Oxygen

Alterations in cellular energy metabolism are a hallmark of cancer and lactate dehydrogenase (LDH) enzymes are overexpressed in many cancers regardless of sufficient oxygen and functional mitochondria. Further, L-lactate plays signaling roles in multiple cell types. We evaluated the effect of singlet oxygen and hypochlorous acid (HOCl) on pig heart LDH-B, which shares 97% homology with human LDH-B. Singlet oxygen was generated photochemically using methylene blue or the chlorophyll metabolites, pheophorbide A and chlorin e6. Singlet oxygen induced protein crosslinks observed by SDS-PAGE under reducing conditions and inhibited LDH-B activity. Ascorbate, hydrocaffeic acid, glutathione and sodium azide were employed as singlet oxygen scavengers and shown to protect LDH-B. Using fluorescein-modified maleimide, no changes in cysteine availability as a result of singlet oxygen damage were observed. This was in contrast to HOCl, which induced the formation of disulfides between LDH-B subunits, thereby decreasing LDH-B labeling with fluorescein. HOCl oxidation inhibited LDH-B activity; however, disulfide reduction did not restore it. LDH-B cysteines were resistant to millimolar H₂O₂, chloramines and Angeli’s salt. In the absence of pyruvate, LDH-B enhanced NADH oxidation in a chain reaction initiated by singlet oxygen that resulted in H₂O₂ formation. Once damaged by either singlet oxygen or HOCl, NADH oxidation by LDH-B was impaired. Full article

Noble gases are a valuable but overlooked source of effective and safe therapeutics. Being monoatomic and chemically inert, they nonetheless have a surprisingly wide range of biochemical and medically valuable properties. This mini review briefly summarizes these properties for the most widely used noble gases and focuses and research gaps and missed opportunities for wider use of these intriguing ‘atomic’ drugs. The main research gaps and opportunities lie firstly in the application of advanced computational modelling methods for noble gases and recent developments in accurate predictions of protein structures from sequence (AlphaFold), and secondly in the use of very efficient and selective drug delivery technologies to improve the solubility, efficacy, and delivery of noble gases to key targets, especially for the lighter, poorly soluble gases. Full article

Bacteria-related infections remain a leading cause of dental implant failures. Despite the successful history of titanium implants, naturally forming oxides lack antibacterial properties. Crystalline oxides, modified through anodization processes, have shown photocatalytic-induced antibacterial properties when exposed to sufficient energy sources such as UVA light. Chemically doping these oxides with some metallic and non-metallic elements has been shown to enhance their photocatalytic activity (PCA). The present study’s objectives were to assess the relative UVA and violet-light-irradiated PCA levels, bacterial attachment levels, and pre-osteoblast early cell viability levels of phosphorus-doped and phosphorus-and-silver-doped anatase-phase oxides. Each oxide revealed similar surface topographies and surface porosity levels. However, the phosphorus-and-silver-doped oxides exhibited significantly higher PCA levels compared to the phosphorus-doped oxide counterpart after irradiation with 365 nm UVA (p < 0.0001) or 410 nm violet (p = 0.007 and 0.03) light. The phosphorus-doped oxides and phosphorus-and-silver-doped oxides revealed similar Staphylococcus aureus attachment levels after 60 min of UVA irradiation. The phosphorus-and-silver-doped oxides exhibited significantly increased 7-day cell viability compared to their phosphorus-doped oxide counterparts. Thus, it was concluded that the silver doping additions to the oxides show much promise for biomaterials applications and warrant further exploration. Full article

The diffusional dynamics and vibrational spectroscopy of molecular hydrogen (H₂) in myoglobin (Mb) is characterized. Hydrogen has been implicated in a number of physiologically relevant processes, including cellular aging or inflammation. Here, the internal diffusion through the protein matrix was characterized, and the vibrational spectroscopy was investigated using conventional empirical energy functions and improved models able to describe higher-order electrostatic moments of the ligand. Depending on the energy function used, H₂ can occupy the same internal defects as already found for Xe or CO (Xe1 to Xe4 and B-state). Furthermore, four additional sites were found, some of which had been discovered in earlier simulation studies. Simulations using a model based on a Morse oscillator and distributed charges to correctly describe the molecular quadrupole moment of H₂ indicate that the vibrational spectroscopy of the ligand depends on the docking site it occupies. This is consistent with the findings for CO in Mb from experiments and simulations. For H₂, the maxima of the absorption spectra cover ∼20 cm⁻¹ which are indicative of a pronounced Stark effect of the surrounding protein matrix on the vibrational spectroscopy of the ligand. Electronic structure calculations show that H₂ forms a stable complex with the heme iron (stabilized by ∼−12 kcal/mol), but splitting of H₂ is unlikely due to a high activation energy (∼50 kcal/mol). Full article

Skin grafting is a critical procedure for treating skin defects from burns, trauma, and surgical interventions, yet complications such as ischemia, necrosis, and infection can limit graft success. Hyperbaric Oxygen Therapy (HBOT) has emerged as a promising adjunctive treatment that enhances skin graft viability through mechanisms including enhanced oxygenation, angiogenesis, reduced inflammation, and anti-infective effects. This review synthesizes findings from clinical studies, comparative analyses, and case reports to clarify HBOT’s efficacy in improving skin graft outcomes. Methods include a comprehensive analysis of HBOT’s impact on graft take rates, healing times, and complication rates. Results indicate that HBOT significantly improves graft survival by mitigating ischemia and infection, while comparative studies show a reduction in major amputations and improved healing in complex cases, such as diabetic foot ulcers and traumatic injuries. These findings suggest that HBOT can serve as a valuable adjunct to standard grafting procedures, offering a multifaceted approach to improve graft viability, especially in high-risk cases. This review highlights HBOT’s potential for integration into wound management protocols, providing a foundation for further exploration into its efficacy and applications in reconstructive surgery. Full article

The success of heated tobacco products (HTPs) and electronic cigarettes (e-cigs) has been largely attributed to their ability to mimic the gestural experience of traditional cigarette smoking, while being perceived as a safer alternative due to the absence of combustion, as well as to their appeal, particularly among younger populations. Despite the initial idea that these new devices were harmless, recent literature reveals a concerning expanding body of evidence on their potential toxicity. Thus, this literature review aims to elucidate the mechanisms by which reactive oxygen species generated by HTPs and e-cigs induce oxidative stress and inflammation and the subsequent biological and health consequences, in order to raise awareness on the significance of addressing the potential toxicological effects associated with these devices, which are commonly believed to be safe. Full article

Evidence suggests that COVID-19 infection increases the risk of type 1 (T1D) and type 2 diabetes (T2D). Diabetes, in turn, increases COVID-19 susceptibility and contributes to increased COVID-19 morbidity and mortality. Oxidative stress has emerged as a common factor driving the pathogenesis of diabetes and COVID-19 caused by the severe acute respiratory syndrome coronavirus. The mechanistic links between oxidative stress, diabetes, and COVID-19 have primarily been studied in adults and will be summarized in this review. However, we suggest that studying these interconnections in children and young adults is critical since early intervention is optimal for improving outcomes. At the height of the pandemic, COVID-19 was a leading cause of death in children and young people, and people in this age group are as susceptible to COVID-19 as adults and the elderly. Glutathione is the primary water-soluble intracellular antioxidant and can be deficient in both diabetes and COVID-19. Glutathione is a tripeptide containing cysteine, glutamic acid, and glycine. Strategies to increase glutathione levels may be beneficial in helping to manage COVID-19-induced diabetes and diabetes-induced COVID-19 risk. Dietary supplementation with glycine plus n-acetyl-l-cysteine may be optimal since it contains two metabolic glutathione precursors. Full article

Cancer remains one of the leading causes of death despite advancements in research and treatment, with traditional therapies often causing significant side effects and resistance. Oxyhydrogen gas, a mixture of 66% molecular hydrogen (H₂) and 33% molecular oxygen (O₂) has shown exceptional promise as a novel therapeutic agent due to its ability to modulate oxidative stress, inflammation, and apoptosis. H₂, a key component of oxyhydrogen gas, neutralises reactive oxygen and nitrogen species, enhancing existing treatments and reducing harmful oxidative states in cancer cells. H₂ also lowers proinflammatory mediators including chemokines, cytokines, and interleukins, inhibiting cancer cell proliferation and boosting the effectiveness of conventional therapies. Additionally, hydrogen can induce apoptosis in cancer cells by modulating pathways such as MAPK and inhibiting the PI3K/Akt phosphorylation cascade. Preclinical and clinical evidence supports oxyhydrogen gas’s potential in treating various cancers. In lung cancer models, it inhibits cell proliferation, induces apoptosis, and enhances chemotherapy sensitivity. Similar results have been observed in breast cancer, where patients reported improved quality of life. In colorectal cancer, oxyhydrogen gas suppresses tumour growth, induces apoptosis, and improves intestinal microflora dysbiosis. The unique properties of oxyhydrogen gas make it a promising adjunctive or standalone cancer treatment. However, further research is needed to understand H₂s’ mechanisms, optimise treatment protocols, and evaluate long-term safety and efficacy in human patients. Full article

Oxidative stress, characterized by an imbalance between the production of reactive oxygen species and the body’s antioxidant defenses, plays an important role in the pathogenesis of various health conditions, including cancer and neurological disorders. For example, excessive ROS can lead to mutations, genomic instability, and uncontrolled cell proliferation in cancer. In neurological disorders, oxidative stress contributes to neuronal damage, inflammation, and the progression of diseases such as Alzheimer’s and Parkinson’s diseases. Adenosine, a nucleoside involved in energy transfer and signal transduction, is crucial to maintaining cellular homeostasis. Its role extends to modulating oxidative stress. Adenosine receptors are implicated in various physiological processes and in the pathophysiology of diseases. The interplay between oxidative stress and adenosine signaling is complex and critical. Adenosine can modulate oxidative stress responses, providing therapeutic potential for conditions where oxidative stress is a key player. Understanding this connection opens up avenues for novel therapeutic strategies targeting adenosine receptors to mitigate oxidative damage. Full article

This study explored the use of mandarin peels as an important source of health-promoting compounds by utilizing green methods (i.e., pulsed electric field and ultrasound-assisted extraction), along with conventional stirring. The impact of several extraction parameters, such as extraction duration, temperature, and solvent composition, on the recovery of bioactive compounds was evaluated through a response surface methodology. To identify the most effective conditions for all assays, a partial least-squares analysis was implemented. It was revealed that a combination of the above techniques was optimal at 80 °C for 30 min, with 75% v/v of ethanol in water as the extraction solvent. The concentration of bioactive compounds in the optimum extract had a total polyphenol content of 18.69 mg of gallic acid equivalents (GAE) per gram of dry weight (dw), and an ascorbic acid concentration of 18.25 mg/g dw. However, correlation analyses revealed a rather negative relationship between these bioactive compounds. The chromatographic analysis of optimum extracts supported this result by quantifying 20.53 mg/g dw of total individual polyphenols, with hesperidin being the dominant compound (13.98 mg/g dw). The antioxidant assays, including ferric-reducing antioxidant power and DPPH^• inhibition activity, were measured at 123.21 and 65.12 μmol of ascorbic acid equivalents (AAE) per gram of dw, respectively. This research enhances the valorization of mandarin peels as a renewable source of bioactive compounds, providing the opportunity to generate high-added-value products from food waste in the food and pharmaceutical sectors. Full article

This study focuses on post-harvest pest management in agriculture, in particular the transition to modified atmospheres as a sustainable alternative to conventional pesticide methods. Using Computational Fluid Dynamics (CFD) simulations, we analysed the dynamics of oxygen distribution within a pest control chamber. We tested four different configurations of nitrogen inlet and outlet positions to determine the most effective setup. The simulations used the twoLiquidMixingFoam solver in OpenFOAM to model gas mixing and diffusion. Our results show that the configuration with the nitrogen inlet at the top and the outlet at the bottom (Case D) was the most efficient. This configuration reached the target oxygen concentration of 1.5% in 4.4 h, significantly faster than the other configurations. These results highlight the importance of inlet and outlet positioning in improving the efficiency of oxygen reduction and ensuring a consistent low oxygen level throughout the chamber. Optimising the placement of nitrogen inlets and outlets has significant potential to improve the effectiveness of modified atmosphere treatments for pest control. Future research should consider additional environmental factors, different storage conditions and insect mortality models to further refine these methods. Full article

Lower limb muscle fatigue is the main reason for withdrawal from diving. Therefore, this study aimed to determine the local muscle oxygen saturation and hemoglobin concentration in the vastus lateralis muscle during different freediving disciplines. One freediver participated in this study, and his chronological age was 40 years, body mass 75.0 kg, body height 184.0 cm, and body fat 13.7%. The participant has been practicing freediving for 6 years. The variables in this study included anthropometric indices, heart rate, and muscle oxygen dynamics parameters (SmO₂ (oxygen muscle saturation) and tHb (total hemoglobin)). The variables were measured during five diving disciplines: static apnea, bifin, dynamic no fins (DNF), monofin, and sneaking. Measurements were performed during intensive training/competition during the diving season in August 2023. The results of this study showed that when oxygen starts to decrease during the dive, the tHb increases. Furthermore, the times at which maximal tHb and minimal SmO₂ were achieved are also shown. These parameters occurred at almost the same time across all disciplines: static (SmO₂, 142; tHb, 150 s), bifin (SmO₂, 153; tHb, 148 s), DNF (SmO₂, 162; tHb, 178 s), monofin (SmO₂, 96; tHb, 94 s), and sneaking (SmO₂, 212; tHb, 228 s). Also, differences in tHb and SmO₂ were present between diving disciplines. In particular, the highest increase in tHb was present in bifin (0.0028 AU/s), whereas monofin showed a decrease (−0.0009 AU/s). On the other hand, the highest desaturation was seen in bifin (−0.87%/s) and the lowest in sneaking (−0.29%/s) These findings emphasize the physiological characteristics of freedivers engaging in different freediving disciplines that influence muscles during the dive. Such responses could be observed through a concurrent hypoxia/hypercapnia and a transient reduction in the Fahraeus effect. Full article

Liquid organic hydrogen carriers (LOHCs) are aromatic molecules that are being considered for the safe storage and release of hydrogen. The thermodynamic properties of a range of aromatic ethers were investigated using various experimental and theoretical methods to assess their suitability as LOHC materials. The absolute vapour pressures were measured for benzyl phenyl ether, dibenzyl ether and 2-methoxynaphthalene using the transpiration method. The standard molar enthalpies and entropies of vaporisation/sublimation were derived from the temperature dependence of the vapour pressures. The combustion energies of benzyl phenyl ether and dibenzyl ether were measured using high-precision combustion calorimetry, and their standard molar enthalpies of formation were derived from these data. High-level quantum chemical calculations were used to calculate the standard molar enthalpies of formation in the gas phase for benzyl phenyl ether, dibenzyl ether and 2-methoxynaphthalene. The latter values agreed very well with the experimental results obtained in this work. The thermodynamic properties of the hydrogenation/dehydrogenation reactions in liquid phase in LOHC systems based on methoxy–benzene, diphenyl ether, benzyl phenyl ether, dibenzyl ether and 2-methoxynaphthalene were derived and compared with the data for similarly structured hydrogen carriers based on benzene, diphenylmethane, 1,2-diphenylethane, 1,3-diphenylpropane and naphthalene. The influence of the oxygen functionality on the thermodynamic properties of the hydrogenation/dehydrogenation reactions was evaluated. Full article

Rheumatoid arthritis (RA) is a well-known autoimmune inflammatory disease that affects the diarthrodial joints. Inflammation increases the production of reactive oxygen species (ROS), which may explain why RA is one of the diseases that induce oxidative stress. This study aimed to evaluate the potential differences in biochemical, hematological, and oxidative stress markers in the early stages of RA and after different treatment regimens. The study involved 111 patients, 28 men and 83 women aged 34 to 59 years, who were divided based on their c-reactive protein (CRP) levels into inactive RA patients (IRA) with CRP < 1.3 (n = 57, 22 men and 35 women) and active RA patients (ARA) with CRP ≥ 1.3 (n = 54, 6 men and 48 women). The study participants were divided into two groups, A and B, based on their treatment regimen. Group A, 90% of which were IRA patients, received methotrexate (MTX) monotherapy. Group B, which comprised 90% ARA patients, received a combination of leflunomide, a conventional disease-modifying antirheumatic drug (DMARD), and a biologic DMARD. The hematological, biochemical, oxidative stress, and RA-specific biomarkers were measured twice in groups A and B in the early stage of the disease, before and 3 months post-treatment, using conventional colorimetric, fluorometric, and immunological assays. According to the results of our study, glutathione peroxidase (GPx), ROS, calcium (Ca) and phosphorus (P) ions, vitamin C and D, and lipid profiles could serve as potential diagnostic markers in the early stages of the disease. Both treatment options were equally effective at improving the overall health of the patients. However, treatment resulted in a further increase in ROS levels and a decrease in antioxidant markers. Full article

Uterine fibroids are the most common tumors in females, affecting up to 70% of women worldwide, yet targeted therapeutic options are limited. Oxidative stress has recently surfaced as a key driver of fibroid pathogenesis and provides insights into hypoxia-induced cell transformation, extracellular matrix pathophysiology, hypoxic cell signaling cascades, and uterine biology. Hypoxia drives fibroid tumorigenesis through (1) promoting myometrial stem cell proliferation, (2) causing DNA damage propelling the transformation of stem cells to tumor-initiating cells, and (3) driving excess extracellular matrix (ECM) production. Common fibroid-associated DNA mutations include MED12 mutations, HMGA2 overexpression, and fumarate hydratase loss of function. Evidence suggests an interaction between hypoxia signaling and these mutations. Fibroid development and growth are promoted by hypoxia-triggered cell signaling via various pathways including HIF-1, TGFβ, and Wnt/β-catenin. Fibroid-associated hypoxia persists due to antioxidant imbalance, ECM accumulation, and growth beyond adequate vascular supply. Current clinically available fibroid treatments do not take advantage of hypoxia-targeting therapies. A growing number of pre-clinical and clinical studies identify ROS inhibitors, anti-HIF-1 agents, Wnt/β-catenin inhibition, and TGFβ cascade inhibitors as agents that may reduce fibroid development and growth through targeting hypoxia. Full article

This review explores the unique structural and functional characteristics of natural products featuring highly oxygenated cyclobutane rings, with a specific focus on oxetane and 1,2-dioxetane motifs. It presents the structures and biological activities of compounds containing these rings, highlighting their contribution to molecular stability and pharmacological potency. Through detailed case studies and recent research findings, it has been demonstrated that these oxygen-rich rings enhance the molecular diversity and biological efficacy of natural products, potentially offering new avenues for drug development. Notably, these compounds are predominantly synthesized by microorganisms and can also be found in extracts from fungi, plants, and certain marine invertebrates. Compounds with oxetane and 1,2-dioxetane rings are primarily noted for their strong antineoplastic properties, among other biological activities. In contrast, most 1,2-dioxetanes exhibit potent antiprotozoal effects. It is important to note that 1,2-dioxetanes often serve as intermediate products in oxidation reactions, characterized by their instability and propensity to decompose into new compounds. Full article

Halophyte plants and seaweed are described in the literature as rich sources of antioxidant compounds that can be used in the pharmaceutical and food industries. In this work, we studied the antioxidant composition of five species of halophytic plants (Suaeda vera Forssk, Halimione portulacoides L., Inula crithmoides L., Salicornia ramosissima (Hook.f.) J. Woods and Sarcocornia perennis (Mill.) A.J.Scott) and three seaweeds (Gracilaria gracilis (Stackhouse) Steentoft, L.Irvine and Farnham, Fucus spiralis L. and Ulva rigida C. Agardh) collected in Sado Estuary, Portugal. In the case of the plants, different parts of the plant were also assessed. Various extraction procedures were also performed to understand which methods were most suitable for extracting the various antioxidant compounds. Therefore, the aim of this study was to characterize the antioxidant compounds in halophytes and seaweed using various methods (ABTS, DPPH and FRAP), as well as the phenolic (TPC) and flavonoid (TFC) contents in the different extracts obtained. The amount of soluble protein in each extract was also determined. The results show that methanolic extracts generally have a higher antioxidant capacity, while the highest soluble protein content was observed in aqueous extracts. The seaweed Fucus Spiralis showed the highest antioxidant content, while in halophytic plants the highest antioxidant content was detected in the leaves. In general, this work confirms the potential of halophytes and seaweed as sources of antioxidant compounds for use in the food and pharmaceutical industries. Full article

Background: In otorhinolaryngology and head and neck surgery, oxygen is a therapeutic tool used for various pathologies. Oxidative stress is the imbalance between the production of free radicals (ROS) and the antioxidant capacity of the body, which can represent the pathogenesis of several pathologies or contribute to their worsening. This narrative review aims to analyze the benefits, indications, and side effects of hyperbaric oxygen therapy (HBOT) in different head and neck disorders. Methods: The search was carried out on multiple electronic databases such as PubMed and Google Scholar, and prospective, randomized, and reviewed studies were analyzed from January 1982 to February 2024. Results and Conclusions: The most common tools used to manage oxidative stress in the ear, nose, and throat (ENT) field are continuous positive airway pressure (CPAP) and HBOT. A common ENT pathology, while the latter can be used for osteoradionecrosis treatment in head and neck cancer patients, infections, malignant external otitis, head and neck reconstruction, facial cosmetic surgery, and among patients with sudden sensorineural hearing loss. From our analysis, it emerged that HBOT is a currently used effective therapy in various ENT pathologies’ treatment, alone or in association with other treatments; it can guarantee functional recovery and healing depending on the type of pathology for which it is used and on its severity. Full article

In this review, in addition to the potential cardiovascular applications of β-blockers and, more specifically, propranolol, we wanted to list the more recent applications in psychiatry as well as current knowledge on the impact of oxidative stress on propranolol hydrochloride and the oxidative stress that could be limited by the latter. In fact, a number of studies show that this molecule is modified by oxidative stress but is also able to limit it. Mention is also made to studies on the increasingly important problem of eliminating drug waste and its impact on the environment, particularly the marine environment. Given the increase in the consumption of medicines, more rigorous waste management is needed to avoid impacting biodiversity. Full article