Search Results (265)

Photosynthesis in plants and the electron transport chain in mitochondria are examples of life-sustaining electron transfer processes. The benzoquinones plastoquinone and ubiquinone are key components of these pathways that cycle through their oxidized and reduced forms. Previously, we reported direct photoreduction of biologically relevant quinones mediated by photosensitizers, red light and electron donors. Herein we examined direct photoreduction of the quinone imine 2,6-dichlorophenolindophenol (DCPIP) using red light, methylene blue as the photosensitizer and ethylenediaminetetraacetic acid (EDTA) as the electron donor. Photoreduction of DCPIP by methylene blue and EDTA was very pH-dependent, with three-fold enhanced rates at pH 6.9 vs. pH 7.4. Photochemical redox cycling of DCPIP produced hydrogen peroxide via singlet oxygen-dependent reoxidation of reduced DCPIP. Histidine enhanced photoreduction by scavenging singlet oxygen, whereas increased molecular oxygen exposure slowed DCPIP photoreduction. Attempts to photoreduce DCPIP with pheophorbide A, a chlorophyll metabolite, and triethanolamine as the electron donor in 20% dimethylformamide were unsuccessful. Photoreduced benzoquinones including 2,3-dimethoxy-5-methyl-p-benzoquinone (CoQ₀), methoxy-benzoquinone and methyl-benzoquinone were used to examine electron transfer to DCPIP. For photoreduced CoQ₀ and methoxy-benzoquinone, electron transfer to DCPIP was rapid and complete, whereas for reduced methyl benzoquinone, it was incomplete due to differences in reduction potential. Nonetheless, electron transfer from photoreduced quinols to DCPIP is a rapid and sensitive method to investigate quinone photoreduction by chlorophyll metabolites. Full article

Miraruira is a medicinal plant-based product (MPBP) that is widely used in the state of Amazonas for the treatment of diabetes, though its botanical identity remains unclear, which raises concerns about authenticity and therapeutic consistency. One solution to this problem is the use of mass spectrometry-based approaches, which have emerged as powerful tools for verifying botanical origin based on chemical composition. Thus, to confirm the botanical authenticity of miraruira, direct-injection mass spectrometry (DI-MS) and chemometric analyses (PCA and HCA) were conducted on methanol fractions of Salacia impressifolia and Connarus ruber, both suspected sources of miraruira, as well as commercial samples obtained in street markets in Manaus, Brazil. Additionally, the hexane extracts of C. ruber and the commercial samples were screened for benzoquinones using DI-MS, as these compounds are recurrent in the genus Connarus. The DI-MS and PCA analyses revealed distinct chemical profiles for each species, and identified mangiferin and epicatechin as chemical markers for S. impressifolia and C. ruber, respectively. Furthermore, PCA demonstrated that all the commercial samples exhibited chemical profiles closely aligned with C. ruber. However, the HCA indicated variability among these samples, suggesting C. ruber or related Connarus species are the primary sources of miraruira. Moreover, embelin, rapanone, and suberonone were identified as the main compounds in the hexane extracts of C. ruber and the commercial products. This study successfully confirmed the botanical authenticity of miraruira, identified key bioactive compounds related to its traditional use in the treatment of diabetes symptoms, and demonstrated the effectiveness of DI-MS as a valuable tool for addressing authenticity issues in MPBPs. Full article

The Carabidae family, or ground beetles, is a wide and ecologically significant group within the Coleoptera order, known for its role as natural predators of agricultural pests and as bioindicators of ecosystem health. These beetles employ a variety of behavioral, morphological, and chemical defense strategies to protect themselves from predators. These mechanisms include gregariousness, stridulation, regurgitation, and chemical defenses, such as the secretion of irritating compounds from specialized glands. The defensive strategies of carabids are classified into passive and active systems, each with varying energetic costs. Chemical substances (e.g., Formic acid, Methacrylic acid, Tiglic acid, Ethacrilic acid, Isovaleric acid, Salicylaldehyde, 1,4-Benzoquinone, Toluquinone, 13-2Kt tridecan-2-one, Undecane, Tridecane, Pentadecane, M-cresol) are particularly important, as they serve to deter predators and combat pathogens like bacteria and fungi. Ground beetles utilize both polar and non-polar compounds in their defense, all contributing to their ecological success. This review explores the array of defensive mechanisms in the Carabidae family, highlighting experimental studies, field observations, and reviews published over the last five decades. The aim is to provide a comprehensive understanding of how these strategies enhance the survival and fitness of carabid beetles in their natural environments. Full article

The synthesis and characterization of two novel redox-active MOFs/CPs based on 3d transition metal ions and 3,6-ditriazolyl-2,5-dihydroxybenzoquinone (trz₂An) are reported herein. By combining trz₂An with Ni^II and Mn^II ions via the hydrothermal method, two phases, formulated as [Ni₂(trz₂An)₂]·2.5H₂O (1) and [Mn(trz₂An)(H₂O)]·1.5H₂O (2), are obtained. Both compounds crystallize as neutral polymeric 3D frameworks, where the metal ions are coordinated through the oxygen atoms of the anilate linkers forming either straight (1) or zig-zag (2) 1D chains. In particular, (1) is a MOF, where these chains are connected through the nitrogen atom at the 4 position of the triazolyl group, which completes the coordination sphere of each metal ion, affording a 3D structure containing a void volume of 28.7% and voids that can be useful for the sorption of small molecules. Interestingly, (1) and (2) show a redox behavior due to the presence of the anilate linker, being reduced electrochemically in the −0.7 to −0.9 V range due to the benzoquinone–semiquinone one-electron reduction and magnetic behavior dominated by antiferromagnetic interactions in the anilate 1D chains. Full article

N-acetyl para-aminophenol was suggested as a safer alternative to other drugs on the market for pain and fever in 1948. It was given the generic name “acetaminophen” in 1951 and the trade name “Tylenol” when it was put on the market in the USA in 1955 as a prescription drug to treat pediatric fever. It also received the generic name “paracetamol” in the UK where it was initially marketed in 1956 under the name “Panadol.” Toxicity from overdose of acetaminophen was reported in 1966. Research at the US National Institutes of Health uncovered the mechanisms of toxicity and proposed a treatment in a foundational series of papers in 1973 and 1974. A nomogram was developed in 1973 and published in 1975 to guide estimation of patient risk of hepatic toxicity. Rapid development followed utilizing acetylcysteine given both orally and intravenously. Various protocols and methods of administration have been employed over time with the primary use today of acetylcysteine intravenously as the therapeutic method. The nomogram has been revised over time to the current version, published in 2023, which allows stratification of patients to a high-risk group over 300 mg/L at 4 h and standard risk above 150 mg/L at 4 h, except in the UK where the standard risk is defined very conservatively with a line above 100 mg/L at 4 h. Adjunct therapy with fomepizole in patients with massive ingestions, delay until arrival in a health care facility or renal injury has been proposed. The mortality rate with treatment has been substantially reduced and recovery from hepatic injury is achieved in almost all patients. Full article

Cistanche deserticola, a holoparasitic plant widely used in traditional Chinese medicine, relies on chemical signals from its host plant, Haloxylon ammodendron, to initiate seed germination and haustorium induction. This study employed UPLC-MS/MS to analyze the root metabolites of H. ammodendron. The results showed that 11 substances such as phenolic acids, flavonoids, and alkaloids were mainly contained in the roots of H. ammodendron, among which phenolic acids accounted for the largest proportion, accounting for 18.00% in winter samples and 16.11% in autumn samples. Based on the reported exogenous substances that promote haustorium induction in C. deserticola and the differential metabolites in H. ammodendron roots, we selected seven exogenous signaling substances: 2,6-dimethoxy-1,4-benzoquinone, resorcinol, ferulic acid, syringic acid, vanillic acid, vanillin, and pelargonidin. Through concentration-gradient experiments (0.1–100 μM), we assessed their effects on haustorium induction in C. deserticola seeds. The results showed that among the seven substances, syringic acid, vanillic acid, and vanillin had the best impact on promoting the haustorium induction of C. deserticola seeds. Vanillic acid had the best impact at the concentration of 10 μmol/L, and the highest haustorium induction rate was 50.2%. There was no significant difference in the concentrations of vanillin and syringic acid. The results showed that phenolic acids in the host root system stimulated haustoria induction in C. deserticola seeds, with different substances requiring different optimal concentrations. This study not only identifies specific phenolic acids that enhance C. deserticola productivity but also establishes a chemical ecology framework for investigating host–parasite interactions in other root parasitic species. Full article

N-(1,3-dimethylbutyl)-N’-phenyl-p-benzoquinone (6PPD-Q) is an emerging environmental contaminant that is widely distributed in aquatic environments and presents significant toxicological risks to aquatic organisms. As 6PPD-Q is primarily derived from oxidative transformation of the tire antioxidant N-(1,3-dimethylbutyl)-N’-phenyl-p-phenylenediamine (6PPD), its persistence and potential for bioaccumulation in aquatic organisms have raised widespread concerns. This study reviews the environmental sources, spatial distribution, migration, and transformation behaviors of 6PPD-Q, as well as its degradation mechanisms in different environmental media. Additionally, this review systematically explores the toxicological effects of 6PPD-Q on aquatic organisms, including its physiological, biochemical, and molecular impacts on fish, crustaceans, mollusks, and algae, with a focus on potential toxicological mechanisms. Finally, we discuss the limitations of current research on 6PPD-Q and propose key directions for future studies, including long-term ecological risk assessments, mechanisms of bioaccumulation, metabolic pathway analysis, and optimization of pollution control strategies, aiming to provide a scientific basis for the ecological risk assessment and pollution management of 6PPD-Q. Full article

The electro-oxidation of p-Benzoquinone (p-BQ) was investigated in a flow-by reactor (FM01-LC) without separation, with two boron-doped diamond (BDD) electrodes as both the anode and cathode, in batch recirculation mode. The optimal operating conditions were determined using response surface methodology, specifically a face-centered central composite design. The initial pH (pH₀) and applied current density (j) were evaluated as factors, while the p-BQ (η (%)) served as the response variable. The optimal conditions, a pH₀ of 6.52 and a j of 0.124 A/cm², achieved a maximum removal efficiency of 97.32% after 5 h of electrolysis. The specific energy consumption and total operating cost were 127.854 kWh/m³ and USD 3.7 USD/L, respectively. Full article

The photoreduction of plastoquinone, a para-benzoquinone, by chlorophyll initiates photosynthesis in chloroplasts. The direct photoreduction of biologically relevant quinones by dietary chlorophyll metabolites has been reported and may influence health outcomes. We examined red light-mediated photoreduction of ortho- and para-naphthoquinones including vitamin K₃ using the photosensitizers methylene blue and pheophorbide A, a chlorophyll metabolite. Naphthoquinone reduction was monitored by UV/Visible spectroscopy and required a photosensitizer, red light and a tertiary amine electron donor. Combinations of methylene blue and ethylenediaminetetraacetic acid or pheophorbide A and triethanolamine in 20% dimethylformamide were employed for all photoreduction experiments. Hydrogen peroxide was generated during the photochemical reactions by singlet oxygen-dependent oxidation of the reduced naphthoquinones. Hydrogen peroxide was quantified with horseradish peroxidase following irradiation; the reduced naphthoquinones acted as peroxidase co-substrates. Histidine, a singlet oxygen scavenger, enhanced the rate of photoreduction by limiting the re-oxidation process. Catalase slowed the rate of photoreduction by regenerating molecular oxygen from hydrogen peroxide so that it could be photoexcited to singlet oxygen. The rates and extent of naphthoquinone photoreduction were dependent on molecular oxygen exposure in different reaction formats including in a cuvette and a plate well. Reduction of the tetrazolium salt MTT to the formazan via electron transfer from the photoreduced quinones was also used to quantitate the extent of photoreduction. Full article

The valorization of agricultural waste has gained attention due to the need for sustainable technologies addressing environmental and economic challenges. The aim of this work is to investigate the electrochemical transformation of anacardic acid, a major component of cashew nut shell liquid (CNSL), into organic acids and polymeric materials. Cyclic voltammetry (CV) was carried out on ethanolic anacardic acid solutions with NaOH as the supporting electrolyte to induce oxidation reactions. CV, FTIR spectroscopy, and electrochemical impedance spectroscopy (EIS) were used to analyze the transformation processes. The results revealed oxidation sequences involving phenoxyl radicals, hydroquinones, and benzoquinones, leading to ring-opening reactions and the production of low-molecular-weight organic acids, including propionic, formic, oxalic, lactic, and acetic acids, as confirmed by HPLC. Polymerization processes were also observed, leading to the attainment of polymeric materials. FTIR spectra showed changes in phenol and carboxylic acid bands, confirming chemical transformations. CV and EIS indicated irreversible oxidation processes with charge transfer coefficients between 0.397 and 0.414 controlled by diffusion–adsorption. This work demonstrates the feasibility of electrochemical oxidation as a green method for producing organic acids from anacardic acid, aligning with circular economy principles and reducing reliance on petrochemical sources. It highlights the potential of electrochemical approaches for sustainable biomass utilization and fine chemical synthesis. Full article

Two new heteroleptic cobalt(II) complexes (3,6-Cat)Co(R-DAD) (where (3,6-Cat)²⁻ is a dianion of 3,6-di-tert-butyl-o-benzoquinone, R-DAD is diisopropyl-1,4-diaza-1,3-butadiene (R = i-Pr (1)) or dicyclohexyl-1,4-diaza-1,3-butadiene (R = c-Hex (2)) have been synthesized and characterized in detail by IR, UV–Vis–NIR spectroscopy, and elemental analysis. The molecular structure of 1 was determined by X-ray diffraction analysis. Magnetic properties of 1 and 2 were measured both in a solid state and in a solution. According to the single-crystal X-ray diffraction analysis, the metal ion in 1 has a planar coordination environment, but magnetic susceptibility measurements of the microcrystalline samples of 1 and 2 indicate the formation of both forms with tetrahedral (d⁷, h.s., S_Co = 3/2) and planar (d⁷, l.s., S_Co = ½) coordination environments of the metal ion. Absorption spectra of crystalline samples of 1 and 2 possess intense absorption band in the NIR region. Electrochemical measurements of 1 and 2 were also performed. Full article

Vasorelaxant and antiplatelet agents play an important role in preventing and combating endothelial dysfunction, atherosclerosis and a plethora of associated cardiovascular diseases (CVDs). CVDs are the leading cause of death worldwide and nowadays occur not only in developed but also in developing societies. They include, among others, coronary heart disease, cerebrovascular disease and peripheral artery disease. Due to their high prevalence, it is important to seek efficient preventive measures, such as lifestyle changes and the implementation of appropriate herbal dietary supplementation and treatment alternatives. Plant-derived quinones have recently drawn researchers’ attention due to their interesting biological potential. Embelin and rapanone are two plant-derived benzoquinones with anti-inflammatory and antioxidant properties. Embelin has already been shown to have vasorelaxant and antiplatelet activity, but little is known about rapanone in the context of CVDs. Therefore, we decided to comparatively evaluate their activity in a specially designed experimental protocol. Following the isolation of both benzoquinones from plant sources (rapanone from Ardisia crenata leaves; embelin from Lysimachia punctata roots), their effects were comparatively assessed in a biofunctional study on isolated rat aorta (precontracted with phenylephrine) and in vitro on platelet aggregation. Both benzoquinones showed 50% vasorelaxation in an NO-dependent manner. Interestingly, rapanone was slightly more effective as an antiplatelet agent than embelin. The antiplatelet effect of both benzoquinones was specific, as no cytotoxicity towards platelets was observed at the concentrations tested. This is the first report on the vasorelaxant and antiplatelet activity of rapanone. Full article

In this study, a novel slow-release material using recycled waste foamed polystyrene (WFPS) as the carrier was developed for the degradation of aniline-contaminated groundwater. Sodium persulfate (SPS) and zero-valent iron (ZVI) were embedded in WFPS, enabling the controlled and sustained release of reactive species. Systematic investigations were conducted to optimize the material’s composition and evaluate its performance under various conditions, including pH, initial aniline concentration, and the presence of common groundwater anions. The results revealed that the slow-release material effectively enhanced aniline degradation, achieving a maximum removal rate of 93.45% under flowing conditions. The degradation pathway was analyzed using GC-MS, identifying intermediates such as benzoquinone, hydroquinone, and dodecane, with eventual mineralization into CO₂ and H₂O. The material demonstrated robust performance, offering an efficient, cost-effective, and environmentally sustainable approach for in situ groundwater remediation. Full article

2,6-Dichloro-1,4-benzoquinone (2,6-DCBQ) is an emerging chlorinated disinfection byproduct (DBP) in bodies of water. However, this compound poses an unknown toxic effect on cyanobacteria. In this study, the toxicological mechanisms of 2,6-DCBQ in Microcystis aeruginosa (M. aeruginosa) were investigated through physiological and nontargeted metabolomic assessments. The results show that 2,6-DCBQ inhibited the growth of M. aeruginosa, reduced its photosynthetic pigment and protein contents, increased the levels of reactive oxygen species, damaged the antioxidant defense system, and aggravated the cytomembrane. Meanwhile, 2,6-DCBQ stimulated the production and release of microcystin-LR (MC-LR) and altered the transcripts of genes associated with its synthesis (mcyA, mcyD) and transport (mcyH). In addition, nontargeted metabolomics of M. aeruginosa cells exposed to 0.1 mg/L 2,6-DCBQ identified 208 differential metabolites belonging to 10 metabolic pathways and revealed the considerable interference caused by 2,6-DCBQ among ABC transporters, the two-component system, and folate biosynthesis. This study deepens the understanding of the physiological and nontargeted metabolomic responses of M. aeruginosa exposed to 2,6-DCBQ, offers insights into the toxic effect of 2,6-DCBQ on M. aeruginosa, and provides a theoretical basis for the ecological risk assessment of emerging DBPs in accordance with water quality criteria. Full article

Geldanamycin, a benzoquinone ansa antibiotic, has been extensively applied in medical, agricultural, and health research areas due to its antitumor, antifungal, herbicidal, and antiradiation effects. In this study, an improvement of geldanamycin production by Streptomyces geldanamycininus FIM18-0592 was first performed by protoplasts combined with UV mutagenesis and ribosome engineering technology, respectively. The results showed that strains induced by UV mutagenesis of protoplasts were superior to protoplasts treated with erythromycin in terms of the positive variability, average relative titer, and maximum relative titer, with values of 51.95%, 99%, and 136%, respectively. A mutant strain that produced 3742 μg/mL geldanamycin was generated by protoplast UV mutagenesis, with a 36% higher yield than the initial strain. Multi-omic analysis revealed that the high-yielding geldanamycin in mutant strain 53 could upregulate GdmG and GdmX by 1.59 and 2.38 times in the ansamycin synthesis pathway, and downregulate pks12, pikAI, and pikAII by 0.25, 0.37, and 0.48 times in the fatty acid synthesis pathway, which was crucial for geldanamycin production. Our study provides a novel S. geldanamycininus geldanamycin production strategy and offers valuable insights for mutagenesis and breeding of other microorganisms. Full article