Search Results (143)

The electro-oxidation of eugenol (EUG) natural antioxidant was studied by cyclic voltammetry in phosphate buffer solutions (PBS) of different pH at electrochemically partially reduced graphene oxide (GCE/ePRGO). The voltammetric responses were mainly controlled by adsorption at this modified electrode. Current values were higher at pH 2.0 PBS, therefore, this pH was chosen to perform all experiments. DFT calculations of pKa’s and standard potentials defined the possible pathways of eugenol and its oxidation products. These pathways were evaluated through the comparison of voltammetric simulations of adsorbed species with experiments at pH 2.0, which also allowed for the estimation of the values of the kinetic parameters involved in electrochemistry. Our findings suggest a multi-step redox process in which Eugenol is first oxidized to the radical species and then to a cationic product. At this stage, the pathways branch into to methylenquinone and a 4-allyl-1,2-diquinone molecules. 4-allyl-1,2-diquinone is finally reduced in single or double reversible electrochemical step to the hydroquinone species. The present physicochemical work allows for a deeper understanding of the eugenol oxidation mechanism, which was only partially proposed in previous studies. Full article

Background/Objectives: The gut–liver axis plays a central role in cholesterol homeostasis, linking intestinal absorption, microbial metabolites, and hepatic lipid regulation. Dysregulation of this axis contributes to hypercholesterolemia and cardiometabolic risk, beyond classical cholesterol synthesis pathways. This study evaluated a novel multi-botanical formulation (MIX) that combines Gastrodia elata, Black Garlic, Primula veris, and Emblica officinalis (AMLA) to integrate modulation of cholesterol metabolism through intestinal and hepatic mechanisms. Methods: Individual extracts were chemically characterised for polyphenols, flavonoids, polysaccharides, S-allyl-L-cysteine (SAC), and tannins. Caco-2 cells were treated with varying doses to determine optimal concentrations and for viability, transepithelial electrical resistance, and permeability analysis. Supernatants post-intestinal passage were applied to HepG2 cells under high-glucose conditions to assess viability, oxidative stress, SRC/ERK-MAPK signalling, cholesterol synthesis (HMGR), LDL uptake, PCSK9–LDLR–SREBP-2 axis, and bile acid production. Results: MIX enhanced intestinal barrier integrity (TEER, tight junctions, permeability) and preserved cell viability compared with single extracts. In HepG2 cells, MIX demonstrated synergistic effects: it reduced HMGR expression by 83–90% relative to individual extracts, increased LDLR expression by 43–97%, suppressed PCSK9 by up to 92%, and lowered total cholesterol and LDL uptake more effectively than RYRF. MIX also amplified bile acid production and free cholesterol excretion, indicating improved hepatic clearance pathways. SRC and ERK-MAPK signalling were favourably modulated, supporting hepatocyte survival under metabolic stress. Conclusions: The multi-botanical formulation exerts complementary and synergistic effects on intestinal absorption and hepatic cholesterol regulation, integrating suppression of cholesterol synthesis, enhanced LDL clearance, and stimulated elimination via bile acids. These findings highlight the potential of the MIX formulation to modulate metabolically induced cholesterol dysregulation, supporting further in vivo and clinical investigation. Full article

As a source of non-protein nitrogen, ammonium chloride (NH₄Cl) is widely utilized in ruminant diets to reduce feed costs. However, the impact of its supplementation level on the flavor of sheep meat remains unclear, despite the known influence of fat on meat flavor. This study aimed to investigate the effects of dietary NH₄Cl supplementation levels on the lipidome and flavor compounds of subcutaneous adipose tissue in Tibetan sheep, providing a scientific basis for dietary optimization in Tibetan sheep farming. Eighty 2-month-old early-weaned Tibetan lambs were selected and randomly allocated into four groups, fed diets supplemented with 0% (N0 group), 1.49% (N1 group), 2.24% (N2 group), and 3.01% (N3 group) NH₄Cl for an experimental period of 105 days. The study conducted histomorphological observations, lipidomics analysis, and determination of flavor compounds. The results showed that NH₄Cl supplementation significantly reduced (p < 0.05) the contents of various unsaturated fatty acids and n-3 polyunsaturated fatty acids (n-3 PUFA) in the subcutaneous adipose tissue of Tibetan sheep. Specifically, the total saturated fatty acid (total SFA) content in the N3 group was significantly higher than that in the other groups, while the total monounsaturated fatty acid (total MUFA) content was significantly lower than that in the N1 and N2 groups (p < 0.05). The absolute contents of phosphatidylcholine (PC), phosphatidylethanolamine (PE), and the sum of triglycerides (TGs) and diglycerides (DGs) in the N3 group were significantly higher (p < 0.05) than those in the other groups. Regarding flavor compounds, the contents of ketone aroma compounds, such as 2-propanone and 2-butanone monomer, were significantly higher (p < 0.05) in the N0 group than in the other groups. The ammonia content in the N1 and N3 groups was significantly higher (p < 0.05) than that in the N0 and N2 groups, while the allyl sulfide content in the N2 group was significantly higher (p < 0.05) than that in the other groups. Correlation analysis revealed that the majority of TG and DG differential lipids were significantly positively correlated with allyl sulfide, and most differential lipids belonging to the PC, PE, and hexosylceramide (Hex1Cer) classes were significantly positively correlated with ammonia (|r| ≥ 0.80, p < 0.01). Conversely, PC (16:0_18:3) exhibited significant negative correlations with multiple beneficial aroma compounds (|r| ≥ 0.80, p < 0.01). The study indicates that dietary NH₄Cl supplementation levels exceeding 2.24% are associated with alterations in lipid metabolism and reduced synthesis of unsaturated fatty acids and beneficial flavor compounds, such as 2-propanone and 2-butanone, in subcutaneous adipose tissue. This is also associated with the abnormal accumulation of phospholipids and ceramides, which correlate strongly with elevated ammonia concentrations in adipose tissue and the generation of oxidation products such as propanal, potentially compromising meat flavor quality. Full article

Slug herbivory is an important but poorly explored driver of plant defence and belowground multitrophic interactions. This study examined how aboveground feeding by Arion vulgaris and Deroceras reticulatum affects oxidative status, photosynthetic pigments, and volatile organic compound (VOC) emissions in cabbage (Brassica oleracea L. var. capitata), and whether these changes influence slug-parasitic nematodes. Slug feeding induced strong oxidative stress in leaves and roots, reflected by depletion of total ascorbate and glutathione contents and increased proportions of their oxidized forms, indicating a systemic redox imbalance. Photosynthetic pigments were also markedly affected, characterized by decreased chlorophylls and carotenoids and activation of the xanthophyll cycle towards more zeaxanthin, particularly in plants attacked by D. reticulatum. Headspace SPME–GC–MS analysis revealed tissue-specific, herbivory-induced shifts in VOC profiles. Based on these changes, three VOCs—3-phenylpropionitrile, allyl isothiocyanate, and 2-hexenal—were selected for chemotaxis assays. Behavioural experiments showed that VOC identity and nematode species markedly influenced motility and chemotactic responses. Phasmarhabditis papillosa exhibited the strongest attraction to 3-phenylpropionitrile, whereas allyl isothiocyanate acted as a weak repellent to P. papillosa, Oscheius myriophilus, and Oscheius onirici. In contrast, 2-hexenal elicited no consistent directional response. These results demonstrate that slug herbivory alters cabbage metabolism and volatile signalling, shaping species-specific nematode behaviour and highlighting its potential for sustainable slug management. Full article

High-temperature proton exchange membranes (HT-PEMs) are critical components of high-temperature fuel cells, facilitating proton transport and acting as a barrier to fuel and electrons; however, their performance is hampered by persistent issues of phosphoric acid leaching and oxidative degradation. Herein, a novel HT-PEM with abundant hydrogen bond network is constructed by incorporating nanoscale polyhedral oligomeric silsequioxane functionalized with eight pendent sulfhydryl groups (POSS-SH) into poly(4,4′-diphenylether-5,5′-bibenzimidazole) (OPBI) matrix. POSS, a cage-like nanostructured hybrid molecule, features a well-defined silica core and highly designable surface organic groups, offering unique potential for enhancing membrane performance at the molecular level. Through controlled reactions between sulfhydryl groups and allyl glycidyl ether (AGE), two functional POSS crosslinkers—octa-epoxide POSS (OE-POSS) and mixed sulfhydryl-epoxy POSS (POSS-S-E)—were synthesized. These were subsequently used to fabricate crosslinked OPBI membranes (OPBI-OE-POSS and OPBI-POSS-S-E) via epoxy–amine coupling. The OPBI-POSS-S-E membranes demonstrated exceptional oxidative stability, which is attributed to the free radical scavenging ability of the retained sulfhydryl groups on the nano-sized POSS framework. After soaking in Fenton’s reagent at 80 °C for 108 h, the OPBI-POSS-S-E-20% membrane retained 79.4% of its initial weight, significantly surpassing both the OPBI-OE-POSS-20% and pristine OPBI membranes. The PA-doped OPBI-POSS-S-E-20% membrane achieved a proton conductivity of 50.8 mS cm⁻¹ at 160 °C, and the corresponding membrane electrode assembly delivered a peak power density of 724 mW cm⁻², highlighting the key role of POSS as a nano-modifier in advancing HT-PEM performance. Full article

2-Oxazolines are five-membered heterocyclic compounds with significant biological properties. They also play an important role in organic synthesis, acting as chiral ligands and protecting groups for hydroxyamino acids and amino alcohols. Poly(2-oxazolines) are known coating materials, for example, in biomedicine. Classic synthetic methods of 2-oxazolines involve a dehydrative cyclisation reaction between amino alcohols and carboxylic acids, acid chlorides, nitriles, imidates, and aldehydes. However, the electrophilic intramolecular cyclization of unsaturated amides is becoming an increasingly important synthetic method for the preparation of 2-oxazolines. This brief review summarizes procedures for synthesizing oxazolines using the electrophilic intramolecular oxidative cyclisation of N-allyl and N-propargyl amides, as published between 2014 and 2024. It covers the synthesis of 5-halomethyl-, 5-trifluoromethyl-, 5-sulfonylmethyl-, 5-sulfenylmethyl-, 5-selenylmethyl-, 5-acetoxymethyl-, 5-hydroxymethyl-, 5-aminomethyl-, 5-alkilo-, and 5-alkylideneoxazolines. Full article

Hydroxamic acids are emerging as versatile chiral ligands for metal-catalyzed asymmetric oxidations due to their tunable electronic and steric environments. In this study, we systematically compared the catalytic behavior of C₂- and C₁-symmetric hydroxamic acid ligands in the vanadium-catalyzed asymmetric epoxidation of allylic alcohols. A series of chiral hydroxamic acids (HA1–HA7) was synthesized and evaluated under varied conditions to elucidate the influence of ligand symmetry on enantioinduction and reactivity. The results demonstrate that C₂-symmetric bishydroxamic acids generate a highly organized chiral environment, leading to high enantioselectivity but often limited conversion, consistent with the Sabatier principle. Conversely, certain C₁-symmetric ligands—particularly HA3—produced notable enantioselectivity (up to 71% e.e.) and full conversion under optimized conditions with VO(OiPr)₃ in CH₂Cl₂. A quadrant-based stereochemical model is proposed to rationalize the differential performance of these ligands. These findings highlight the critical role of ligand desymmetrization in modulating the chiral environment around vanadium centers, providing valuable design principles for next-generation hydroxamic acid-based catalysts in asymmetric synthesis. The optimized system (VO(OiPr)₃/HA3 in CH₂Cl₂) afforded >99% conversion and 71% e.e., providing a basis for extending hydroxamic acid scaffolds to diverse allylic alcohols. Full article

Background: Metabolic Syndrome (MetS) is a multifactorial condition characterized by insulin resistance, dyslipidemia, hypertension, and abdominal obesity, which collectively increase the risk of type 2 diabetes mellitus and cardiovascular diseases. Lifestyle modification represents the first-line strategy in its management, whereas pharmacological interventions are complex and typically require long-term polypharmacotherapy. In this context, natural bioactive compounds with pleiotropic effects are gaining increasing attention. Among these, S-allyl cysteine (SAC), the major sulfur-containing compound derived from black garlic, has been identified as a promising candidate due to its well-documented antioxidant and anti-inflammatory properties. Methods: This narrative review examines the pathophysiological mechanisms underlying MetS and summarizes current evidence on the protective role of SAC against key pathological features of this condition, including oxidative stress, inflammation, glucose and lipid dysmetabolism, endothelial dysfunction, and gut microbiota alterations. Results: Preclinical studies indicate that SAC counteracts lipid accumulation, insulin resistance, endothelial dysfunction, and gut dysbiosis through multiple mechanisms, including hydrogen sulfide release, reactive oxygen species scavenging, inhibition of advanced glycation end products, and modulation of metabolic pathways. Conclusions: SAC emerges as a promising nutraceutical for the prevention and management of MetS and its complications. This underscores the broader relevance of nutraceuticals as promising tools in mitigating metabolic dysfunctions and reducing the burden of cardiometabolic diseases. Full article

The maintenance of intracellular redox homeostasis depends on the GSH/GSSG pair, which is the primary intracellular redox buffer. However, the NADPH/NADP⁺ pair also plays a vital role in this process. The primary source of NADPH is the pentose phosphate pathway and deficiency in the enzymes responsible for NADPH production in this pathway leads to developing of alternative NADPH supply strategies. The choice of compensation strategy has several consequences for cells physiology. The present study investigates how Saccharomyces cerevisiae yeast strains defective in generating NADPH via the pentose phosphate pathway due to deletion of ZWF1, GND1, or GND2 genes, respond to redox homeostasis disruption caused by allyl alcohol, a metabolic precursor of acrolein. Acrolein is a highly reactive aldehyde that rapidly depletes glutathione and triggers oxidative stress. Therefore, cells respond to acrolein through attempts to increase glutathione synthesis, but also by increasing NADPH production. The response requires coordinated action of glutathione- and NADPH-dependent systems. The high sensitivity of the Δgnd1 strain, which is unable to activate an adequate stress response, is evidence of this. The strategy employed by this strain to maintain redox homeostasis is inadequate and may even exacerbate allyl alcohol toxicity. Full article

Catalase is a pivotal antioxidant enzyme that decomposes hydrogen peroxide and reduces oxidative stress. However, its low thermal and operational stability limits applications in challenging environments, particularly those contaminated with emerging pollutants such as polystyrene-based microplastics (PS-MPs). In this study, cryogels composed of Poly(2-hydroxyethyl methacrylate-co-allyl glycidyl ether) [Poly(HEMA-co-AGE)] were synthesized and evaluated as immobilization matrices to enhance catalase stability. Cryogels containing varying AGE concentrations were characterized using FT-IR, SEM, TEM, TGA, and BET analyses. The formulation with 250 µL AGE exhibited optimal physicochemical properties, including improved water retention, increased surface area, and high immobilization capacity (356.3 mg·g⁻¹). Immobilized catalase maintained superior activity under PS-MP-induced stress across a range of concentrations (0–1.0 mg·mL⁻¹), temperatures (4–60 °C), and exposure times (up to 5 h). Kinetic modeling revealed a significant improvement in substrate affinity, with Km decreasing from 54.9 to 17.1 mM, while Vmax decreased moderately. Long-term stability tests showed that immobilized catalase retained ~80% activity after 70 days at 4 °C and 55% after 15 reuse cycles. Desorption studies confirmed the reusability of the cryogel system. These findings suggest that Poly(HEMA-co-AGE) cryogels provide a robust and reusable platform for catalase stabilization, offering potential for applications such as wastewater treatment and biosensing in microplastic-contaminated systems. Full article

The synthesis of cannabigerol—a cannabinoid with significant pharmaceutical potential—is described. The synthesis involves four stages. In the first step, (E)-non-3-en-2-one reacts with dimethyl malonate to yield a cyclic enone, which is subsequently oxidized with bromine to produce the olivetol ester. This ester then undergoes an alumina-catalyzed coupling reaction with geraniol, followed by ester hydrolysis to obtain cannabigerol. By modifying the chain length of the enone in the initial step and employing allylic alcohols other than geraniol, a range of cannabigerol derivatives can be synthesized, including the natural product cannabigerovarin. Full article

This study investigates the potential for the microbial transformation of camelliagenin B, a saponin derived from Camellia oleifera seed cake meal, to develop novel metabolites. We employed three microbial strains, specifically Bacillus subtilis ATCC 6633, Bacillus megaterium CGMCC 1.1741, and Streptomyces griseus ATCC 13273, to biotransform camelliagenin B into its derivatives. The compounds were purified and separated using chromatographic techniques, such as high-performance liquid chromatography (HPLC). Structural identification was carried out using spectroscopic methods, including nuclear magnetic resonance (NMR) and mass spectrometry (MS). Ten bioactive compounds were obtained (1a-1j), of which nine were novel with multiple tailoring reactions, such as allyl oxidation, C-C double-bond rearrangement, hydroxylation, dehydrogenation, and glycosylation, observed in camelliagenin B analogs. The structures of these compounds were determined by 1D/2D NMR and HR-ESI-MS analysis. Therefore, this study showcases the capacity of microbial transformation as a sustainable and environmentally friendly method for generating bioactive compounds from C. oleifera seed cake meals. The individual chemicals can potentially facilitate the design of novel medicinal agents, functional foods, and natural preservatives. Full article

A novel metal–organic framework based on zinc ions, designated as Zn-URJC-12, has been synthesized and applied for the first time in the cycloaddition reaction between carbon dioxide and epoxides. This MOF is constructed from two different organic linkers: 5-aminoisophthalic acid and 4,4′-biphenyldicarboxylic acid. The framework features –NH₂ functional groups coordinated to Zn(II) centers, as confirmed by single-crystal X-ray diffraction analysis. Zn-URJC-12 demonstrates exceptional chemical stability in polar organic solvents, such as methanol, while maintaining thermal stability up to 250 °C. The material exhibits high catalytic efficiency in the cycloaddition of CO₂ with epoxides, achieving yields of 100% and 76% for propylene oxide and allyl glycidyl ether, respectively. Additionally, Zn-URJC-12 maintains its structural integrity and catalytic performance during five successive reaction cycles. These findings underscore Zn-URJC-12 as a promising heterogeneous catalyst for the valorization of CO₂ into cyclic carbonates. Full article

Garlic is a spice widely used worldwide, but ingestion of garlic can cause unpleasant breath odor that can be offensive in interpersonal interactions. Among several sulfur-containing components of garlic, allyl methyl sulfide is considered the primary causative agent of unpleasant garlic breath and body odor. We discovered that hop cone powder exhibits potent deodorizing activity against allyl methyl sulfide. Oxidation products of the hop bitter acids humulinone and hulupone were detected in a partially purified sample of hop cone powder. Oxidation products of the α-acids cohumulinone and n-humulinone showed approximately 10- and 15-fold stronger deodorizing activity than the parent α-acids, respectively. The deodorizing activity of oxidation products of β-acids was comparable to that of n-humulinone. It is presumed that the oxidation products of hop powder play an important role in the strong deodorizing activity of hop cone powder against allyl methyl sulfide. Full article

Copper complexes have attracted significant interest for catalyzing oxidative dehydrogenative carboxylation of alkanes to form esters. Here, we report a heterogeneous catalyst, in which copper complexes are immobilized on coal-bearing kaolin for the synthesis of allylic esters via C(sp³)-H bond activation through cross-dehydrogenation coupling reactions between cyclic alkanes and aromatic carboxylic acids. Systematic optimization of reaction conditions—including catalyst loading, copper content, oxidant, temperature, and reaction time—resulted in a high yield of 71% of allylic ester, comparable to homogeneous transition metal catalysts. The catalyst is easily recoverable via centrifugation and retains its activity over five consecutive reuse cycles. This system demonstrates broad substrate compatibility with various aromatic carboxylic acids and cyclic alkanes. Beyond offering an efficient and reusable catalytic route for allylic ester synthesis, this work highlights the potential of coal-bearing kaolin as a sustainable support material for transition metal catalysis and provides an environmentally benign method for activating inert C(sp³)–H bonds. Full article