Search Results (4,356)

Perillyl alcohol, a rare monoterpenoid, can be widely used in chemical, agriculture, and food industries and shows promise in medicine as an anticancer agent. The artificial synthesis of perillyl alcohol from β-pinene epoxide using inexpensive and abundant turpentine is chosen for improving its pharmaceutical and industrial applications. This work presents a green and sustainable catalytic process for the rearrangement of β-pinene epoxide to perillyl alcohol. A novel ammonium phosphomolybdate solid acid (AC-COIMI-NH₄PMo) was built via phosphomolybdic acid chemisorption onto an N-basylous site of imidazolized activated carbon followed by ammonia fumigation, which exhibits outstanding catalytic performance in the rearrangement of β-pinene epoxide to perillyl alcohol in nitromethane under mild conditions. At 80 °C over 80 min, nearly complete conversion of the epoxide is achieved with a perillyl alcohol selectivity of 77.3%. Moreover, the used catalyst can be readily recycled after washing with hot nitromethane. The favorable proton-donating capacity of nitromethane for the rearrangement and the comparison of adsorption energies between substrates and main products on ammonium phosphomolybdate are revealed through DFT calculation. Kinetic analysis based on the Langmuir adsorption model indicates that the surface reaction of strongly adsorbed β-pinene epoxide is a rate-determining step and follows a zero-order reaction process; the activation energy is 29.64 kJ/mol within the temperature range of 50–80 °C. Finally, a parallel catalytic rearrangement mechanism is proposed, and an eight-step reaction pathway toward perillyl alcohol is elaborated for β-pinene epoxide conversion on AC-COIMI-NH₄PMo. Full article

Machupo virus (MACV) is the causal agent of Bolivian Hemorrhagic fever. It is highly pathogenic, has a high mortality rate, and currently lacks specific treatments or vaccines. MACV belongs to the Arenaviridae family, which uses a cap-snatching mechanism during the transcription process. Its viral polymerase, the L protein, harbors the endonuclease activity required for cap snatching, making it a suitable target for the development of antiviral therapeutics. We combined experimental and computational methods to characterize MACV endonuclease activity and evaluate inhibitors. A fluorescence resonance energy transfer (FRET) assay was used to measure the enzymatic activity of endonuclease and identify potent inhibitors via high-throughput screening. FRET assays identified BW-148, an inhibitor with a 48.4 µM (95% CI: 37.3–59.3 µM; R² = 0.98) IC₅₀, and a K_D of 13.7 µM (95% CI: 8.2–19.2 µM, n = 3). Docking studies reveal that BW-148 may bind near the MACV endonuclease catalytic site, inhibiting enzymatic activities by metal chelating. BW-148 is a useful lead compound for further optimization of Machupo endonuclease inhibitors. Full article

Demand for greener and safer chemistries has driven the innovation of bioinspired and enzyme-mimicking catalysts for selective and efficient oxidation and hydrogenation under mild conditions. Natural catalysts, including peroxidases, oxidases, hydrogenases, oxygenases and dehydrogenases, boast remarkable activity, specificity, stability, selectivity, low energy requirements and atom economy. Disadvantages of enzymes, such as poor thermal stability, a narrow operational range, low recovery yield and the expense of purification, are motivating the discovery and design of enzyme substitutes. Several artificial platforms have appeared recently: nanozymes, artificial metalloenzymes, biomimetic metal Complexes, MOFs, atomic catalysts, bioinorganic hybrid systems, among others. These systems aim to replicate key structural and mechanistic features of enzymes while providing greater operational stability, recyclability, and scalability. Recent work has demonstrated the benefit of enzyme mimics in increasing eco-sustainability in reactions such as alcohol oxidation, selective alkane oxidation, waste degradation, catalytic photooxygen activation and biomass waste conversion. Similarly, biomimetic hydrogenation catalysts have shown outstanding activity in asymmetrically hydrogenating chemicals, reducing CO₂ into chemicals, hydrogenation by hydrogen transfer and creating hydrogen through water. Through control of active sites, second coordination sites, defects and electrons/protons in the system, significant gains have been seen in reaction selectivity and frequency of turning over substrate into product. Nanozymes, biohybrid catalysis and artificial catalysts guided by deep learning are further broadening the applications of biomimetic catalysis in oxidation and hydrogenation. The article review aims to provide a summary of the most current progress with bioinspired and enzyme-mimicking catalysts, focusing on catalytic mechanisms, how to design such catalysts, how green chemistry benefits from their development and where further application is likely in the coming years. Full article

Ubiquitin-specific protease 22 (USP22) regulates epigenetic gene expression by deubiquitinating histone H2B (H2Bub1) and upregulating oncogenic proteins and pathways, while antagonizing p53-mediated tumor suppression. USP22 is frequently overexpressed in cancers and associated with therapy resistance and poor prognosis yet remains largely untargeted pharmacologically. Here, using a fluorescence-based USP22 deubiquitinase assay to screen the LOPAC^®1280 library, we identified β-Lapachone, a natural ortho-naphthoquinone with strong anticancer activities, as a potent USP22 inhibitor. β-Lapachone potently inhibited USP22 enzymatic activity, with a half-maximal inhibitory concentration (IC₅₀) of ~0.75 μM, and molecular docking revealed its occupation of the catalytic pocket adjacent to the USP22 active-site triad, supporting a potential binding mode. Functionally, β-Lapachone suppressed proliferation and induced apoptosis in A549 and H1299 RAS-mutant lung adenocarcinoma (LUAD) cells, while USP22 knockout conferred marked resistance, indicating partial USP22 dependence. In patient-derived LUAD models, β-Lapachone inhibited sphere formation and reduced CD133⁺ cancer stem cell populations. Notably, it synergized with cisplatin to enhance DNA damage and apoptosis. In vivo, β-Lapachone significantly suppressed tumor growth in a syngeneic KRAS-mutant/p53-Null mouse lung cancer model and further potentiated cisplatin-induced antitumor effects. Collectively, these findings identify β-Lapachone as a potent inhibitor of USP22 and validate USP22 inhibition as a key mechanism underlying its anticancer activity in LUAD cells, both in vitro and in vivo. Full article

Traditional electro-Fenton systems for chlorinated antibiotic wastewater suffer from low mineralization, catalyst deactivation, and secondary pollution caused by chloride ions. In this work, nitrogen-functionalized graphite felt cathodes were synthesized by electrodeposition-pyrolysis. Pyridinic N and graphitic N were identified by XPS. The obtained cathodes were employed in a metal-free electro-Fenton system for effective tetracycline (TC) removal and mineralization. The results show that the optimal electrode (N-GF-3) achieved 93% degradation efficiency and 73% mineralization of TC in 60 min, when the optimized conditions (pH = 3 and current density = 20 mA/cm²) were employed. Unusually, with the presence of Cl⁻, the system showed even higher catalytic performance, having a degradation kinetic constant 2.4 times higher than that without chloride. The electrode was also reusable, maintaining a TC degradation efficiency above 90% in the fifth cycle. Based on fluorescence analysis of ·OH, a possible dual-path reaction mechanism is proposed. This mechanism provides new insights into designing advanced oxidation processes for the treatment of complex chlorinated organic wastewater. Nevertheless, the potential formation of chlorinated byproducts requires additional investigation. Full article

Nervonic acid (NA, C24:1 Δ15) is a vital extra-long-chain monounsaturated fatty acid essential for neural development, myelin sheath formation, and neurological health. As the most abundant natural source of NA, Malania oleifera Chun & S.K.Lee has become a key model for studying NA biosynthesis and regulation. This review systematically summarizes the metabolic pathways of nervonic acid biosynthesis in M. oleifera, including plastidial de novo fatty acid synthesis, endoplasmic reticulum (ER)-based very-long-chain fatty acid elongation, and Δ15 desaturation. We focus on the catalytic mechanisms and rate-limiting roles of the elongase complex (KCS, KCR, HCD, ECR) and Δ15 desaturase. Additionally, we integrate recent multi-omics data to analyze key enzyme KCS gene families, their phylogenetic relationships, and syntenic distribution patterns. Furthermore, transcriptional regulatory networks (MYB, bZIP, WRI1, ABI3, FUS3) and epigenetic regulation underlying NA accumulation are also discussed. Finally, we highlight advances, challenges, and prospects in metabolic engineering and synthetic biology for sustainable NA production. This review provides a theoretical basis for the conservation, molecular breeding, and biotechnological utilization of M. oleifera. Full article

RelA/SpoT homologue family enzymes participate in controlling the cellular levels of the alarmone (p)ppGpp, thereby activating the stringent response and promoting survival under stress conditions. These proteins contain an N-terminal catalytic domain and a C-terminal regulatory domain. They catalyze both the synthesis of ppGpp/pppGpp from ATP and GDP/GTP and their hydrolysis to GDP/GTP and pyrophosphate. Here, we report the crystal structure of the N-terminal domain of Rel from Streptococcus equisimilis in complex with pppGpp at 3.2 Å resolution. The asymmetric unit contains a dimer with asymmetric ligation: pppGpp occupies only the synthetase site in one monomer, whereas in the other monomer, it is bound in both the hydrolase and synthetase sites. The two monomers exhibit distinct conformational states, with pronounced rearrangements of the flexible loops surrounding the binding pockets, including the α2/α3 and α8/α9 loops that act as steric gates. Molecular dynamics simulations support the dual binding arrangement and reveal additional probable transient binding sites, including a region in the linker between hydrolase and synthetase subdomains. These findings provide a structural framework for understanding how pppGpp binding modulates the opposing catalytic activities of bifunctional Rel enzymes and suggest possible mechanisms for (p)ppGpp-mediated autoregulation. Full article

Background: Uridine diphosphate glucose (UDP-Glc) is one of the key substrates for the biosynthesis of gallotannins in plants. UDP-glucose dehydrogenase (UGD) catalyzes the irreversible oxidation of UDP-Glc to UDP-glucuronic acid (UDP-GlcA), thus affecting the biosynthesis and accumulation of gallotannins in the Chinese gallnut. Methods and Results: In this study, we identified three members of the RcUGD family from the Rhus chinensis genome. Protein sequence alignment revealed that all three RcUGDs possess the conserved NAD⁺ coenzyme binding motif GAGYVGG and the catalytic motif GFGGSCFQKDIL. qRT-PCR analysis revealed that the expression levels of RcUGD3 in stem and root tissues were respectively 10-fold and 13-fold greater than that in the leaves, in which gallotannin accumulation was higher. RcUGD3 expression level declined by 63% during early (24 d) gallnut development, suggesting an inverse relationship between RcUGD3 expression level and gallotannin biosynthesis. In addition, subcellular localization analysis using the tobacco transient transformation system showed that RcUGD proteins are broadly distributed throughout the cell. Moreover, an in vitro enzyme activity assay indicated that the recombinant RcUGD3 protein catalyzed UDP-Glc to produce UDP-GlcA as shown by HPLC. Taken together, our results suggested that RcUGD3 protein is responsible for UDP-Glc degradation and probably plays a regulatory role in gallotannin biosynthesis in the Chinese gallnut. Conclusions: This study lays a foundation for further elucidating the function and expression regulation mechanism of the RcUGD gene family and provides new insights for the super-accumulation mechanisms of gallotannins in Chinese gallnuts. Full article

To improve the sluggish low-temperature hydrogen storage kinetics of RE-Mg-based alloys, Bi₂O₃ is introduced into CeMg₁₁Ni as a functional dopant for microstructural regulation, and CeMg₁₁Ni + x wt.% Bi₂O₃ (x = 0, 3, 5, 7, 10) composites are fabricated through planetary ball milling. Multiple characterization methods including XRD, SEM and TEM were used to explore the effects of Bi₂O₃ on the microstructure and hydrogen storage properties. Bi₂O₃ maintains stable phase during cycling and does not participate in reversible hydrogen storage reactions. It cooperates with in situ formed CeH₂ nanocrystals to construct high-density interfacial defects. The 5 wt.% Bi₂O₃-doped alloy exhibits the optimal balance between exposed catalytic sites and open hydrogen diffusion channels, achieving complete dehydrogenation within 144 s at 633 K, a reduced dehydrogenation activation energy of 63.89 kJ mol⁻¹, and an 84.7% hydrogen absorption ratio within 5 min at 423 K. Bi₂O₃ has a weak effect on the thermodynamic properties of the alloy, with only a slight enthalpy change of less than 1 kJ/mol within the experimental error range. Bi₂O₃ enhances hydrogen storage reactions through a synergistic “active sites–diffusion channels” mechanism, in which oxygen vacancies promote H₂ dissociation and heterogeneous interfaces facilitate hydrogen diffusion, thereby reducing the reaction energy barrier. Full article

Access to clean and safe drinking water for all remains a global challenge, mainly for rural populations and areas affected by natural disasters or humanitarian crises. The traditional water quality treatment technologies can work well in laboratory or controlled settings, but they are usually applied under conditions unavailable in these types of conditions. Traditional water quality treatment methods are limited by established infrastructure, expensive operating costs, energy requirements, and the ability to perform in-field water treatment. To improve the barriers of traditional water quality treatment technologies, recently developed scientific discoveries of nanozymes, a new class of nanomaterials with enzyme-like catalytic activity, have shown the ability to decentralise water purification. Nanozymes provide a mechanism for water treatment that does not require the infrastructure or the cost of traditional water quality treatment methods. Also, nanozymes possess extremely high catalytic activity, chemical stability, are inexpensive, and are suitable for a variety of contaminants. This review gives a systematic overview of the development of suitable nanozyme-based portable water purification systems. It shows their catalytic mechanisms, the class of nanozymes used, and the design characteristics related to their working use, also highlighting the developments that consider the specific needs of rural contexts, provide rapid responses to disaster areas, and offer drinking water with reliable, simple, and sustainable apparatus. Full article

Hydrogen is a promising clean-energy carrier, but its low ignition energy, high diffusivity, and wide flammability range demand reliable leak detection. Chemiresistive sensors based on n-type metal oxide semiconductors are attractive owing to their simple architecture, low cost, large resistance modulation, thermal robustness, and compatibility with miniaturized devices. This review focuses on n-type metal oxide semiconductor nanomaterials for hydrogen sensing, particularly ZnO, SnO₂, In₂O₃, WO₃, TiO₂, and related mixed oxides. The fundamental sensing mechanisms are examined, including oxygen chemisorption, electron-depletion-layer modulation, grain-boundary barrier control, catalytic hydrogen spillover, and hydrogen-induced surface reduction or metallization, together with the way these mechanisms compete and cooperate under different operating conditions. Recent performance-enhancement strategies are organized around morphology and porosity control, noble-metal sensitization, defect and dopant engineering, n–n heterojunctions, molecular sieving, and low-temperature activation. Density functional theory is discussed as a design tool for evaluating adsorption energetics, vacancy formation, work-function shifts, band alignment, and interfacial charge transfer, along with its current limitations for modeling humid surfaces. Finally, key challenges and future directions, including humidity tolerance, standardized reporting, device integration, and emerging materials, are summarized to guide the development of high-performance hydrogen sensors. Full article

Castration-resistant prostate cancer (CRPC) remains a significant clinical challenge due to the ability of tumor cells to undergo intratumoral androgen synthesis, a process catalyzed by the CYP17A1 enzyme. The only CYP17A1 inhibitor available in therapy, abiraterone acetate, faces significant limitations due to its steroidal structure, which causes off-target effects and generates agonistic metabolites that paradoxically stimulate the androgen receptor (AR). This study presents the development of the D2AAK1M series, a novel class of non-steroidal potential CYP17A1 inhibitors based on a pyridine–piperidine scaffold. Through biomimetic design and molecular docking, we demonstrated that these compounds have the potential to coordinate the heme iron while achieving high shape complementarity within the catalytic pocket. In silico ADME profiling indicated superior physicochemical properties compared to abiraterone, including optimal lipophilicity, enhanced water solubility, and the potential to penetrate the blood–brain barrier for targeting CNS metastases. In vitro assay results correlated with a suggested mechanism, showing preferential cytotoxicity toward androgen-dependent LNCaP cells (AR+) while sparing AR-negative lines (DU145, PC3) and healthy human fibroblasts (BJ). Our compounds present a promising starting point for further development of non-steroidal CYP17A1 inhibitors. Full article

Microbial α-L-rhamnosidases are increasingly recognised as selective biocatalysts in food biotechnology, nutraceutical production, and health-related applications. These glycoside hydrolases catalyse the hydrolysis of terminal alpha-L-rhamnose residues from flavonoids, terpenoids, saponins, and other glycosylated natural products, thereby modulating sensory properties, solubility, intestinal absorption, and biological activity. While their traditional uses include debittering citrus juice and enhancing wine aroma, recent evidence demonstrates their wider value in selective flavonoid biotransformation, production of rare mono-glycosylated derivatives, probiotic fermentations, and microbiome-associated metabolism. This review summarises microbial sources, catalytic mechanisms, CAZy classification, substrate specificity, structure–function relationships, analytical methods, industrial process engineering, and emerging applications in functional foods and targeted nutraceutical applications. Particular attention is given to the distinction between alpha-(1→2)- and alpha-(1→6)-linked substrates, the production of isoquercitrin and prunin, recombinant enzyme platforms, immobilised biocatalysts, and potential future opportunities arising from metagenomics, synthetic biology, and AI-assisted protein engineering. Full article

Effective abatement of nitrogen oxides (NO_x) is achieved by ammonia selective catalytic reduction (NH₃-SCR). In this paper, the effects of single WO₃ doping and WO_x-VO_x co-doping into the MnO_x/TiO₂ catalyst on NH₃-SCR of NO_x removal, sulfur and water resistance, and reaction mechanisms were systematically investigated. The 5MnO_x/TiO₂, WO₃-5MnO_x/TiO₂, and WO₃-V₂O₅-5MnO_x/TiO₂ were prepared using the incipient-wetness impregnation method. Furthermore, the monolithic WO₃-V₂O₅-5MnO_x/TiO₂-CC (cordierite support) catalyst involved a coating process. The WO₃-V₂O₅-5MnO_x/TiO₂ catalyst demonstrated superior NO conversion and maintained over 80% activity following prolonged exposure to SO₂ and H₂O. Characterization results indicated that the introduction of WO₃ regulated Mn valence through the formation of W-O-Mn bonds. The synergistic effect of V₂O₅ and WO₃ further promoted electron transfer, increased surface chemisorbed oxygen and oxygen vacancies, and strengthened reactant adsorption and activation. In situ DRIFTS analysis suggested that WO₃ modulated the reaction pathway, and while 5MnO_x/TiO₂ followed the Langmuir–Hinshelwood (L-H) mechanism, both WO₃-5MnO_x/TiO₂ and WO₃-V₂O₅-5MnO_x/TiO₂ exhibited a combined L-H and Eley–Rideal (E-R) pathway. This study confirmed that WO₃ played a crucial regulatory role in both single-metal and multi-metal systems, and the synergistic interaction between V₂O₅ and WO₃ was the key to achieving superior denitration performance and poisoning resistance. Full article

The development of highly efficient, stable, and cost-effective non-precious metal electrocatalysts to replace conventional platinum-based materials holds profound significance for accelerating the commercialization of advanced energy conversion devices, such as zinc–air batteries (ZABs). Herein, we propose a facile and highly efficient strategy to prepare a defect-rich, highly active nitrogen-doped porous carbon-based electrocatalyst (denoted U-Fe-N-C, urea-assisted iron–nitrogen–carbon material), via high-temperature co-pyrolysis of heme with urea. Our results demonstrate that urea not only serves as an excellent nitrogen source during pyrolysis, introducing abundant topological defects and heteroatom doping sites, but also induces the carbon substrate to form a hierarchical sponge-like porous structure with a high specific surface area. This unique microenvironment effectively prevents the agglomeration of iron species at high temperatures, achieving enhanced dispersion of iron species stabilized within the nitrogen-rich carbon matrix. Electrochemical evaluations reveal that under the optimal synthesis conditions (a precursor mass ratio of 1:3, calcination at 900 °C), U-Fe-N-C exhibits excellent oxygen reduction reaction (ORR) catalytic performance, delivering a half-wave potential of 0.731 V vs. RHE, and shows long-term operational durability that significantly surpasses that of commercial Pt/C. Furthermore, liquid rechargeable zinc–air batteries assembled with U-Fe-N-C as the air cathode deliver remarkable cycling stability, operating for up to 270 h of charge–discharge cycling without noticeable performance degradation. This study not only provides useful insights into the mechanisms of pore formation and assistance but also offers a practical perspective for the rational design and scalable synthesis of high-performance metal–nitrogen–carbon (M-N-C) electrocatalysts. Full article