Initial Oxidation Product Research Articles

Insight into the formation mechanism of oxidation layer on the amorphous boron nanocluster surface

Boron (B) powder with a high-energy density can enhance the energy of propellants. It has two different forms, namely amorphous B and crystalline B, which have different behaviors during the oxidation. Especially, the oxidation layer (OL) on its surface inhibits the ignition and combustion (IC). To comprehend the formation of OL on the amorphous B nanocluster (BNC) and elucidate its oxidation mechanism, the investigation was conducted on the oxidation of amorphous BNC at various oxygen contents and temperatures (300–1900 K). An analysis of the initial oxidation products (OP), the formation process of the oxidation layer, the reaction path, and the oxidation rate were encompassed and the microscopic oxidation mechanism that cannot be observed experimentally was revealed. The morphology of B (crystalline or amorphous B) does not significantly affect the OP and the thickness of OL. The initial OP of amorphous BNC are BO2 rather than B2O3, and the ultimate OP consist of BO2, BO, and polymer BmOn (m≠1). The oxidation layer on the B surface exhibits a relatively thin thickness. The oxidation rates of two different types of B both follow a parabolic law. The atomic structure of B cluster has an important influence on the reactivity of B. The oxidation rate is influenced by both the surface structure and the oxygen content of amorphous BNC. Based on the above research, a novel oxidation mechanism of amorphous BNC was proposed.

Water vapor oxidation behavior and mechanism of high-entropy (TiZrNbTaCr)C at 1200°C

High-entropy (TiZrNbTaCr)C ceramics with different Cr content were oxidized at 1200°C in water vapor. Zr6(Nb, Ta)2O17, (Nb, Ta)2O5 and (Ti, Nb, Ta, Cr)O2 were initial oxidation products. After a 4-h oxidation, TiO2-(Nb, Ta)2O5 was produced and changed from Ti(Nb, Ta)2O7 to Ti2(Nb, Ta)10O29 with increasing Cr content, resulting in better oxidation resistance. TiO2-(Nb, Ta)2O5 with large size and relatively dense microstructure impeded the inward diffusion of water vapor, slowing down the oxidation rate and causing the change of oxidation kinetics from linear to parabolic. The formation process of the oxide scale was discussed and the corrosion mechanism was proposed.

Detoxification of aflatoxin B1 by a Bacillus subtilis spore coat protein through formation of the main metabolites AFQ1 and epi-AFQ1.

A variety of important agricultural crops host fungi from the Aspergillus genus can produce cancerogenic secondary metabolites such as aflatoxins. Consequently, novel strategies for detoxification and their removal from food and feed chains are required. Here, detoxification of Aflatoxin B1 (AFB1) by the Bacillus subtilis multi-copper oxidase CotA (BsCotA) was investigated. This laccase was recombinantly produced in E. coli while codon optimization led to duplication of the amount of active protein obtained. CuCl2 was added to the cultivation medium leading to a 25-fold increase of V max corresponding to improved incorporation of Cu2+ into the enzyme protein which is essential for the catalytic reaction. To avoid potential cytotoxicity of Cu2+, cultivation was performed at microaerobic conditions indeed leading to 100x more functional protein when compared to standard aerobic conditions. This was indicated by an increase of V max from 0.30 ± 0.02 to 33.56 ± 2.02 U/mg. Degradation kinetics of AFB1 using HPLC with fluorescence detection (HPLC-FLD) analysis indicated a theoretical substrate saturation above solubility in water. At a relatively high concentration of 500 μg/L, AFB1 was decomposed at 10.75 μg/Lh (0.17 nmol*min-1*mg-1) at a dosage of 0.2 μM BsCotA. AFQ1 and epi-AFQ1 were identified as the initial oxidation products according to mass spectrometry (i.e., HPLC-MS, HPLC-QTOF). None of these molecules were substrates for laccase but both decomposed in buffer. However, decomposition does not seem to be due to hydration of the vinyl ether in the terminal furan ring. Genotoxicity of the formed AFB1 was assessed in several dilutions based on the de-repression of the bacterial SOS response to DNA damage indicating about 80-times reduction in toxicity when compared to AFQ1. The results of this study indicate that BsCotA has high potential for the biological detoxification of aflatoxin B1.

Biochemical analysis of H2O2-induced mutation spectra revealed that multiple damages were involved in the mutational process

Reactive oxygen species (ROS) are a major threat to genomic integrity and believed to be one of the etiologies of cancers. Here we developed a cell-free system to analyze ROS-induced mutagenesis, in which DNA was exposed to H2O2 and then subjected to translesion DNA synthesis by various DNA polymerases. Then, frequencies of mutations on the DNA products were determined by using next-generation sequencing technology. The majority of observed mutations were either C>A or G>A, caused by dAMP insertion at G and C residues, respectively. These mutations showed similar spectra to COSMIC cancer mutational signature 18 and 36, which are proposed to be caused by ROS. The in vitro mutations can be produced by replicative DNA polymerases (yeast DNA polymerase δ and ε), suggesting that ordinary DNA replication is sufficient to produce them. Very little G>A mutation was observed immediately after exposure to H2O2, but the frequency was increased during the 24 h after the ROS was removed, indicating that the initial oxidation product of cytosine needs to be maturated into a mutagenic lesion. Glycosylase-sensitivities of these mutations suggest that the C>A were made on 8-oxoguanine or Fapy-guanine, and that G>A were most likely made on 5-hydroxycytosine modification.

Unveiling Alternative Oxidation Pathways and Antioxidant and Cardioprotective Potential of Amaranthin-Type Betacyanins from Spinach-like Atriplex hortensis var. 'Rubra'.

A comprehensive oxidation mechanism was investigated for amaranthin-type betacyanins with a specific glucuronosylglucosyl moiety isolated from Atriplex hortensis 'rubra' using liquid chromatography coupled to diode array detection and electrospray ionization tandem mass spectrometry (LC-DAD-ESI-MS/MS) and LC-Quadrupole-Orbitrap-MS (LC-Q-Orbitrap-MS). By employing one-dimensional (1D) and two-dimensional (2D) NMR, this study elucidates the chemical structures of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS)-oxidized celosianins for the first time. These findings demonstrate alternative oxidation pathways for acylated betacyanins compared to well-known betanidin, betanin, and gomphrenin pigments. Contrary to previous research, we uncover the existence of 17-decarboxy-neo- and 2,17-bidecarboxy-xanneo-derivatives as the initial oxidation products without the expected 2-decarboxy-xan forms. These oxidized compounds demonstrated potent free radical scavenging properties. Celosianin (IC50 = 23 μg/mL) displayed slightly higher antioxidant activity compared to oxidized forms, 17-decarboxy-neocelosianin (IC50 = 34 μg/mL) and 2,17-bidecarboxy-xanneocelosianin (IC50 = 29 μg/mL). The oxidized compounds showed no cytotoxic effects on H9c2 rat cardiomyoblasts (0.1-100 μg/mL). Additionally, treatment of H9c2 cells with the oxidized compounds (0.1-10 μg/mL) elevated glutathione levels and exhibited protective effects against H2O2-induced cell death. These findings have significant implications for understanding the impact of oxidation processes on the structures and biological activities of acylated betalains, providing valuable insights for future studies of the bioavailability and biological mechanism of their action in vivo.

Oxidation of caspase-8 by hypothiocyanous acid enables TNF-mediated necroptosis

Necroptosis is a form of regulated cell death triggered by various host and pathogen-derived molecules during infection and inflammation. The essential step leading to necroptosis is phosphorylation of the mixed lineage kinase domain-like protein by receptor-interacting protein kinase 3. Caspase-8 cleaves receptor-interacting protein kinases to block necroptosis, so synthetic caspase inhibitors are required to study this process in experimental models. However, it is unclear how caspase-8 activity is regulated in a physiological setting. The active site cysteine of caspases is sensitive to oxidative inactivation, so we hypothesized that oxidants generated at sites of inflammation can inhibit caspase-8 and promote necroptosis. Here, we discovered that hypothiocyanous acid (HOSCN), an oxidant generated invivo by heme peroxidases including myeloperoxidase and lactoperoxidase, is a potent caspase-8 inhibitor. We found HOSCN was able to promote necroptosis in mouse fibroblasts treated with tumor necrosis factor. We also demonstrate purified caspase-8 was inactivated by low concentrations of HOSCN, with the predominant product being a disulfide-linked dimer between Cys360 and Cys409 of the large and small catalytic subunits. We show oxidation still occurred in the presence of reducing agents, and reduction of the dimer was slow, consistent with HOSCN being a powerful physiological caspase inhibitor. While the initial oxidation product is a dimer, further modification also occurred in cells treated with HOSCN, leading to higher molecular weight caspase-8 species. Taken together, these findings indicate major disruption of caspase-8 function and suggest a novel mechanism for the promotion of necroptosis at sites of inflammation.

Selective methane oxidation by molecular iron catalysts in aqueous medium.

Using natural gas as chemical feedstock requires efficient oxidation of the constituent alkanes-and primarily methane1,2. The current industrial process uses steam reforming at high temperatures and pressures3,4 to generate a gas mixture that is then further converted into products such as methanol. Molecular Pt catalysts5-7 have also been used to convert methane to methanol8, but their selectivity is generally low owing to overoxidation-the initial oxidation products tend to be easier to oxidize than methane itself. Here we show that N-heterocyclic carbene-ligated FeII complexes with a hydrophobic cavity capture hydrophobic methane substrate from an aqueous solution and, after oxidation by the Fe centre, release a hydrophilic methanol product back into the solution. We find that increasing the size of the hydrophobic cavities enhances this effect, giving a turnover number of 5.0 × 102 and a methanol selectivity of 83% during a 3-h methane oxidation reaction. If the transport limitations arising from the processing of methane in an aqueous medium can be overcome, this catch-and-release strategy provides an efficient and selective approach to using naturally abundant alkane resources.

Thermodynamic Study on Initial Oxidation Behavior of TiAl-Nb Alloys at High Temperature

The initial oxidation behavior of TiAl-Nb alloys was systematically investigated against the composition, temperature, and partial pressure of O2 with the CALculation of PHAse Diagrams (CALPHAD) technique. The mole fraction of each oxidation product at the initial oxidation stage of the alloys at the corresponding temperatures was predicted. The initial oxidation products of the alloys are oxides of Al, Ti, and Nb, with the oxidation order of Al, Ti, and Nb. As P(O2) increases, the Ti and Nb oxidation products move towards a high oxygen content, and the mole fractions of the Al and Ti oxides gradually decrease and increase, respectively. It was found that the temperature and partial pressure of O2 determined the types of the oxides and the oxidation order, while the concentration of Nb and Al determined the mole fraction of the oxides. The CALPHAD results are in good agreement with the experiments.

'Omics-guided prediction of the pathway for metabolism of isoprene by Variovorax sp. WS11.

Bacteria that inhabit soils and the leaves of trees partially mitigate the release of the abundant volatile organic compound, isoprene (2-methyl-1,3-butadiene). While the initial steps of isoprene metabolism were identified in Rhodococcus sp. AD45 two decades ago, the isoprene metabolic pathway still remains largely undefined. Limited understanding of the functions of isoG, isoJ and aldH and uncertainty in the route of isoprene-derived carbon into central metabolism have hindered our understanding of isoprene metabolism. These previously uncharacterised iso genes are essential in Variovorax sp. WS11, determined by targeted mutagenesis. Using combined 'omics-based approaches, we propose the complete isoprene metabolic pathway. Isoprene is converted to propionyl-CoA, which is assimilated by the chromosomally encoded methylmalonyl-CoA pathway, requiring biotin and vitamin B12, with the plasmid-encoded methylcitrate pathway potentially providing robustness against limitations in these vitamins. Key components of this pathway were induced by both isoprene and its initial oxidation product, epoxyisoprene, the principal inducer of isoprene metabolism in both Variovorax sp. WS11 and Rhodococcus sp. AD45. Analysis of the genomes of distinct isoprene-degrading bacteria indicated that all of the genetic components of the methylcitrate and methylmalonyl-CoA pathways are not always present in isoprene degraders, although incorporation of isoprene-derived carbon via propionyl-CoA and acetyl-CoA is universally indicated.

Preferential redox regulation of cysteine-based protein tyrosine phosphatases: structural and biochemical diversity.

Protein phosphorylation is a major post-translational modification involved in cell signalling that regulates many physiological and pathological processes. Despite their biological importance, protein phosphatases are less studied than protein kinases. Importantly, the activity of Cys-based protein tyrosine phosphatases (PTPs) can be regulated by reversible oxidation. The initial two-electron oxidation product of the active site Cys is a sulfenic acid (Cys-SOH) that can then undergo distinct outcomes, such as the disulfide bond or a sulfenyl amide formation. Here, we review the biochemical and structural features of PTPs to find patterns that might specify their oxidation products, aiming to get insights into redox regulatory mechanisms. Initially, the structure and biochemistry of PTP1B is presented. Then, we describe structural aspects that are relevant for substrate recognition and catalysis. Notably, all PTPs contain critical Cys residues for the catalysis of dephosphorylation that is prone to oxidative inactivation, which are frequently found oxidized in cells under physiological conditions, such as upon growth factor stimuli. However, direct oxidations of Cys residues in PTPs by H2 O2 are rather slow. Therefore, we discuss possible mechanisms that may account for this apparent contradiction between biological and chemical redox aspects of PTPs. Furthermore, we performed a systematic analysis of the distance between active site cysteine and its backdoor cysteine with the attempt to analyse the preference between disulfide bond formation or sulfenyl amide interaction upon oxidation. In summary, PTPs have been showing many possibilities to auto-protect from irreversible oxidation, which is important for cell signalling regulation.

Moderation of Oxidative Damage on Aromatic Hydrocarbon-Based Polymers

During the operation of aromatic hydrocarbon-based proton exchange membrane fuel cells, formed radical species attack the membrane. The most deleterious radical formed is HO·, both strongly electrophilic and oxidising. Oligomers of α-methylstyrene sulfonates (PAMSS) were used as model compounds. We report on the complex reaction cascade following the oxidative attack on aromatic cores bearing proton conductive sulfonate groups. UV-absorption bands of initial oxidation products indicate the formation of radical adducts and aromatic cation radicals. Subsequently, a transformation associated with an absorbance build-up at 580 nm is observed, presumably also related to aromatic cation radicals. Build-up and decay are significantly accelerated at high ionic strength levels that are also typical in fuel cells. Increased ionic strength causes phase separation: dynamic light scattering experiments indicate particle formation that is dependent both on chain length and on ionic strength. Aromatic cation radicals are known strong oxidants. With a presumed redox potential of E°((PAMSS-580 nm)·+/PAMSS) ∼ 2 V this oxidizing species should react also with mediocre reductants. Here, Mn(II) was oxidised to Mn(III) with rate constants of (5–10) × 106 M−1s−1. Implications for experimental design of kinetics experiments and understanding chemical mechanisms are discussed.

Microscopic mechanism of α-rhombic crystal boron nanocluster oxidation in oxygen

The oxidation of boron (B) powder plays an important role in its ignition and combustion. However, the microscopic mechanism of boron oxidation is controversy, so the detailed oxidation process of α-rhombic crystalline boron nanocluster in oxygen (T < 1900 K) was investigated by a molecular dynamics method based on the reaction force field (ReaxFF). The chemical reaction mechanism, oxidation products, and their properties were clarified. The microscopic dynamic process of boron oxidation was explored. The results show that the initial oxidation products of boron are BO2 and BO, and the final oxidation products are diverse complex boron-oxygen polymers (BmOn) (m ≠ 1) instead of B2O3. Boron and oxygen atoms can react with the oxide layer of boron nanocluster, and simultaneously diffuse in both directions. Oxygen molecules can react with the outer boron first and then gradually diffuse to the inner core, while they cannot react directly with the inner boron core through the oxide layer. Compared with the reaction of oxygen atoms with the oxide layer, the reaction of boron atoms with the oxide layer is easier. The α-rhombic crystalline boron cluster exhibits a strong inertness at low temperature, but the oxidation rate of boron surface accelerates as the temperature increases. During the oxidation process, electrons are transferred from boron atoms to oxygen atoms and polar covalent bonds are formed between boron and oxygen. When the temperature is close to the ignition temperature of the oxide layer, the oxidation products in the oxide layer start to evaporate and leave the surface of boron nanocluster. Different oxygen concentrations result in different starting times of oxidation reaction and different types of later oxidation products.

New degradation mechanism of black tea pigment theaflavin involving condensation with epigallocatechin-3-O-gallate

Theanaphthoquinone (TNQ) is the initial and main oxidation product of theaflavin, a representative black tea pigment. Nevertheless, TNQ is virtually undetected in the high-performance liquid chromatography analysis of black tea leaves using photodiode array detection. To elucidate the degradation mechanism of theaflavin in the black tea production process, this study investigated the reaction of TNQ with epigallocatechin-3-O-gallate (EGCg), which is the most abundant polyphenol in tea leaves. In citrate–phosphate buffer solution at pH 6 and room temperature, TNQ reacted nonenzymatically with EGCg to afford three products, whose structures were determined on the basis of spectroscopic data. The results indicated that the double bond of the ortho-naphthoquinone moiety in TNQ reacted with the autoxidation product of EGCg. This study demonstrates novel reactions occurring in the process of theaflavin degradation, which might be involved in the formation of thearubigins, the major black tea pigments composing oligomeric catechin oxidation products.

The Exploitation of Xanthan Cryogels as Pattern for Edible Oleogel Preparation

In this study, xanthan gum was used to produce cryogel and conversion of cryogel to oleo-gels, and the structural and chemical characteristics of the produced oleo-gels was investigated. Results showed, the produced oleo-gels (COS) contained about 66% oil content and they have able to holding oil at about 60%. The pseudo-second order model can predict the oil absorption kinetics of cryogels. There was no difference between the amount of fatty acids of sunflower oil and COS. 1H NMR and 13C NMR signals, the hydro peroxide (initial oxidation product) and aldehydes (secondary product oxidation) was not revealed in COS. Also, it was observed no exothermic process in the curve in the differential thermal analysis curve (DTA) up to 350 °C. AFM the formation of a uniform, homogeneous, and stable gel network that matched the results of the mechanical properties of the COS.

Thermal Decomposition and Kinetics of Pentlandite-Bearing Ore Oxidation in the Air Atmosphere

The roasting of sulfide ores and concentrates is one of the most important steps in pyrometallurgical metal production from primary raw materials, due to the necessity of excess sulfur removal, present in the virgin material. Pentlandite is one of the main sources for nickel pyrometallurgical production. The knowledge of its reaction mechanism, products distribution during oxidation and reaction kinetics is important for optimizing the production process. Raw pentlandite-bearing ore from the Levack mine (Ontario, Canada) was subjected to oxidative roasting in the air atmosphere. A chemical analysis of the initial sample was conducted according to EDXRF (Energy-Dispersive X-ray Fluorescence) and AAS (Atomic Adsorption Spectrometry) results. The characterization of the initial sample and oxidation products was conducted by an XRD (X-ray Diffraction) and SEM/EDS (Scanning Electron Microscopy with Energy Dispersive Spectrometry) analysis. Thermodynamic calculations, a phase analysis and construction of Kellogg diagrams for Ni-S-O and Fe-S-O systems at 298 K, 773 K, 923 K and 1073 K were used for proposing the theoretical reaction mechanism. A thermal analysis (TG/DTA—Thermogravimetric and Differential Thermal Analyses) was conducted in temperature range 298–1273 K, under a heating rate of 15° min−1. A kinetic analysis was conducted according to the non-isothermal method of Daniels and Borchardt, under a heating rate of 15° min−1. Calculated activation energies of 113 kJ mol−1, 146 kJ mol−1 and 356 kJ mol−1 for three oxidation stages imply that in every examined stage of the oxidation process, temperature is a dominant factor determining the reaction rate.

Improved Mechanistic Model of the Atmospheric Redox Chemistry of Mercury.

We present a new chemical mechanism for Hg0/HgI/HgII atmospheric cycling, including recent laboratory and computational data, and implement it in the GEOS-Chem global atmospheric chemistry model for comparison to observations. Our mechanism includes the oxidation of Hg0 by Br and OH, subsequent oxidation of HgI by ozone and radicals, respeciation of HgII in aerosols and cloud droplets, and speciated HgII photolysis in the gas and aqueous phases. The tropospheric Hg lifetime against deposition in the model is 5.5 months, consistent with observational constraints. The model reproduces the observed global surface Hg0 concentrations and HgII wet deposition fluxes. Br and OH make comparable contributions to global net oxidation of Hg0 to HgII. Ozone is the principal HgI oxidant, enabling the efficient oxidation of Hg0 to HgII by OH. BrHgIIOH and HgII(OH)2, the initial HgII products of Hg0 oxidation, respeciate in aerosols and clouds to organic and inorganic complexes, and volatilize to photostable forms. Reduction of HgII to Hg0 takes place largely through photolysis of aqueous HgII-organic complexes. 71% of model HgII deposition is to the oceans. Major uncertainties for atmospheric Hg chemistry modeling include Br concentrations, stability and reactions of HgI, and speciation and photoreduction of HgII in aerosols and clouds.

Dynamics and Multiconfiguration Potential Energy Surface for the Singlet O2 Reactions with Radical Cations of Guanine, 9-Methylguanine, 2'-Deoxyguanosine, and Guanosine.

Reactions of electronically excited singlet oxygen (1O2) with the radical cations of guanine (9HG•+), 9-methylguanine (9MG•+), 2'-deoxyguanosine (dGuo•+), and guanosine (Guo•+) were studied in the gas phase by a combination of guided-ion-beam mass spectrometric measurement of product ions and cross sections as a function of collision energy (Ecol) and electronic structure calculations of the reaction potential energy surface (PES) at various levels of theory. No product could be captured in the 1O2 reaction with bare 9HG•+ or 9MG•+, because energized products decayed rapidly to reactants before being detected. To overcome this unfavorable kinetics, monohydrated 9HG•+·H2O and 9MG•+·H2O were used as reactant ions, of which the peroxide product ions were stabilized by energy relaxation via elimination of the water ligand. Reaction cross sections for 9HG•+·H2O and 9MG•+·H2O decrease with increasing Ecol, becoming negligible above 0.6 eV. This indicates that the reactions are exothermic with no barriers above reactants and the heat of formation of the products is sufficiently large to overcome their water ligand elimination energy (0.7 eV). Peroxide product ions were also detected in the 1O2 reactions with unhydrated dGuo•+ and Guo•+, in which intramolecular vibrational redistribution was able to stabilize oxidation products. 9MG•+ was utilized as a model system to explore the reaction PES for the initial 1O2 addition to the guanine radical cation. Calculations were carried out using single-reference ωB97XD, RI-MP2, and DLPNO-CCSD(T) and multireference CASSCF and CASPT2. Although the same PES profile was obtained at different levels of theory, the energies of the mixed open- and closed-shell 1O2 reactant and the open-shell reaction intermediates, transition states, and products are sensitive to the theories. By taking into account both static and dynamic electron correlations, the CASPT2 PES has provided the best agreement with the experimentally measured reaction thermodynamics and predicted 8-peroxide as the most probable initial oxidation product of the guanine radical cation.

Electrocatalytic Oxidation of Hydroxide Ions by Co3O4 and Co3O4@SiO2 Nanoparticles Both at Particle Ensembles and at the Single Particle Level

AbstractWe report that the Co3O4 nanoparticle‐mediated electrochemical oxidation under alkaline conditions of the hydroxide ion on a glassy carbon macroelectrode leads to hydrogen peroxide as the initial oxidation product of electron transfer. The latter is inferred to subsequently partially decompose to dioxygen by catalytic chemical reaction at the nanoparticles. At the single particle level, electrochemical particle‐electrode impacts point out the rate‐determining step and the limiting kinetics of the reaction. Furthermore, particles with a core‐shell structure of a Co3O4 core and SiO2 shell are synthesised, and their electrochemical behaviour is studied and compared with bare Co3O4 nanoparticles, suggesting the very likely broken or highly porous state of the silica shell, which is not otherwise easily distinguished, for example, by electron microscopy.

Capture and Reactivity of an Elusive Carbon-Sulfur Centered Biradical.

The initial oxidation product of dimethyl sulfide in the marine boundary layer, the methyl thiomethyl radical, has remained elusive. A structurally analogous biradical with one radical center in the α-position to a sulfur atom could now be obtained by UV irradiation of p-nitrobenzaldehyde dithiane isolated in solid dinitrogen (N2) or Ar at cryogenic temperatures. A spin-forbidden reaction with triplet dioxygen (3O2) does not occur. The dithiane of o-nitrobenzaldehyde rather undergoes a series of rearrangements under the same conditions, resulting in overall photodeprotection.

Determination of the Thermal Oxidation Stability and the Kinetic Parameters of Commercial Extra Virgin Olive Oils from Different Varieties

The use of olive oil with cooking purposes, as final seasoning or within cooked foods is increasing worldwide due to its numerous nutritional and health benefits. These attributes are mainly determined by olive oil chemical composition, which can be altered after thermal processing, oxidation processes, or incorrect practices. For this reason, and due to the numerous factors which have influence in olive oil quality, the correct chemical characterization is highly relevant. In this study, fatty acid composition of four extra virgin olive oil (EVOO) varieties was studied. The major fatty acid (FA) determined was oleic acid (77.1% on average), followed by palmitic (11.5% on average). In addition, thermal oxidation behaviour of the four EVOO samples was studied as an indicator of their quality and stability during thermal processing. This was performed through differential scanning calorimetry (DSC) from a temperature of 40°C at six different heating rates in the range of 0.5–10°C min−1. DSC records showed the same pattern and a small shoulder in the thermo-oxidation peak was present for all samples and all heating rates. The presence of initial and final oxidation products (by monitoring K232 and K270 values, respectively) was discarded according to the International Olive Council method.