Radical Oxidation Research Articles

Chromatographic determination of volatile compounds of Achillea micranthoides Klok. et Krytzka

The processes of free radical oxidation are known to play a crucial role in the pathogenesis of many diseases. Therefore, the use of antioxidants is considered both pathogenetically justified and rational. Plants belonging to the genus Achillea L. are noted for their diverse content of biologically active substances, which contributes to their antioxidant activity. Given the availability of raw materials and the high biological activity of volatile compounds, it is particularly advisable to explore promising species within the genus Achillea L., such as yarrow (Achillea micrantoides Klok. et Krytzka). Yarrow is widespread in Ukraine, characterized by a long vegetation period, and holds promise for further pharmacognostic study. Aim. The purpose of the work is to study the volatile compounds of the yarrow extract (Achillea micrantoides Klok. et Krytzka) and to establish their component composition. Materials and methods. The Thin-Layer Chromatography (TLC) method and Gas Chromatography-Mass Spectrometry (GC/MS) on an Agilent Technology 7890 B chromatograph were employed to determine the component composition of volatile compounds in Achillea micranthoides Klok. et Krytzka. The NIST14 mass spectral library was utilized for identifying the components of the samples. Results. Identification of volatile compound components was carried out by chromatography of ethyl acetate extracts from the leaves and inflorescences of the subject TLC in the mobile phase ethyl acetate – toluene (5:95). By the gas method Chromatography-mass spectrometry determined the presence of 30 volatile compounds of grass A. micranthoides Klok. et Krytzka, 26 of the compounds were identified, which accounted for 86.76 % of the total number of compounds.

Fe3C-modified carbon composites for boosted peroxymonosulfate activation and organic pollutant decontamination: Contributions of dual radical and nonradical pathways

In this study, we prepared a hydrothermal carbonation carbon (HTCC) coated with Fe3​C nano-catalyst (Fe/C nano-catalyst) for water decontamination. We first fabricated HTCC via a hydrothermal carbonization process with abundant Fe3+ dopants, and the subsequent calcination transformed iron species into magnetic Fe3​C nanoparticles. The Fe/C nano-catalyst was employed for activating peroxymonosulfate (PMS) and degrading phenolic pollutants. The Fe3​C species significantly enhanced the activity of HTCC to generate reactive species, achieving 100 % phenol degradation in 30 min. Radical capture and electrochemical tests revealed that organic pollutant was oxidized via two pathways: sulfate radical oxidation and direct electron transfer pathway over the Fe/C nano-catalyst. The findings will inspire the development of green and high-performance purification system for organic wastewater treatment.

Parameters of oxidative, nitrasive and anti-oxidative status in men with erectile dys-function due to combat trauma

The development of oxidative and nitrative stress and the processes of free radical oxidation are associated with many pathological processes. Damage of any origin leads to the activation of free radical processes not only in the place of damage, but also in the whole organism. The aim of the study is to assess the state of lipid peroxidation, content of GSH and GSSG and the activity of NO-synthase and arginase in lymphocytes and peripheral blood serum in men with erectile dysfunction due to combat trauma. The research was conducted on peripheral blood lymphocytes of men injured as a result of combat operations (shrapnel and bullet wounds) in the Russian-Ukrainian war, and who were treated at the Military Medical Clinical Center of the Western Region (Lviv, Ukraine). The research group of men with combat injuries was divided into two age groups: men aged 20–39 years and men aged 40–53 years. The MDA content in the blood serum of patients of both age groups was 1.35 times higher than in the control group. In peripheral blood lymphocytes, the MDA content in patients of the young age group was 1.27, and in patients of the middle age group in 1.39 times higher than in the control group. Simultaneously, no significant changes in the concentration of oxidized glutathione in blood serum and blood lymphocytes were found between men with erectile dysfunction due to combat trauma and healthy men. GSH content in blood serum in patients of both age groups was significantly lower than in the control group. The arginase/NOS ratio in blood serum was 9.75 times lower in the young age group and in 20.45 times lower in the middle age group compared to healthy men. It was established that in the blood serum and blood lymphocytes of men with erectile dysfunction due to combat trauma, processes of lipid peroxidation were intensified and the GSH level was reduced. The GSH/GSSG ratio was reduced only in blood serum. It was found that the oxidative stress is associated with development of nitrative stress. The arginase/NOS ratio was shifted towards increased NOS activity. Activation of iNOS was accompanied by significant inhibition of cNOS. Further study of biochemical mechanisms is important to understand the triggers of erectile dysfunction due to combat trauma.

Determining the Oxidation Mechanism through Radical Intermediates in Polysorbates 80 and 20 by Electron Paramagnetic Resonance Spectroscopy.

Polysorbates 20 and 80 (PS20 and PS80) are added to many commercial biologic and vaccine pharmaceuticals. It is commonly known that these polysorbates undergo a radical oxidation mechanism; however, the identity of these radical intermediates has not been clearly determined. Furthermore, PS20 and PS80 differ by the presence of a lauric acid instead of an oleic acid, respectively. The oxidation of PS80 is thought to be centered around the double bond of the oleic acid even though PS20 also undergoes oxidation, making the mechanism of oxidation unclear for PS20. Using commercial stocks of PS20 and PS80 alkyl (R•), alkoxyl (C-O•) and peroxyl (C-OO•) radicals were detected by electron paramagnetic resonance spectroscopy likely originating from radical-initiating species already present in the material. When dissolved in water, the peroxyl radicals (C-OO•) originally in the stocks were not detected but poly(ethylene oxide) radicals were. An oxidative pathway for polysorbates was suggested based on the radical species identified in the polysorbate stock material and solutions.

A review of carbon-based catalysts and catalyst supports for simultaneous organic electro-oxidation and hydrogen evolution reactions

Producing organic electro-oxidation and hydrogen evolution reactions (HER) simultaneously in an electrolytic cell is an appealing method for generating valuable chemicals at the anode while also producing H2 at the cathode. Within this framework, the task of designing energy-saving electrocatalysts with high selectivity and stability is a considerable challenge. Carbon-based catalysts, along with their supports, have emerged as promising candidates due to their diverse sources, large specific surface area, high porosity and multidimensional characteristics. This review summarizes progress from 2012 to 2022, in the use of carbon-based catalysts and their supports for organic electrooxidation and HER. It delves into outer-sphere electrooxidation mechanisms involving molecule-mediated oxidation and oxidative radical coupling reactions, as well as inner-sphere electrooxidation mechanisms, encompassing both acidic and alkaline electrolytes. The review also explores prospective research directions within this domain, addressing various aspects such as the design of electrocatalytic materials, the study of the relationship between the structure and properties of electrocatalysts, as well as examining their potential industrial applications.

Pathogenetic Bases of Systemic Morphological Manifestations of Coal Worker’s Pneumoconiosis: A Review

Introduction: Miners are at increased risk of developing pneumoconiosis that poses a serious threat to their health. Progressive pneumosclerosis and bronchial mucosa atrophy are typical pathological changes in this disease. At the same time, there is evidence of systemic manifestations of pneumoconiosis. In this regard, a deeper understanding of how long-term exposure to coal dust affects pathophysiological processes not only in the target organ, but also in the whole body is required. Objective: To generalize and systematize ideas about the pathogenetic foundations of systemic morphological manifestations of black lung disease. Materials and methods: To obtain information, we have carried out a search for relevant studies published in 1995–2022 in Scopus, PubMed, and RISC databases using the following keywords: pneumoconiosis, miners, morphological changes, pathogenesis, free radical oxidation, inflammation, immune response, cytokines, growth factors, and endothelial dysfunction. We selected 59 full-text publications presenting the results of completed studies on the mechanisms of development of systemic morphological changes in coal miner’s pneumoconiosis. The systematic review was made according to PRISMA guidelines and using certain PICO(S) criteria. Results: It has been shown that long-term exposure to coal dust causes activation of macrophage-related inflammation in the respiratory system, free radical oxidation, modulation of intracellular signaling pathways, and programmed cell death. Numerous studies have demonstrated the role of inflammation as the main pathogenetic factor of pneumoconiosis, which is closely related to oxidative stress and immune response. Inflammatory mediators ensure the immune response, regeneration and sclerosis of damaged tissues. In case of high cumulative doses of coal dust, these processes begin to have a destructive and tissue-damaging effect in both the lungs and other organs due to the systemic action of the above mediators. The key role of the endothelium in the development, course and outcome of inflammation is noted.

A Study on Estimation of Phytochemical, Nutrition and the Antioxidant Activity of Dried Madhuca longifolia Flowers

Abstract: Food derived phytochemicals possess various therapeutic properties to benefit the health of individuals against the illness or diseases caused due to oxidation of free radicals. Mahua (Madhuca longifolia) flowers are one of the most efficient therapeutic agents used through the ancient age mainly among the tribal communities. The present study aimed to analyze the phytochemicals content (both qualitative and quantitative) and antioxidant activity against DPPH (2, 2-diphenyl-1- picrylhydrazyl) of dried mahua flowers using aqueous extract. Phytochemical screening revealed the presence of alkaloids, flavonoids, phenols, terpenoids, cardiac glycosides, coumarins, and steroids whereas anthraquinone was absent in the qualitative analysis. The total phenol and total alkaloids content was found to be 107 and 12.28 mg/g dry extract respectively depicting it as an abundant source. The aqueous extract at the concentration of 8.64 μg/ml showed maximum inhibitory activity (IC50) against DPPH (2, 2-diphenyl-1-picrylhydrazyl). They are also rich in key nutrients such as carbohydrate (48.79 g/100g), fibre (19.16 g/100g) and iron (8.064 mg/100g) of the dry fruit. The reported data reveals mahua flowers to be an excellent source of phytochemical content, nutrition content and antioxidant property emphasizing its therapeutic potential. Thus, further investigation in this regard may contribute to its utilization in the field of nutraceuticals and pharmaco-therapy aiding against various chronic health conditions.

Single-Atom Mn–N4 Catalyst with Electron-Rich O and S Self-Doping for Cooperative Nonradical and Radical Oxidation: Overlooked Nonmetal Heteroatomic Sites

Single-Atom Mn–N₄ Catalyst with Electron-Rich O and S Self-Doping for Cooperative Nonradical and Radical Oxidation: Overlooked Nonmetal Heteroatomic Sites

The use of salicylic acid and glucocorticosteroids in vulgar psoriasis

Among all forms of psoriasis, vulgar psoriasis (VP) occupies a leading place. The pathogenesis of VP is complex and involves significant participation of various components of the immune system, which manifests itself in the development of not only local, but also systemic inflammation. Also, the course of psoriasis is characterized by disturbances at the level of cellular metabolism, which is reflected in the activation of free radical oxidation and a change in the redox potential. As a consequence, the course of VP is often accompanied by many chronic diseases. The treatment of patients with uncomplicated VP and without articular manifestations is based on the use of local therapy – topical glucocorticosteroids (tGCS), vitamin D analogues, calcineurin inhibitors, keratolytics, as well as targeted phototherapy. At the same time, tGCS monotherapy requires long-term supportive treatment, which is associated with the presence of specific side effects of tGCS. This, in turn, makes it rational to use a combination of local drugs. Considering the variety of approaches to the treatment of VP, it is relevant to study the effectiveness of the use of a combination of various local and systemic drugs of psoriasis therapy. The addition of keratolytics can potentiate the positive effects of tGCS and is especially effective with pronounced peeling. In addition, the use of systemic cytoprotective therapy in the treatment strategy of VP can improve the clinical effect due to the acceleration of degradation of free radical oxydation products and normalization of the redox potential of blood and tissues, which is disrupted in psoriasis. The article shows the clinical effectiveness of the use of combined local therapy based on salicylic acid and tGCS in medicinal forms of ointment and lotion for VP based on clinical examples.

Photoinduced Decarboxylative Radical Phosphinylation.

Reported herein is an unprecedented protocol for C(sp3 )-phosphinylation. With 1 mol % 4CzIPN (1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene) as the catalyst, the visible light induced reaction of redox-active esters of aliphatic carboxylic acids with dimethyl arylphosphonites or diethyl alkylphosphonites at room temperature provides the corresponding decarboxylative phosphinylation products in satisfactory yields. The protocol exhibits broad substrate scope and wide functional-group compatibility, enabling the late-stage modification of complex molecules and rapid synthesis of bioactive phosphinic acids such as glutamine synthetase phosphinothricin and a kynureninase inhibitor. A radical-polar crossover mechanism involving the formation and subsequent oxidation of phosphoranyl radicals followed by nucleophilic demethylation (or deethylation) is proposed.

Photoinduced Decarboxylative Radical Phosphinylation

AbstractReported herein is an unprecedented protocol for C(sp3)‐phosphinylation. With 1 mol % 4CzIPN (1,2,3,5‐tetrakis(carbazol‐9‐yl)‐4,6‐dicyanobenzene) as the catalyst, the visible light induced reaction of redox‐active esters of aliphatic carboxylic acids with dimethyl arylphosphonites or diethyl alkylphosphonites at room temperature provides the corresponding decarboxylative phosphinylation products in satisfactory yields. The protocol exhibits broad substrate scope and wide functional‐group compatibility, enabling the late‐stage modification of complex molecules and rapid synthesis of bioactive phosphinic acids such as glutamine synthetase phosphinothricin and a kynureninase inhibitor. A radical‐polar crossover mechanism involving the formation and subsequent oxidation of phosphoranyl radicals followed by nucleophilic demethylation (or deethylation) is proposed.

Facile tuning Non-radical/Radical oxidation by nitrogen doping on Fe-S doped carbonaceous catalysts for peroxymonosulfate activation

In this paper, iron-sulfur-nitrogen co-doped carbonaceous materials (Fe@SxNyC) was prepared by doping N during the preparation of iron-sulfur co-doped carbonaceous material (Fe@SC), which was used to activate PMS and effectively modulate the radical and non-radical oxidation pathways in the catalytic system to achieve efficient degradation of sulfamerazine (SMR). N doping introduced multiple N sites (graphitic N, pyridinic N and pyrrolic N) in the Fe@SxNyC while promoting the generation of thiophene sulfur of the pristine active sites. Meanwhile, N doping introduced more defects in Fe@S4NC and thus exhibited better catalytic activity than Fe@SC, promoting the decomposition of PMS with a maximum k value (0.1721 min−1). Notably, the involvement of nitrogen shifted the cooperative oxidation reaction from a non-radical (1O2) to a radical-dominated (SO4·–) oxidation pathway with more oxidative intensity, resulting in deeper mineralization of organic pollutants. Moreover, compared with Fe@SC/PMS system, the radical-dominated Fe@S4NC/PMS system had better cycling stability, and the efficiency of SMR degradation could still reach 85 % after 4 cycles. The prepared Fe@S4NC catalytic ceramic membrane exhibited stable water flux and exceptional catalytic activity, demonstrating that Fe@S4NC had good potential for practical applications. This work elucidated the improvement of the catalytic mechanism of iron-carbon based materials by doping with various heteroatoms and provided a theoretical basis to design Fenton-like heterogeneous catalysts suitable for different water matrix.

Long-lasting UV-blocking Mechanism of Lignin: Origin and Stabilization of Semiquinone Radicals.

Semiquinone (SQ) radicals play a critical role in the long-lasting UV-blocking application of lignin, while their origin and stable structure are unclear. Here, the organosolv lignin extracted from poplar (OL-P) is self-assembled into normal micelles (LNM) with more phenolic hydroxyl groups on the surface, and reverse micelles (LRM) with more methoxyl groups on the surface. After 12h UV irradiation, the SQ radical contents in LNM and LRM increase 33% and 78% respectively. The performance of LNM based sunscreen keeps upswinging due to radical stabilization of phenolic hydroxyl groups. LRM based sunscreen experiences a gradual decrease after reaching maximum UV absorbance due to the quick generation and over oxidation of SQ radicals. Density functional theory (DFT) simulations reveal that methoxyl groups in OL-P has bigger bond length and smaller bond dissociation enthalpy than phenolic hydroxyl groups, and are easy to form SQ radicals. The Gibbs free energy (ΔG) needed for SQ-quinone transformation is above 26.10kcalmol.-1 , while that for SQ-hydroquinone transformation is below -66.78kcalmol.-1 . Hydroquinone is the stable structure of SQ radicals. This work discloses the origin and stable structure of SQ radicals in lignin under UV irradiation, and provides an important guidance for its long-lasting UV-blocking application.

Fenton-like activity and pathway modulation via single-atom sites and pollutants comediates the electron transfer process.

The studies on the origin of versatile oxidation pathways toward targeted pollutants in the single-atom catalysts (SACs)/peroxymonosulfate (PMS) systems were always associated with the coordination structures rather than the perspective of pollutant characteristics, and the analysis of mechanism commonality is lacking. In this work, a variety of single-atom catalysts (M-SACs, M: Fe, Co, and Cu) were fabricated via a pyrolysis process using lignin as the complexation agent and substrate precursor. Sixteen kinds of commonly detected pollutants in various references were selected, and their lnkobs values in M-SACs/PMS systems correlated well (R2 = 0.832 to 0.883) with their electrophilic indexes (reflecting the electron accepting/donating ability of the pollutants) as well as the energy gap (R2 = 0.801 to 0.840) between the pollutants and M-SACs/PMS complexes. Both the electron transfer process (ETP) and radical pathways can be significantly enhanced in the M-SACs/PMS systems, while radical oxidation was overwhelmed by the ETP oxidation toward the pollutants with lower electrophilic indexes. In contrast, pollutants with higher electrophilic indexes represented the weaker electron-donating capacity to the M-SACs/PMS complexes, which resulted in the weaker ETP oxidation accompanied with noticeable radical oxidation. In addition, the ETP oxidation in different M-SACs/PMS systems can be regulated via the energy gaps between the M-SACs/PMS complexes and pollutants. As a result, the Fenton-like activities in the M-SACs/PMS systems could be well modulated by the reaction pathways, which were determined by both electrophilic indexes of pollutants and single-atom sites. This work provided a strategy to establish PMS-based AOP systems with tunable oxidation capacities and pathways for high-efficiency organic decontamination.

Directing the persulfate activation reaction pathway by control of Fe-Nx/C single-atom catalyst coordination

In the reaction systems involving peroxymonosulfate (PMS) activation, the degradation of organic pollutants is influenced by the distinct roles played by the oxidation of free radicals and non-free radicals. The synergistic effect resulting from both oxidation pathways is often more efficient compared to a single oxidation pathway, as it allows for the optimal utilization of oxidation capacity and adaptation to complex reaction environments. Nitrogen-doped carbon substrates hosting single-atom catalysts (SACs) are anticipated to serve as an optimal platform for managing the dual oxidation pathways in the PMS activation reaction. This is attributed to the availability of numerous reaction sites that meet the activation requirements. However, there's a lack of substantial reports on this subject. Herein, we synthesized a series of single-atoms Fe nitrogen-doped carbon catalysts with different coordination structures by adjusting the coordination numbers between Fe and N atoms. It is used to investigate the reaction pattern of PMS over SACs, so as to enhance the catalytic efficacy of SACs through distinct coordination structures. The experimental and theoretical results indicate that PMS functions as both an electron receiver and provider on FeNx/C catalysts. Moreover, the specific arrangement of the Fe-N-C structure influences the exchange of electrons between the catalysts and PMS. Hence, the co-oxidation pathway of free radicals (OH, SO4− and O2−) and non-free radicals (1O2) can be modulated by altering the coordination number of Fe and N atoms during PMS activation. The elimination efficiency of tetracycline hydrochloride was significantly enhanced due to the abundance of both free radical and non-free radical species generated in the FeN3/C/PMS reaction system, exhibiting a degradation kinetic constant of 0.564 min−1. In addition, it showed promising potential for application in practical wastewater degradation, exhibiting high anti-interference to general environmental disturbances (such as humic acid, chloride ions, bicarbonate ions and nitrate ions).

Effects of different oxidation systems on the interfacial properties of bamboo fiber/epoxy resin composites

The objective of this study was to improve the interfacial properties of bamboo fabric (BF)/epoxy (EP) composites and thus enhance their mechanical properties. BF was treated with 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) oxidation system and N-hydroxyphthalimide (NHPI) oxidation system, respectively, to obtain BFO- T and BFO- N oxidation products with different surface morphologies. The effects of different oxidation treatments on the tensile strength (σc) and elongation at break (εc) of the composites were evaluated. Compared with the untreated BF/EP samples, BFO- T/EP showed a 56.9% increase in σc with a non-significant change in the increase in εc. BFO- N/EP showed a 30.1% increase in σc, but the improvement of εc reached 473.7%. The results of single-yarn pull-out tests and atomic force microscopy indicated that the proper size of grooves may be the key to improve the strength of the two-phase interface. The larger size of the grooves, the easier it is for the resin to infiltrate and fill the voids, thus forming occlusal structures that strengthen the interfacial bonding. Small-sized grooves, on the other hand, are not conducive to resin impregnation and therefore voids at the two-phase interface, thus hindering load transfer.

Assessment of Mitochondrial Gene Activity in Dopaminergic Neuron Cultures Derived from Induced Pluripotent Stem Cells Obtained from Parkinson's Disease Patients

Introduction. Induced pluripotent stem cells (iPSCs) culturing allows modelling of neurodegenerative diseases in vitro and discovering its early biomarkers.
 Our objective was to evaluate the activity of genes involved in mitochondrial dynamics and functions in genetic forms of Parkinson's disease (PD) using cultures of dopaminergic neurons derived from iPSCs.
 Materials and methods. Dopaminergic neuron cultures were derived by reprogramming of the cells obtained from PD patients with SNCA and LRRK2 gene mutations, as well as from a healthy donor for control. Expression levels of 112 genes regulating mitochondrial structure, dynamics, and functions were assessed by multiplex gene expression profiling using NanoString nCounter custom mitochondrial gene expression panel.
 Results. When comparing the characteristics of the neurons from patients with genetic forms of PD to those of the control, we observed variations in the gene activity associated with the mitochondrial respiratory chain, the tricarboxylic acid cycle enzyme activities, biosynthesis of amino acids, oxidation of fatty acids, steroid metabolism, calcium homeostasis, and free radical quenching. Several genes in the cell cultures with SNCA and LRRK2 gene mutations exhibited differential expression. Moreover, these genes regulate mitophagy, mitochondrial DNA synthesis, redox reactions, cellular detoxification, apoptosis, as well as metabolism of proteins and nucleotides.
 Conclusions. The changes in gene network expression found in this pilot study confirm the role of disrupted mitochondrial homeostasis in the molecular pathogenesis of PD. These findings may contribute to the development of biomarkers and to the search for new therapeutic targets for the treatment of SNCA- and LRRK2-associated forms of the disease.

Gas-Phase Phenyl Radical + O2 Reacts via a Submerged Transition State.

In the gas-phase chemistry of the atmosphere and automotive fuel combustion, peroxyl radical intermediates are formed following O2 addition to carbon-centered radicals which then initiate a complex network of radical reactions that govern the oxidative processing of hydrocarbons. The rapid association of the phenyl radical-a fundamental radical related to benzene-with O2 has hitherto been modeled as a barrierless process, a common assumption for peroxyl radical formation. Here, we provide an alternate explanation for the kinetics of this reaction by deploying double-hybrid density functional theory (DFT), at the DSD-PBEP86-D3(BJ)/aug-cc-pVTZ level of theory, and locate a submerged adiabatic transition state connected to a prereaction complex along the reaction entrance pathway. Using this potential energy scheme, experimental rate coefficients k(T) for the addition of O2 to the phenyl radical are accurately reproduced within a microcanonical kinetic model. This work highlights that purportedly barrierless radical oxidation reactions may instead be modeled using stationary points, which in turn provides insight into pressure and temperature dependence.

Identification of novel F2-isoprostane metabolites by specific UDP-glucuronosyltransferases

UDP-glucuronosyltransferases (UGTs) catalyze the conjugation of glucuronic acid with endogenous and exogenous lipophilic small molecules to facilitate their inactivation and excretion from the body. This represents approximately 35 % of all phase II metabolic transformations. Fatty acids and their oxidized eicosanoid derivatives can be metabolized by UGTs. F2-isoprostanes (F2-IsoPs) are eicosanoids formed from the free radical oxidation of arachidonic acid. These molecules are potent vasoconstrictors and are widely used as biomarkers of endogenous oxidative damage. An increasing body of evidence demonstrates the efficacy of measuring the β-oxidation metabolites of F2-IsoPs rather than the unmetabolized F2-IsoPs to quantify oxidative damage in certain settings. Yet, the metabolism of F2-IsoPs is incompletely understood. This study sought to identify and characterize novel phase II metabolites of 15-F2t-IsoP and 5-epi-5-F2t-IsoP, two abundantly produced F2-IsoPs, in human liver microsomes (HLM). Utilizing liquid chromatography-mass spectrometry, we demonstrated that glucuronide conjugates are the major metabolites of these F2-IsoPs in HLM. Further, we showed that these molecules are metabolized by specific UGT isoforms. 15-F2t-IsoP is metabolized by UGT1A3, 1A9, and 2B7, while 5-epi-5-F2t-IsoP is metabolized by UGT1A7, 1A9, and 2B7. We identified, for the first time, the formation of intact glucuronide F2-IsoPs in human urine and showed that F2-IsoP glucuronidation is reduced in people supplemented with eicosapentaenoic and docosahexaenoic acids for 12 weeks. These studies demonstrate that endogenous F2-IsoP levels can be modified by factors other than redox mechanisms.

Nitrogen and sulfur doped carbon dots coupled cellulose nanofibers: A surface functionalized nanocellulose membranes for air filtration

BackgroundThe current study demonstrates a process to produce a hybrid bio-organic cellulose nanofiber (CNF) membrane with high filtration performance and mechanical strength. This was accomplished by 1) tailoring the functional groups of CNFs, notably using the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical oxidation and 2) coupling them with carbon dots (CDs). MethodsThe surface chemistry of CNF was modified through TEMPO oxidation. Subsequently, a coupling reaction was conducted with CDs synthesized hydrothermally, as well as synthesized N/S-CDs derived from palm bunch. The impact of these modifications on the formation of air filters was investigated. Modification and coupling of surface modified CNF were evaluated by advanced analytical techniques. The toxicity of pristine and N/S-CDs coupled cellulose nanofibers was studied by cytotoxicity assay. Vacuum filtration and sequential compression molding techniques were applied to fabricate CNF filters, and the particle filtration efficiency of different filters was determined. Significant findingsThe coupling of N/S-CDs to CNF significantly enhanced the tensile strength of the membranes. Coupling of N/S-CDs to TEMPOCNF membrane showed the highest tensile strength (9.3 ± 1.9 MPa), while N/S-CDs coupling to CNF membrane exhibited slightly lower tensile strength (9.0 ± 1.3 MPa). The average pore diameter of the filters was slightly reduced after the CNF surface modification, which led to higher differential pressure across the filters. Both the pristine and TEMPO-modified CNF filters displayed high filtration efficiency for 0.3 μm-aerosol particles (∼70–81 %) and 0.1 μm-aerosol model particles (∼50–68 %), which was in a range of bacteria and viruses. This study provided detailed information about the fabrication of modified CNF filters with high air filtration efficiency for micro/nano-sized particles using cost-effective biodegradable raw materials.