Search Results (696)

The cleavage of cumene hydroperoxide (CHP) via the Hock rearrangement is a cornerstone process in the chemical industry, responsible for over 90% of global phenol and acetone production. Despite its industrial significance, the conventional use of homogeneous sulfuric acid catalysis presents critical drawbacks, including severe equipment corrosion, generation of hazardous waste, and the need for complex neutralization steps. This review explores the transition toward heterogeneous solid acid catalysts as a sustainable alternative, emphasizing the relationship between catalyst structure, surface acidity, and reaction performance. Key catalyst families—such as ion-exchange resins, zeolites, and heteropolyacids—are systematically evaluated, with a focus on how Brønsted acid site density and porous architecture influence catalytic activity and selectivity. Particular attention is given to deactivation mechanisms, including coking, leaching of active species, and poisoning by inorganic cations, alongside mitigation strategies enabled by rational catalyst design and regeneration protocols. Additionally, we highlight recent progress in reactor engineering, particularly the integration of solid acid catalysts in reactive distillation and microchannel configurations. These insights offer a strategic perspective for developing more efficient and environmentally benign industrial processes for the Hock cleavage of cumene hydroperoxide. Full article

Background/Objectives: The valorization of bioactive compounds from food industry by-products aligns with sustainable development goals and represents a strategy for obtaining functional ingredients. Hazelnut (Corylus avellana L.) skins are a phenolic-rich residue with high antioxidant potential, but their extraction conditions and cellular mechanisms of action remain insufficiently explored. Methods: Ultrasound-assisted extraction was optimized using a 3³ Full Factorial Design (FFD) by investigating temperature (30–50–70 °C), extraction time (1–2–3 h), and solvent composition (water/ethanol). Antioxidant activity was evaluated using multiple in vitro assays, including Total Phenolic Content (TPC), DPPH, ABTS, FRAP, and β-carotene bleaching (BCB) assays. The optimized extract (OE) was chemically characterized by UHPLC–MS/MS and its activity was evaluated in HepG2 cells for biocompatibility, modulation of intracellular ROS levels, and antioxidant pathway activation. Results: Optimal extraction conditions were identified as 30 °C, 70.86 min (1.181 h), and 21.13% ethanol (v/v), yielding an extract with enhanced antioxidant capacity. UHPLC–MS/MS analysis revealed 25 bioactive compounds, mainly flavonoids and phenolic acids, relevant for oxidative stress modulation. The extract significantly reduced tert-butyl hydroperoxide (TBH)-induced intracellular ROS levels, restoring antioxidant proteins involved in the Nuclear Factor erythroid 2-related factor 2 (NRF-2)-mediated defense pathway. Conclusions: The optimized hazelnut skin extract combines strong antioxidant efficacy with cellular compatibility, supporting its potential application as a functional ingredient for nutraceutical and pharmaceutical strategies targeting oxidative stress-related conditions. Full article

This study investigates the synthesis of 1-hydroperoxyadamantane, addressing discrepancies in the prior literature. Our results demonstrate that previous authors were unable to obtain the claimed compound under the conditions they described. We confirmed that 1-hydroperoxyadamantane can be synthesized in good yields via the reaction of 1,3-dehydroadamantane with concentrated hydrogen peroxide in DCM. Structure of 1-hydroperoxyadamantane was confirmed by SC XRD analysis. These findings clarify the conditions necessary for successful synthesis of this compound and highlight the importance of comprehensive analytical verification. This study also provides a very detailed, repeatedly verified method for synthesizing 1,3-dehydroadamantane and a description of the necessary laboratory equipment. Full article

Background: Cryopreservation induces oxidative stress, membrane disruption, and mitochondrial injury in spermatozoa, leading to impaired motility and fertility. Selenium, as an essential trace element, protects cells from oxidative damage through selenoproteins such as glutathione peroxidase 4 (GPX4), a critical enzyme that detoxifies lipid hydroperoxides and inhibits ferroptosis. This study investigated whether supplementation with L-selenomethionine (L-SeMet), an organic selenium source with superior bioavailability and lower toxicity than inorganic forms, could alleviate cryo-induced sperm injury by suppressing ferroptosis. Methods & Results: Dairy goat sperm were cryopreserved with 0, 2, 4, 6, 8, 10 μM L-SeMet. Supplementation with 6 μM L-SeMet significantly improved motility, membrane and acrosome integrity, and mitochondrial membrane potential. Biochemical assays showed reduced iron, ROS, and MDA levels, alongside increased ATP, SOD, and GSH contents. Proteomic analysis identified 148 differentially expressed proteins, including up-regulation of GPX4, FTH1, VDAC2, and VDAC3—core ferroptosis regulators. Metabolomic profiling further revealed enrichment in unsaturated fatty acid biosynthesis, amino acid metabolism, and the TCA cycle, pathways closely linked to ferroptosis regulation. Transmission electron microscopy confirmed that L-SeMet preserved mitochondrial ultrastructure. Mechanistically, L-SeMet mirrored the ferroptosis inhibitor N-acetyl-L-cysteine and reversed RSL3-induced oxidative damage. Western blotting verified activation of the NRF2–SLC7A11–GPX4 antioxidant axis and inhibition of KEAP1 expression. Conclusions: Collectively, these findings demonstrate that L-SeMet protects spermatozoa from cryo-induced injury by stabilizing redox homeostasis, maintaining mitochondrial function, and inhibiting ferroptosis. The results highlight ferroptosis as a critical mechanism of sperm cryodamage and identify L-SeMet as a promising metabolic intervention to enhance post-thaw sperm quality and fertility. Full article

Immunosenescence is characterized by an age-associated decline in immune function, particularly involving T-cell dysfunction, which increases susceptibility to infections and chronic diseases. This study investigated the anti-aging and immunomodulatory effects of American ginseng extract (G1899) using in vitro and in vivo models of aging. Cellular senescence was induced in HepG2 cells by D-galactose treatment, followed by exposure to G1899 (20 and 100 μg/mL). Senescence-associated markers were assessed to evaluate cellular aging. An aging mouse model was established in male C57BL/6 mice through intraperitoneal administration of D-galactose (500 mg/kg) and tert-butyl hydroperoxide (0.4 mmol/kg), and G1899 was orally administered at 400 mg/kg. Thymic immune cell subsets and aging-related protein expression were analyzed using flow cytometry and Western blotting. G1899 significantly reduced p21 expression and senescence-associated β-galactosidase activity in senescent HepG2 cells. In aging-induced mice, G1899 restored CD4⁺ and CD8⁺ T-cell populations, normalized naïve T-cell levels, and reduced anergic CD28-negative T cells. Furthermore, G1899 regulated the expression of key aging-related proteins, including FOXO1, Sirt1, p53, and CD38. These findings demonstrate that G1899 attenuates age-related immune alterations by restoring thymic T-cell homeostasis and regulating aging-associated molecular pathways. Full article

Glutathione (GSH) is a central regulator of redox homeostasis, melanogenesis, and cellular repair, and has gained increasing attention in dermatology for its potential roles in skin brightening, anti-aging, and tissue regeneration. This systematic review evaluated molecular, clinical, and translational evidence of glutathione’s applications and safety across different delivery modalities. The review followed PRISMA guidelines and included studies published between 2000 and 2025. A total of 194 studies met the inclusion criteria, evaluating the effectiveness of glutathione in esthetic dermatology and regenerative medicine. Topical and oral glutathione demonstrated favorable effects on pigmentation, skin brightness, hydration, and oxidative stress markers. Injectable glutathione increases systemic levels rapidly, but is associated with short-lasting effects and potential safety concerns. Glutathione S-transferases facilitate the conjugation of glutathione to electrophilic xenobiotics, thereby protecting proteins and nucleic acids from electrophile-induced damage. Glutathione Peroxidase employs GSH as an electron donor to reduce hydrogen peroxide and lipid hydroperoxides, thus protecting membrane lipids, mitochondrial membranes, and DNA from oxidative damage. Glutathione facilitates the regeneration of other antioxidants, such as vitamin C and vitamin E, through redox cycling. A consistent correlation exists between reduced GSH levels and neuronal dysfunction. Elevated GSH levels enhance cellular resistance to oxidative stress and reduce apoptotic signaling. GSH plays a pivotal role in cutaneous aging and tissue repair through redox regulation, mitochondrial protection, and the modulation of inflammatory and extracellular matrix pathways. To elucidate the clinical significance of glutathione, future research should focus on conducting randomized controlled trials, developing standardized formulations, and performing long-term safety assessments. Full article

The roots of Panax ginseng are well known for their bioactive properties, while its berries have recently attracted attention for their pharmacological potential. This study investigated whether fermentation with Lactiplantibacillus plantarum enhances the antioxidant properties of ginseng roots and berries and their protective effects against oxidative stress in vitro. Fermentation significantly increased total polyphenol, flavonoid, and saponin contents and promoted the conversion of major ginsenosides (ginsenoside Rg1, ginsenoside Rb1, and ginsenoside Rb2), which are relatively less bioavailable, into minor ginsenosides (ginsenoside Rh1, ginsenoside Rg2, and ginsenoside Rg3) with enhanced biological activity and bioavailability. Fermented extracts exhibited higher radical-scavenging activities in 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and ferric reducing antioxidant power (FRAP) assays than non-fermented extracts. In tert-butyl hydroperoxide (t-BHP)-stimulated Chang liver cells, fermented extracts reduced intracellular reactive oxygen species (ROS) generation, inhibited lipid peroxidation, restored the reduced glutathione/oxidized glutathione (GSH/GSSG) ratio, and enhanced antioxidant enzyme activities, including superoxide dismutase (SOD) and catalase (CAT). These results demonstrate that L. plantarum-mediated fermentation effectively enhances the antioxidant and cytoprotective potential of ginseng roots and berries, supporting their application as functional food ingredients. Full article

In this study, we first focused on measuring H₂S and oxidative stress as indicators of in-hospital mortality observed within 24 h from admission in hospitalized non-survivor and survivor patients affected by COVID-19. Then, we analyzed whether N-acetylcysteine (NAC) can increase H₂S and GSH concentrations in different cell lines. H₂S levels were significantly increased in all COVID-19 patients (both survivors and non-survivors) compared to non-COVID-19 subjects (p = 0.0016), but non-survivors showed significantly lower H₂S plasma levels than survivors (p = 0.008). Oxidative stress measured as circulating malondialdehyde (MDA) resulted in lower levels in non-COVID-19 subjects than in the two COVID-19 patient groups (p = 0.03). However, non-survivors had significantly higher plasma MDA than survivors (p = 0.0001). A Kaplan–Meier curve for H₂S indicates a markedly reduced survival probability in COVID-19 patients with lower H₂S levels (log-rank p = 0.004). NAC activity significantly reduced reactive oxygen species and lipid peroxidation induced by tert-butyl hydroperoxide in cultured cells (p from <0.01 to <0.001). Furthermore, NAC increased the cellular production of H₂S (p < 0.01) and GSH (p < 0.01). These findings indicate the important prognostic role of H₂S in COVID-19 patients at hospital admission and that NAC might be helpful in all clinical situations characterized by low levels of H₂S. Full article

Glutathionyl-hemoglobin (HbSSG) reversibly forms under oxidative stress in erythrocytes, where it constitutes the main redox buffer, in a dynamic equilibrium with the thiol (GSH) and disulfide (GSSG) forms of glutathione, that quickly revert to the reduced thiols when oxidative pressure is relieved. Under acute challenge, the “oxidized” GSH pool distributes between GSSG and HbSSG. Recalculation with electrochemical metrics based on redox potentials of the GSSG/GSH and HbSSG/HbSH pairs, plotted in their phase space, improves the understanding of the competing reduction processes. The first process is reduction of the GSSG pool, while, later, HbSSG reduction occurs as a two-step process. HbSSG accumulation in chronic oxidative stress follows an impairment of these steps. In 30 strong smokers, homogeneous levels of HbSSG are in the range of 2.4–11.7% (E_h −120–−95 mV), but the E_h of the GSSG/GSH redox pair is wider (−160–−240 mV), suggesting that HbSSG accumulation does not depend on GSH availability but on enzyme activity impaired by exogenous and endogenous electrophiles. As hinted by HbSSG measurements, one such species is the dehydro-alanine analog of GSH, produced both from butadiene in exposed petrochemical workers and from the drug busulfan in a treated patient. Inactivation of the low-copy recycling enzymes can thus explain the increase of HbSSG. Full article

Background/Objectives: Oxidized lipid droplet formation and cardiolipin (CL) profile abnormality in mitochondrial membranes are associated with metabolic dysfunction-associated steatotic liver disease (MASLD). However, studies on cell models to easily and simultaneously assess the preventive effects on oxidized lipid droplet formation and CL abnormality by indirect antioxidants are limited. Here, we aimed to develop a lipidomics-based cell screening platform to simultaneously evaluate the preventive effects of indirect antioxidants on oxidized lipid droplet formation and mitochondrial membrane lipid abnormalities. Methods: We created a novel lipidomics-based cell screening platform using oxidized low-density lipoprotein (oxLDL) and a human liver-derived cell line (C3A), and screened indirect antioxidants to promote the expression of cellular antioxidant enzymes, preventing oxidized lipid droplet formation. Results: Mass spectrometry revealed that oxLDL increased the levels of cholesteryl ester hydroperoxides. Thus, oxidized lipid droplet formation was confirmed. Three indirect antioxidants (kaempferol, quercetin, and hesperetin) were examined in the lipidomics-based platform. Consequently, quercetin significantly decreased major lipids and lipid hydroperoxide species, particularly triglycerides and triglyceride hydroperoxides with five or more double bonds. Furthermore, fluorescence microscopy revealed that quercetin reduced the size of small oxidized lipid droplets; it also decreased monolysocardiolipin, which could be associated with mitochondrial dysfunction. Conclusions: Overall, we demonstrated that this method could be useful for screening indirect antioxidants with excellent preventive effects against oxidized lipid droplet formation and CL abnormality by simultaneously analyzing various lipids. Full article

The oxidation of flexible polyurethane (PUR) foams significantly impacts product durability, vehicle indoor air quality, and volatile organic compound (VOC) emissions. This study investigates oxidation kinetics and VOC emissions (65–155 °C) from foams with indices between 70 and 115 (molar ratio of NCO to NCO-reactive groups × 100), where a higher index represents greater hard segment (methylene diphenyl diisocyanate) and lower soft segment (polyether polyol) content. Using a flow-through setup with PTFE chambers and Tenax thermodesorption tubes and dinitrophenylhydrazine (DNPH) cartridges, VOCs from initial analyte loading, hydroperoxide degradation, and autoxidation were distinguished, providing robust kinetic data unaffected by diffusion interference. A higher index accelerated soft segment degradation, increasing oxidation rates and VOC emissions. The activation energy of 1,2-propanediol-1-acetate-2-formate increased from 87 kJ/mol in low-index to 108 kJ/mol in high-index formulations. VOC emissions from high-index foams were tripled for acetaldehyde during long-term aging at 65 °C. While most emissions followed Arrhenius behavior, formaldehyde and acrolein deviated above 100 °C, with higher hard-segment content extending their Arrhenius range. These findings link PUR composition to degradation behavior and emissions, enabling formulation improvements. The results advance methods for evaluating raw material contributions and the performance of antioxidants under realistic aging conditions. Full article

The effect of cold atmospheric plasma (CAP) (a pin-to-liquid DBD) (28–32 kV, 1–10 min) on virgin olive oil (VOO) lipid oxidation was kinetically investigated. Quality assessment was performed (bioactive compound concentrations and fatty acid profiles) while the samples were further characterized by Fourier Transform Infrared (FTIR) spectroscopy and proton Nuclear Magnetic Resonance (¹H NMR). Intense processing (>5 min and voltages > 31 kV) significantly affected the quality of VOO, enhancing the oxidative reactions. CAP treatment led to an eight-fold increase in peroxide values and to a decrease in total antioxidants by up to 80% compared to untreated VOO. Carbonyl compounds (aldehydes, carboxylic acids) and hydroperoxide intermediates were the main oxidation products, while polyunsaturated fatty acids (PUFAs) dropped from 81.17% to 76.51%. The double bonds in the acyl chains were also highly reactive and facilitate the oxidation and subsequent fragmentation of the VOO. Full article

Thermal oxidation of edible oils during high-temperature cooking produces complex fumes containing harmful volatile compounds. However, the role of water, a common co-reactant in practical cooking, remains insufficiently understood. In this study, oleic acid was used as a model compound to investigate thermal oxidation. Online monitoring using synchrotron radiation photoionization mass spectrometry (SR-PIMS) revealed that water significantly increased the emission of volatile acetaldehyde and acrolein, with maximum increases of 164% and 123% at 10% water addition. Complementary offline GC-MS analysis showed enhanced formation of (E)-2-decenal, (E,E)-2,4-decadienal, and (E)-2-undecenal, suggesting these unsaturated aldehydes may be key intermediates. Mechanistically, oleic acid underwent free radical-mediated peroxidation to form (E)-2-decenal, (E)-2-undecenal, and (E,E)-2,4-decadienal. These intermediates subsequently decomposed into acetaldehyde and acrolein via hydration, retro-aldol condensation, and hydroperoxide scission, with water accelerating both processes. Overall, these findings highlight water’s critical role in promoting the generation of harmful volatile aldehydes in oil fumes. Full article

Selective functionalisation of inert C(sp³)–H bonds in alkanes and cycloalkanes remains one of the main challenges in the field of environmentally sustainable chemistry. This review provides a critical assessment of current catalytic strategies, in particular addressing the persistent problem of overoxidation and low selectivity. Going beyond traditional compartmentalised summaries, this work identifies a significant trend towards the integration of non-traditional activation methods, including ultrasonic cavitation, photocatalysis, and nanosecond pulse discharges, in both homogeneous and heterogeneous systems. Key contributions include a comparative analysis of radical control strategies, in particular highlighting how intermediate hydroperoxides can be used to shift reaction pathways towards selectivity of over 97% for alcohols and ketones. In addition, we discuss the emerging role of carbon nanomaterials (e.g., fullerenes and brominated nanotubes) as active electron-rich carriers and catalysts that lower the energy barriers for C–H activation under mild, ‘green’ conditions. The review concludes that the future of scalable hydrocarbon oxidation lies in ‘hybrid’ approaches such as stabilising active metal centres in protective matrices (zeolites, polymers) while using physical stimuli (ultrasound) to overcome diffusion limitations. This unique perspective highlights the transition from purely chemical catalyst design to integrated process intensification, offering a roadmap for energy-efficient and environmentally friendly industrial technologies. Full article

Plant-based extracts are rich sources of phenolic compounds, which may act as skin antiaging mediators. Herein, Cistus albidus L. (Ca), Cistus ladanifer L. subsp. ladanifer (Cl) and Cistus salviifolius L. (Cs) were selected to test whether their phytochemical profile and bioactive potential align to target human skin aging. Hydroethanolic extracts (HEs) were prepared and characterized using infrared vibrational spectroscopy (FTIR-ATR) and liquid chromatography–mass spectrometry (LC-MS). Non-toxic concentrations were screened, and cytoprotective and antioxidant effects were studied in tert-butyl hydroperoxide-stimulated normal human dermal fibroblasts (NHDFs). Lipopolysaccharide-stimulated RAW 264.7 macrophages were used to assess anti-inflammatory activity, the Organization for Economic Co-operation and Development (OECD) Test Guideline No. 439 was used to assess irritant effects, and the anti-senescence potential was assessed in etoposide-stimulated NHDFs. A series of enzymatic inhibition assays was performed. All extracts comprised ellagic acid derivatives, as well as myricetin and quercetin derivatives in Cs and Ca. The HE of Cs was also markedly composed of ligstroside. At non-toxic concentrations, cytoprotective effects were observed in NHDFs. However, only Cs and Cl exhibited significant antioxidant activity in these cells (p < 0.001 and p < 0.0001, respectively). In addition to that, Cl demonstrated highly significant anti-inflammatory (p < 0.0001) and anti-senescence (p < 0.0001) effects. Cs and Cl showed a remarkable potential to inhibit elastase; in addition, Cs also showed anti-hyaluronidase and anti-tyrosinase activities. Meaningfully, Cs and Cl extracts did not exhibit skin irritant effects. The unveiled potential of Cl in skin aging offset highlights the need to elucidate the detailed mechanisms of action, paving the way for the development of skin anti-aging formulations. Full article