A mechanistic study on conversion of carbon dioxide into formic acid promoted by 1-ethyl-2, 3-dimethyl-imidazolium nitrite.

CONTEXT: The conversion of carbon dioxide (CO2) to formic acid (FA) through hydrogenation using 1-ethyl-2,3- dimethyl imidazolium nitrite (EDIN) ionic liquid was studied to understand the catalytic roles within EDIN. CO2 hydrogenation in various solvents has been explored, but achieving high efficiency and selectivity remains challenging due to the thermodynamic stability and kinetic inertness of CO2. This study explored two mechanistic pathways through theoretical calculations, revealing that the nitrite (NO2-) group is the most active site. The oxygen site on nitrite favorably activates H2, while the nitrogen site shows a minor activation barrier of 108.90 kJ/mol. The Gibbs energy variation indicates stable FA formation via EDIN, suggesting effective hydrogen (H2) activation and subsequent CO2 conversion. These insights are crucial for developing improved catalytic sites and processes in ionic liquid catalysts for CO2 hydrogenation. METHODS: Quantum chemical calculations were conducted using the ORCA software package at the Restricted Hartree-Fock (RHF) and density functional theory (DFT) levels. The RHF method, known for its predictive abilities in simpler systems, provided a baseline description of electronic structures. In contrast, DFT was employed for its effectiveness in complex interactions involving significant electron correlation. A valence triple-zeta polarization (def2-TZVPP) basis set was employed for both RHF and DFT, ensuring accurate and correlated calculations. The B3LYP functional was utilized for its rapid convergence and cost-efficiency in larger molecules. Dispersion corrected functionals (DFT-D) addressed significant dispersion forces in ionic liquids, incorporating Grimme's D2, D3, and D4 corrections. Geometry optimizations, kinetics, and thermodynamic calculations were performed in the gas phase. The Nudged Elastic Band Transition State (NEB-TS) approach, combining Climbing Image-NEB (CINEB) and Eigenvector-Following (EF) methods, was used to find the minimum energy path (MEP) between reactants and products. Thermochemical analyses based on vibrational frequency calculations evaluated properties such as Enthalpy, Entropy, and Gibbs energy using ideal gas statistical mechanics.

Formic acid stability in different solvents by DFT calculations.

CONTEXT: New technologies have been developed toward the use of green energies. The production of formic acid (FA) from carbon dioxide (CO[Formula: see text]) hydrogenation with H[Formula: see text] is a sustainable process for H[Formula: see text] storage. However, the FA adduct stabilization is thermodynamically dependent on the type of solvent and thermodynamic conditions. The results suggest a wide range of dielectric permittivity values between the dimethyl sulfoxide (DMSO) and water solvents to stabilize the FA in the absence of base. The thermodynamics analysis and the infrared and charge density difference results show that the formation of the FA complex with H[Formula: see text]O is temperature dependent and has a major influence on aqueous solvents compared to the FA adduct with amine, in good agreement with the experiment. In these conditions, the stability thermodynamic of the FA molecule may be favorable at non-organic solvents and dielectric permittivity values closer to water. Therefore, a mixture of aqueous solvents with possible ionic composition could be used to increase the thermodynamic stability of H[Formula: see text] storage in CO[Formula: see text] conversion processes. METHODS: Using the Quantum ESPRESSO package, density functional theory (DFT) calculations were performed with periodic boundary conditions, and the electronic wave functions were expanded in plane waves. For the exchange-correlation functional, we use the vdW-DF functional with the inclusion of van der Waals (vdW) forces. Electron-ion interactions are treated by the projector augmented wave (PAW) method with pseudopotentials available in the PSlibrary repository. The wave functions and the electronic densities were expanded employing accurate cut-off energies of 6.80[Formula: see text]10[Formula: see text] and 5.44[Formula: see text]10[Formula: see text] eV, respectively. The electronic density was computed from the wave functions calculated at the [Formula: see text]-point in the first Brillouin-zone. Each structural optimization was minimized according to the Broyden-Fletcher-Goldfarb-Shanno (BFGS) algorithm, with force and energy convergence criteria of 25 meV[Formula: see text]Å[Formula: see text] and 1.36 meV, respectively. The electrostatic solvation effects were performed by the [Formula: see text] package with the Self-Consistent Continuum Solvation (SCCS) approach.

Solar-driven CO2 reduction using modified earth-abundant ilmenite catalysts.

Photocatalytic CO2 reduction is an alternative technology to the depletion of highly pollutant fossil fuels through the generation of renewable solar-based fuels. This technology requires that the photocatalysts be obtained directly from nature to scale up the process. Taking that into consideration, this work proposed the fabrication of sodium iron titanate (NaFeTiO4) photocatalysts from earth-abundant ilmenite mineral. The photocatalysts exhibited full spectrum light response, good electron transfer due to its unique tunnel structure that favored the formation of rod-like morphology. These properties promoted the solar-driven CO2 reduction to generate formic acid (HCOOH) with high selectivity (157 µmol g-1 h-1). It was found that higher synthesis temperatures promoted the formation of Fe3+ species, which decreased the efficiency for CO2 reduction. Also, the possibility of reduced the CO2 molecules in the air was studied with the NaFeTiO4 samples, which resulted in an efficiency of up to 93 µmol g-1 h-1 of HCOOH under visible light. The stability of the solar-driven CO2 reduction with the NaFeTiO4 photocatalysts was confirmed after seven days of continuous evaluation.

Evaluation of the Use of Diluted Formic Acid in Sample Preparation for Elemental Determination in Crustacean Samples by MIP OES.

A simple procedure for determination of Al, Cr, K, Mg, Mn, and Zn using diluted organic acid in the preparation of shrimp (Macrobrachium amazonicum) and crab samples (Ucides cordatus) was proposed in this study. Determinations were performed using microwave-induced plasma optical emission spectrometer (MIP OES). The contents of elements were evaluated after solubilization of samples in 50% formic acid (v v-1) and subsequent heating in bath with stirring and heating at 90 °C. The accuracy of the proposed procedure was assessed using certified fish protein reference material (DORM-4) and the recovery percentages ranged from 91 to 117%. Microwave-assisted acid decomposition was used for a comparison of results with the procedure proposed using diluted formic acid, and the values obtained for all analytes were statistically equal at 95% confidence level. Cr levels were below the limit of detection. Potassium (7917-19,644 mg kg-1), Mg (1319-5376 mg kg-1), and Zn (43-307 mg kg-1) were the most abundant elements in the crustacean species studied can be considered good sources of these constituents for human diet. The proposed procedure using diluted formic acid was considered simple and suitable to determine Al, Cr, K, Mg, Mn, and Zn concentrations in crustaceans using MIP OES.

Interference effects of oxyanions commonly found in natural waters on the catalytic reduction of nitrate in water.

In this work, the influence of oxyanions on the catalytic reduction of nitrates using formic acid as the reducing agent was studied as well as the influence of bicarbonate, sulfate, and phosphate co-anions on the catalytic nitrate reduction with Pd:In/Al2O3 (1:0.25 wt.%). A negative effect on nitrate conversion was observed in the following order: phosphate > sulfate > bicarbonate, showing a strong influence of electrostatic adsorption on the catalytic reduction of nitrate. However, no direct trend was observed relating the levels of interferents to the impact on the selectivity of the bimetallic catalyst using formic acid as a reducing agent. For both bicarbonate and phosphate, at lower levels, higher selectivity to nitrogen was obtained than for the reaction in the absence of interferents. On the other hand, increasing sulfate concentration led to a decrease in nitrate conversion. The mixtures of co-anions also showed a decrease in the catalytic activity. At 120 min, a N2 selectivity higher than 95% was obtained, except for the C50-S20 (bicarbonate 50 ppm-sulfate 20 ppm) mixture which showed the lowest selectivity to N2 value (87.3%). The loss of catalyst activity was found to be reversible and not permanent.

Electronically excited states of formic acid investigated by theoretical and experimental methods.

Absolute cross-section values are reported from high-resolution vacuum ultraviolet (VUV) photoabsorption measurements of gas-phase formic acid (HCOOH) in the photon energy range 4.7-10.8 eV (265-115 nm), together with quantum chemical calculations to provide vertical energies and oscillator strengths. The combination of experimental and theoretical methods has allowed a comprehensive assignment of the electronic transitions. The VUV spectrum reveals various vibronic features not previously reported in the literature, notably associated with (3pa'←10a'), (3p'a'←10a'), (3sa'←2a″) and (3pa'←2a″) Rydberg transitions. The assignment of vibrational features in the absorption bands reveal that the C=O stretching, v3'a', the H'-O-C' deformation, v5'a', the C-O stretching, v6'a', and the O=C-O' deformation, v7'a' modes are mainly active. The measured absolute photoabsorption cross sections have also been used to estimate the photolysis lifetime of HCOOH in the upper stratosphere (30-50 km), showing that solar photolysis is an important sink at altitudes above 30 km but not in the troposphere. Potential energy curves for the lowest-lying electronic excited states, as a function of the C=O coordinate, are obtained employing time dependent density functional theory (TD-DFT). These calculations have shown the relevance of internal conversion from Rydberg to valence character governing the nuclear dynamics, yielding clear evidence of the rather complex multidimensional nature of the potential energy surfaces involved.

Characterization and in vitro evaluations of Baru pulp from almond production waste ensiled with different additives.

The silage process is an efficient way of storing nutrients for animal nutrition. Our hypothesis was that the Baru pulp can be preserved in the form of silage, regardless of the use of additives to aid the process. Silages of Baru pulp containing different additives were evaluated through in vitro analysis, fermentation parameters, and composition and thermal analysis including differential scanning calorimetry and thermogravimetry. The treatments consisted of (1) silage with Baru pulp (BP) in natura without additive; (2) BP in natura with acetic acid; (3) BP in natura with formic acids; and (4) BP in natura added with microbial inoculums in a randomized experimental design with three replications per treatment and analyzed in duplicate. The ensiled material was kept in anaerobic conditions for a period of 30 days. BP before and after the silage process presented averages of 67.31 and 66.24% for in vitro digestibility of DM (IVDMD). Microbial inoculant additive was the most effective in reducing pH, followed by acetic acid and formic acid. There were effects of additives on silages for all degradation parameters in ruminal liquid in vitro. It was observed that BP before ensiling had the highest A fraction (7.9 mL gas/100 mg DM), without differing from the silage treated with formic acid (7.1 mL gas/100 mg DM). Similar effects were observed on mass loss (TG) and heat flux (DSC) between the silages. Our findings suggest that Baru pulp with formic acid is more efficient in the conservation and preservation of fermentable carbohydrates as well as in silage production.

The influence of the environment in chemical reactivity: the HCOOH formation from the H2O + CO reaction.

The reaction between carbon monoxide and water was studied occurring in an aerosol medium rich in methanol. This environment is plausible for the primitive and prebiotic Earth atmosphere. The chemical environment is expressed in terms of dielectric constant (ε) and the chemical system was modeled employing the polarizable continuum model (PCM). The main results were acquired from calculations employing the M06-2X density functional for the electronic structure calculations and the canonical variational theory with small curvature tunneling for the chemical kinetic calculations. The rise of ε affects both the thermochemistry and the kinetics of the reaction, increasing the barrier height and decreasing the rate constant for the reaction occurring at room temperature. For example, the rate constant at 300 K is 5-10× 10- 53 cm3 ⋅molecule- 1 ⋅s- 1 for low dielectric constant (ε < 3) and around 2-4× 10- 53 cm3 ⋅molecule- 1 ⋅s- 1 for ε between 7 and 40. Our results indicate that the ε variation allows a fine tuning to the rate of the reaction.

Gastrointestinal metabolism of monomeric and polymeric polyphenols from mango (Mangifera indica L.) bagasse under simulated conditions.

Mango bagasse (MB) is an agro-industrial by-product rich in bioactive polyphenols with potential application as a functional ingredient. This study aimed to delineate the metabolic fate of monomeric/polymeric MB polyphenols subjected to simulated gastrointestinal digestion. The main identified compounds by LC/MS-TOF-ESI were phenolic acids [gallic acid (GA) and derivates, and chlorogenic acid], gallotannins and derivatives [di-GA (DA) and 3GG-to-8GG], benzophenones [galloylated maclurins (MGH, MDH)], flavonoids [Quercetin (Quer) and (QuerH)] and xanthones [mangiferin isomers]. The bioaccessibility depended on the polyphenols' structure, being Quer, 5G to 8G the main drivers. The results suggested that the gastrointestinal fate of MB polyphenols is mainly governed by benzophenones and gallotannins degalloylation and spontaneous xanthone isomerization in vitro to sustain GA bioaccessibility.

Production of Chitosan/Hyaluronan Complex Nanofibers. Characterization and Physical Properties as a Function of the Composition.

In this work, optimized conditions for preparation of chitosan and hyaluronan polyelectrolyte complex are proposed. The objective was to produce new biomaterials being biocompatible and bioresorbable in the body as well as approaching the extracellular matrix (ECM) structure. These materials will be tested for chondrocyte development in tissue engineering and wound healing applications. Nanofibers made of the polyelectrolyte complex (PEC) were successfully manufactured by electrospinning, and casted films were used as a model for properties comparison. To our knowledge, it is the first time that stable chitosan/hyaluronan fibers are produced, which were observed to be long-lasting in buffer at pH~7.4. The role of thermal treatment at 120 °C for 4 h is examined to control the degree of swelling by crosslinking of the two polysaccharides by H-bonds and amide bonds formation. The properties of the materials are tested for different PEC compositions at different pH values, based on swelling and solubility degrees, diameters of nanofibers and mechanical performances. The influence of the solvent (acidic potential and composition) utilized to process biomaterials is also examined. Acid formic/water 50/50 v/v is observed to be the more appropriated solvent for the carried-out procedures.

Catalytic Semi-Water-Gas Shift Reaction: A Simple Green Path to Formic Acid Fuel.

Formic acid (FA) is a promising CO and hydrogen energy carrier, and currently its generation is mainly centered on the hydrogenation of CO2 . However, it can also be obtained by the hydrothermal conversion of CO with H2 O at very high pressures (>100 bar) and temperatures (>200 °C), which requires days to complete. Herein, it is demonstrated that by using a nano-Ru/Fe alloy embedded in an ionic liquid (IL)-hybrid silica in the presence of the appropriate IL in water, CO can be catalytically converted into free FA (0.73 m) under very mild reactions conditions (10 bar at 80 °C) with a turnover number of up to 1269. The catalyst was prepared by simple reduction/decomposition of Ru and Fe complexes in the IL, and it was then embedded into an IL-hybrid silica {1-n-butyl-3-(3-trimethoxysilylpropyl)-imidazolium cations associated with hydrophilic (acetate, SILP-OAc) and hydrophobic [bis((trifluoromethyl)sulfonyl)amide, SILP-NTf2 ] anions}. The location of the alloy nanoparticles on the support is strongly related to the nature of the anion, that is, in the case of hydrophilic SILP-OAc, RuFe nanoparticles are more exposed to the support surface than in the case of the hydrophobic SILP-NTf2 , as determined by Rutherford backscattering spectrometry. This catalytic membrane in the presence of H2 O/CO and an appropriate IL, namely, 1,2-dimethyl-3-n-butylimidazolium 2-methyl imidazolate (BMMIm⋅MeIm), is stable and recyclable for at least five runs, yielding a total of 4.34 m of free FA.

Atividade antimicrobiana de ácidos orgânicos com e sem extrato vegetal no controle in vitro de Escherichia coli e Salmonella Typhi / Antimicrobial activity of organic acids with or without vegetable extracts for in vitro control of Escherichia coli and Salmonella Typhi

Os ácidos orgânicos e alguns extratos herbais podem ser uma alternativa no controle microbiano. Este estudo avaliou a atividade antimicrobiana de uma combinação de ácidos orgânicos com ou sem adição de extratos de Catanea sativa e Acacia decurrens no controle in vitro de Escherichia coli e Salmonella Typhi. Para o estudo, foram utilizadas cepas padrões: Escherichia coli O157:H7 (ATCC 43888) e Salmonella enterica subsp. enterica serovar Typhi (CCCD S003). A combinação de ácidos orgânicos foi composta por 25% de ácido benzoico, 30% de ácido fórmico, 25% de ácido fumárico e 20% de dióxido de sílica. Já a combinação de ácidos orgânicos associada ao extrato vegetal foi composta por 21,2% de ácido benzoico, 25,5% de ácido fórmico, 21,2% de ácido fumárico, 17,1% de dióxido de sílica e 15% de extrato vegetal, sendo este último composto por 50% de castanha portuguesa (Castanea sativa) e 50% de acácia negra (Acacia decurrens). Ambos foram testados em concentrações de 0,00%; 0,40%; 1,70%; 3,20%; 6,25%; 12,50%; 25,00%; 50,00% e 100,00%. O estudo das Concentrações Inibitórias Mínimas (CIM) e Concentrações Bactericidas Mínimas (CBM) das misturas demostraram para Escherichia coli um CIM de 50% e CBM de 100%, tanto para o produto composto pela mistura de ácidos orgânicos quanto para a mistura de ácidos orgânicos com adição do extrato de plantas. Em relação à cepa de Salmonella estudada verificou-se CIM e CBM de 100%, alcançados com 100% de concentração dos compostos estudados. As concentrações de E. coli e Salmonella Typhi expostas a ambos os tratamentos de ácidos orgânicos com ou sem os extratos de plantas diferiram quanto ao tempo de exposição ao produto (p<0,05). A atividade antibacteriana dos produtos depende da concentração empregada dos ácidos orgânicos com ou sem os extratos de plantas e do tempo de exposição aos mesmos.

Organic acids and some herbal extracts can be an alternative in microbial control. This study evaluated the antimicrobial activity of a combination of organic acids with or without the addition of extracts of Catanea sativa and Acacia decurrens in the in vitro control of Escherichia coli and Salmonella Typhi. For the study, standard strains were used: Escherichia coli O157: H7 (ATCC 43888) and Salmonella enterica subsp. enterica serovar Typhi (CCCD S003). The combination of organic acids was composed of 25% benzoic acid, 30% formic acid, 25% fumaric acid and 20% silica dioxide. The combination of organic acids associated with the plant extract was composed of 21.2% benzoic acid, 25.5% formic acid, 21.2% fumaric acid, 17.1% silica dioxide and 15% extract vegetable, the latter consisting of 50% Portuguese chestnut (Castanea sativa) and 50% black wattle (Acacia decurrens). Both were tested at concentrations of 0.00%; 0.40%; 1.70%; 3.20%; 6.25%; 12.50%; 25.00%; 50.00% and 100.00%. The study of Minimum Inhibitory Concentrations (MIC) and Minimum Bactericidal Concentrations (MBC) of the mixtures showed for Escherichia coli a MIC of 50% and MBC of 100%, both for the product composed of the mixture of organic acids and for the mixture of organic acids with the addition of plant extract. Regarding the Salmonella strain studied, MIC and MBC of 100% were found, achieved with 100% concentration of the studied compounds. The concentrations of E. coli and Salmonella Typhi exposed to both treatments of organic acids with or without plant extracts differed regarding the time of exposure to the product (p<0.05). The antibacterial activity of the products depends on the concentration of organic acids used with or without plant extracts and the time of exposure to them.

Atividade antimicrobiana de ácidos orgânicos com e sem extrato vegetal no controle in vitro de Escherichia coli e Salmonella Typhi / Antimicrobial activity of organic acids with or without vegetable extracts for in vitro control of Escherichia coli and Salmonella Typhi

Os ácidos orgânicos e alguns extratos herbais podem ser uma alternativa no controle microbiano. Este estudo avaliou a atividade antimicrobiana de uma combinação de ácidos orgânicos com ou sem adição de extratos de Catanea sativa e Acacia decurrens no controle in vitro de Escherichia coli e Salmonella Typhi. Para o estudo, foram utilizadas cepas padrões: Escherichia coli O157:H7 (ATCC 43888) e Salmonella enterica subsp. enterica serovar Typhi (CCCD S003). A combinação de ácidos orgânicos foi composta por 25% de ácido benzoico, 30% de ácido fórmico, 25% de ácido fumárico e 20% de dióxido de sílica. Já a combinação de ácidos orgânicos associada ao extrato vegetal foi composta por 21,2% de ácido benzoico, 25,5% de ácido fórmico, 21,2% de ácido fumárico, 17,1% de dióxido de sílica e 15% de extrato vegetal, sendo este último composto por 50% de castanha portuguesa (Castanea sativa) e 50% de acácia negra (Acacia decurrens). Ambos foram testados em concentrações de 0,00%; 0,40%; 1,70%; 3,20%; 6,25%; 12,50%; 25,00%; 50,00% e 100,00%. O estudo das Concentrações Inibitórias Mínimas (CIM) e Concentrações Bactericidas Mínimas (CBM) das misturas demostraram para Escherichia coli um CIM de 50% e CBM de 100%, tanto para o produto composto pela mistura de ácidos orgânicos quanto para a mistura de ácidos orgânicos com adição do extrato de plantas. Em relação à cepa de Salmonella estudada verificou-se CIM e CBM de 100%, alcançados com 100% de concentração dos compostos estudados. As concentrações de E. coli e Salmonella Typhi expostas a ambos os tratamentos de ácidos orgânicos com ou sem os extratos de plantas diferiram quanto ao tempo de exposição ao produto (p<0,05). A atividade antibacteriana dos produtos depende da concentração empregada dos ácidos orgânicos com ou sem os extratos de plantas e do tempo de exposição aos mesmos.(AU)

Organic acids and some herbal extracts can be an alternative in microbial control. This study evaluated the antimicrobial activity of a combination of organic acids with or without the addition of extracts of Catanea sativa and Acacia decurrens in the in vitro control of Escherichia coli and Salmonella Typhi. For the study, standard strains were used: Escherichia coli O157: H7 (ATCC 43888) and Salmonella enterica subsp. enterica serovar Typhi (CCCD S003). The combination of organic acids was composed of 25% benzoic acid, 30% formic acid, 25% fumaric acid and 20% silica dioxide. The combination of organic acids associated with the plant extract was composed of 21.2% benzoic acid, 25.5% formic acid, 21.2% fumaric acid, 17.1% silica dioxide and 15% extract vegetable, the latter consisting of 50% Portuguese chestnut (Castanea sativa) and 50% black wattle (Acacia decurrens). Both were tested at concentrations of 0.00%; 0.40%; 1.70%; 3.20%; 6.25%; 12.50%; 25.00%; 50.00% and 100.00%. The study of Minimum Inhibitory Concentrations (MIC) and Minimum Bactericidal Concentrations (MBC) of the mixtures showed for Escherichia coli a MIC of 50% and MBC of 100%, both for the product composed of the mixture of organic acids and for the mixture of organic acids with the addition of plant extract. Regarding the Salmonella strain studied, MIC and MBC of 100% were found, achieved with 100% concentration of the studied compounds. The concentrations of E. coli and Salmonella Typhi exposed to both treatments of organic acids with or without plant extracts differed regarding the time of exposure to the product (p<0.05). The antibacterial activity of the products depends on the concentration of organic acids used with or without plant extracts and the time of exposure to them.(AU)

Coupled Dynamics of Anode and Cathode in Proton-Exchange Membrane Fuel Cells.

An external reference electrode was used to monitor individually the evolution of the anodic and cathodic potentials during the stationary as well as oscillatory operation of a Direct Formic Acid Fuel Cell (DFAFC) and a Direct Methanol Fuel Cell (DMFC). Besides evidencing the large activation loss in both cells, we were able to observe how the oscillatory operation of such devices affects their cathodes. In fact, cathodic oscillations synchronized with the cell voltage dynamics were observed, hitherto never reported on fuel cells. We have addressed these phenomena taking into account two main coupling processes: through the proton concentration and a global coupling stemming from the control mode (potentiostatic or galvanostatic).

Antifungal and anti-inflammatory potential of eschweilenol C-rich fraction derived from Terminalia fagifolia Mart.

ETHNOPHARMACOLOGICAL RELEVANCE: Folk knowledge transmitted between generations allows traditional populations to maintain the use of medicinal plants for the treatment of several diseases. In this context, the species Terminalia fagifolia Mart., native to Brazil, is used for the treatment of chronic and infectious diseases. Plants rich in secondary metabolites, such as this species and their derivatives, may represent therapeutic alternatives for the treatment of diseases that reduce the quality of life of people. AIM OF THE STUDY: The aim of this study was to evaluate the antifungal and anti-inflammatory potential of aqueous fraction from ethanolic extract of T. fagifolia, with in silico study of the major compound of the fraction. MATERIAL AND METHODS: The phytochemical study of the aqueous fraction was performed by HPLC, LC/MS and NMR. The antifungal activity was evaluated against yeasts, by determination of the minimum inhibitory concentration and minimum fungicidal concentration. The effect on Candida albicans was analyzed by AFM. The antibiofilm potential against biofilms of C. albicans was also tested. The anti-inflammatory potential of the aqueous fraction was evaluated in vivo by the carrageenan-induced paw edema and peritonitis. A microglial model of LPS-induced neuroinflammation was also studied. Further insights on the activation mechanism were studied using quantum chemistry computer simulations. Toxicity was evaluated in the Galleria mellonella and human erythrocytes models. RESULTS: Eschweilenol C was identified as the major constituent of the aqueous fraction of the ethanolic extract of T. fagifolia. The aqueous fraction was active against all Candida strains used (sensitive and resistant to Fluconazole) with MICs ranging from 1000 to 0.4 µg/mL. By AFM it was possible to observe morphological alterations in treated Candida cells. The fraction significantly (p < 0.05) inhibited paw edema and decreased levels of malondialdehyde induced by carrageenan. In a microglial cell model, aqueous fraction demonstrated the ability to inhibit NF-κB after induction with lipopolysaccharide. The theoretical studies showed structural similarity between eschweilenol C and indomethacin and an excellent antioxidant potential. The aqueous fraction did not present toxicity in the studied models. CONCLUSION: The results indicate that the aqueous fraction of T. fagifolia has potential for biomedical applications with low toxicity. This finding can be attributed to the predominance of eschweilenol C in the aqueous fraction.

Increase of global DNA methylation patterns in beauty salon workers exposed to low levels of formaldehyde.

Formaldehyde (FA) is a carcinogenic aldehyde illegally added to creams as a hair straightening agent for the Brazilian blowout (BB). This study aimed to investigate the possible effects of occupational exposure to FA on global DNA methylation in salon workers with different exposure levels. FA exposure was monitored using environmental and biological measurements. The study included 49 salon workers divided by FA levels in the workplace into group A (FA < 0.01 ppm; n = 8), group B (0.03 ppm < FA < 0.06 ppm; n = 15), and group C (0.08 ppm < FA < 0.24 ppm; n = 26). The global DNA methylation levels were 3.12%, 4.55%, and 4.29% for groups A, B, and C, respectively, with statistically higher values for groups B and C compared to group A (p = 0.002). A correlation was found between FA in passive samplers and global DNA methylation (rs = 0.307, p = 0.032). Additionally, when only taking into account the hairdressers that performed the BB on clients instead of the whole group, a stronger correlation was observed between FA in personal passive samplers and global DNA methylation (rs = 0.764, p = 0.006). For the first time, an increase in DNA methylation was observed in subjects occupationally exposed to FA. In conclusion, our results indicated that even low levels of FA exposure could cause a disturbance in DNA methylation, leading to epigenetic changes, which is associated with cancer development. These data suggest a possible contribution of FA to cancer development through occupational exposure.

Acyl homoserine lactone changes the abundance of proteins and the levels of organic acids associated with stationary phase in Salmonella Enteritidis.

Quorum sensing (QS) is cell-cell communication mechanism mediated by signaling molecules known as autoinducers (AIs) that lead to differential gene expression. Salmonella is unable to synthesize the AI-1 acyl homoserine lactone (AHL), but is able to recognize AHLs produced by other microorganisms through SdiA protein. Our study aimed to evaluate the influence of AI-1 on the abundance of proteins and the levels of organic acids of Salmonella Enteritidis. The presence of N-dodecyl-homoserine lactone (C12-HSL) did not interfere on the growth or the total amount of extracted proteins of Salmonella. However, the abundance of the proteins PheT, HtpG, PtsI, Adi, TalB, PmgI (or GpmI), Eno, and PykF enhanced while the abundance of the proteins RplB, RplE, RpsB, Tsf, OmpA, OmpC, OmpD, and GapA decreased when Salmonella Enteritidis was anaerobically cultivated in the presence of C12-HSL. Additionally, the bacterium produced less succinic, lactic, and acetic acids in the presence of C12-HSL. However, the concentration of extracellular formic acid reached 20.46 mM after 24 h and was not detected when the growth was in the absence of AI-1. Considering the cultivation period for protein extraction, their abundance, process and function, as well as the levels of organic acids, we observed in cells cultivated in presence of C12-HSL a correlation with what is described in the literature as entry into the stationary phase of growth, mainly related to nitrogen and amino acid starvation and acid stress. Further studies are needed in order to determine the specific role of the differentially abundant proteins and extracellular organic acids secreted by Salmonella in the presence of quorum sensing signaling molecules.

Evaluation of genotoxicity in workers exposed to low levels of formaldehyde in a furniture manufacturing facility.

Formaldehyde (FA) is a chemical widely used in the furniture industry and has been classified as a potential human carcinogen. The purpose of this study was to evaluate the occupational exposure of workers to FA at a furniture manufacturing facility and the relationship between environmental concentrations of FA, formic acid concentration in urine, and DNA damage. The sample consisted of 46 workers exposed to FA and a control group of 45 individuals with no history of occupational exposure. Environmental concentrations of FA were determined by high-performance liquid chromatography. Urinary formic acid concentrations were determined by gas chromatography with flame ionization detector. DNA damage was evaluated by the micronucleus (MN) test performed in exfoliated buccal cells and comet assay with venous blood. The 8-h time-weighted average of FA environmental concentration ranged from 0.03 ppm to 0.09 ppm at the plant, and the control group was exposed to a mean concentration of 0.012 ppm. Workers exposed to higher environmental FA concentrations had urinary formic acid concentrations significantly different from those of controls (31.85 mg L(-1) vs. 19.35 mg L(-), p ≤ 0.01 Mann-Whitney test). Significant differences were found between control and exposed groups for the following parameters: damage frequency and damage index in the comet assay, frequency of binucleated cells in the MN test, and formic acid concentration in urine. The frequency of micronuclei, nuclear buds, and karyorrhexis did not differ between groups. There was a positive correlation between environmental concentrations of FA and damage frequency (Spearman's rank correlation coefficient [r s] = 0.24), damage index (r s = 0.21), binucleated cells (r s = 0.34), and urinary formic acid concentration (r s = 0.63). The results indicate that, although workers in the furniture manufacturing facility were exposed to low environmental levels of FA, this agent contributes to the observed increase in cytogenetic damage. In addition, urinary formic acid concentrations correlated strongly with occupational exposure to FA.

Environmental and biological monitoring of occupational formaldehyde exposure resulting from the use of products for hair straightening.

The evaluation of formaldehyde (FD) exposure in beauty salons, due to the use of hair straightening products, and its relation with genotoxicity biomarkers was performed in this study. Regardless of official recommendations, the inappropriate use of homemade hair creams has became a popular practice in Brazil, and high formaldehyde content in the "progressive straightening" creams can contain mutagens that could increase the incidence of neoplasia in those people who use them. Damage to DNA was assessed by conducting a micronuclei test (MNT) on buccal cells and the comet assay on heparinized venous blood samples. A total of 50 volunteers were recruited at six different beauty salons (labeled A to F). At two salons that used products that did not contain FD (salons D and E), environmental FD concentrations were 0.04 and 0.02 ppm. In contrast, the products used at salons A, B, C, and F contained 5.7, 2.61, 5.9, and 5.79% of FD, and these salons had environmental FD concentrations of 0.07, 0.14, 0.16, and 0.14 ppm, respectively. Comparison of the beauty salon workers from each of the six beauty salons revealed significant differences in urinary formic acid (FA) concentration before exposure (p = 0.016), urinary FA after exposure (p = 0.004), variation in FA concentration before and after exposure (p = 0.018), environmental FD concentration (p < 0.001), cytogenetic damage detected by the comet assay according to both damage index (p < 0.001) and frequency of damage (p < 0.001), and for karyorrhexis only according to the MNT (p = 0.001).

Use of acids as additives in sugarcane silage / Uso de ácidos como aditivos en el ensilaje de caña de azúcar / Uso de ácidos como aditivos na silagem de cana de açúcar

Background: sugarcane silage often becomes a problem for the producers due to its high population of yeast and its high content of soluble carbohydrates. Objective: to evaluate the effect of formic and phosphoric acid on the chemical composition, fermentation characteristics, and digestibility of sugarcane silages. Methods: sugarcane was ensiled in experimental mini-silos. Five treatments were evaluated in the ensilage process (sugarcane added with 0.5 or 1% formic acid and 0.5 or 1% phosphoric acid, and a control treatment without additives). A completely randomized design was used. Results: the dry matter content of silages containing phosphoric acid was lower. Lower values of NDF, ADF, and hemicellulose were observed in the control and formic acid treatments. Conclusions: formic and phosphoric acids promote beneficial changes in the chemical composition of sugar cane silage.

Antecedentes: debido a la elevada presencia de levaduras y a la alta proporción de carbohidratos, el ensilaje de caña de azúcar presenta problemas de manejo para los productores. Objetivo: evaluar el efecto de la adición de ácidos fórmico y fosfórico sobre la composición química, características fermentativas y digestibilidad del ensilaje de caña de azúcar. Métodos: la caña de azúcar se ensiló en mini silos. Fueron evaluados cinco tratamientos en el proceso de ensilaje de caña de azúcar (caña de azúcar adicionada con 0,5 o 1% de ácido fórmico, o con 0,5 o 1% de ácido fosfórico, y un tratamiento control sin aditivos). Se utilizó un diseño completamente aleatorizado. Resultados: la proporción de materia seca de los ensilajes con ácido fosfórico fue menor. Se observaron menores proporciones de NDF, ADF y hemicelulosa en los ensilajes sin adición de ácido y en los adicionados con ácido fórmico. Conclusiones: el uso de ácidos fórmico y fosfórico en el ensilaje de caña de azúcar promueve modificaciones benéficas en su composición química.

Antecedentes: devido à elevada presença de leveduras como também excessiva proporção de carboidratos, a silagem de cana apresenta problemas de manejo para os produtores. Objetivo: avaliar o efeito da adição do ácido fórmico e ácido fosfórico sobre composição química, características fermentativas e digestibilidade de silagens de cana-de-açúcar. Métodos: a cana-de-açúcar foi ensilada em mini silos. Foram avaliados cinco tratamentos no processo de ensilagem de cana de açúcar (cana-de-açúcar adicionada com 0,5 ou 1% de ácido fórmico ou com 0,5 ou 1% de ácido fosfórico, e um tratamento controle sem aditivos), utilizando um delineamento inteiramente casualizado. Resultados: os teores de matéria seca das silagens contendo ácido fosfórico foram menores. Menores valores de NDF, ADF e hemicelulose foram observados para as silagens de cana-de-açúcar in natura e adicionadas de ácido fórmico. Conclusões: o uso de ácido fórmico e fosfórico promove mudanças benéficas na composição química da silagem de cana de açúcar.