Phenol and catechol induce prehemolytic and hemolytic changes in human erythrocytes

Chitosan/starch based unoxidized tannic acid modified microparticles for rapid hemostasis with broad spectrum antibacterial activity

The development of a rapid hemostat through a facile method with co-existing antibacterial activity and minimum erythrocyte lysis property stands as a major requirement in the field of hemostasis. Herein, a series of novel microparticle hemostats were synthesized using chitosan, different hydrothermally-treated starches, and cross-linked with tannic acid (TA) simultaneously in an unoxidized environment via ionotropic gelation method. Hemostats' comparative functional properties, such as adjustable antibacterial and erythrocyte compatibility upon various starch additions were evaluated. The in vivo hemostatic study revealed that the developed hemostats for mouse liver laceration and rat tail amputation had clotting times (13 s and 38 s, respectively) and blood loss (51 mg and 62 mg, respectively) similar to those of Celox™. The erythrocyte adhesion test suggested that erythrocyte distortion can be lowered by modifying the antibacterial hemostats with different starches. The broad-spectrum antibacterial efficacy of the hemostats remained intact against S. aureus (>90 %), E. coli (>80 %), and P. mirabilis bacteria upon starch modification. They also demonstrated high hemocompatibility (<3 % hemolysis ratio), moderate cell viability (>81 %), in vivo biodegradation, and angiogenesis indicating adequate biocompatibility and wound healing. The developed hemostats hold significant promise to be employed as rapid hemostatic agents for preventing major bleeding and bacterial infection in emergencies.

A pipeline for rapidly evaluating activity and inferring mechanisms of action of prospective antifungal compounds

BACKGROUND

Fungal phytopathogens are a significant threat to crops and food security, and there is a constant need to develop safe and effective compounds that antagonize them. In-planta assays are complex and tedious and are thus not suitable for initial high-throughput screening of new candidate antifungal compounds. We propose an in vitro screening pipeline that integrates five rapid quantitative and qualitative methods to estimate the efficacy and mode of action of prospective antifungal compounds.

RESULTS

The pipeline was evaluated using five documented antifungal compounds (benomyl, catechol, cycloheximide, 2,4-diacetylphloroglucinol, and phenylacetic acid) that have different modes of action and efficacy, against the model soilborne fungal pathogen Fusarium oxysporum f. sp. radicis cucumerinum. We initially evaluated the five compounds' ability to inhibit fungal growth and metabolic activity using green fluorescent protein (GFP)-labeled F. oxysporum and PrestoBlue staining, respectively, in multiwell plate assays. We tested the compounds' inhibition of both conidial germination and hyphal elongation. We then employed FUN-1 and SYTO9/propidium iodide staining, coupled to confocal microscopy, to differentiate between fungal growth inhibition and death at the cellular level. Finally, using a reactive oxygen species (ROS)-detection assay, we were able to quantify ROS production in response to compound application.

CONCLUSIONS

Collectively, the proposed pipeline provides a wide array of quantitative and qualitative data on the tested compounds that can help pinpoint promising novel compounds; these can then be evaluated more vigorously using in planta screening assays. © 2024 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Engineering non-conservative substrate recognition sites of extradiol dioxygenase: Computation guided design to diversify and accelerate degradation of aromatic compounds

Extradiol dioxygenases (EDOs) catalyzing meta-cleavage of catecholic compounds promise an effective way to detoxify aromatic pollutants. This work reported a novel scenario to engineer our recently identified Type I EDO from Tcu3516 for a broader substrate scope and enhanced activity, which was based on 2,3-dihydroxybiphenyl (2,3-DHB)-liganded molecular docking of Tcu3516 and multiple sequence alignment with other 22 Type I EDOs. 11 non-conservative residues of Tcu3516 within 6 Å distance to the 2,3-DHB ligand center were selected as potential hotspots and subjected to semi-rational design using 6 catecholic analogues as substrates; the mutants V186L and V212N returned with progressive evolution in substrate scope and catalytic activity. Both mutants were combined with D285A for construction of double mutants and final triple mutant V186L/V212N/D285A. Except for 2,3-DHB (the mutant V186L/D285A gave the best catalytic performance), the triple mutant prevailed all other 5 catecholic compounds for their degradation; affording the catalytic efficiency kcat/Km value increase by 10-30 folds, protein Tm (structural rigidity) increase by 15 °C and the half-life time enhancement by 10 times compared to the wild type Tcu3516. The molecular dynamic simulation suggested that a stabler core and a more flexible entrance are likely accounting for enhanced catalytic activity and stability of enzymes.

In Vitro Evaluation of the Antioxidant Capacity of 3,3-Disubstituted-3H-benzofuran-2-one Derivatives in a Cellular Model of Neurodegeneration

Oxidative stress represents a hallmark for many degenerative pathologies of the Central Nervous System. Throughout life, the constant pressure of noxious stimuli and/or episodes of traumatic events may expose the brain to a microenvironment where the non-balanced reactive oxygen species inevitably lead to neuronal loss and cognitive decline. HO-1, a 32 kDa heat-shock protein catalyzing the degradation of heme into carbon monoxide (CO), iron and biliverdin/bilirubin is considered one of the main antioxidant defense mechanisms playing pivotal roles in neuroprotection. Restoring the redox homeostasis is the goal of many natural or synthetic antioxidant molecules pursuing beneficial effects on brain functions. Here, we investigated the antioxidant capacity of four selected benzofuran-2-one derivatives in a cellular model of neurodegeneration represented by differentiated SH-SY5Y cells exposed to catechol-induced oxidative stress. Our main results highlight how all the molecules have antioxidant properties, especially compound 9, showing great abilities in reducing intracellular ROS levels and protecting differentiated SH-SY5Y cells from catechol-induced death. This compound above all seems to boost HO-1 mRNA and perinuclear HO-1 protein isoform expression when cells are exposed to the oxidative insult. Our findings open the way to consider benzofuran-2-ones as a novel and promising adjuvant antioxidant strategy for many neurodegenerative disorders.

Distribution and toxicity of dihydroxybenzenes in drinking water sources in Nigeria

This study provides, for the first time, data on the distribution and toxicity of catechol (CAT) and hydroquinone (HQ) in drinking water sources from Africa. Groundwater (boreholes and hand-dug wells) and surface water in three Southwestern States in Nigeria served as sampling sites. The concentrations of CAT and HQ in groundwater and surface water were determined throughout a period of 12 months, evaluating the effects of seasonal variation (rainy and dry seasons). Mean concentrations of CAT in water samples were higher than those of HQ. In this study, CAT was more frequently detected, with its mean concentration in groundwater samples higher in the rainy season (430 μg L-1) than in the dry season (175 μg L-1). Multivariate analysis using the Principal Component Analysis Software suggests that in most sample sites, CAT and HQ in water samples were from entirely different anthropogenic sources. The most impacted population groups were the toddlers and infants. Similarly, maximum and median concentrations of CAT in water samples pose serious risks to Daphnia at both acute and chronic levels. The results from this study suggest the need for further control of these dihydroxybenzenes through regular monitoring and removal from drinking water during treatment.

Advances in photocatalytic degradation of organic pollutants in wastewaters: harnessing the power of phthalocyanines and phthalocyanine-containing materials

Access to clean water is increasingly challenging worldwide due to human activities and climate change. Wastewater treatment and utilization offer a promising solution by reducing the reliance on pure underground water. However, it is crucial to develop efficient and sustainable methods for wastewater purification. Among the emerging wastewater treatment strategies, photocatalysis has gained significant attention for decomposing organic pollutants in water, especially when combined with sunlight and a recoverable photocatalyst. Heterogeneous photocatalysts have distinct advantages, as they can be recovered and reused without significant loss of activity over multiple cycles. Phthalocyanine dyes, with their exceptional photophysical properties, are particularly valuable for homogeneous and heterogeneous photocatalysis. By immobilizing these photosensitizers in various supports, hybrid materials extend their light absorption into the visible spectrum, complementing most supports' limited UV light absorption. The novelty and research importance of this review stems from its discussion of the multifaceted approach to treating contaminated wastewater with phthalocyanines and materials containing phthalocyanines. It highlights key aspects of each study, including photocatalytic efficiency, recyclability characteristics, investigation of the generation of oxygen species responsible for degradation, identification of the major degradation byproducts for each pollutant, and others. Moreover, the review includes tables that illustrate and compare the various phthalocyanines and supporting materials employed in each study for pollutant degradation. Additionally, almost all photocatalysts mentioned in this review could degrade at least 5% of the pollutant, and more than 50 photocatalysts showed photocatalytic rates above 50%. When immobilized in some support, the synergistic effect of the phthalocyanine was visible in the photocatalytic rate of the studied pollutant. However, when performing these types of works, it is necessary to understand the degradation products of each pollutant and their relative toxicities. Along with this, recyclability and stability studies are also necessary. Despite the good results presented in this review, some of the works lack those studies. Moreover, none of the works mentions any study in wastewater.

Mancozeb-induced cytotoxicity in human erythrocytes: enhanced generation of reactive species, hemoglobin oxidation, diminished antioxidant power, membrane damage and morphological changes

Mancozeb is an ethylene bis-dithiocarbamate fungicide extensively used in agriculture to safeguard crops from various fungal diseases. The general population is exposed to mancozeb through consumption of contaminated food or water. Here, we have investigated the effect of mancozeb on isolated human erythrocytes under in vitro conditions. Erythrocytes were treated with different concentrations of mancozeb (0, 5, 10, 25, 50, 100 μM) and incubated for 24 h at 37 °C. Analysis of biochemical parameters and cell morphology showed dose-dependent toxicity of mancozeb in human erythrocytes. Mancozeb treatment caused hemoglobin oxidation and heme degradation. Protein and lipid oxidation were enhanced, while a significant decrease was seen in reduced glutathione and total sulfhydryl content. A significant increase in the generation of reactive oxygen and nitrogen species was detected in mancozeb-treated erythrocytes. The antioxidant capacity and the activity of key antioxidant enzymes were greatly diminished, while crucial metabolic pathways were inhibited in erythrocytes. Damage to the erythrocyte membrane on mancozeb treatment was apparent from increased cell lysis and osmotic fragility, along with the impairment of the plasma membrane redox system. Mancozeb also caused morphological alterations and transformed the normal discoid-shaped erythrocytes into echinocytes and stomatocytes. Thus, mancozeb induces oxidative stress in human erythrocytes, impairs the antioxidant defense system, oxidizes cellular components, that will adversely affect erythrocyte structure and function.

Relationships between Isomeric Metabolism and Regioselective Toxicity of Hydroxychrysenes in Embryos of Japanese Medaka (Oryzias latipes)

Oxygenated polycyclic aromatic hydrocarbons (oxy-PAHs) are ubiquitous contaminants that can be formed through oxidation of parent PAHs. Our previous studies found 2-hydroxychrysene (2-OHCHR) to be significantly more toxic to Japanese medaka embryos than 6-hydroxychrysene (6-OHCHR), an example of regioselective toxicity. We have also previously identified a sensitive developmental window to 2-OHCHR toxicity that closely coincided with liver development, leading us to hypothesize that differences in metabolism may play a role in the regioselective toxicity. To test this hypothesis, Japanese medaka embryos were treated with each isomer for 24 h during liver development (52-76 hpf). Although 6-OHCHR was absorbed 97.2 ± 0.18% faster than 2-OHCHR, it was eliminated 57.7 ± 0.36% faster as a glucuronide conjugate. Pretreatment with cytochrome P450 inhibitor, ketoconazole, reduced anemia by 96.8 ± 3.19% and mortality by 95.2 ± 4.76% in 2-OHCHR treatments. Formation of chrysene-1,2-diol (1,2-CAT) was also reduced by 64.4 ± 2.14% by ketoconazole pretreatment. While pretreatment with UDP-glucuronosyltransferase inhibitor, nilotinib, reduced glucuronidation of 2-OHCHR by 52.4 ± 2.55% and of 6-OHCHR by 63.7 ± 3.19%, it did not alter toxicity for either compound. These results indicate that CYP-mediated activation, potentially to 1,2-CAT, may explain the isomeric differences in developmental toxicity of 2-OHCHR.

Products of Bisphenol A Degradation Induce Cytotoxicity in Human Erythrocytes (In Vitro)

The aim of this work has been to study the possible degradation path of BPA under the Fenton reaction, namely to determine the energetically favorable intermediate products and to compare the cytotoxicity of BPA and its intermediate products of degradation. The DFT calculations of the Gibbs free energy at M06-2X/6-311G(d,p) level of theory showed that the formation of hydroquinone was the most energetically favorable path in a water environment. To explore the cytotoxicity the erythrocytes were incubated with BPA and three intermediate products of its degradation, i.e., phenol, hydroquinone and 4-isopropylphenol, in the concentrations 5-200 μg/mL, for 1, 4 and 24 h. BPA induced the strongest hemolytic changes in erythrocytes, followed by hydroquinone, phenol and 4-isopropylphenol. In the presence of hydroquinone, the highest level of RONS was observed, whereas BPA had the weakest effect on RONS generation. In addition, hydroquinone decreased the level of GSH the most. Generally, our results suggest that a preferable BPA degradation path under a Fenton reaction should be controlled in order to avoid the formation of hydroquinone. This is applicable to the degradation of BPA during waste water treatment and during chemical degradation in sea water.

Scaffold Hopping of α-Rubromycin Enables Direct Access to FDA-Approved Cromoglicic Acid as a SARS-CoV-2 MPro Inhibitor

The COVID-19 pandemic is still active around the globe despite the newly introduced vaccines. Hence, finding effective medications or repurposing available ones could offer great help during this serious situation. During our anti-COVID-19 investigation of microbial natural products (MNPs), we came across α-rubromycin, an antibiotic derived from Streptomyces collinus ATCC19743, which was able to suppress the catalytic activity (IC50 = 5.4 µM and Ki = 3.22 µM) of one of the viral key enzymes (i.e., MPro). However, it showed high cytotoxicity toward normal human fibroblasts (CC50 = 16.7 µM). To reduce the cytotoxicity of this microbial metabolite, we utilized a number of in silico tools (ensemble docking, molecular dynamics simulation, binding free energy calculation) to propose a novel scaffold having the main pharmacophoric features to inhibit MPro with better drug-like properties and reduced/minimal toxicity. Nevertheless, reaching this novel scaffold synthetically is a time-consuming process, particularly at this critical time. Instead, this scaffold was used as a template to explore similar molecules among the FDA-approved medications that share its main pharmacophoric features with the aid of pharmacophore-based virtual screening software. As a result, cromoglicic acid (aka cromolyn) was found to be the best hit, which, upon in vitro MPro testing, was 4.5 times more potent (IC50 = 1.1 µM and Ki = 0.68 µM) than α-rubromycin, with minimal cytotoxicity toward normal human fibroblasts (CC50 > 100 µM). This report highlights the potential of MNPs in providing unprecedented scaffolds with a wide range of therapeutic efficacy. It also revealed the importance of cheminformatics tools in speeding up the drug discovery process, which is extremely important in such a critical situation.

The Metabolomic-Gut-Clinical Axis of Mankai Plant-Derived Dietary Polyphenols

BACKGROUND

Polyphenols are secondary metabolites produced by plants to defend themselves from environmental stressors. We explored the effect of Wolffia globosa 'Mankai', a novel cultivated strain of a polyphenol-rich aquatic plant, on the metabolomic-gut clinical axis in vitro, in-vivo and in a clinical trial.

METHODS

We used mass-spectrometry-based metabolomics methods from three laboratories to detect Mankai phenolic metabolites and examined predicted functional pathways in a Mankai artificial-gut bioreactor. Plasma and urine polyphenols were assessed among the 294 DIRECT-PLUS 18-month trial participants, comparing the effect of a polyphenol-rich green-Mediterranean diet (+1240 mg/polyphenols/day, provided by Mankai, green tea and walnuts) to a walnuts-enriched (+440 mg/polyphenols/day) Mediterranean diet and a healthy controlled diet.

RESULTS

Approximately 200 different phenolic compounds were specifically detected in the Mankai plant. The Mankai-supplemented bioreactor artificial gut displayed a significantly higher relative-abundance of 16S-rRNA bacterial gene sequences encoding for enzymes involved in phenolic compound degradation. In humans, several Mankai-related plasma and urine polyphenols were differentially elevated in the green Mediterranean group compared with the other groups (p < 0.05) after six and 18 months of intervention (e.g., urine hydroxy-phenyl-acetic-acid and urolithin-A; plasma Naringenin and 2,5-diOH-benzoic-acid). Specific polyphenols, such as urolithin-A and 4-ethylphenol, were directly involved with clinical weight-related changes.

CONCLUSIONS

The Mankai new plant is rich in various unique potent polyphenols, potentially affecting the metabolomic-gut-clinical axis.

Full insights into the roles of pH on hydroxylation of aromatic acids/bases and toxicity evaluation

Advanced oxidation processes (AOPs) based on hydroxyl radicals (•OH) are the most important technologies for the removal of bio-recalcitrant organic pollutants in industrial wastewater. The pH is one of the crucial environmental parameters that affect the removal efficiency of pollutants in AOPs. In this work, the mechanistic and kinetic insights into the roles of pH on the hydroxylation of five aromatic acids and bases in UV/H₂O₂ process have been investigated using theoretical calculation methods. Results show that the reactivity of •OH towards the twelve ionic/neutral species is positively correlated with electron-donating effect of substituents, which contributes to the positively pH-dependent reactivity of aromatic acids and bases towards •OH. The hydroxylation apparent rate constants (k_app, M^-1 s^-1) (at 298 K) increase as the pH values increase from about 1 to 10, but they decrease as the pH values increase from about 10 to 14. However, the best pH values for degradation are not around 10 because the [•OH] decreases continuously with the increasing pH values from 3 to 9.5. Combining the factors of k_app and [•OH], the best degradation pH values are around 5.5~7.5 for p-hydroxybenzoic acid, p-aminophenol, aniline and benzoic acid, 3.0~7.5 for phenol and 5.5~7.5 for mixed pollutants of these aromatic acids/bases in UV/H₂O₂ process. Moreover, a significant number of hydroxylation by-products are more toxic or harmful to aquatic organisms and rat (oral) than their parental pollutants. Altogether, this work provides comprehensive understanding of the roles of pH on •OH-initiated degradation behavior of aromatic acids and bases.

Intensification of Dihydroxybenzenes Degradation over Immobilized TiO2 Based Photocatalysts under Simulated Solar Light

The work is focused on the assessment of possible methods for intensification of photocatalytic degradation of common water borne pollutants. Solar photocatalysis poses certain limitations for large scale application with several possible reactor designs which have shown an optimal performance. In the current study, a comparison between two types of pilot scale reactors was made: a flat-plate cascade reactor (FPCR) and tubular reactor with a compound parabolic collector (CPC). Apart from the reactor design, another aspect of possible intensification was a photocatalyst formulation. The efficiency of photocatalytic films that consisted of pure TiO2 nanoparticles was compared to the efficiency of films that consisted of TiO2/CNT composites. Intensification assessment was performed via detailed kinetic modelling, combining the optical properties of films, irradiation conditions and reactor mass balance. Intensification was expressed via intensification indices. Results showed the advantage of the CPC-based reactor design and an unbiased effect of sensitizing agent (CNT) in the photocatalytic film formulation.

Phenolic lipids as unique bioactive compounds: a comprehensive review on their multifunctional activity toward the prevention of Alzheimer's disease

Phenolic lipids are multifunctional compounds which play an important biological role in the body. Their unique biologic functionality stems from their strong amphiphilic character which allows them to be incorporated in erythrocytes. Through membrane incorporation, these compounds exert their biological effects on neurons which are not modulated by hydrophilic compounds. These bioactive compounds are present in nature as secondary plant metabolites, and consequently their availability is limited, for dietary and medical purposes. In this review, the pathways and mechanisms associated with the pathogenesis of Alzheimer's disease will be described. In addition, the modulatory effects of phenolic lipids on these pathways and a list of several synthetic, semi synthetic and natural sources of phenolic lipids will be examined as having the potential to prevent or combat Alzheimer's disease.

In silico and in vitro studies to elucidate the role of 1HYN and 1QKI activity in BPA induced toxicity and its amelioration by Gallic acid

Bisphenol A (BPA) is well known as an artificial environmental endocrine disrupting (ED) chemical. BPA also leads to many deleterious impacts on human blood through the production of reactive oxygen species and by some unknown mechanism. Up to now, very few studies have been conducted to assess the impact of BPA on Red Blood Corpuscle (RBC), Complete Blood Count (CBC), and no study on 1HYN (Erythrocyte Band 3 membrane protein) and 1QKI (Human Glucose 6 Phosphate Dehydrogenase) have been so far carried out. Besides, no study has been conducted to assess the ameliorating impact of the most commonly available antioxidant like Gallic Acid (GA). The present investigation revealed that BPA exposure (50-200  μg ml^-1) causes significant increase in percent hemolysis and morphological alteration of RBC, as well as significant reduction in CBC except White Blood Cell (WBC), Platelet, and Red blood density width (RDW). BPA exposure also caused a significant reduction in G6PD activity. In silico docking study revealed that BPA effectively binds with 1HYN and 1QKI protein to alter its activity. Concurrent addition of GA (10-50  μg ml^-1) with highest dose of BPA (200  μg ml^-1) ameliorates all parameters significantly as compared to BPA (200  μg ml^-1) treatment. Ameliorating effect of GA is mainly due to its antioxidant property and interaction with BPA, was confirmed using UV-VIS-NIR Spectrophotometric, molecular dynamic simulation and docking approach by YASARA software.

Highly selective colorimetric determination of catechol based on the aggregation-induced oxidase–mimic activity decrease of δ-MnO2

A new determination mechanism for catechol: aggregation-induced oxidase-mimic activity decrease of δ-MnO₂.

Pentachlorophenol-induced cytotoxicity in human erythrocytes: enhanced generation of ROS and RNS, lowered antioxidant power, inhibition of glucose metabolism, and morphological changes

Pentachlorophenol (PCP) is a class 2B human carcinogen that is used as an insecticide, herbicide, and wood preservative. PCP is rapidly absorbed and enters the blood where it can interact with erythrocytes. We have examined the effect of PCP on human erythrocytes. Treatment of erythrocytes with PCP increased the intracellular generation of reactive oxygen and nitrogen species. It also increased lipid and protein oxidation accompanied by decrease in glutathione levels and total sulfhydryl content. The activities of all major antioxidant enzymes were altered. The antioxidant power was significantly impaired resulting in lower free radical quenching and metal reducing ability of the PCP-treated cells. PCP exposure also inhibited the activities of enzymes of glycolysis and pentose phosphate shunt, the two pathways of glucose metabolism in erythrocytes. Heme degradation was enhanced leading to the release of free iron. Incubation of erythrocytes with PCP caused significant cell lysis suggesting plasma membrane damage which was also evident from inhibition of bound enzymes. Scanning electron microscopy of erythrocytes confirmed these biochemical results and showed that PCP treatment converted the normal biconcave discoids to echinocytes and other irregularly shaped cells. Thus, PCP induces oxidative and nitrosative stress in erythrocytes, alters the enzymatic and nonenzymatic antioxidant defense systems, inhibits glucose metabolism, and causes significant modifications in cellular morphology.

Directed aryl sulfotransferase evolution toward improved sulfation stoichiometry on the example of catechols

Sulfation is an important way for detoxifying xenobiotics and endobiotics including catechols. Enzymatic sulfation occurs usually with high chemo- and/or regioselectivity under mild reaction conditions. In this study, a two-step p-NPS-4-AAP screening system for laboratory evolution of aryl sulfotransferase B (ASTB) was developed in 96-well microtiter plates to improve the sulfate transfer efficiency toward catechols. Increased transfer efficiency and improved sulfation stoichiometry are achieved through the two-step screening procedure in a one-pot reaction. In the first step, the p-NPS assay is used (detection of the colorimetric by-product, p-nitrophenol) to determine the apparent ASTB activity. The sulfated product, 3-chlorocatechol-1-monosulfate, is quantified by the 4-aminoantipyrine (4-AAP) assay in the second step. Comparison of product formation to p-NPS consumption ensures successful directed evolution campaigns of ASTB. Optimization yielded a coefficient of variation below 15% for the two-step screening system (p-NPS-4-AAP). In total, 1760 clones from an ASTB-SeSaM library were screened toward the improved sulfation activity of 3-chlorocatechol. The turnover number (k_cat = 41 ± 2 s^-1) and catalytic efficiency (k_cat/K_M = 0.41 μM^-1 s^-1) of the final variant ASTB-M5 were improved 2.4- and 2.3-fold compared with ASTB-WT. HPLC analysis confirmed the improved sulfate stoichiometry of ASTB-M5 with a conversion of 58% (ASTB-WT 29%; two-fold improvement). Mass spectrometry (MS) and nuclear magnetic resonance spectroscopy (NMR) confirmed the chemo- and regioselectivity, which yielded exclusively 3-chlorocatechol-1-monosulfate. For all five additionally investigated catechols, the variant ASTB-M5 achieved an improved k_cat value of up to 4.5-fold and sulfate transfer efficiency was also increased (up to 2.3-fold).

Date stone based activated carbon/graphite electrode for catechol analysis: physico-chemical properties and application in beverage samples

The purpose of this paper is the modification of a carbon paste electrode (CPE) with activated carbon synthesized from date stones using a pyrolysis system followed by physical activation.

Hydroxyl radical production by a heterogeneous Fenton reaction supported in insoluble tannin from bark of Pinus radiata

Fenton reactions driven by dihydroxybenzenes (DHBs) have been used for pollutant removal via advanced oxidation processes (AOPs), but such systems have the disadvantage of DHB release into the aqueous phase. In this work, insoluble tannins from bark can be used to drive Fenton reactions and as a heterogeneous support. This avoids the release of DHBs into the aqueous phase and can be used for AOPs. The production of ·OH was investigated using a spin-trapping electron paramagnetic resonance technique (5-dimethyl-1-pyrroline-N-oxide/·OH) in the first minute of the reaction and a high-performance liquid chromatography-fluorescence technique (coumarin/7-hydroxycoumarin) for 20 min. The ·OH yield achieved using insoluble tannins from Pinus radiata bark was higher than that achieved using catechin to drive the Fenton reaction. The Fenton-like system driven by insoluble tannins achieved 92.6 ± 0.3 % degradation of atrazine in 30 min. The degradation kinetics of atrazine was linearly correlated with ·OH production. The increased reactivity in ·OH production and insolubility of the ligand are promising for the development of a new technique for degradation of pollutants in wastewater using heterogeneous Fenton systems.

Preparation of Cu@Cu₂O Nanocatalysts by Reduction of HKUST-1 for Oxidation Reaction of Catechol

HKUST-1, a copper-based metal organic framework (MOF), has been investigated as a catalyst in various reactions. However, the HKUST-1 shows low catalytic activity in the oxidation of catechol. Therefore, we synthesized Fe₃O₄@HKUST-1 by layer-by layer assembly strategy and Cu@Cu₂O by reduction of HKUST-1 for enhancement of catalytic activity. Cu@Cu₂O nanoparticles exhibited highly effective catalytic activity in oxidation of 3,5-di-tert-butylcatechol. Through this method, MOF can maintain the original core-shell structure and be used in various other reactions with enhanced catalytic activity.

Neurobehavioral and Antioxidant Effects of Ethanolic Extract of Yellow Propolis

Propolis is a resin produced by bees from raw material collected from plants, salivary secretions, and beeswax. New therapeutic properties for the Central Nervous System have emerged. We explored the neurobehavioral and antioxidant effects of an ethanolic extract of yellow propolis (EEYP) rich in triterpenoids, primarily lupeol and β-amyrin. Male Wistar rats, 3 months old, were intraperitoneally treated with Tween 5% (control), EEYP (1, 3, 10, and 30 mg/kg), or diazepam, fluoxetine, and caffeine (positive controls) 30 min before the assays. Animals were submitted to open field, elevated plus maze, forced swimming, and inhibitory avoidance tests. After behavioral tasks, blood samples were collected through intracardiac pathway, to evaluate the oxidative balance. The results obtained in the open field and in the elevated plus maze assay showed spontaneous locomotion preserved and anxiolytic-like activity. In the forced swimming test, EEYP demonstrated antidepressant-like activity. In the inhibitory avoidance test, EEYP showed mnemonic activity at 30 mg/kg. In the evaluation of oxidative biochemistry, the extract reduced the production of nitric oxide and malondialdehyde without changing level of total antioxidant, catalase, and superoxide dismutase, induced by behavioral stress. Our results highlight that EEYP emerges as a promising anxiolytic, antidepressant, mnemonic, and antioxidant natural product.

Modeling the reactivity of ozone and sulphate radicals towards organic chemicals in water using machine learning approaches

QSRR modeling and correlative distribution of measured and model predicted values of rate constants (k_O3andkS_O4) of reactions of O₃and SO₄˙⁻radicals with diverse organic chemicals in aqueous medium.

Surface molecularly imprinted electrochemical sensor for phenol based on SiO2 nanoparticles

A novel surface molecularly imprinted electrochemical sensor for the recognition and detection of phenol was constructed. It has a specific recognition ability for phenol over other phenolic compounds for real samples with excellent repeatability.

Comparative study of the effect of BPA and its selected analogues on hemoglobin oxidation, morphological alterations and hemolytic changes in human erythrocytes

Bisphenol A (BPA) has been shown to provoke many deleterious impacts on human health, and thus it is now successively substituted by BPA analogues, whose effects have been poorly investigated. Up to now, only one study has been realized to assess the effect of BPA on human erythrocytes, which showed its significant hemolytic and oxidative potential. Moreover, no study has been conducted to evaluate the effect of BPA analogues on red blood cells. The purpose of the present study was to compare the impact of BPA and its selected analogues such as bisphenol F (BPF), bisphenol S (BPS) and bisphenol AF (BPAF) on hemolytic and morphological changes and hemoglobin oxidation (methemoglobin formation) of human erythrocytes. The erythrocytes were incubated with different bisphenols concentrations ranging from 0.5 to 500μg/ml for 1, 4 and 24h. The compounds examined caused hemolysis in human erythrocytes with BPAF exhibiting the strongest effect. All bisphenols examined caused methemoglobin formation with BPA inducing the strongest oxidative potential. Flow cytometry analysis showed that all bisphenols (excluding BPS) induced significant changes in erythrocytes size. Changes in red blood cells shape were conducted using phase contrast microscopy. It was noticed that BPA and BPAF induced echinocytosis, BPF caused stomatocytosis, while BPS did not provoke significant changes in shape of red blood cells. Generally, the results showed that BPS, which is the main substituent of bisphenol A in polymers and thermal paper production, exhibited significantly lower disturbance of erythrocyte functions than BPA.

In vitro and in vivo toxicological evaluations of methyl ferulate, methyl p-coumarate, and pulegone 1,2-epoxide

CONTEXT

Toxicological screening of natural compounds for medicinal purposes.

OBJECTIVES

The objective of this study is to evaluate the toxicity of methyl ferulate (MF), methyl p-coumarate (MpC), and pulegone 1,2-epoxide (PE) with in vitro and in vivo assays.

MATERIALS AND METHODS

The in vitro toxicity of MF, MpC, and PE was assessed at a concentration of 10 mg/ml with the Ames assay using two strains of Salmonella typhimurium TA98 and TA100. Human red blood cells (RBC) were used to determine the hemolytic activity of these compounds. The cytotoxicity of above compounds was determined with brine shrimp lethality bioassay (BSLB) at the concentrations of 0.1-20 mg/ml. While dermal and ocular irritation studies were conducted on healthy rabbits (n = 8) for 96 and 12 h post-topical application of test compounds, respectively.

RESULTS

PE produced 6-8% hemolysis of RBCs at all the tested concentrations while MF and MpC produced 10-5% hemolysis up to 20 mg/ml, and 50-85% hemolysis at concentrations of 40 and 80 mg/ml, respectively. The Ames assay indicated that MF, MpC, and PE were non-mutagenic as the test values were not significantly higher as compared with background values of the assay. BSLB suggested the lethal concentration (LC50) values of MF, MpC, and PE as 4.38, 6.74, and 25.91 mg/ml, respectively. In vivo ocular and dermal irritation scores of MF, MpC, and PE were comparable with ethanol (control) in rabbits indicating the non-irritant nature of these natural compounds.

CONCLUSION

The present studies suggest that these compounds are non-toxic/non-irritant and might be used for medicinal purposes.

Silymarin prevents the toxicity induced by benzo(a)pyrene in human erythrocytes by preserving its membrane integrity: an in vitro study

Silymarin, the purified extract from milk thistle Silybum marianum (L.) Gaertn, consists mainly of four isomeric flavonolignans: silibinin, isosilibinin, silidianin, and silichristin. The present study was carried out to evaluate the protective potential of silymarin in human erythrocytes against in vitro exposure to the carcinogen benzo(a)pyrene (B(a)P). Erythrocytes isolated from human blood were divided into four groups and treated with Vehicle [Group I], B(a)P (300 μM) [Group II], Silymarin (500 μM) + B(a)P (300 μM) [Group III], and Silymarin alone (500 μM)] [Group IV]. Silymarin treatment maintains the integrity of erythrocytes by preventing hemolysis, protein thiol oxidation and by decreasing the activity of AChE. SEM observations indicate that B(a)P induced significant alteration in the morphology of erythrocytes to echinocytes, which may be due to the interaction of B(a)P with the membrane's outer phopholipid monolayer. The light microscopic and SEM images show that silymarin treatment maintains the normal discocytic morphology of erythrocytes. The protective effect of silymarin might be attributed to its chemical structure and membranotrophic nature. The components silibinin, silydianin, and silychristin have OH in the 3rd, 5th, and 7th carbon atoms that may account for its increased antioxidant activity and removal of ROS formed during B(a)P metabolism.

Selenium pretreatment attenuates formaldehyde-induced genotoxicity in A549 cell lines

Formaldehyde is a major industrial chemical and has been extensively used in the manufacture of synthetic resins and chemicals. Numerous studies indicate that formaldehyde can induce various genotoxic effects in vitro and in vivo. A recent study indicated that formaldehyde impaired antioxidant cellular defences and enhanced lipid peroxidation. Selenium is an important antioxidant. We hypothesized that reactive oxygen species (ROS) and lipid peroxidation are involved in formaldehyde-induced genotoxicity in human lung cancer cell line, A549 cell line. To test the hypothesis, we investigated the effects of selenium on formaldehyde-induced genotoxicity in A549 cell lines. The results indicated that exposure to formaldehyde showed the induction of DNA–protein cross-links (DPCs). Formaldehyde significantly increased the malondialdehyde levels and decreased the activities of superoxide dismutase and glutathione peroxidase. In addition, the activations of necrosis factor-κB (NF-κB) and activator protein 1 (AP-1) were induced by the formaldehyde treatment. The pretreatment with selenium counteracted the formaldehyde-induced oxidative stress, ameliorated DPCs and attenuated the activation of NF-κB and AP-1 in A549 cell lines. All the results suggested that the pretreatment with selenium attenuated the formaldehyde-induced genotoxicity through its ROS scavenging and anti-DPCs effects in A549 cell lines.

Protective effect of curcumin against formaldehyde-induced genotoxicity in A549 Cell Lines

Formaldehyde is ubiquitous in the environment. It is known to be a genotoxic substance. We hypothesized that reactive oxygen species (ROS) and lipid peroxidation are involved in formaldehyde-induced genotoxicity in human lung cancer cell lines A549. To test this hypothesis, we investigated the effects of antioxidant on formaldehyde-induced genotoxicity in A549 Cell Lines. Formaldehyde exposure caused induction of DNA-protein cross-links (DPCs). Curcumin is an important antioxidant. Formaldehyde significantly increased malondialdehyde (MDA) levels, and decreased superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity. In addition, the activation of NF-κB and AP-1 were induced by formaldehyde treatment. Pretreatment with curcumin counteracted formaldehyde-induced oxidative stress, ameliorated DPCs and attenuated activation of NF-κB and AP-1 in A549 Cell Lines. These results, taken together, suggest that formaldehyde induced genotoxicity through its ROS and lipid peroxidase activity and caused DPCs effects in A549 cells.

Protective effect of lutein against benzo(a)pyrene-induced oxidative stress in human erythrocytes

The present study was carried out to evaluate the in vitro antioxidant properties and protective effect of lutein in human erythrocyte against benzo(a)pyrene (B(a)P). It is a well-known environmental carcinogen that produces free radicals under normal metabolic circumstances. B(a)P reacts with cellular macromolecules and produces oxidation of protein, lipid and DNA. Lutein is a carotenoid possessing antioxidant, anticarcinogenic and anti-inflammatory properties. In the present investigation, the protective effect of lutein was assessed in vitro against B(a)P-induced oxidative stress by monitoring antioxidant enzymes, lipid peroxidation (LPO), protein carbonyl content, total sulfhydryl (SH) and nonprotein SH groups and methemoglobin in five groups of erythrocytes that include (i) control group, (ii) vehicle control group, (iii) B(a)P-exposed group, (iv) lutein-exposed group and (v) B(a)P coincubation with lutein group. It was observed that the activities of antioxidant enzymes and SH groups were significantly decreased in B(a)P-treated group when compared with control group. LPO level and protein carbonyl and methemoglobin contents were increased in B(a)P-treated group when compared with control group. The erythrocyte that was coincubated with B(a)P and lutein showed significant increase in the  antioxidant enzyme activities and a significant reduction in the level of LPO, methemoglobin and protein carbonyl contents  when compared with B(a)P-treated group. The results of the present investigation suggest that lutein possess protective effect against B(a)P-induced oxidative stress, possibly by combating oxidative stress by its  free radical scavenging activity.

Intervention of glutathione in pre-mutagenic catechol-mediated DNA damage in the presence of copper(II) ions

The catechol-mediated DNA damage in the presence of Cu(II) ions involves oxidation of guanine to 8-oxoguanine (8-oxoG) and DNA strand scission. It proceeds through the reactive oxygen species (ROS) generation. The mutagenicity of 8-oxoG lesions is due to its miscoding propensity reflected in GC→TA transversion taking place during the DNA repair process. To gain new insights into the nature of catechol-mediated DNA damage and its prevention, we have investigated the changes in DNA melting characteristics and 8-oxoG formation as the indicators of DNA damage in a model calf-thymus DNA system. A novel fluorescence method for DNA melting temperature determination, based on DAPI fluorescent-probe staining, has been proposed. The DNA melting-onset temperature has been found to be more sensitive to DNA damage than the standard melting temperature due to the increased width of the melting transition observed in oxidatively damaged DNA. We have found that the efficiency of Fenton cascade in generating DNA-damaging ROS is higher for catechol than for GSH, two strong antioxidants, mainly due to the much longer distance between ROS-generating radical group in GS to nucleobases than that of semiquinone radical group to nucleobases (2.1nm vs. 0.27nm), making the ROS transport from GSH an order of magnitude less likely to damage DNA because of short lifetime of HO radicals. The antioxidant and DNA-protecting behaviors of GSH have been elucidated. We have found that the redox potential of GSH/GSSG couple is lower than that of catechol/semiquinone couple. Hence, GSH keeps catechol in the reduced state, thereby shutting down the initial step of the catechol-mediated Fenton cascade. The catechol-induced DNA damage in the presence of Cu(II) ions has also been confirmed in studies of ON-OFF hairpin-oligonucleotide beacons.

Erythrocyte damage of crucian carp (Carassius auratus) caused by microcystin-LR: in vitro study

Fish suffer from anemia and hypovolemic hypotensive shock after in vivo exposure with microcystins.However, except for in vivo causes for anemia and hypotension, an in vitro study of fish erythrocytes exposed to MC is necessary. For a better understanding of hematology toxicity of MC, the main aim of the present study was to investigate the toxic effects of microcystin on fish erythrocytes in vitro. Crucian carp erythrocytes were incubated in vitro with microcystin-LR (MC-LR) at doses of 0, 1, 10, 100 and 1,000 nM.The level of lipid peroxidate significantly increased in MC-LR treatment groups. Glutathione decreased after exposure to MC-LR. The activities of antioxidative enzymes, including superoxide dismutase, catalase,glutathione peroxidase and glutathione-S-transferase,were significantly increased after exposure with MC-LR.The hemolysis was significantly increased, while the activities of acetylcholinesterase, Na?–K?-ATPase and Ca2?–Mg2?-ATPase were significantly decreased. In addition, pathological alterations in agglomerated and jagged erythrocytes were observed in blood smears. The findings indicate that damages to erythrocytes should also be responsible for anemia and hypotensive shock or even death.

Uncaria tomentosa extracts protect human erythrocyte catalase against damage induced by 2,4-D-Na and its metabolites

The effect of ethanolic and aqueous extracts from leaves and bark of Uncaria tomentosa was studied, with particular attention to catalase activity (CAT - EC. 1.11.1.6). We observed that all tested extracts, at a concentration of 250 μg/mL were not toxic to erythrocyte catalase because they did not decreased its activity. Additionally, we investigated the protective effect of extracts on changes in CAT activity in the erythrocytes incubated with sodium salt of 2,4-dichlorophenoxyacetic acid (2,4-D-Na) and its metabolites i.e., 2,4-dichlorophenol (2,4-DCP) and catechol. Previous investigations showed that these chemicals decreased activity of erythrocyte catalase (Bukowska et al., 2000; Bukowska and Kowalska, 2004). The erythrocytes were divided into two portions. The first portion was incubated for 1 and 5h at 37°C with 2,4-D-Na, 2,4-DCP and catechol, and second portion was preincubated with extracts for 10 min and then incubated with xenobiotics for 1 and 5h. CAT activity was measured in the first and second portion of the erythrocytes. We found a protective effect of the extracts from U. tomentosa on the activity of catalase incubated with xenobiotics studied. Probably, phenolic compounds contained in U. tomentosa scavenged free radicals, and therefore protected active center (containing -SH groups) of catalase.

Protective activity of the Uncaria tomentosa extracts on human erythrocytes in oxidative stress induced by 2,4-dichlorophenol (2,4-DCP) and catechol

The purpose of this study was to evaluate the effect of the ethanolic and aqueous extracts of Uncaria tomentosa on human erythrocytes and additionally the assessment of protective effect of these extracts on hemolysis induction, hemoglobin oxidation, and changes in the level of reactive oxygen species (ROS) and lipid peroxidation, which were provoked by selected xenobiotics, i.e. 2,4-dichlorophenol (2,4-DCP) and catechol. All tested extracts, even at a very high concentration of 500 μg/ml were not toxic to the erythrocytes because they did not cause lipid peroxidation, increase methemoglobin and ROS levels nor provoked hemolysis. The results of this study also revealed protective effect of extracts of U. tomentosa. The extracts studied depleted the extent of hemoglobin oxidation and lipid peroxidation as well as decreased the level of ROS and hemolysis, which was provoked by 2,4-DCP. No protective activity of the extracts against catechol action, which is a precursor of semiquinones in cell was found. A difference in the effect of the extracts studied was observed. Ethanol-based extracts revealed more pronounced ability to inhibit oxidation processes in human erythrocytes.

Role of galloylation and polymerization in cytoprotective effects of polyphenolic fractions against hydrogen peroxide insult

Byproducts and wastes generated by agricultural, food, and forestry industries contain large amounts of polyphenols, which can be potentially used as sources of natural or semisynthetic antioxidants. This study examined and compared the protection against peroxidative damage induced in erythrocytes and 3T3 cell line of polyphenolic fractions from white grape pomace, pine bark, and witch hazel bark. The work pays special attention to the different degrees of polymerization and galloylation of the extracts to contribute to the understanding of their mechanisms of action. Fractions demonstrated different protections against erythrocyte lipid peroxidation, hemolysis, and 3T3 cytotoxicity caused by H(2)O(2). Galloylation is claimed to be related to antioxidant protective capacity, and it is also responsible for the pro-oxidant effect observed at high doses. The results show that not only the percentage of galloylation but also the degree of polymerization are important modulators of their antioxidant capacity. In this sense, it is crucial that novel polyphenolic fractions were prepared attending a value of 3 for the mean degree of polymerization and did not exceed a 30% of galloylation to reach the highest antioxidant capacity with the lowest cytotoxic effects. For this reason, the grape extracts appear to be the best strategy to fight against hydrogen peroxide cell damage.

The efficiacy of bismuth subnitrate against genotoxicity and oxidative stress induced by aluminum sulphate

Aluminum (Al) is commonly used in industrial processes and drugs and is thought to induce erythrocytes damage via activation of oxidative stress. Recently, bismuth (Bi)-containing drugs are used in the treatment of various diseases. However, uncertain effects of Bi in blood tissue may participate in the therapeutic efficacy of Bi compounds as related to metals. Hence, this study aimed to determine the roles on human blood cells of the various concentrations of aluminum sulphate (Al2 (SO4)3) and bismuth subnitrate (BSN), separate and together. With this aim, oxidative status was assessed on erythrocytes by measuring following oxidative stress markers: reduced glutathione (GSH), superoxide dismutase (SOD), glucose-6-phosphate dehydrogenase (G-6-PDH) and catalase (CAT). Two chemicals were tested for their ability to induce cytogenetic change in human lymphocytes using assays for chromosome aberrations (CAs) and sister chromatid exchanges (SCEs). Our results showed that high dose of Al2(SO4)3 (20 µg/mL) caused oxidative stress and increased CA and SCE frequencies. Whereas, BSN doses did not change CA and SCE rates. Moreover, it led to changes of antioxidant capacity at different concentrations. After concomitant treatment with Al2(SO 4)3 and BSN, the effects of BSN doses were different on enzyme activities and decreased the genotoxic damage. However, the high dose of BSN and Al2(SO4)3 was shown to enhance the frequencies of CAs and SCEs in a synergistic manner. In conclusion, BSN could be effective in the protection against the blood toxicity of Al 2(SO4)3.

The role of catechols and free radicals in benzene toxicity: an oxidative DNA damage pathway

Benzene is a widespread volatile compound and an environmental contaminant. Since it causes important toxic effects in workers exposed to low levels, long-term exposure to this compound has been extensively studied. Leukemia, blood disorders, bone marrow depression, and some types of cancer are directly related to benzene-initiated toxicity. Bioactivation of benzene can lead to the formation of hazardous metabolites such as phenol, hydroquinone, and catechol. Catechol forms semiquinones and reactive quinones that are presumed to play an important role in the generation of reactive oxygen species (ROS). ROS formation can directly induce single and double strand breaks in the DNA, oxidized nucleotides, and hyper-recombination, and consequently produces deleterious genetic changes. In this review, we have addressed the cytotoxic effects of benzene and its main metabolite, catechol, focusing on the oxidative pathway and further DNA damage.

Prediction of rate constants for radical degradation of aromatic pollutants in water matrix: a QSAR study

We present the results of the QSAR/QSPR study on the degradation rate constants of 78 aromatic compounds by the hydroxyl radicals in water. A genetic algorithm and multiple regression analysis were applied to select the descriptors and to generate the correlation models. Additionally to DRAGON descriptors, the parameters from quantum-chemical calculations at semiempirical and at density functional theory level (B3LYP/6-31G(d,p)) were applied. The most predictive model is a four-variable model that had a good ratio of the number of variables and the predictive ability to avoid overfitting. As it was expected, the main contribution to the degradation rate was given by the E(HOMO) parameter. Additionally, a number of topological descriptors in selected models showed an importance of polarizability term regarding the degradation rate of compounds. Overall, the applied GA-MLRA approach with the use of quantum-chemical and DRAGON generated descriptors showed good results in this study. The obtained statistically robust structure-degradation rate model can be used for future studies of the presence of organic compounds in the environment, and especially their degradation by hydroxyl radicals as a part of a water/wastewater treatment.

Effects of phenol in antioxidant metabolism in matrinxã, Brycon amazonicus (Teleostei; Characidae)

Parameters of the antioxidant defense systems of Brycon amazonicus (matrinxã--a neotropical fish) exposed to phenol for 96 h plus the recovery over 1 and 2 weeks were studied in erythrocytes and liver. Hematocrit increase was observed during phenol exposure and recovery for 1 week. Total superoxide dismutases (SOD), glutathione peroxidase (GPx) and reduced glutathione (GSH) did not change during phenol exposure. Erythrocyte glucose-6-phosphate dehydrogenase (G6PDH) increased during that period while catalase (CAT) activity decreased during phenol exposure and recovery for 2 weeks. In the liver, SOD and CAT did not change, whereas GPx increased in the first week of recovery and decreased after 2 weeks. A late response was observed for G6PDH activity which increased only at the second week. Ascorbate concentration in the brain decreased during phenol exposure and increased over recovery. From our results it appears that the oxidative stress was limited in matrinxã exposed to phenol, but seemed to occur during the recovery period.