•Oudemansiella canarii laccase was produced in solid-state fermentation.•A single 41 KDa-laccase was produced in this condition.•Laccase was used in the degradation of Congo red.•Several Congo red ...degradation products were identified by mass spectrometry.•Laccase treatment reduced the toxicity of Congo red.
A single laccase with molecular weight of 41 kDa was produced by the white-rot fungus Oudemansiella canarii cultured on solid state fermentation using a mixture of sugarcane bagasse-wheat bran as substrate. The enzyme (5 U) was able to decolourize 80% of 50 mg/L Congo red within 24 h at 30 °C and pH 5.5. The relationship between the decolorization rate and dye concentration obeyed Michaelis–Menten kinetics, with KM and Vmax values of 46.180 ± 6.245 µM and 1.840 ± 0.101 µmol/min, respectively. Fourier transform infrared spectroscopy (FTIR) and mass spectrometry allowed to conclude that the laccase acts not only on the dye chromophore group, but also that it cleaves different covalent bonds, causing an effective fragmentation of the molecule. The action of the laccase caused a significant reduction in toxicity, as indicated by the Microtox test. In conclusion, O. canarii laccase could be useful in future biological strategies aiming at degrading azo dyes.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Non-digestible oligosaccharides are versatile sources of chemical diversity, well known for their prebiotic actions, found naturally in plants or produced by chemical or enzymatic synthesis or by ...hydrolysis of polysaccharides. Compared to polyphenols or even polysaccharides, the antioxidant potential of oligosaccharides is still unexplored. The aim of the present work was to provide an up-to-date, broad and critical contribution on the topic of antioxidant oligosaccharides.
The search was performed by crossing the words oligosaccharides and antioxidant. Whenever possible, attempts at establishing correlations between chemical structure and antioxidant activity were undertaken.
The most representative in vitro and in vivo studies were compiled in two tables. Chitooligosaccharides and xylooligosaccharides and their derivatives were the most studied up to now. The antioxidant activities of oligosaccharides depend on the degree of polymerization and the method used for depolymerization. Other factors influencing the antioxidant strength are solubility, monosaccharide composition, the type of glycosidic linkages of the side chains, molecular weight, reducing sugar content, the presence of phenolic groups such as ferulic acid, and the presence of uronic acid, among others. Modification of the antioxidant capacity of oligosaccharides has been achieved by adding diverse organic groups to their structures, thus increasing also the spectrum of potentially useful molecules.
A great amount of high-quality evidence has been accumulating during the last decade in support of a meaningful antioxidant activity of oligosaccharides and derivatives. Ingestion of antioxidant oligosaccharides can be visualized as beneficial to human and animal health.
Carbonyl compounds are widely explored in medicinal inorganic chemistry and have drawn attention due to their signaling functions in homeostasis. Carbon-monoxide-releasing molecules (CORMs) were ...developed with the purpose of keeping the CO inactive until its release in the intracellular environment, considering its biological relevance. However, for therapeutic applications, the mechanisms of photorelease and which electronic and structural variations influence its rates must be fully understood. In this work, four ligands containing a pyridine, a secondary amine, and a phenolic group with different substituents were used to prepare new Mn(I) carbonyl compounds. Structural and physicochemical characterization of these complexes was carried out and confirmed the proposed structures. X-ray diffractometry structures obtained for the four organometallic compounds revealed that the substituents in the phenolic ring promote only negligible distortions in their geometry. Furthermore, UV-Vis and IR kinetics showed the direct dependence of the electron-withdrawing or donating ability of the substituent group, indicating an influence of the phenol ring on the CO release mechanism. These differences in properties were also supported by theoretical studies at the DFT, TD-DFT, and bonding situation analyses (EDA-NOCV). Two methods were used to determine the CO release constants (k
and k
), where Mn-HbpaBr (1) had the greatest k
by both methods (K
= 2.36 × 10
s
and k
= 2.37 × 10
s
). Carbon monoxide release was also evaluated using the myoglobin assay, indicating the release of 1.248 to 1.827 carbon monoxides upon light irradiation.
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The Front Cover shows the utilization of benzimidazole‐derivatized ligands and their mononuclear iron(III) complexes as a viable alternative for hydrolyzing organophosphate pesticides and also to ...evaluate the second coordination sphere effect of the benzimidazole moieties. Organophosphates are widely employed in safeguarding crops against pests and insects. However, due to their inherent toxicity, catalysts become imperative to facilitate their efficient degradation. The manuscript explores the investigation of the catalytic role played by benzimidazole groups, employing a comprehensive approach that encompasses experimental facets, as well as computational methods like DFT calculations. The findings skillfully strike a balance between the incorporation of aromatic‐nucleophilic groups within the second coordination sphere and the optimization of side chain length in order to augment phosphoesterase activity. More information can be found in the Research Article by F. R. Xavier, R. A. Peralta, and co‐workers.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, OILJ, SBCE, SBMB, UPUK
Biomimetics hold potential for varied applications in biotechnology and medicine but have also attracted particular interest as benchmarks for the functional study of their more complex biological ...counterparts, e.g. metalloenzymes. While many of the synthetic systems adequately mimic some structural and functional aspects of their biological counterparts the catalytic efficiencies displayed are mostly far inferior due to the smaller size and the associated lower complexity. Nonetheless they play an important role in bioinorganic chemistry. Numerous examples of biologically inspired and informed artificial catalysts have been reported, designed to mimic a plethora of chemical transformations, and relevant examples are highlighted in reviews and scientific reports. Herein, we discuss biomimetics of the metallohydrolase purple acid phosphatase (PAP), examples of which have been used to showcase synergistic research advances for both the biological and synthetic systems. In particular, we focus on the seminal contribution of our colleague Prof. Ademir Neves, and his group, pioneers in the design and optimization of suitable ligands that mimic the active site of PAP.
Synopsis: Biomimetics hold potential for varied applications in biotechnology and medicine but have also attracted interest as simple models for their complex biological counterparts. The development of biomimetic complexes of purple acid phosphatase (PAP), in particular the contributions towards these designs by prof. Ademir Neves, is showcased in this minireview. Display omitted
•Prof. Ademir Neves pioneered the synthesis of mimics for purple acid phosphatases.•Biomimetics reproduce characteristic purple color of the enzyme.•Their ability to cleave DNA illustrates their potential as chemotherapeutic.•Second sphere modifications led to improved substrate binding.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Three new copper(II) mononuclear complexes containing different organoselenium groups (1–3) were synthesized and characterized by the following techniques: elemental analysis, IR and UV‐Vis ...spectroscopies, electrochemical and conductimetric analysis, and mass spectrometry. Three new complexes, with substituents made in the para position of the aromatic portion of the N,N‐bis(2‐(phenylselanyl)ethyl)amine ligand: p‐OCH3 (1), p‐CH3 (2), and p‐Cl (3), were synthetized to compare with the already published complex (4), with no substituents. The ligand coordinates to the copper(II) center in a tridentate way with Se, N, Se as donor atoms. The hydrolytic activity in phosphate diester cleavage of the complexes was investigated using 2,4‐BDNPP as substrate. The modifications in the ligand are reflected in the difference between the catalytic and activation parameters, where the kcat values follow the order: 4 > 2 > 3 > 1.
The kinetics of the hydrolysis of the model substrate bis(2,4‐dinitrophenyl)phosphate (BDNPP) were studied in the presence of three mononuclear copper(II) complexes containing different organoselenium groups. Three equivalents of the 2,4‐dinitrophenolate ion (DNP) were liberated for each equivalent of BDNPP, and the kH/kD value obtained for the complexes indicates that there is no proton transfer in the rate‐limiting determinant of the reaction, suggesting that an intramolecular nucleophilic attack occurs at this step.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Inspired by copper-containing enzymes such as galactose oxidase and catechol oxidase, in which distinct coordination environments and nuclearities lead to specific catalytic activities, we summarize ...here the catalytic properties of dinuclear and mononuclear copper species towards benzyl alcohol oxidation using a multivariate statistical approach. The new dinuclear Cu2(μ-L1)(μ-pz)2+ (1) is compared against the mononuclear CuL2Cl (2), where (L1)− and (L2)− are the respective deprotonated forms of 2,6-bis((bis(pyridin-2-ylmethyl)amino)methyl)-4-methylphenol, and 3-((bis(pyridin-2-ylmethyl)amino)methyl)-2-hydroxy-5-methylbenzaldehyde and (pz)− is a pyrazolato bridge. Copper(II) perchlorate (CP) is used as control. The catalytic oxidation of benzyl alcohol is pursued, aiming to assess the role of the ligand environment and nuclearity. The multivariate statistical approach allows for the search of optimal catalytic conditions, considering variables such as catalyst load, hydrogen peroxide load, and time. Species 1, 2 and CP promoted selective production of benzaldehyde at different yields, with only negligible amounts of benzoic acid. Under normalized conditions, 2 showed superior catalytic activity. This species is 3.5-fold more active than the monometallic control CP, and points out to the need for an efficient ligand framework. Species 2 is 6-fold more active than the dinuclear 1, and indicates the favored nuclearity for the conversion of alcohols into aldehydes.
The catalytic properties of the dinuclear and mononuclear bioinspired copper species towards benzyl alcohol oxidation using a multivariate statistical approach were described. The role of the ligand environment and nuclearity were assessed. Under normalized conditions, the mononuclear compound showed superior catalytic activity. Display omitted
•A new bioinspired copper complex was prepared.•Multivariate analysis was applied to the catalytic oxidation of benzyl alcohol.•The catalytic role of complexes' nuclearity and ligand framework was probed.•The mononuclear copper complex is the best catalyst.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Coordination compounds that mimic Purple Acid Phosphatases (PAPs) have drawn attention in the bioinorganic field due to their capacity to cleave phosphodiester bonds. However, their catalytic ...activity upon phosphate triesters is still unexplored. Thus, we report the synthesis and characterization of two binuclear complexes, MnIIMnIII(L1)(OAc)2BF4 (1) and MnIIFeIII(L1)(OAc)2BF4 (2) (H2L1 = 2-N,N-bis-(2- pyridilmethyl)aminomethyl-4-methyl-6-N-(2-hydroxy-3-formyl-5-methylbenzyl)-N-(2-pyridylmethyl)aminomethylphenol), their hydrolytic activity and antioxidant potential. The complexes were fully characterized, including the X-Ray diffraction (XRD) of 1. Density functional theory (DFT) calculations were performed to better understand their electronic and structural properties and phosphate conjugates. The catalytic activity was analyzed for two model substrates, a diester (BDNPP) and a triester phosphate (DEDNPP). The results suggest enhancement of the hydrolysis reaction by 170 to 1500 times, depending on the substrate and complex. It was possible to accompany the catalytic reaction of DEDNPP hydrolysis by phosphorus nuclear magnetic resonance (31P NMR), showing that both 1 and 2 are efficient catalysts. Moreover, we also addressed that 1 and 2 present a relevant antioxidant potential, protecting the yeast Saccharomyces cerevisiae, used as eukaryotic model of study, against the exposure of cells to acute oxidative stress.
MnIIMnIII and FeIIIMnII complexes, their characterization, DFT studies and kinetics assays using a phosphate esters as substrates are reported. The results suggest enhancement of the hydrolysis reaction by 170 to 1500 times, depending on the system. We also addressed the relevant antioxidant potential, protecting cells against oxidative stress. Display omitted
•Dinuclear complexes showed activity in the degradation of phosphate triester and diester.•The degradation reaction of phosphate esters were followed by 31P NMR.•FeIIIMnII and MnIIIMnII complexes protected cells against oxidative stress.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
PDF
