Resumo em Inglês:

Biogenic silver nanoparticles are synthesized through silver(I) reduction, which is promoted by biomolecules available in the biological world and mostly obtained from plant extracts, fungal bioproduction, and some bacteria. The exact mechanisms accounting for such oxidoreduction processes are not fully known. However, some studies have already mentioned oxidoreductases, cofactors (nicotinamide adenine dinucelotide hydrogen (NADH), dihydroflavine-adenine dinucleotid (FADH2)), and phenolic compounds, as the main reductive species engaged in the formation of silver(0) and silver nanoparticles (silver NPs) synthesis. Biosynthesis is a one-pot process that leads to stable silver NP colloids that, regarding their size, shape, and uniformity, can be successfully controlled; and show great stability when one takes into account their surface capping by some biomolecules that as well take part in their synthesis. Although great efforts have been made to feature capping biomolecules and their interactions with silver NP surfaces, knowledge of the quantity (exact number per cm2) and type of biomolecules that cap or surround silver NPs remains limited. The literature provides detailed information on protein capping, but it still shows gaps regarding many aspects of fine biophysical protein featuring. The reason why certain proteins prefer to interact with silver NP surface and form chemical bonds, whereas others rather have intermolecular interaction with the first layer of proteins remains unknown. Assessing capping proteins’ involvement in the bioactivity of biogenic silver NPs is another relevant research field. Certain proteins enhance bioactivity of silver NPs and lower toxicity; however, the way antimicrobial processes benefit from protein capping is yet to be discovered. Finally, biogenic silver NPs can be found both in the environment and in water; moreover, their additional activity and behavior must be known or, at least, hypothesized.

Resumo em Inglês:

Herein, a polysaccharide-based hydrogel from seeds of Salvia spinosa (SSH) was evaluated as a pH-responsive, superporous, hemocompatible, non-toxic, and sustained release material. The SSH-based tablets showed pH-dependent swelling (pH 7.4 > 6.8 > 4.5 > 1.2) as well as swelling and de-swelling behavior at pH 7.4 and 1.2, respectively. Sustained release of febuxostat was achieved by mimicking the gastrointestinal tract conditions for 14 h and following the zero-order kinetics and super case-II transport mechanism. Scanning electron microscopy revealed the porous nature of SSH even after compression. SSH was found to be hemocompatible with antioxidant properties. Acute toxicity studies ensured the safety of SSH at a maximum dose level of 2.0 g kg-1 body weight of the animals. SSH was also found as non-irritant to the eye. The histopathology of vital organs did not show any lesions or inflammation. Conclusively, SSH can be considered a safe ingredient for oral, dermal, and ophthalmic formulations.

Resumo em Inglês:

Phenylphosphonates of zinc (Zn-PPh), calcium (Ca-PPh) and magnesium (Mg-PPh) were synthesized by the hydrothermal method. Samples showed characteristic X-ray diffraction (XRD) patterns of layered compounds with basal spacing in the range of 14-15 Å. According to Fourier transform infrared spectroscopy (FTIR), all compositions showed the presence of characteristic bands attributed to phenyl aromatic rings, phosphonate and lattice metal-oxygen (M-O) vibrations. Different concentrations of phenylphosphonate particles were applied to stabilize water-in-oil Pickering emulsions using vaseline oil in different w/o fractions. The three particle types showed greater affinity for the oil phase (wettability) and the ability to stabilize the emulsions via the Pickering effect. Ca-PPh particles contained a greater emulsified fraction after 20 days of evaluation. This result can be attributed to the particle morphology observed by scanning electron microscopy (SEM). The fibrous morphology of Ca-PPh particles is believed to increase the steric hindrance effect at the surface around the droplets, while the Zn-PPh and Mg-PPh layered particles tended to form clusters.

Resumo em Inglês:

The aim of this study was to produce and to characterize dietary fiber concentrates (DFCs) obtained from the peach palm by-product (PPB). Subcritical water extraction (SWE) and aqueous extractions at low pressure in magnetic (LPMS) and orbital (LPOS) stirring were carried out to DFCs production. DFCs and the untreated PPB were analyzed for composition, functional properties, scanning electron microscopy and infrared spectroscopy. The aqueous extraction treatments increased the total dietary fiber content, due to the removal of sugars (88.7-99.6%) and the partial leaching of proteins and ashes. The DFC obtained by SWE had the highest content of soluble and insoluble dietary fiber. The methods of aqueous extraction changed the structure of fiber components, that becomes more porous and fragmented, improving the functional properties, as water and oil absorption. Cellulose was the most abundant component of the samples and the alteration in its conformation was observed in the infrared spectra. The principal component analysis showed that the changes on the composition and functional properties were associated with the treatments applied. DFCs produced in this work, specially by SWE, are considered interesting alternatives to promote the utilization of peach palm by-product as a fiber-rich component.

Resumo em Inglês:

Research to identify plant bioactive compounds led to the evolution of extraction methods. This study optimized ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE) to extract the flavonoids of Croton grewioides Baill. species contributing to characterize the polar extract profile and understand the antioxidant potential of these plant constituents. The use of experimental design and statistical treatments enabled the determination of the ideal conditions for each technique. The extracts of five accessions of C. grewioides were obtained under the optimized extraction conditions and were analyzed using ultra high-resolution mass spectrometry (FT-Orbitrap MS) operating at negative ionization mode for flavonoids detection. The accurate experimental mass obtained to the main compounds was used to attribute the molecular formula. Chemical structures of the main compounds detected were proposed using structure data bases. Chemometric analysis were performed with two FT-Orbitrap MS spectra samples using the identified metabolites and, the antioxidant activity data, showing that for this species the MAE was most effective in extracting the antioxidant compounds. It was possible to propose the structures for forty compounds in the C. grewioides extracts, demonstrating the excellent performance of the FT-Orbitrap MS in providing information on the chemical profile of polar compounds in plant extracts.

Resumo em Inglês:

In this study, we propose a microextraction method for the determination of CdII in produced waters. The process is based on the conversion of CdII ions into a hydrophobic diethyldithiocarbamate (DDTC) complex with its subsequent dispersive liquid phase microextraction (DLPME) from the aqueous medium with chloroform. The organic phase was then diluted with ethanol and Cd absorbance was measured by graphite furnace atomic absorption spectrometry (GF AAS). The experimental conditions related to the DLPME process were investigated, and the best microextraction conditions were achieved at pH = 6.0 (acetate buffer), 7.5 × 10-6 mol L-1 of DDTC, and when using 200 µL of chloroform as the extracting solvent. No dispersing solvent was needed, which allowed the recovery of approximately 140 µL of chloroform extract. Pyrolysis and atomization temperatures of the GF AAS program were determined through the construction of the respective curves. The estimated limits of detection (LOD) and quantification (LOQ) were 5 and 17 ng L-1, respectively, whereas the enrichment factor for the method was 17. Six samples of seawater and five samples of produced waters with salinities between 30 and 270‰ were analyzed as well as two certified reference materials of saline waters.

Resumo em Inglês:

Metal-based catalysts are indispensable in modern chemistry and one of the biggest challenges for industrial applications is to quantify their performance and stability. The metrics of performance can be obtained in terms of the turnover number and turnover frequency, and the stability might be associated with the leaching of the heterogeneous catalysts. Thus, metal quantification is the starting point to understand and evaluate the features of catalysts. Among the technologies for metal determination, spectrophotometric analysis stands out for being cheap and easy to perform. However, the challenge is the sample preparation to direct quantification from the heterogeneous materials. Herein, it is shown how important is the photochemical pre-treatment for the quantification of the total iron from heterogeneous thin films composed of iron-based materials. The photochemical approach was used to ensure a full dissociation of iron ions before the quantification. This method was revealed to be highly effective and precise, having a wide range of applications for different iron-based catalysts.

Resumo em Inglês:

One of the greatest challenges faced by agriculture is the use of agrochemicals and the balance between food production and environmental problems associated with the excessive use of these substances. To overcome this issue, pheromones have been used to trap pests that harm crops. This work reports the use of a layered monocarboxylate, manganese laurate (MnL2), as adsorbing matrix for undecan-2-one (methyl nonyl ketone (MNK)), one of the components of the pheromone of the insect Lobiopa insularis, which is a pest in the strawberry cultivar. The manganese laurate was synthesized by a coprecipitation method and was later characterized using X-ray diffractometry, vibrational spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. The characterization techniques showed that MNK was adsorbed in the manganese laurate structure in a range of 0.08 to 1.13 mg g-1, and this interaction was investigated in a factorial design experiment, in which the variables temperature, time of contact, and matrix:MNK ratio were investigated. A negative effect of increasing temperatures was observed and attributed to substrate volatilization. The adsorption was favored in increasing molar ratios and times of contact, and ideal conditions for the adsorption could be found, indicating that manganese laurate could be applied in controlled-release tests.

Resumo em Inglês:

Melon is a pollinator-dependent crop that relies mainly on bees to set fruits. However, man-selected varieties vary in their attractiveness to flower visitors, and some flower genders and melon types may be less visited than others, harming pollination. We investigated the nectar composition of male, female and hermaphrodite flowers of 270 individuals of five commercial melons Cucumis melo (Cantaloupe, Charentais, Galia, Piel de Sapo, and Yellow), and its role in flower visit by Apis mellifera foragers. We found that melon nectar is composed mainly of sugars and amino acids such as tyrosine, phenylalanine, tryptophan, and flavonoids kaempferol-3-O-neohesperidoside, luteolin hexoside, and kaempferol rhamnoside. But the amount of these chemical compounds varies among the flower genders. We also developed an accurate regression model to predict the number of bee visits to melon flowers based on the nectar composition. Our results indicate that nectar composition plays little role in bee discrimination among flowers of different melon types but is essential to the honeybee choice between flower gender. The amounts of phenylalanine (49.40%) and tryptophan (12.05%) in the nectar are related to bee preference for hermaphrodite flowers. More visits to hermaphrodite flowers contribute to setting and developing well-formed fruits, increasing productivity.

Resumo em Inglês:

Different Al2O3 carriers were synthesized by co-precipitation and sol-gel method. From them, 4%NiO-20%MoO3/Al2O3 catalysts were prepared by incipient wetness impregnation. The catalysts were characterized by X-ray diffraction analysis (XRD), N2 adsorption-desorption, NH3 temperature programmed desorption (TPD) and H2-temperature programmed reduction (TPR) and subsequently used for selective hydrogenation of naphthalene to high-value tetralin. The results showed that Ni-Mo/so-ge Al2O3 (900) exhibited better catalytic performance than Ni Mo/commercial Al2O3, achieving 99.56% naphthalene conversion and 99.43% tetralin selectivity.

Resumo em Inglês:

Synthesis routes and parameters such as synthesis time, precursor molar ratio, pH, and temperature are critical for generating oxides of various sizes and morphological aspects. However, there is no information on how to prepare silver tungstate (Ag2WO4) crystals of different shapes and sizes under laboratory conditions and without using sulfating agents. In this study, we attempted to fill this gap by preparing α-Ag2WO4 crystals of various sizes and morphologies using the coprecipitation method in a 3 h interval at room temperature and without using sulfating agents. The powder X-ray diffraction analysis confirmed that all crystals had an orthorhombic structure, whereas Fourier-transform infrared spectroscopy revealed the degree of structural disorder in the bonds between the atoms in the materials. Scanning electron microscopy revealed that the α-Ag2WO4 crystals had different sizes (5.37-26.83 µm) and morphologies (tetragonal prism, rod, and cypress leave-like rod), whereas ultraviolet-visible diffuse reflectance spectroscopy analysis indicated the optical band gap energy (2.92-3.05 eV), calculated using the method proposed by Kubelka and Munk. Catalytic tests revealed that the synthesized samples with the smallest crystals (AW1) and a tetragonal prism morphology degraded dye more efficiently (apparent rate constant (k) = 5.86 × 10-3 min-1) than other samples.

Resumo em Inglês:

Designing highly efficient dialkylphosphinic acid extractant for zirconium/hafnium separation relies on systematic structure-property studies. In this paper, dialkylphosphinic acids with different substituents at β-C, γ-C and δ-C for zirconium and hafnium extraction and separation from H2SO4 media were investigated. The results show that substituents at β-C, γ-C and δ-C reduce the extraction ability of dialkylphosphinic acids for both zirconium and hafnium. The substituent effect at β-C is greater than that at γ-C and δ-C. The larger steric hindrance of the substituents (ethyl > methyl > H), the weaker extraction ability of the dialkylphosphinic acids. The zirconium and hafnium separation behavior is related to the extraction ability of dialkylphosphinic acids. Dialkylphosphinic acids with stronger extraction ability show better zirconium/hafnium separation performance at higher acidity of 2.0 mol L-1 H2SO4, while those with weaker extraction ability show better zirconium and hafnium separation performance at lower acidity of 0.25 mol L-1 H2SO4. The highest hafnium/zirconium separation factor (βHf/Zr) in the current study occurs with (2-ethylhexyl)(2,4,4-trimethylpentyl)phosphinic acid (USTB-1), which reaches 19.2.

Resumo em Inglês:

Progenesis QI (PQI) is a multiplatform bioinformatics tool that facilitates the identification workflow for metabolomics experiments. PQI uses fragmentation data provided by MassBank of North America (MoNA) libraries, among others, for metabolite annotation. However, PQI does not officially support MoNA libraries and other libraries based on structure-data files (.sdf). This paper describes the development and application of a software named MoNA to Progenesis QI Library Converter, allowing PQI and MoNA by correcting the fragmentation data of the library for Progenesis readability. We evaluated several public experimental datasets, including human plasma, plant extracts, cultured cells, bacteria, rat serum, and rat hippocampus. The results showed that it is mandatory to proceed with file conversion of each library to allow PQI to access fragmentation information from .msp (main spectra profile) files. This step is highly recommended to improve the identification level of the metabolites.

Resumo em Inglês:

Pectis brevipedunculata is native species and widely available in dry and semi-arid ecosystems showing high biotechnological potential. The objective of this study was to evaluate the circadian and seasonal chemical variation of the essential oil (EO) of P. brevipedunculata, as well as its acaricide effect on Rhipicephalus microplus larvae. Aerial parts were collected and submitted to the hydrodistillation process, and the chemical composition was determined by gas chromatography mass spectrometry (GC-MS). For the assays with R. microplus, the larval immersion test was performed. The main constituents were citral (75% of the EO), followed by α-pinene and limonene. In the seasonality analysis, the highest yields were in the months of April (2.08%) and August (2.05%), while in the study of circadian rhythm, the percentage was 2.0% at 6 p.m. in the rainy season, and 1.2%, dry season at 6 p.m. Concerning acaricidal activity (50% lethal concentration (LC50)), the April (1.17 mg mL-1), March (1.28 mg mL-1), June (1.37 mg mL-1), and October (1.27 mg mL-1) oils obtained were the most active and assays performed with circadian rhythm revealed in the rain season (April) at 6 p.m. and dry season (September) at 12 a.m. LC50 values of 1.75 and 1.75 mg mL-1, respectively. Additionally, this EO is selective to non-target organisms, i.e., ladybeetles and lacewing.

Resumo em Inglês:

Infections in fruits caused by fungi reduce the quantity and quality of food for human consumption, in addition to causing economic losses. In this sense, this study aimed to address the effects of eugenol nanocapsules (NCs) based on chitosan and carboxymethylcellulose in protecting nectarines against Monilinia fructicola, a brown rot agent, a worldwide important disease. NCs were prepared by layer-by-layer (LbL) self-assembly starting from an anionic template and deposition with up to two polymeric layers. The hydrodynamic diameters ranged from 158 nm (nanoemulsion), 360 nm (one polymeric layer) to 398 nm (two polymeric layers). NCs presented, during the in vitro release, the release of eugenol following a first order process. In addition to being in the region of stability (zeta potential ca. |30| mV), the capsules showed good adhesion to the nectarine surface. In relation to brown rot, the eugenol NCs with chitosan proved to be the best formulation compared to nanoemulsion and NCs with two polymeric layers for its control, increasing the probability that the fruits remain without symptoms, even after 7 days. Therefore, this study demonstrated that chitosan NCs containing eugenol could be an alternative to preserve fruit for longer periods in post-harvest.