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The coordination chemistry of an amine-rich CpN3 ligand has been explored with cobalt. We demonstrate that in the presence of NaCo(CO)4, the cationic precursor [CpN3]+ yields the complex CpN3CoI(CO)2. While 2e− oxidation generates new CoIII complexes such as [CpN3Co(NCMe)3]2+ and CpN3CoI2(CO), subsequent ligand loss is facile, generating free [CpN3]+ or the protonated dication [CpN3H]2+. We have structurally characterized both these ligand release products via single crystal X-ray diffraction and obtained thermochemical C–H bond strengths via experiment and density functional theory (DFT). Upon reversible 1e− reduction, the radical cation [CpN3H]˙+ has a weak C–H BDFE of 52 kcal mol−1 in acetonitrile. Mechanistic analysis shows that [CpN3H]˙+ undergoes radical–radical disproportionation in the absence of exogenous H-atom acceptors, which is supported by deuterium isotope labelling experiments. Structural comparison of these organic molecules shows a high degree of iminium-like electron delocalization over the C–N bonds connected to the central five-membered ring. [ABSTRACT FROM AUTHOR]

The successive steps of the oxidation mechanism of crocin, a major compound of saffron, by the free OH• radical are investigated by pulse radiolysis, steady-state (gamma) radiolysis methods, and molecular simulations. The optical absorption properties of the transient species and their reaction rate constants are determined. The absorption spectrum of the oxidized radical of crocin resulting from the H-abstraction presents a maximum of 678 nm and a band of 441 nm, almost as intense as that of crocin. The spectrum of the covalent dimer of this radical contains an intense band at 441 nm and a weaker band at 330 nm. The final oxidized crocin, issued from radical disproportionation, absorbs weaker with a maximum of 330 nm. The molecular simulation results suggest that the OH• radical is electrostatically attracted by the terminal sugar and is scavenged predominantly by the neighbor methyl site of the polyene chain as in a sugar-driven mechanism. Based on detailed experimental and theoretical investigations, the antioxidant properties of crocin are highlighted. [ABSTRACT FROM AUTHOR]

During their life cycle, plants constantly respond to environmental changes. Abiotic stressors affect the photosynthetic and respiratory processes of plants. Reactive oxygen species (ROS) are produced during aerobic metabolism and play an important role as regulatory mediators in signaling processes, activating the plant's protective response to abiotic stress and restoring "oxidation-reduction homeostasis". Cells develop normally if the rates of ROS production and the ability to neutralize them are balanced. To implement oxidation-reduction signaling, this balance must be disrupted either by an increase in ROS concentration or a decrease in the activity of one or more antioxidant systems. Under abiotic stress, plants accumulate excessive amounts of ROS, and if the ROS content exceeds the threshold amount dangerous for living organisms, it can lead to damage to all major cellular components. Adaptive resistance of plants to abiotic stressors depends on a set of mechanisms of adaptation to them. The accumulation of ROS in the cell depends on the type of abiotic stress, the strength of its impact on the plant, the duration of its impact, and the recovery period. The aim of this review is to provide a general understanding of the processes occurring during ROS homeostasis in plants, oxidation-reduction processes in cellular compartments in response to abiotic stress, and the participation of ROS in signaling processes activating adaptation processes to abiotic stress. [ABSTRACT FROM AUTHOR]

Harnessing solar energy by photocatalytically converting oxygen and water into high-value-added H2O2 is a promising way of alleviating both environmental and energy issues. It is worth noting that suppressing detrimental side reactions, such as the generation of •O2−, is a critical approach to enhancing H2O2 production. Herein, a 2-fold interpenetrating 3D uranium-organic framework (YTU-W-1) was developed and introduced for photocatalytic H2O2 production. The material demonstrates a different photocatalytic mechanism when employing uranyl as an initiator, as compared with the conventional semiconductor photocatalytic pathway involving photo-generated charge carriers. Benefiting from the strong hydrogen abstraction effect of the U≡O• and the direct one-step oxygen reduction pathway, YTU-W-1 exhibits enhanced photocatalytic performance for H2O2 production with yield efficiency of 221 µmol h−1 g−1. Furthermore, YTU-W-1 displays a high H2O2 selectivity of 68%, confirmed by rotating ring-disk electrode (RRDE) measurement. DFT calculations were used to elucidate the critical role of uranyl in the photocatalytic oxygen reduction reaction for H2O2 production. This research introduces an innovative approach to photo driven H2O2 production, underscoring the potential for heterogeneous catalysts to engage in photocatalytic reactions independently of photo-generated charge carriers. [ABSTRACT FROM AUTHOR]

In this study, a long-lived triplet state urea-functionalized carbon nitride (urea-CNx) was successfully synthesized. It possesses a significant specific surface area, an extended excited state lifetime, and a wide band gap and can be used as recyclable and efficient photocatalyst. Urea-CNx was applied for metal-free photo atom transfer radical polymerization (photo-ATRP) of methyl methacrylate as a heterogeneous catalyst without any co-catalysts and it exhibited impressive catalytic activity. It combines both photosensitization and catalytic effects within the ATRP system. The ATRP process utilizing methyl methacrylate as the monomer yields polymers with well-matched molecular weights and narrow PDI (Đ = 1.38) when exposed to blue light irradiation. Good time control and high end group fidelity were demonstrated through intermittent on–off light experiments, precise polymerization of various monomers, and synthesis of block copolymers. The oxygen-tolerant photo-ATRP polymerization was proposed to operate via a reactive oxygen species (ROS)-mediated oxidative quenching pathway mechanism, which was found to significantly enhance the reaction rate of the radical polymerization system. Remarkably, even after 10 cycles, the catalytic efficiency of urea-CNx catalyzed oxygen-tolerant photo-ATRP remained largely unaffected. The system’s advantageous features include being completely metal-free, requiring no cocatalysts, and its good sustainability and “oxygen acceleration” behavior. These features provide a new idea and reliable experimental basis for exploring greener, simpler and more economical photo-ATRP polymerisation processes and applications. [ABSTRACT FROM AUTHOR]

Advances in the field of frustrated Lewis pair (FLP) chemistry have led to the discovery of radical pairs, obtained by a single-electron transfer (SET) from the Lewis base to the Lewis acid. Radical pairs are intriguing for their potential to enable cooperative activation of challenging substrates (e.g., CH4, N2) in a homolytic fashion, as well as the exploration of novel radical reactions. In this review, we will cover the two known mechanisms of SET in FLPs—thermal and photoinduced—along with methods (i.e., CV, DFT, UV-vis) to predict the mechanism and to characterise the involved electron donors and acceptors. Furthermore, the available techniques (i.e., EPR, UV-vis, transient absorption spectroscopy) for studying the corresponding radical pairs will be discussed. Initially, two model systems (PMes3/CPh3+ and PMes3/B(C6F5)3) will be reviewed to highlight the difference between a thermal and a photoinduced SET mechanism. Additionally, three cases are analysed to provide further tools and insights into characterizing electron donors and acceptors, and the associated radical pairs. Firstly, a thermal SET process between LiHMDS and [TEMPO][BF4] is discussed. Next, the influence of Lewis acid complexation on the electron acceptor will be highlighted to facilitate a SET between (pBrPh)3N and TCNQ. Finally, an analysis of sulfonium salts as electron acceptors will demonstrate how to manage systems with rapidly decomposing radical species. This framework equips the reader with an expanded array of tools for both predicting and characterizing SET events within FLP chemistry, thereby enabling its extension and application to the broader domain of main-group (photo)redox chemistry. [ABSTRACT FROM AUTHOR]

Crops are often affected by NaCl, giant ragweed (Ambrosia trifida L.) and freeze-thaw stress simultaneously during their growth, and many areas in Northeast China are facing such serious ecological stress problems. In this experiment, the physiological responses of rye seedlings to NaCl and A. trifida extract stressor (AES) in a freeze-thaw environment were studied by artificial simulation technique. Malondialdehyde (MDA) content, soluble protein (SP) content, superoxide dismutase (SOD) activity, catalase (CAT) activity, net photosynthetic rate (Pn) and transpiration rate (Tr) were determined and analyzed. The results showed that: After stress treatment, MDA and SP contents of rye seedlings increased by 19.48%-88.96% and 22.54%-107.30%, SOD and CAT activities increased by 4.42%-26.60% and 23.31%-64.68% and Pn and Tr decreased by 40.00%-71.67% and 20.00%-80.00%. In the face of stress, rye seedlings can reduce the damage caused by stress by increasing osmotic substance and antioxidant enzyme activity, so as to adapt to the environment. The results revealed that combined NaCl, AES and freeze-thaw stress had a significant superposing effect on plants compared with single NaCl, AES and freeze-thaw stress. Net photosynthetic rate (Pn) and transpiration rate (Tr)as photosynthetic indices, are easily affected by the environment, and the photosynthetic physiological characteristics of plants will decrease significantly under external stress. [ABSTRACT FROM AUTHOR]

Organosilanes have secured a special place in the synthetic world for several decades. However, among them, allylsilanes are a choice reagent for organic chemists to develop novel organic transformations. In recent years researchers have proved that visible-light photoredox catalysis has emerged as one of the most mild, sustainable, straightforward, and efficient strategies to construct simple to complex molecules with or without enantioselectivity. This review provides an in-depth analysis of recent advances and strategies employed in visible-light photoredox catalysis for allylsilane and its analogues for the development of various organic transformations. The review is divided into sections, each focused on a specific reactivity of allylsilane under light irradiation with C(sp2) center arene or alkene, C(sp2) center carbonyl, and C(sp3) center carbon functionality. In this review, we present optimization data, reaction scope, and mechanistic aspects to bring forward specific reactivity and selectivity trends of allylsilane in photoredox conditions. [ABSTRACT FROM AUTHOR]

Myeloperoxidase is a key enzyme that plays an important role in innate immune defense, while overexpression of this enzyme implies the development of inflammatory damage, making it an interesting target for the identification of new anti-inflammatory drugs of natural origin to limit the use of synthetic substances with toxic effects. To this end, our work focuses on the phytochemical compounds of P.nigra buds. In the present study, Box–Behnken design response surface methodology was introduced to optimize ultrasound-assisted extraction parameters of phenolic compounds followed by the evaluation of myeloperoxidase enzymatic activity in vitro as well as molecular docking to further elucidate macromolecular–ligand interactions. Optimization results by ultrasound-assisted extraction revealed a total phenolic content of around 42.87 ± 0.33 mg GAE/g dw obtained with a lactic acid percentage of 66.54% at a temperature of 35 °C for 20 min. In addition, evaluation of the enzymatic activity of the optimized extract in vitro revealed a strong inhibitory activity involving an IC50 of 0.084%. Furthermore, molecular docking of the most abundant phytochemical compounds in the extract tested in interaction with the myeloperoxidase active site showed the formation of hydrogen bonds; Pi-alkyl and Pi-sigma with a high affinity equal to − 9.0 and − 10.1 kcal/mol attributed to esculoside and rhamnosyl-hexosyl-acyl-quercetin, respectively. Based on the data obtained, our results demonstrate the efficiency of phenolic compound extraction using ultrasound as an energy source and lactic acid as an alternative solvent. In addition, the selected compounds exhibit a strong anti-inflammatory activity and can serve as a core structure for the design of more potent inhibitors. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to investigate the protective mechanism of dihydromyricetin PLGA nanoparticles (DMY-PLGA NPs) against myocardial ischemia-reperfusion injury (MIRI) in vitro and the improvement of oral bioavailability in vivo. Methods: DMY-PLGA NPs was prepared and characterized by emulsifying solvent volatilization, and the oxidative stress model of rat H9c2 cardiomyocyte induced by H2O2 was established. After administration, cell survival rate, lactate dehydrogenase (LDH), malondialdehyde (MDA) and superoxide dismutase (SOD) were detected, and the expressions of PGC1α and PPARα were detected by western blot (WB). At the same time, the pharmacokinetics in rats were studied to explore the improvement of bioavailability. Results: DMY-PLGA NPs can significantly increase cell survival rate, decrease LDH and MDA content, increase SOD content and PGC1α、PPARα protein expression. Compared with DMY, the peak time of DMY-PLGA NPs was extended (P<0.1), and the bioavailability was increased by 2.04 times. Conclusion: DMY-PLGA NPs has a significant protective effect on H9c2 cardiomyocytes, which promotes the absorption of DMY and effectively improves bioavailability. [ABSTRACT FROM AUTHOR]

Artificial diets for silkworms overcome the seasonal limitations of traditional rearing methods with fresh mulberry leaves. However, the current wet artificial diets, steamed at high temperatures, are not favored by silkworms, and they are cumbersome and challenging to preserve. These conditions adversely affected the development of artificial diet-based sericulture production. In this study, we disinfected dry powder diets with radiation and added distilled water without steaming before use. Then, the nutritional value of finished diets and their impact on silkworm development was assessed. Compared with steamed diets, nonsteamed diets were more attractive to silkworms. Chemical assays showed significantly more essential nutrients for silkworms, including l -ascorbic acid, vitamin B1, vitamin B2, and urease in nonsteamed diets than in steamed diets. Feeding fifth-instar silkworm larvae with nonsteamed diets significantly improved the ammonia utilization efficiency of the diet and increased the cocoon shell rate and diet/silk protein conversion efficiency by 5.9% and 13.3%, respectively. When fed with nonsteamed diets, the abundance of aerobic microorganisms in silkworm intestines increased and the abundance of pathogenic bacteria decreased. Furthermore, the vitality of the silkworm, measured by the dead worm cocoon rate, significantly improved by 16.90%. In summary, preparing sterile wet diets without high-temperature steaming effectively improved the nutritional value of the diet and enhanced silkworm growth. [ABSTRACT FROM AUTHOR]

This study aimed to elucidate the mechanism of velvet antler polypeptide (VAP) in improvement of learning and memory function in mild cognitive impairment (MCI) rats model, specifically by investigating the PI3K, AKT and mTOR pathway. The type and content of amino acids (AA) in VAP were determined using pre-column derivatization-high performance liquid chromatography (PD-HPLC). Wistar rats were randomly divided into 5 groups (n=10 per group): control, model, piracetam (PIR), VAPH (300 mg/ kg VAP) and VAPL (200 mg/kg VAP) groups. After intragastric administration, the rats’ behavioral indexes were observed through the open field test (OFT), and the levels of superoxide dismutase (SOD), malondialdehyde (MDA), brain-derived neurotrophic factor (BDNF), and nerve growth factor (NGF) in serum were detected using ELISA. The protein expression levels of phosphoinositide 3-kinase (PI3K), protein kinase B (Akt) and mammalian target of rapamycin (mTOR) in the hippocampus were detected through western blotting. In the results, VAP contained 17 kinds of AA, including 7 essential AA, with a content of 394.08 g/kg, the total AA content was 831.55 g/kg. In the OFT, the PIR, VAPH and VAPL groups showed significant decreases in slient period, significant increases in exercise time and behavior path, and center residence time in the PIR and VAPH groups were also increased significantly. The MDA content in serum of PIR, VAPH and VAPL groups significantly decreased, while the SOD, BDNF and NGF content in serum of PIR and VAPH groups significantly increased. The expression levels of PI3K and mTOR in the hippocampus of PIR, VAPH and VAPL groups were significantly increased, and the expression level of Akt in the hippocampus of PIR and VAPH groups was significantly increased. In summary, VAP could improve the learning and memory abilities of MCI model rats, and its mechanism may be related to the regulation of PI3K, Akt and mTOR expression levels in the hippocampus of rats. This study provides a basis for further development and utilization of VAP and a better understanding of its mechanism of improving MCI [ABSTRACT FROM AUTHOR]

Dissociation energies (DC—H) of labile C—H bonds in radical adducts formed by coordination of thiyl radicals across the cyclohexadiene rings of 1,4-benzoquinone, N-phenyl-1,4-benzoquinone monoimine, and N,N′-diphenyl-1,4-benzoquinone diimine have been determined using composite methods of the Gaussian family and data on the enthalpies of formal homodesmotic reactions involving the adducts and simpler reference compounds. The DC—H values were found to be in the range of 140–170 kJ mol−1. These values are typical of the strength of bonds between atomic hydrogen and olefins. The weakness of the C—H bonds in both types of compounds is due to the compensation of bond breaking by the stabilization of the reaction products, viz., an olefin molecule or the cyclohexadiene ring of a quinoid. The proximity of the DC—H values in these adducts and the significant difference (∼50 kJ mol−1) between these values and the strength of the C—H bond in the adduct of atomic hydrogen with a benzene molecule confirms the fact that quinones and quinone imines are not aromatic compounds. The obtained DC—H values are required for the quantitative interpretation of the kinetic regularities found for the chain reactions of thiols with quinoids, as well as the catalysis of these reactions at the stage of chain propagation under the action of compounds with X—H groups (X = O, S, etc.). [ABSTRACT FROM AUTHOR]

Geological models for petroleum generation suggest thermal conversion of oil-prone sedimentary organic matter in the presence of water promotes increased liquid saturate yield, whereas absence of water causes formation of an aromatic, cross-linked solid bitumen residue. To test the influence of hydrogen from water, organic-rich (22 wt% total organic carbon, TOC) mudrock samples from the Eocene lacustrine Green River Formation Mahogany zone oil shale were pyrolyzed under hydrous and anhydrous conditions in closed system batch reactors at temperatures between 300 and 370 °C for 72 h. Pre- and post-pyrolysis samples were characterized using petrographic approaches including optical microscopy, reflectance, Raman spectroscopy, and scanning electron and transmission electron microscopy to quantify differences in relative appearance, abundance, and composition of solid bitumen newly generated during the pyrolysis experiments. Petrographic analyses were supplemented by geochemical screening measurements (TOC content and programmed temperature pyrolysis). Results show post-hydrous pyrolysis residues contain lower TOC, are comprised of solid bitumen with greater aromaticity, and have textures indicative of lower viscosities, relative to anhydrous residues from the same temperature pyrolysis conditions. These observations suggest solid bitumen forming from thermal conversion of oil-prone sedimentary organic matter under anhydrous conditions may be less aromatic, although more cross-linked, than solid bitumen forming under hydrous conditions at the same time-temperature combination. To explain these results, we suggest that a radical disproportionation mechanism is favored in the presence of hydrogen donated from water, and that this disproportionation promotes aromatization in the solid residue with concomitant expulsion of saturated hydrocarbons. • Organic-rich mudrock was pyrolyzed under hydrous and anhydrous conditions. • Solid bitumen generated during pyrolysis was evaluated via petrography. • Hydrous pyrolysis enhanced expulsion and formed low viscosity, aromatic solid bitumen. • Anhydrous pyrolysis formed cross-linked, less aromatic solid bitumen. • Radical disproportionation promotes aromatization in the presence of water. [ABSTRACT FROM AUTHOR]

Here we report the use of a base metal complex [(tBupyrpyrr2)Fe(OEt2)] (1‐OEt2) (tBupyrpyrr22−=3,5‐tBu2‐bis(pyrrolyl)pyridine) as a catalyst for intermolecular amination of Csp3−H bonds of 9,10‐dihydroanthracene (2 a) using 2,4,6‐trimethyl phenyl azide (3 a) as the nitrene source. The reaction is complete within one hour at 80 °C using as low as 2 mol % 1‐OEt2 with control in selectivity for single C−H amination versus double C−H amination. Catalytic C−H amination reactions can be extended to other substrates such as cyclohexadiene and xanthene derivatives and can tolerate a variety of aryl azides having methyl groups in both ortho positions. Under stoichiometric conditions the imido radical species [(tBupyrpyrr2)Fe{=N(2,6‐Me2‐4‐tBu‐C6H2)] (1‐imido) can be isolated in 56 % yield, and spectroscopic, magnetometric, and computational studies confirmed it to be an S = 1 FeIV complex. Complex 1‐imido reacts with 2 a to produce the ferrous aniline adduct [(tBupyrpyrr2)Fe{NH(2,6‐Me2‐4‐tBu‐C6H2)(C14H11)}] (1‐aniline) in 45 % yield. Lastly, it was found that complexes 1‐imido and 1‐aniline are both competent intermediates in catalytic intermolecular C−H amination. [ABSTRACT FROM AUTHOR]

Nowadays, plastic waste (PW) disposal is one of the serious global problems facing humanity and ecosystem balance. As the population increases continuously, the fuel market has been growing so the demand for plastic is also increased to cover the growing levels of consumption that leads to a serious environmental crisis by the PW accumulation. Therefore, recycling processes take place to clean the environment from these accumulated quantities of waste. Many studies accounted that the most suitable chemical recycling technique is pyrolysis which means conversion of the PW into valuable products in presence of heat. This review explained chemical structures, uses, recycling by thermal and catalytic pyrolysis of the plastic materials and discussed a comparison between two processes above. Moreover, investigation effects of the operating conditions such as temperature, pressure, residence time, and catalyst presence on the product distribution. Also, the reaction mechanism details of the process and work of previous researchers were addressed in this paper. [ABSTRACT FROM AUTHOR]

Though electron transfer (ET) and proton transfer (PT) are extensively involved in organic reactions, they remain unclear in acid‐enabled disproportionation of nitroxyl radicals, especially in organic solvents. Here we unveil the acid‐promoted electron transfer (APET) mechanism with inverse kinetic isotope effect (KIE) for the disproportionation of 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) in CH3CN. Kinetic experiments relying on on‐line detection of electron paramagnetic resonance (EPR) was conducted together with theoretical calculations, giving consistent insights on the mechanisms. Moreover, the significant effect of water as cosolvent was revealed. The findings here will encourage further mechanistic understandings and method developments for nitroxyl‐participated organic reactions. [ABSTRACT FROM AUTHOR]

In recent years, there has been a concerted drive to develop methods that are greener and more sustainable. Being an earth‐abundant transition metal, cobalt offers an attractive substitute for commonly employed precious metal catalysts, though reactions engaging cobalt are still less developed. Herein, we report a method to achieve the decarboxylative allylation of nitrophenyl alkanes, nitroalkanes, and ketones employing cobalt. The reaction allows for the formation of various substituted allylated products in moderate‐excellent yields with a broad scope. Additionally, the synthetic potential of the methodology is demonstrated by the transformation of products into versatile heterocyclic motifs. Mechanistic studies revealed an in situ activation of the Co(II)/dppBz precatalyst by the carboxylate salt to generate a Co(I)‐species, which is presumed to be the active catalyst. [ABSTRACT FROM AUTHOR]

Controlling the morphology of ceria nanoparticles (CeNPs) has been proven an effective approach to mimic the activities of antioxidant enzymes including catalase (CAT) and superoxide dismutase (SOD). However, the mechanism of the morphology-dependent enzyme-like activities was elusive. Energy-band structure tailoring of NPs through morphologies closely correlates with their catalytic activities. Herein, three kinds of CeNPs with octahedron, cube and rod morphologies were synthesized. Octahedron-CeO2 with exposed {111} facets, cube-shaped CeO2 with {100} facets and rod-shaped CeO2 with {110} and {111} facets were observed. Due to the lower formation energy of oxygen vacancy (VO) for {110} facets, higher VO content was detected for rod-CeO2, which directly correlated with the energy level of surface defect states (ESDS). The ESDS for rod-CeO2 (0.86 V) roughly lied in the middle point of E0 (H2O2, H+/H2O) and E0(O2, H+/H2O2) (0.83 V), which resulted in higher CAT-like activity. Likewise, the ESDS of octahedron-CeO2 (0.48 V) approximately located at the midpoint of two half-reaction potentials in SOD catalytic cycle (0.39 V) which was agreement with its enhanced SOD-like activity. Overall, regulating ESDS towards the midpoint of the half-reaction potentials becomes a feasible approach to achieve enhanced catalytic efficiency. [ABSTRACT FROM AUTHOR]

Zinc is an essential trace element, which plays an important role in multiple biological activities. However, excessive exposure to zinc can cause toxic damage to living organism. Here, we investigated the relationship between oxidative stress and mitochondrial dynamics in the zinc-induced cytotoxicity. Results showed that excess exposure to zinc could significantly reduce cell viability and induce cell vacuolation in PK-15 cells. Additionally, zinc exposure caused mitochondrial dynamics disorder, manifested as mitochondrial fission, and the elevated mRNA level of Drp1 and downregulated mRNA levels of OPA1, Mfn1, and Mfn2. Meanwhile, zinc could induce oxidative damage, evidenced by the increasing levels of hydrogen peroxide, malondialdehyde, lipid peroxidation, oxidized form of nicotinamide adenine dinucleotide phosphate/nicotinamide adenine dinucleotide phosphate, oxidized glutathione/glutathione, superoxide dismutase activity, and the mRNA expression of SOD-1 and NOQ1, and decreasing levels of catalase activity, glutathione peroxidase activity, glutathione reductase activity, and the mRNA expression of CAT, and GPX1. Interestingly, N-acetyl-L-cysteine, an inhibitor for oxidative stress, could reduce the mitochondrial fission under zinc treatment. Besides, Mdivi-1, a mitochondrial fission inhibitor, could relieve oxidative stress caused by excess zinc. In general, these results suggested that mitochondrial fission and oxidative stress induced by zinc were interrelated in PK-15 cells, which is conducive to explore the new mechanism of zinc toxicity and proposes a theoretical foundation for selecting effective drugs to alleviate the toxic effects caused by zinc. [ABSTRACT FROM AUTHOR]

The efficient use of renewable X/γ-rays or accelerated electrons for chemical transformation of CO2 and water to fuels holds promise for a carbon-neutral economy; however, such processes are challenging to implement and require the assistance of catalysts capable of sensitizing secondary electron scattering and providing active metal sites to bind intermediates. Here we show atomic Cu-Ni dual-metal sites embedded in a metal-organic framework enable efficient and selective CH3OH production (~98%) over multiple irradiated cycles. The usage of practical electron-beam irradiation (200 keV; 40 kGy min−1) with a cost-effective hydroxyl radical scavenger promotes CH3OH production rate to 0.27 mmol g−1 min−1. Moreover, time-resolved experiments with calculations reveal the direct generation of CO2•‒ radical anions via aqueous electrons attachment occurred on nanosecond timescale, and cascade hydrogenation steps. Our study highlights a radiolytic route to produce CH3OH with CO2 feedstock and introduces a desirable atomic structure to improve performance. Most approaches for CH3OH production focus on thermochemical, electrolytic, and photolytic processes. Here the authors report a radiolytic route to produce CH3OH from CO2 and water by atomic Cu-Ni dual sites embedded in a metal-organic framework. [ABSTRACT FROM AUTHOR]

A series of mesoporous silica (MS) materials, including rod-like and spherical SBA-15, spherical MCM-41, and MCM-48, was successfully synthesized and modified by silane coupling agent γ-aminopropyltriethoxysilane. The modified MS was utilized as a microreactor for solution reversible addition–fragmentation transfer (RAFT) polymerization of methyl methacrylate (MMA) using xanthate as a chain transfer agent and azodiisobutyronitrile as an initiator. Notably, modified MS had a low specific surface area and pore volume while maintaining the original morphological structure. Given to the confinement effects, poly(methyl methacrylate) (PMMA) prepared from internal mesoporous channels had higher molecular weight and initial thermal decomposition temperature than those from conventional RAFT polymerization. Moreover, PMMA obtained from spherical SBA-15 and modified MCM-48 exhibited the highest molecular weight (Mn = 8.78 × 104 and Mn = 7.43 × 104, respectively). This work provided a novel approach in designing a polymer microstructure for a more comprehensive application, such as in drug release. [ABSTRACT FROM AUTHOR]

Light quality is a vital environmental signal used to trigger growth and to develop structural differentiation in plants, and it influences morphological, physiological, and biochemical metabolites. In previous studies, different light qualities were found to regulate the synthesis of anthocyanin. However, the mechanism of the synthesis and accumulation of anthocyanins in leaves in response to light quality remains unclear. In this study, the Loropetalum chinense var. rubrum "Xiangnong Fendai" plant was treated with white light (WL), blue light (BL), ultraviolet-A light (UL), and blue light plus ultraviolet-A light (BL + UL), respectively. Under BL, the leaves were described as increasing in redness from "olive green" to "reddish-brown". The chlorophyll, carotenoid, anthocyanin, and total flavonoid content were significantly higher at 7 d than at 0 d. In addition, BL treatment also significantly increased the accumulation of soluble sugar and soluble protein. In contrast to BL, ultraviolet-A light increased the malondialdehyde (MDA) content and the activities of three antioxidant enzymes in the leaves, including catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD), in varying degrees over time. Moreover, we also found that the CRY-like gene, HY5-like gene, BBX-like gene, MYB-like gene, CHS-like gene, DFR-like gene, ANS-like gene, and UFGT-like gene were significantly upregulated. Furthermore, the SOD-like, POD-like, and CAT-like gene expressions related to antioxidase synthesis were found under ultraviolet-A light conditions. In summary, BL is more conducive to reddening the leaves of "Xiangnong Fendai" and will not lead to excessive photooxidation. This provides an effective ecological strategy for light-induced leaf-color changes, thereby promoting the ornamental and economic value of L. chinense var. rubrum. [ABSTRACT FROM AUTHOR]

In aqueous solutions containing ascorbic acid and O 2 , many quinones undergo reduction to the semiquinone followed by reoxidation. This redox cycling mediates the oxidation of ascorbic acid and the reduction of O 2 to superoxide and ultimately hydrogen peroxide. For that reason, redox cycling has attracted attention as a source of reactive oxygen species. This redox cycling is paradoxical, however, because the one-equivalent reduction potentials of the reactants are unfavorable, so the concentrations of the products, monodehydroascorbate and superoxide, must be kept extremely low. Disproportionation is not fast enough to eliminate these products. We have investigated the mechanism of ascorbate-driven redox cycling by monitoring the redox status of the quinone and the rate of redox cycling in parallel. Evidence is presented for a mechanism in which monodehydroascorbate is oxidized by the semiquinone. The result is that cycling of the semiquinone and hydroquinone mediates a rapid disproportionation of monodehydroascorbate. This mechanism accounts for the dependence of the redox cycling rate on quinone and ascorbate concentrations as well as on the reduction potential of the quinone. Therefore, it predicts how fast ascorbate-driven redox cycling will generate hydrogen peroxide under a variety of conditions and with different quinones. [Display omitted] • Redox cycling of quinones produces H 2 O 2 and other reactive oxygen species. • Fast redox cycling requires removal of the products superoxide and ascorbate radical. • Disproportionation reactions are not fast enough to remove radical products. • Elimination of ascorbate radical anion by reaction with semiquinone is significant. • This mechanism explains effects of ascorbate, pH and quinone potential on rate. [ABSTRACT FROM AUTHOR]

We demonstrate that sequential disproportionation reactions can enable selective aggregation of two- or four electron–holes at a hypervalent iodine center. Disproportionation of an anodically generated iodanyl radical affords an iodosylbenzene derivative. Subsequent iodosylbenzene disproportionation can be triggered to provide access to an iodoxybenzene. These results demonstrate multielectron oxidation at the one-electron potential by selective and sequential disproportionation chemistry. [ABSTRACT FROM AUTHOR]

It is well known that exercise is beneficial for cardiovascular health. Oxidative stress is the common pathological basis of many cardiovascular diseases. The overproduction of free radicals, both reactive oxygen species and reactive nitrogen species, can lead to redox imbalance and exacerbate oxidative damage to the cardiovascular system. Maintaining redox homeostasis and enhancing anti‐oxidative capacity are critical mechanisms by which exercise protects against cardiovascular diseases. Moderate‐intensity exercise is an effective means to maintain cardiovascular redox homeostasis. Moderate‐intensity exercise reduces the risk of cardiovascular disease by improving mitochondrial function and anti‐oxidative capacity. It also attenuates adverse cardiac remodeling and enhances cardiac function. This paper reviews the primary mechanisms of moderate‐intensity exercise‐mediated redox homeostasis in the cardiovascular system. Exploring the role of exercise‐mediated redox homeostasis in the cardiovascular system is of great significance to the prevention and treatment of cardiovascular diseases. [ABSTRACT FROM AUTHOR]

Herein, we report efficient visible light-induced photoredox reactions of C–H/N–H and C–X Bonds. These methods have provided access to varied portfolio of synthetically important γ-ketoesters, azaspirocyclic cyclohexadienones spirocyclohexadienones, multisubstituted benzimidazole derivatives, substituted N,2-diarylacetamide, 2-arylpyridines and 2-arylquinolines in good yields and under mild conditions. Moreover, we have successfully discussed the construction through visible light-induction by an intermolecular radical addition, dearomative cyclization, aryl migration and desulfonylation. Similarly, we also spotlight the visible light-catalyzed aerobic C–N bond activation from well-known building blocks through cyclization, elimination and aromatization. The potential use of a wide portfolio of simple ketones and available primary amines has made this transformation very attractive. [ABSTRACT FROM AUTHOR]

The experiments of rapid thermal pyrolysis and catalytic pyrolysis of high density polyethylene (HDPE) were carried out using Py-GC/MS. The distribution of products of rapid pyrolysis and the influence of Fluid Catalytic Cracking catalyst on pyrolysate production were studied both qualitatively and quantitatively at the temperature of 500 °C. The corresponding reaction paths were proposed based on the experimental results. The results demonstrated that olefin production accounts for more than 70 mass% in the products of C7–C40, and remaining products were alkanes, diolefins and aromatics. At the presence of catalyst, product contents of C7–C12 increased from 16.39 to 20.59 mass%, and C33+ from 11.23 to 14.42 mass%, while C13–C32 decreased from 72.22 to 61.45 mass%. The distinctive effects of catalyst on production of monoolefine and alkane were investigated, showing that the proportion of C7–C12 increased and C13–C32 decreased. For the production of diolefin (C7–C32), however, the inhibition of catalyst was found. The thermal and catalytic pyrolysis of HDPE can be reasonably explained using free radical mechanism and carbonium ion mechanism, respectively. [ABSTRACT FROM AUTHOR]

Background: Gout is a progressive metabolic disease closely related to hyperuricemia and urate deposition, with an increasing prevalence and incidence across the globe. Recent studies have shown that the pathological process of gout includes two stages: asymptomatic hyperuricemia and MSU crystal deposition. However, the immune response during the development of hyperuricemia to gouty arthritis is not fully elucidated. Methods: Thus, an overnutrition-induced whole-course gout model was established to clarify the immune response and pathological changes in the development from hyperuricemia to gouty arthritis. The quails without urate oxidase were used as experimental animals. And we confirmed that uric acid metabolic targets were changed when quails were in the asymptomatic hyperuricemia stage. Results: When the quail showed gout symptoms, the NLRP3 inflammasome was activated, and the expressions of IL-1b, TNF-a, IL-6, IL-8, and IL-18 were significantly increased. The relationship between the uric acid metabolism target and the NLRP3 inflammasome may be the critical immune response between hyperuricemia and gouty arthritis. Our data showed that, in the process of gout disease, the expression of xanthine oxidase (XOD) has been increasing, which increases the level of uric acid, disrupts the balance of oxidative stress, generates a large amount of ROS, activates the NLRP3 inflammasome, and release IL-1b. Treatment with the XOD inhibitor can reduce uric acid, restore the body’s degree of peroxidative damage and antioxidant capacity, and inhibit NLRP3 inflammasome and IL-1b. In vitro, we extracted and identified primary fibroblast-like synoviocytes (FLS) from quail for the first time. Stimulating FLS with uric acid also caused ROS release and NLRP3 inflammasome activation. However, treatment with an XOD inhibitor prevented all these responses in FLS. Conclusion: Our results indicate that the immune response between the uric acid metabolism target XOD and NLRP3 inflammasomes plays a crucial role in developing hyperuricemia to gouty arthritis, and inhibition of both XOD and NLRP3 inflammasomes may be an effective treatment for avoiding the development of asymptomatic hyperuricemia to MSU crystal deposition. Meanwhile, this study also provides an advantageous animal model for pathological mechanisms and research and development drugs for gout. [ABSTRACT FROM AUTHOR]

Fruit decay and deterioration in overall quality are the main problems of preserving peaches after they are harvested. In this article, the outcomes of 1‐MCP combined with polylysine atomization on Xinjiang flat peaches were evaluated. Distilled water atomization treatment, 1,000 mg/L polylysine atomization treatment for 10 min and 1,000 mg/L polylysine atomization treatment for 20 min were employed. Results showed that the combined treatment using 1‐MCP and polylysine helped to delay the fruit decay rate, respiration, ethylene production, respiration intensity, organic acids, soluble solids, hardness, and microorganisms. Furthermore, reactive oxygen metabolism of O2− and OH− was inhibited. A combined treatment can effectively improve the antioxidant capacity during almond storage, and thus improve shelf life. Therefore, 1‐MCP combined with polylysine atomization treatment is necessary to control fruit rotting and to extent the storage life. [ABSTRACT FROM AUTHOR]

Lysine acetylation is a common post‐translational modification of proteins within all organisms. However, quantitative acetylome characterization in wheat seed during aging in storage has not been reported. This study reports the first large‐scale acetylome analysis of wheat seeds after artificial aging treatment, using the quantitative proteomic approach. In total, 11,002 acetylation sites, corresponding to 4262 acetylated proteins were identified, of which 1207 acetylated sites, representing 783 acetylated proteins, were significantly more or less acetylated after artificial aging. Functional analysis demonstrated that the majority of the acetylated proteins are closely involved with cellular and metabolic functions. In particular, key enzymes in the oxidative stress response and energy metabolism were significantly differentially acetylated and appear to be heavily involved in wheat seed aging. The acetylome analysis was verified by quantitative real‐time PCR and enzyme activity determination. Lysine‐acetylation results in a weaker oxidative stress response and lower energy production efficiency, resulting in the apoptosis of wheat seed cells, insufficient energy supply at the germination stage, and consequently, marked loss of seed vigor. Practical applications: It is known that the loss of protein function is an important reason for the decrease of seed vigor. Therefore, the change of protein function in the process of wheat seed aging was studied by proteome and lysine acetylome analysis technology. The results showed that the oxidation–reduction imbalance and the decrease of energy production efficiency of seeds were the important reasons for the decrease of their vigor. This will provide a new idea for green and safe storage of grain. [ABSTRACT FROM AUTHOR]

Polymer-based systems have been demonstrated in novel therapeutic and diagnostic (theranostic) treatments for cancer and other diseases. Polymers provide a useful scaffold to develop multifunctional nanosystems that combine various beneficial properties such as drug delivery, bioavailability, and photosensitivity. For example, to provide passive tumour targeting of small drug molecules, polymers have been used to modify and functionalise the surface of water-insoluble drugs. This approach also allows the reduction of adverse side effects, such as retinoids. However, multifunctional polymer conjugates containing several moieties with distinct features have not been investigated in depth. This report describes the development of a one-pot approach to produce a novel multifunctional polymer conjugate. As a proof of concept, we synthesised polyvinyl alcohol (PVA) covalently conjugated with rhodamine B (a tracking agent), folic acid (a targeting agent), and all-trans retinoic acid (ATRA, a drug). The obtained polymer (PVA@RhodFR) was characterised by MALDI-TOF mass spectrometry, gel permeation chromatography, thermal analysis, dynamic light-scattering, NMR, UV-Vis, and fluorescence spectroscopy. Finally, to evaluate the efficiency of the multifunctional polymer conjugate, cellular differentiation treatments were performed on the neuroblastoma SH-SY5Y cell line. In comparison with standard ATRA-based conditions used to promote cell differentiation, the results revealed the high capability of the new PVA@RhodFR to induce neuroblastoma cells differentiation, even with a short incubation time and low ATRA concentration. [ABSTRACT FROM AUTHOR]

Reverse micelles are aggregates of amphiphilic molecules in nonpolar solvents. They have polar cores surrounded by surfactant head groups that can solubilize various hydrophilic compounds such as dyes, proteins, and antibiotics. They are frequently studied for extraction of organic and inorganic compounds. Advantages of reverse micelles are ease of production, high encapsulation efficiency, and protection of encapsulated compounds. The cosmetic market has been continuously growing over the years as more innovative cosmetics products are released into the market. Reverse micelles can be used as nano-sized carriers to encapsulate various hydrophilic active ingredients in cosmetic formulations. They can be prepared using safe, biocompatible, nontoxic, and biodegradable materials, thus are suitable to be incorporated into cosmetic products. The viscoelastic property and the skin permeation property can be adjusted. Targeted delivery and sustained release of active ingredients can be achieved through proper formulation. In addition to being directly included in formulations, reverse micelle systems are also used for the preparation of active ingredients and the analysis of cosmetic products for quality control. Therefore, reverse micelles show great potential for application in the cosmetic sector. This paper reviews related works in past two decades and provides some insights for future studies to broaden the implementation of reverse micelle systems in cosmetic products. [ABSTRACT FROM AUTHOR]

The new β‐diketimine iPrDipnacnacH, HC(iPrCNDip)2H, Dip=2,6‐iPr2‐C6H3, was converted to the magnesium(I) complex [{(iPrDipnacnac)Mg}2] and reaction with 2‐adamantanone (OAd) afforded the ketone‐1,2‐diide complex [{(iPrDipnacnac)Mg}2(μ‐OAd)]. The complex contains the first stable dianion of an aliphatic ketone with an electropositive metal and shows an OAd2− unit with long C−O bond and pyramidal carbon centre. DFT studies reveal an anionic charge on both neighbouring C and O atoms. Reductions of aliphatic ketones with magnesium(I) complexes show that these likely proceed via highly reactive dianions and afforded a 1 : 1 mixture of an alkoxide and an enolate when an enolisable ketone was used, and rapid CH activations reactions, e.g. of stabilising ligand moieties, when non‐enolisable ketones were employed. [ABSTRACT FROM AUTHOR]

Catalytic enantioselective hydroxylation of prochiral dihydrosilanes with water is expected to be a highly efficient way to access Si‐chiral silanols, yet has remained unknown up to date. Herein, we describe a strategy for realizing this reaction: using an alkyl bromide as a single‐electron transfer (SET) oxidant for invoking CuII species and chiral multidentate anionic N,N,P‐ligands for effective enantiocontrol. The reaction readily provides a broad range of Si‐chiral silanols with high enantioselectivity and excellent functional group compatibility. In addition, we manifest the synthetic potential by establishing two synthetic schemes for transforming the obtained products into Si‐chiral compounds with high structural diversity. Our preliminary mechanistic studies support a mechanism involving SET for recruiting chiral CuII species as the active catalyst and its subsequent σ‐metathesis with dihydrosilanes. [ABSTRACT FROM AUTHOR]

In this study, photo-curing kinetics for urethane-acrylate-based photo-inks for 3D printing were evaluated using a photo-differential scanning calorimetry analysis. Initially, the photopolymerization kinetics of di- and monofunctional monomers were separately studied at different temperatures (5–85 °C). Later, the photo-curing kinetics and mechanical properties of photo-inks based on different monomer mixtures (40/60–20/80) were evaluated. The results showed that urethane-dimethacrylate (UrDMA) and urethane-acrylate (UrA) had no light absorption in the region of 280–700 nm, making them a proper crosslinker and a reactive diluent, respectively, for the formulation of 3D-printing photo-inks. The kinetics investigations showed a temperature dependency for the photo-curing of UrDMA, where a higher photopolymerization rate (Rp,max: from 5.25 × 10−2 to 8.42 × 10−2 1/s) and double-bound conversion (DBCtotal: from 63.8% to 92.2%) were observed at elevated temperatures (5–85 °C), while the photo-curing of UrA was independent of the temperature (25–85 °C). Enhancing the UrA content from 60% to 80% in the UrDMA/UrA mixtures initially increased and later decreased the photopolymerization rate and conversion, where the mixtures of 30/70 and 25/75 presented the highest values. Meanwhile, increasing the UrA content led to lower glass transition temperatures (Tg) and mechanical strength for the photo-cured samples, where the mixture of 30/70 presented the highest maximum elongation (εmax: 73%). [ABSTRACT FROM AUTHOR]

BACKGROUND: Gradually aggravated disease caused by phytopathogenic bacteria severely restricts food security and crop yield, and few pesticides can relieve this severe situation. Thus, development and excavation of new agrochemicals with high bioactivity and novel action mechanism may be a feasible strategy to control intractable bacterial diseases. As a privileged molecular framework, steroid molecules exhibit diversiform bioactivities. Herein, a series of novel androst‐4‐ene derivatives were designed, synthesised and investigated for their antibacterial behaviour to excavate novel agrochemicals on the base of steroid molecules. RESULTS: Bioassay results indicated that target compounds displayed high bioactivities toward three destructive phytopathogenic bacteria, including Xanthomonas oryzae pv. oryzae (Xoo), Xanthomonas axonopodis pv. citri (Xac) and Pseudomonas syringae pv. actinidiae (Psa). Compound III19 displayed excellent in vitro antibacterial profiling (EC50 = 2.37 mg L−1 towards Xoo, EC50 = 2.10 mg L−1 towards Xac, EC50 = 9.50 mg L−1 towards Psa). Furthermore, compound III19 showed outstanding in vivo protective activities, with values of 81.81% and 58.75% towards kiwifruit bacterial canker and rice bacterial leaf blight, respectively. Analysis of the antibacterial mechanism disclosed that compound III19 enhanced host defence enzyme activities superoxide dismutase (SOD), peroxidase (POD), phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO), and catalase (CAT) and increased the salicylate synthase content to induce host resistance. In addition, compound III19 increased the membrane permeability, destroyed the cell membrane and killed the bacteria. CONCLUSION: Given these profiles of target compounds, we highlight a new strategy for controlling intractable plant bacterial diseases by inducing plant resistance and targeting the bacterial cell membrane. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The successive steps of the oxidation mechanism of crocin, a major compound of saffron, by the free OH• radical are investigated by pulse radiolysis, steady-state (gamma) radiolysis methods, and molecular simulations. The optical absorption properties of the transient species and their reaction rate constants are determined. The absorption spectrum of the oxidized radical of crocin resulting from the H-abstraction presents a maximum of 678 nm and a band of 441 nm, almost as intense as that of crocin. The spectrum of the covalent dimer of this radical contains an intense band at 441 nm and a weaker band at 330 nm. The final oxidized crocin, issued from radical disproportionation, absorbs weaker with a maximum of 330 nm. The molecular simulation results suggest that the OH• radical is electrostatically attracted by the terminal sugar and is scavenged predominantly by the neighbor methyl site of the polyene chain as in a sugar-driven mechanism. Based on detailed experimental and theoretical investigations, the antioxidant properties of crocin are highlighted.

Puccinia striiformis f. sp. tritici (Pst) secretes an array of specific effector proteins to manipulate host immunity and promote pathogen colonization. In a previous study, we functionally characterized a glycine-serine-rich effector PstGSRE1 with a glycine-serine-rich motif (m9). However, the mechanisms of glycine-serine-rich effectors (GSREs) remain obscure. Here we report a new glycine-serine-rich effector, PstGSRE4, which has no m9-like motif but inhibits the enzyme activity of wheat copper zinc superoxide dismutase TaCZSOD2, which acts as a positive regulator of wheat resistance to Pst. By inhibiting the enzyme activity of TaCZSOD2, PstGSRE4 reduces H2O2 accumulation and HR areas to facilitate Pst infection. These findings provide new insights into the molecular mechanisms of GSREs of rust fungi in regulating plant immunity. Author summary: Pst secretes numerous effectors to modulate host defense systems. However, the mechanisms of these effectors, especially for glycine-rich or serine-rich effectors, remain obscure. In this study, we identified a new glycine-serine-rich effector, PstGSRE4, which exhibits unusual biochemical properties and is highly induced during early stages of infection. Transgenic expression of PstGSRE4-RNAi constructs in wheat significantly reduced virulence of Pst and increased H2O2 accumulation in wheat. Overexpression of PstGSRE4 in wheat significantly increased virulence of Pst and reduced H2O2 accumulation in wheat. PstGSRE4 was shown to target the ROS-associated regulatory factor TaCZSOD2, which was proved as a positive regulator of wheat immunity in this study. Further study revealed that PstGSRE4 inhibited the enzyme activity of TaCZSOD2 and thus compromises the host immune systems. This work reveals a novel strategy that rust fungi exploit to modulate host defense and facilitate pathogen infection. [ABSTRACT FROM AUTHOR]