposes, as well as to explain the mechanisms of action of probiotics already in use in healthcare. This review revises the versatile toolbox, which can be used to assess the antioxidant properties of probiotics.

The Effects of Different Amount of Protein and Vitamin e Supplementation in Rations on Lipid and Antioxidant Metabolism of Broilers Exposed to Heat Stress

ABStRACt Heat stress, causes economic losses and has negative effects on both broiler husbandry and animal welfare. Nutritional strategies are applied for minimizing the negative effects of heat stress. In the present study, at the finishing period (24-39 days of age) of heat stress, the effects of diet involving 21% and 19% proteins and vitamin E on lipid metabolism and antioxidant mechanism of action, aimed to be identified. This study was carried out in six groups as: HPC (24 o C heat + 21% crude protein (CP)), HPS (34 o C heat + 21% CP), LPC (24 o C heat + 19% CP), LPS (34 o C heat + 19% CP), HPSVE (34 o C heat + 21% CP + Vitamin E) and LPSVE (34 o C heat + 19% CP + vitamin E) groups. Superficial pectoral muscles (breast) and liver tissues were used for oxidative stress and antioxidant defence determinations. Triglyceride and cholesterol levels have also been determined in blood serums. During the research, it is found that heat stress increased serum triglyceride and cholesterol levels, where Vitamin E has recovered triglyceride levels limitedly and cholesterol levels significantly. It is also observed that the adverse effect of high temperature was directly related to oxidative stress. Protein levels and vitamin supplementation relatively ameliorated these adverse effects, suggesting the tissue specificity. Consequently, the importance of feeding strategies such as the presence of Vitamin E and protein ratios on broiler nutrition in heat stress was established.

Antiulcer activity of hydroalcoholic extract of unripe fruit of carica papaya in experimental rats

Background: Carica papaya has previously reported antioxidant, analgesic and anti-inflammatory, antibacterial and anti-histaminic activity. Peptic ulcer disease involves inflammation and oxidative stress, so hydroalcoholic extract of Carica papaya fruits may have strong potential for an antiulcer agent. Aim and objectives of the study were in this study pharmacological evaluation of antiulcer effect of hydroalcoholic extract of Carica papaya fruits was performed by pyloric ligation induced gastric ulcers.Methods: Preliminary phytochemical investigation, estimation of phenolic and flavonoid content, In vitro antioxidant activities, antiulcer activity to find out the efficacy of hydroalcoholic extract of Carica papaya fruits.Results: Treatment with 500 mg/kg of hydroalcoholic extract of Carica papaya fruits efficacious in reducing ulcer index in pyloric ligation induced gastric ulcer model. Hydroalcoholic extract Carica papaya of showed a dose dependent decrease in ulcer and reduces ulcer index which was supported by morphological and histological studies.Conclusions: Thus it can be concluded that hydroalcoholic extract of Carica papaya fruits have antiulcer activity, which can be attributed to its antioxidant mechanism of action.

Study of the Antioxidatative Properties of Lithium Cysteine Salt

The actual problem of modern medicine and pharmacology is the opposition to the negative consequences of psycho emotional stress and oxidative stress. The development of oxidative stress is the rationale for finding drugs with an antioxidant mechanism of action. The purpose of this work was to characterize the antioxidant and cytotoxic properties of the new synthesized drug (lithium salt of the amino acid cysteine) and to study the effect on the intensity of free radical processes. The drug synthesized by us is directed mainly to the processes of lipid peroxidation and the antioxidant system, which, in our opinion, is due to the pharmacodynamics of the drug.

Antioxidative Effects of Natural Products on Diabetic Cardiomyopathy.

Diabetic cardiomyopathy (DCM) is a common and severe complication of diabetes and results in high mortality. It is therefore imperative to develop novel therapeutics for the prevention or inhibition of the progression of DCM. Oxidative stress is a key mechanism by which diabetes induces DCM. Hence, targeting of oxidative stress-related processes in DCM could be a promising therapeutic strategy. To date, a number of studies have shown beneficial effects of several natural products on the attenuation of DCM via an antioxidative mechanism of action. The aim of the present review is to provide a comprehensive and concise overview of the previously reported antioxidant natural products in the inhibition of DCM progression. Clinical trials of the antioxidative natural products in the management of DCM are included. In addition, discussion and perspectives are further provided in the present review.

ADEMETHIONINE IN THERAPY OF NON-ALCOHOLIC FATTY LIVER DISEASE

The article describes the current views on the pathogenesis of nonalcoholic fatty liver disease and a short overview of possible methods of therapy. The main mechanisms of antioxidant action of ademetionine in the treatment of NAFLD and the analysis of the evidence base of its effectiveness are discussed. We present clinical cases of a positive impact of ademetionine in NAFLD patients.

Phenolic profile and antioxidant properties of dried buckwheat leaf and flower extracts

Due to a high content of rutin (2-10%), dried buckwheat leaf and flower (DBLF) formulations were shown to be efficient in the treatment of vascular diseases. In order to find a cost effective way for the extraction of antioxidants, the effects of ethanol/water ratio and temperature on the extraction efficiency of phenolic compounds and the mechanisms of antioxidant action of the extracts were tested. Extraction with ethanol/water mixture (80:20, v/v) for 24 h at room temperature, after the mixture was just brought to boil was demonstrated to be an efficient and cheap way for obtaining a high yield of rutin (49.94?0.623 mg/g DBLF). The most abundant phenolic compounds in DBLF extracts were rutin and chlorogenic acid. Flavonoids, especially rutin, were shown to be the most responsible for the antioxidant activity in all investigated lipid model systems, acting as free radical scavengers, electron-donating substances and chelators of iron ions. In ?-carotene bleaching tests, the extracts with the highest activity were as efficient as BHT (butylated hydroxytoluole). Regarding the results of antihemolytic and Schaal oven tests, the extracts demonstrated remarkable ability to inhibit the oxidative destruction of erythrocytes and to prolong the beginning of the oxidation process in sunflower oil.

Theoretical study on the investigation of antioxidant properties of some hydroxyanthraquinones

ABSTRACTAnthraquinones are located in an important class of natural compounds having antioxidant properties. Quantum chemical calculations based on the density functional theory were employed to study the relationship between the structure and the antioxidant activity of four hydroxyanthraquinones. The solvation effects on the antioxidant activity were taken into account by using the conductor-like polarisable continuum model with different dielectric constants (ε = 2.25, C6H6; ε = 78.39, H2O). The three antioxidant action mechanisms, hydrogen atom transfer (HAT), single electron transfer-proton transfer and sequential proton loss electron transfer (SPLET) were elucidated. The reaction enthalpies related to the steps in these mechanisms were computed in gas phase and solvents. The calculated results are in line with experimental values. The results showed that HAT was the most favourable mechanism for describing the antioxidant activity of hydroxyanthraquinones in the gas phase and in benzene, whereas in aqueous solution, SPLET represented the most thermodynamically plausible reaction pathway.

ANTIULCER ACTIVITY OF THE MOST ACTIVE SUB-FRACTION OF METHANOLIC LEAF EXTRACT OF BUCHANANIA LANZAN SPRENG

<p><strong>Objective: </strong>To evaluate the antiulcer<strong> </strong>activity of the most active sub-fraction of <em>Buchanania lanzan</em> Spreng. leaves methanolic extract (BLE).</p><p><strong>Methods: </strong>The antioxidant activity of BLE fractions and sub-fractions has been assayed to determine the most active sub-fraction by using <em>in vitro </em>antioxidant<em> </em>methods like hydrogen peroxide free radical scavenging assay, hydroxyl radical scavenging assay, DPPH (1, 1-diphenyl-2-picryl hydrazyl) radical scavenging activity, total flavonoid and total phenolic content estimation. Then, the antiulcerogenic activity of most active sub-fraction of BLE (50 and 100 mg/kg, b.w., orally) was evaluated employing<strong> a</strong>spirin+pylorus ligation-induced (APL) and HCl/ethanol-induced (HE) gastric ulcer models in rats, and histopathological examination of stomach tissues of rats.</p><p><strong>Results: </strong>The most active sub-fraction of BLE exerted a significant (<em>P<</em>0.01) dose-dependent decrease in the ulcerative lesion index produced by APL and HE ulcer models in rats as compared to the standard drugs omeprazole (30 mg/kg, b.w. orally) and ranitidine (32 mg/kg, b.w. orally) respectively. The reduction in gastric fluid volume, total acidity and an increase in the pH of the gastric fluid in APL treated rats proved the antisecretory activity of most active subfraction of BLE. From histopathological examination, it was found that in tissues of both the models that received pretreatment with most activesub-fraction showed better protection of the gastric mucosa in a dose-dependent manner as indicated by reduction or absence of mucosal erosion and infiltration of leucocytes.</p><p><strong>Conclusion: </strong>These results suggest that leaves of <em>Buchanania lanzan </em>Spreng.<em> </em>possess potential antiulcer activity, which may be attributed to its antioxidant mechanism of action.</p>

Theoretical and Experimental Study of the Antioxidant Behaviors of 5‐O‐Caffeoylquinic, Quinic and Caffeic Acids Based on Electronic and Structural Properties

AbstractThe aim of this study was to elucidate the structural and electronic factors that determine the antioxidant capacity of 5‐O‐caffeoylquinic, caffeic and quinic acids under different experimental conditions. Antioxidant capacity was measured using different in vitro assays, involving diverse mechanisms of antioxidant action, namely, radical scavenging or reduction. The mechanisms of these reactions were analyzed by a theoretical study using the Density Functional Theory. Results allow relating in vitro antioxidant capacity of these three compounds with their chemical structures. The antioxidant capacity experimentally observed for these three acids was interpreted considering the reaction mechanism involved, the nature and stability of the intermediate formed, the formation and reaction of secondary compounds, and the effect of the reaction medium. The main goal of this report is presenting a theoretical analysis of reactions implicated in the antioxidant capacity, identifying the causes that increase or decrease such property. Thus, we present a quantum mechanical description of the antioxidant properties involved with these three compounds, considering equilibria and secondary oxidations involved.

Anti-oxidant activity of 6-gingerol as a hydroxyl radical scavenger by hydrogen atom transfer, radical addition and electron transfer mechanisms

Mechanisms of anti-oxidant action of 6-gingerol as a hydroxyl radical scavenger have been investigated using the transition state theory within the framework of density functional theory. Hydrogen abstraction by a hydroxyl radical from the different sites of 6-gingerol and addition of the former to the different sites of the latter were studied. Electron transfer from 6-gingerol to a hydroxyl radical was also studied. Solvent effect in aqueous media was treated using the integral equation formalism of the polarizable continuum model (IEF-PCM). Reaction rate constants in aqueous media were generally found to be larger than those in gas phase. The tunneling contributions to rate constants were found to be appreciable. Our results show that 6-gingerol is an excellent anti-oxidant and would scavenge hydroxyl radicals efficiently.

MECANISMOS MOLECULARES DE AÇÃO ANTIOXIDANTE DE VIAS CELULARES INTRÍNSECAS E DO RESVERATROL

The increase of intracelular ROS induces oxidative stress, which can trigger cellular death by apoptosis, by the activation of intrinsic apoptotic cascades. Oxidative stress may occur in the organism in different situations and in various organs and tissues. The consumption of fat in the diet is associated with the increase of the oxidative stress and mitochondrial dysfunction in various organs. Antioxidant substances act by inhibiting the excessive production of reative oxygen species (ROS), eliminate freee radicals and reduce apoptosis. Resveratrol is a compound that can be found in plants and has been shown to have various biological properties, one of them is the antioxidant activity. The target of this review is to gather information about the molecular mechanisms of antioxidant action of the intrinsic cellular pathways and

Beneficial effects of a red wine polyphenol extract on high-fat diet-induced metabolic syndrome in rats.

Individuals with metabolic syndrome (MS) show several metabolic abnormalities including insulin resistance, dyslipidaemia, and oxidative stress (OS). Diet is one of the factors influencing the development of MS, and current nutritional advice emphasises the benefits of fruit and vegetable consumption. Here, we assessed the effects of naturally occurring antioxidants, red wine polyphenols (RWPs), on MS and OS. Wistar rats (n=20) weighing 200-220g received a high-fat diet (HFD) for 2months before they were divided into two groups that received either HFD only or HFD plus 50mg/kg RWPs in their drinking water for an additional 2months. A control group (n=10) received a normal diet (ND) for 4months. Rats receiving HFD increased body weight over 20% throughout the duration of the study. They also showed increased blood levels of C-peptide, glucose, lipid peroxides, and oxidised proteins. In addition, the HFD increased OS in hepatic, pancreatic, and vascular tissues, as well as induced pancreatic islet cell hyperplasia and hepatic steatosis. Addition of RWPs to the HFD attenuated these effects on plasma and tissue OS and on islet cell hyperplasia. However, RWPs had no effect on blood glucose levels or hepatic steatosis. RWPs showed an antioxidant mechanism of action against MS. This result will inform future animal studies exploring the metabolic effects of RWPs in more detail. In addition, these findings support the use of antioxidants as adjunctive nutritional treatments for patients with diabetes.