This Review Article is focused on the action of the reactive oxygenated species in inducing oxidative injury of the lipid membrane components, as well as on the ability of antioxidants (of different ...structures and sources, and following different mechanisms of action) in fighting against oxidative stress.
Oxidative stress is defined as an excessive production of reactive oxygenated species that cannot be counteracted by the action of antioxidants, but also as a perturbation of cell redox balance. Reactive oxygenated/nitrogenated species are represented by superoxide anion radical, hydroxyl, alkoxyl and lipid peroxyl radicals, nitric oxide and peroxynitrite.
Oxidative stress determines structure modifications and function modulation in nucleic acids, lipids and proteins. Oxidative degradation of lipids yields malondialdehyde and 4-hydroxynonenal, but also isoprostanes, from unsaturated fatty acids. Protein damage may occur with thiol oxidation, carbonylation, side-chain oxidation, fragmentation, unfolding and misfolding, resulting activity loss. 8-hydroxydeoxyguanosine is an index of DNA damage.
The involvement of the reactive oxygenated/nitrogenated species in disease occurrence is described. The unbalance between the oxidant species and the antioxidant defense system may trigger specific factors responsible for oxidative damage in the cell: over-expression of oncogene genes, generation of mutagen compounds, promotion of atherogenic activity, senile plaque occurrence or inflammation. This leads to cancer, neurodegeneration, cardiovascular diseases, diabetes, kidney diseases.
The concept of antioxidant is defined, along with a discussion of the existent classification criteria: enzymatic and non-enzymatic, preventative or repair-systems, endogenous and exogenous, primary and secondary, hydrosoluble and liposoluble, natural or synthetic. Primary antioxidants are mainly chain breakers, able to scavenge radical species by hydrogen donation. Secondary antioxidants are singlet oxygen quenchers, peroxide decomposers, metal chelators, oxidative enzyme inhibitors or UV radiation absorbers.
The specific mechanism of action of the most important representatives of each antioxidant class (endogenous and exogenous) in preventing or inhibiting particular factors leading to oxidative injury in the cell, is then reviewed. Mutual influences, including synergistic effects are presented and discussed. Prooxidative influences likely to occur, as for instance in the presence of transition metal ions, are also reminded.
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•Oxidative stress initiates structure and function alterations of key biomolecules.•The oxidant/antioxidant unbalance activates factors responsible for cell injury.•Reactive oxygenated/nitrogenated species become the source of disease occurrence.•General and specific antioxidant mechanisms prevent the oxidative damage.•Prooxidative effects may occur in some cases, like in the presence of transition metal ions.
The present review focuses on electrochemical methods for ascorbic acid assessment. The occurence, role, biological importance of vitamin C, as well as the non-electrochemical methods for its ...assessment are firstly reviewed. The electrochemical behavior of ascorbic acid is then illustrated, followed by a description of the potentiometric, voltammetric and amperometric methods for vitamin C content estimation in various media. Different methods for the development of electrochemical sensors are reviewed, from unmodified electrodes to different composites incorporating carbon nanotubes, ionic liquids or various mediators. From this perspective, the interaction between the functional groups of the sensor's material and the analyte molecule is discussed, as it is essential for the analytical characteristics obtained. The analytical performances of the potentiometric, voltammetric or amperometric chemical and biochemical sensors (linear range of analytical response, sensitivity, precision, stability, response time etc) are highlightened. The numerous applications of ascorbic acid electrochemical sensors in fields like food, pharmaceutical or clinical analysis, where vitamin C represents a key analyte, are also presented.
The present paper aims to review the natural food preservatives with antimicrobial properties emphasizing their importance for the future of food manufacturing and consumers' health. The extraction ...procedures applied to natural antimicrobials will be considered, followed by the description of some natural preservatives' antimicrobial mechanism of action, including (i) membrane rupture with ATP-ase activity inhibition, (ii) leakage of essential biomolecules from the cell, (iii) disruption of the proton motive force and (iiii) enzyme inactivation. Moreover, a provenance-based classification of natural antimicrobials is discussed by considering the sources of origin for the major natural preservative categories: plants, animals, microbes and fungi. As well, the structure influence on the antimicrobial potential is considered. Natural preservatives could also constitute a viable alternative to address the critical problem of microbial resistance, and to hamper the negative side effects of some synthetic compounds, while meeting the requirements for food safety, and exerting no negative impact on nutritional and sensory attributes of foodstuffs.
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•Natural antimicrobials can derive from plants, animal sources, microorganisms, algae or mushrooms.•Natural antimicrobial agents may constitute a viable and safer alternative to synthetic ones.•Natural antimicrobials ensure food safety without impairing organoleptic or nutritional properties.•Action mechanism: rupture of microbial cell membrane, decay of proton motive force, interference with biomolecules’ activity.•The influence of structure proved crucial for the exhibited preservation potential of natural antimicrobials.
A method was developed for assessing ascorbic acid concentration in fruit juices and wine by differential pulse voltammetry. The oxidation peak for ascorbic acid occurs at about 530 mV (versus SCE) ...on a Pt strip working electrode and at about 470 mV on a carbon paste working electrode. The influence of the operational parameters like the pulse amplitude and the pulse period on the analytical signal was investigated. The obtained calibration graph shows a linear dependence between the peak height and ascorbic acid concentration within the range 0.31-20 mM with a Pt working electrode, and within the range 0.07-20 mM with a carbon paste working electrode. The equation of the calibration graph was y = 21.839x + 35.726, r² = 0.9940, when a Pt strip electrode was used (where y represents the value of the current intensity measured for the peak height, expressed as µA and x the analyte concentration, as mM). R.S.D. = 2.09%, n = 10, C(ascorbic acid) = 2.5 mM. The equation of the calibration graph was y = 3.4429x + 5.7334, r² = 0.9971, when a carbon paste electrode was used (where y represents the value of intensity measured for the peak height, expressed as µA and x the analyte concentration, as mM). R.S.D. = 2.35%, n = 10, C(ascorbic acid) = 2.5 mM. The developed method was applied to ascorbic acid assessment in fruit juices and wine. The ascorbic acid content determined ranged between 6.83 mg/100 mL juice for soft drinks (Fanta Madness) and 54.74 mg/100 mL for citrus (lemon) juices obtained by squeezing fruit. Different ascorbic acid concentrations (from standard solutions) were added to the analysed samples, the degree of recovery being comprised between 94.74 and 104.97%. The results of ascorbic acid assessment by differential pulse voltammetry were compared with those obtained by cyclic voltammetry. The results obtained by the two methods were in good agreement.
Backround: The present review focuses on
electrochemical methods for antioxidant capacity and
its main contributors assessment. The main reactive
oxygen species, responsible for low density ...lipoprotein
oxidation, and their reactivity are reminded.
The role of antioxidants in counteracting the factors
leading to oxidative stress-related degenerative diseases
occurence, is then discussed. Antioxidants can scavenge
free radicals, can chelate pro-oxidative metal ions, or
quench singlet oxygen. When endogenous factors (uric
acid, bilirubin, albumin, metallothioneins, superoxide
dismutase, catalase, glutathione peroxidase, glutathione
reductase, glutathione-S-transferase) cannot accomplish
their protective role against reactive oxygen species,
the intervention of exogenous antioxidants (vitamin C,
tocopherols, flavonoids, carotenoids etc) is required,
as intake from food, as nutritional supplements or as
pharmaceutical products.
Literature study: The main advantages of
electrochemical methods with respect to traditional,
more laborious instrumental techniques are described:
sensitivity, rapidity, simplicity of the applied analytical
procedure which does not require complicated sample
pre-treatment etc.
The paper reviews minutiously the voltammetric,
amperometric, biamperometric, potentiometric and
coulometric methods for total antioxidant capacity
estimation. For each method presented, the electroactivity
and the mechanism of electro-oxidation of antioxidant
molecules at various electrodes, as well as the influences
on the electroactive properties are discussed. The
characteristics of the developed methods are viewed from
the perspective of the antioxidant molecule structure
influence, as well as from the importance of electrode
material and/or surface groups standpoint.
The antioxidant molecule-electrode surface
interaction, the detection system chosen, the use of
modifiers, as well as the nature of the analysed matrix are
the factors discussed, which influence the performances
of the studied electrochemical techniques.
Conclusions: The electrochemical methods reviewed
in this paper allow the successful determination of the
total antioxidant capacity and of its main contributors in
various media: foodstuffs and beverages, biological fluids,
pharmaceuticals. The advantages and disadvantages
of the electrochemical methods applied to antioxidant
content and antioxidant activity assay are treated and
interpreted, in the case of various analysed matrixes.
Combining advanced materials with classical electrode
construction, provides viable results and can constitute
an alternative for the future.
Therapeutic approaches focused on the inflammatory microenvironment are currently gaining more support, as biomolecules involved in the inflammatory colorectal cancer (CRC) tumor microenvironment are ...being explored. We analyzed tumor and paired normal tissue samples from CRC patients (n = 22) whom underwent tumor resection surgery. We assessed 39 inflammation-involved biomolecules (multiplex magnetic bead-based immunoassay), CEA and CA19-9 (ELISA assay) and the tissue expression levels of occludin and also pErk, STAT1 and STAT3 transcriptional factors (western blot). Tumor staging has been established by histopathological evaluation of HE stained tumor tissue sections. We report 32 biomarkers displaying statistically significant differences in tumor vs. control. Additionally, positive statistical biomarker correlations were found between MMP2-IL8 and BAFF-IL8 (Pearson correlation coefficients > 0.751), while APRIL-MMP2, APRIL-BAFF and APRIL-IL8 were negatively correlated (correlation coefficients < - 0.650). While APRIL, BAFF, IL8 and MMP2 did not modulate with tumor stage, they were inversely related to the immune infiltrate level and CD163 tissue expression. We conclude that the significantly decreased APRIL and increased BAFF, IL8 and MMP2 expression were tumor-specific and deserve consideration in the development of new treatments. Also, the positive correlation between Chitinase 3-like 1 and IL8 (0.57) or MMP2 (0.50) suggest a role in tumor growth and metastasis pathways.
The aim of this paper was to assess the total antioxidant capacity of some commercial fruit juices (namely citrus), spectrophotometrically and by the biamperometric method, using the redox couple ...DPPH. (2,2-diphenyl-1-picrylhydrazyl)/DPPH (2,2-diphenyl-1-picrylhydrazine). Trolox was chosen as a standard antioxidant. In the case of the spectrophometric method, the absorbance decrease of the DPPH. solution was followed. For the biamperometric method, the influence of some parameters like the potential difference, DeltaE, DPPH. concentration, and Trolox concentration was investigated. The calibration graph obtained for Trolox presents linearity between 5 and 30 microM, (y=0.059 x + 0.0564, where y represents the value of current intensity, expressed as microA and x the value of Trolox concentration, expressed as muM; r(2)=0.9944). The R.S.D. value for the biamperometric method was 1.29% (n=10, c=15 microM Trolox). In the case of the spectrophotometric method, the calibration graph obtained for Trolox presents linearity between 0.01 and 0.125 mM (y= -9.5789 x+1.4533, where y represents the value of absorbance and x, the value of Trolox concentration, expressed as mM; r(2)=0.9963). The R.S.D. value for the spectrophotometric method was 2.05%. Both methods were applied to total antioxidant activity determination in real samples (natural juices and soft drinks) and the results were in good agreement.
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•Aflatoxins represent highly toxic secondary metabolites of fungi.•Sample preparation relies on liquid–liquid or solid-phase extraction.•Chromatographic methods ensure advanced ...purification of analytes.•Optical methods, mass spectrometry and electrochemical techniques are used for detection.•Sensitivity, selectivity, time, procedure complexity, influence the choice of the method.
Aflatoxins represent secondary metabolites of fungi, being characterized by a high degree of toxicity. They are classed as poisonous mycotoxins, hence the interest in the control of their level. 20 fungal metabolites compose the class of aflatoxins, that structurally derive from difuranocoumarin. Aspergillus flavus and Aspergillus parasiticus are the main species producing fungal metabolites in cereals, peanuts and animal feeds. Aflatoxins B1, B2, G1, G2, M1 and M2 are the most often encountered. Sample preparation techniques are crucial steps in aflatoxin analysis: they rely on liquid–liquid extraction or solid-phase extraction. Chromatographic methods ensure separation, advanced purification of analytes, which are subsequently quantified through detection techniques. The latter encompass optical methods, mass spectrometry and electroassay. Many analytical methods like ELISA, fluorescence polarization immunoassay, lateral flow immunoassay or PCR impart selectivity by using biorecognition elements: enzymes, antibodies or a DNA sequence. Given the high toxicity and presence of aflatoxins in food and agricultural products, their determination is an essential element in food safety. The analysis method is chosen according to the nature of the sample (type of matrix), the available equipment, the concentration range in which the toxin’s level is placed, sensitivity and detection limit, precision, selectivity, required analysis time, personnel training. The present paper provides a comprehensive view, and critically compares the performances of aflatoxin analysis methods, encompassing extraction, separation and detection techniques.
The present review paper focuses on the chemistry of oxidative stress mitigation by antioxidants. Oxidative stress is understood as a lack of balance between the pro-oxidant and the antioxidant ...species. Reactive oxygen species in limited amounts are necessary for cell homeostasis and redox signaling. Excessive reactive oxygenated/nitrogenated species production, which counteracts the organism’s defense systems, is known as oxidative stress. Sustained attack of endogenous and exogenous ROS results in conformational and oxidative alterations in key biomolecules. Chronic oxidative stress is associated with oxidative modifications occurring in key biomolecules: lipid peroxidation, protein carbonylation, carbonyl (aldehyde/ketone) adduct formation, nitration, sulfoxidation, DNA impairment such strand breaks or nucleobase oxidation. Oxidative stress is tightly linked to the development of cancer, diabetes, neurodegeneration, cardiovascular diseases, rheumatoid arthritis, kidney disease, eye disease. The deleterious action of reactive oxygenated species and their role in the onset and progression of pathologies are discussed. The results of oxidative attack become themselves sources of oxidative stress, becoming part of a vicious cycle that amplifies oxidative impairment. The term antioxidant refers to a compound that is able to impede or retard oxidation, acting at a lower concentration compared to that of the protected substrate. Antioxidant intervention against the radicalic lipid peroxidation can involve different mechanisms. Chain breaking antioxidants are called primary antioxidants, acting by scavenging radical species, converting them into more stable radicals or non-radical species. Secondary antioxidants quench singlet oxygen, decompose peroxides, chelate prooxidative metal ions, inhibit oxidative enzymes. Moreover, four reactivity-based lines of defense have been identified: preventative antioxidants, radical scavengers, repair antioxidants, and those relying on adaptation mechanisms. The specific mechanism of a series of endogenous and exogenous antioxidants in particular aspects of oxidative stress, is detailed. The final section resumes critical conclusions regarding antioxidant supplementation.
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•Pro-oxidant/antioxidant imbalance results in oxidative stress.•Oxidative stress implies deleterious alterations in biomolecules and disease occurrence.•The results of oxidative insults become themselves sources of oxidative stress.•Endogenous and exogenous antioxidants neutralize ROS and oxidative enzymes.•Supplements are recommended when oxidative stress surpasses the endogenous defense.
Differentiation of amniotic fluid stem cells (AFSCs) into multiple lineages is controlled by epigenetic modifications, which include DNA methylation, modifications of histones, and the activity of ...small noncoding RNAs. The present study investigates the role of miRNAs in the differentiation of AFSCs and addresses how their unique signatures contribute to lineage-specific differentiation. The miRNA profile was assessed in AFSCs after 4 weeks of endothelial and muscular differentiation. Our results showed decreased expression of five miRNAs (miR-18a-5p, miR-125b-5p, miR-137, miR-21-5p, and let-7a) and increased expression of twelve miRNAs (miR-134-5p, miR-103a-3p, let-7i-5p, miR-214-3p, let-7c-5p, miR-129-5p, miR-210-3p, let-7d-5p, miR-375, miR-181-5p, miR-125a-5p, and hsa-let-7e-5p) in endothelial progenitor cells (EPCs) compared with undifferentiated AFSCs. AFSC differentiation into smooth muscle revealed notable changes in nine out of the 84 tested miRNAs. Among these, three miRNAs (miR-18a-5p, miR-137, and sa-miR-21-5p) were downregulated, while six miRNAs (miR-155-5p, miR-20a-5p, let-7i-5p, hsa-miR-134-5p, hsa-miR-214-3p, and hsa-miR-375) exhibited upregulation. Insights from miRNA networks promise future advancements in understanding and manipulating endothelial and muscle cell dynamics. This knowledge has the potential to drive innovation in areas like homeostasis, growth, differentiation, and vascular function, leading to breakthroughs in biomedical applications and therapies.
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