Radical Scavenging Agents Research Articles

Synthesis, bioactivity, and molecular docking of pyrazole bearing Schiff-bases as prospective dual alpha-amylase and alpha-glucosidase inhibitors with antioxidant activity

A series of pyrazole-Schiff base derivatives, 3a-i, were synthesized by reacting arylamines 2a-i with pyrazole aldehyde 1, utilizing two catalysts: ammonium chloride (catalystA) or acetic acid (catalystB). The compounds were analyzed using spectroscopic methods, including 1H and 13C NMR, along with high-resolution mass spectrometry. Their antidiabetic and antioxidant activities were assessed through various in vitro assays, encompassing evaluation of inhibitory effects on α-glucosidase, α-amylase enzymes and determination of reducing power, free radical scavenging activity. The most promising in vitro antidiabetic results were also observed with analogs 3c (α-amylase IC50 = 19.57 ± 0.07 µM, α-glucosidase IC50 = 17.13 ± 0.28 µM) and 3h (α-amylase IC50 = 22.50 ± 0.06 µM, α-glucosidase IC50 = 20.75 ± 0.17 µM). Both products 3c and 3h revealed activity near to the standard acarbose (IC50 (α-amylase) =16.28 ± 0.24 µM, IC50 (α-glucosidase) =13.19 ± 0.26 µM). Among all compounds, 3c and 3h exhibited the highest transition metal reducing activity at levels of 75.27 ± 1.99 and 78.42 ± 0.58 µM Trolox equivalents (TE), respectively, along with the most significant free radical scavenging effects at levels of 73.79 ± 0.11 and 72.98 ± 0.33 µM TE, respectively. The antioxidant results of the current set of pyrazole-Schiff base derivatives 3a–i indicated their potential benefits as free radical scavenging and metal-reducing agents, thus proving their antioxidant capability. Their higher antidiabetic and antioxidant activities compared to other compounds might be explained by the presence of a free phenolic hydroxy group in 3c and a benzothiazole motif in 3h. These findings also lend support to the multifaceted biological functions associated with their antidiabetic activity, including their antioxidant activity. In silico molecular docking studies confirm the antihyperglycemic impact, elucidating the nature of interactions between 3c and 3h and HPA/HLAG catalytic sites.

Green synthesis, characterization, and photocatalytic activity of superparamagnetic MgFe2O4@ZnAl2O4 nanocomposites

MgFe2O4@ZnAl2O4 magnetic nanocomposites were synthesized with the easy and green sol–gel method, and their photocatalytic efficiency was followed toward degradation of reactive blue 222 (RB222) dye under visible light irradiation. Prepared nanocomposites were fully characterized. The SEM and TEM images revealed the spherical morphology of the produced nanocomposites, with average size of 20–25 nm. The XRD pattern of sample exhibited the successful synthesis of the MgFe2O4@ZnAl2O4 MNCs with crystallite size 13 nm. The saturation magnetization (Ms) of the nanocomposites was examined using VSM, indicating a value of 6.59 emu/g. The absence of Hc and Mr values confirms the superparamagnetic nature of the nanoparticles. In addition, the surface area was calculated to be 78.109 m2/g utilizing BET analysis, and the band gap was determined to be 1.88 eV by DRS analysis. The photocatalytic, photolysis, and adsorption performance were investigated and result shown photodegradation activity was higher than others. These results confirm the synergetic effect between the MgFe2O4@ZnAl2O4 MNCs and visible light irradiation to degradation of organic dye. The results indicate that rapid degradation of 96% of RB222 dye occurred in just 10 min, with a TOC removal rate of approximately 59%. Furthermore, radical scavenger agents also clarified photodegradation of RB222 dye.

Synthesis, characterization, and molecular docking studies of novel hippuric acid anhydrides as potential antiurolithic, analgesic and free radical scavenging agents

Hippuric acid is a biotransformation product in humans which is excreted through urine. Dietary intake of phenolic compounds increases its concentration in urine. Hippuric acid is experimentally proved to be a regulator of calcium oxalate super saturation in human urine and has a solvent effect on oxalate salts. Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used analgesics employed in associated renal colic of urolithiasis. The objective of the present study was to chemically link hippuric acid through anhydride linkage to various NSAIDs to synthesize potential mutual prodrugs for urolithiasis and associated renal colic. Hippuric acid was linked to eleven NSAIDs through anhydride linkage by first synthesizing hippuryl chloride using oxalyl chloride as chlorinating agent, followed by its reaction with sodium salts of NSAIDs. Structures of obtained compounds were elucidated using UV spectrophotometry, FTIR spectrometry, 1H NMR and C-13 NMR spectrometry. Synthesized compounds were evaluated for in vitro antioxidant, in vivo acute toxicity, in vivo antiurolithic, in vivo analgesic and in vitro hydrolysis studies. Molecular docking analysis on TNF-α and COX-2 was carried out to determine target protein binding. Synthesized compounds showed stability at acidic pH which indicate potential gastro protective effect of synthesized conjugates. Compounds P9 an P6 showed maximum in vivo antiurolithic activity while P9 and P8 showed maximum in vitro antioxidant activity. All the conjugates except P2 showed significant analgesic activity which show that conjugation of hippuric acid to NSAIDs did not result in loss of analgesic potential. Docking studies showed better affinity with TNF-α as compared to COX-2.

Green synthesis and characterization of spinel CoAl2O4 nanoparticles: Efficient photocatalytic degradation of organic dyes

CoAl2O4 nanoparticles (NPs) were synthesized using the sol–gel method and employed for the photocatalytic degradation of Direct Blue 129 (DB129) and Direct Red 31 (DR31) in an aqueous solution. The synthesized CoAl2O4 NPs have been fully characterized by X-ray powder diffraction (XRD), UV–vis diffuse reflectance spectroscopy (UV–vis DRS), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy with an energy-dispersive X-ray spectroscope (SEM-EDS), transmission electron microscope (TEM), and Brunauer Emmett Teller (BET). The experiment investigated the optimal conditions for photocatalysis, including the amount of photocatalyst dosage, contact time, visible light irradiation, pH, and initial dye concentration. The results demonstrated that CoAl2O4 nanoparticles have great potential for efficiently photodegradation of direct blue 129 (DB129) and direct red 31 (DR31). Furthermore, the use of radical scavenger agents helped to clarify the mechanism by which the dyes are degraded through photodegradation.

The case for neuregulin-1 as a clinical treatment for stroke.

Ischemic stroke is the leading cause of serious long-term disability and the 5th leading cause of death in the United States. Revascularization of the occluded cerebral artery, either by thrombolysis or endovascular thrombectomy, is the only effective, clinically-approved stroke therapy. Several potentially neuroprotective agents, including glutamate antagonists, anti-inflammatory compounds and free radical scavenging agents were shown to be effective neuroprotectants in preclinical animal models of brain ischemia. However, these compounds did not demonstrate efficacy in clinical trials with human patients following stroke. Proposed reasons for the translational failure include an insufficient understanding on the cellular and molecular pathophysiology of ischemic stroke, lack of alignment between preclinical and clinical studies and inappropriate design of clinical trials based on the preclinical findings. Therefore, novel neuroprotective treatments must be developed based on a clearer understanding of the complex spatiotemporal mechanisms of ischemic stroke and with proper clinical trial design based on the preclinical findings from specific animal models of stroke. We and others have demonstrated the clinical potential for neuregulin-1 (NRG-1) in preclinical stroke studies. NRG-1 significantly reduced ischemia-induced neuronal death, neuroinflammation and oxidative stress in rodent stroke models with a therapeutic window of >13 h. Clinically, NRG-1 was shown to be safe in human patients and improved cardiac function in multisite phase II studies for heart failure. This review summarizes previous stroke clinical candidates and provides evidence that NRG-1 represents a novel, safe, neuroprotective strategy that has potential therapeutic value in treating individuals after acute ischemic stroke.

Green synthesis and characterization of α-Mn2O3 nanoparticles for antibacterial activity and efficient visible-light photocatalysis

In this study, green synthesis, characterizations, photocatalytic performance, and antibacterial applications of α-Mn2O3 nanoparticles are reported. The synthesized nanoparticles were characterized by Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD), transmission electron microscope (TEM), Scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), Brunauer Emmett Teller (BET), Electrochemical Impedance Spectroscopy (EIS), Photoluminescence (PL), and Differential reflectance spectroscopy (DRS) analysis. The investigation verified that the α-Mn2O3 nanoparticles possessed a cubic structure, with a crystallite size of 23 nm. The SEM and TEM techniques were used to study the nanoscale morphology of α- Mn2O3 nanoparticles, which were found to be spherical with a size of 30 nm. Moreover, the surface area was obtained as 149.9 m2 g−1 utilizing BET analysis, and the band gap was determined to be 1.98 eV by DRS analysis. The photocatalysis performance of the α-Mn2O3 NPs was evaluated for degrading Eriochrome Black T (EBT) dye under visible light and degradation efficiency was 96% in 90 min. The photodegradation mechanism of EBT dye was clarified with the use of radical scavenger agents, and the degradation pathway was confirmed through Liquid Chromatography–Mass Spectrometry (LC–MS) analysis. Additionally, the produced nanoparticles could be extracted from the solution and continued to exhibit photocatalysis even after five repeated runs under the same optimal conditions. Also, the antibacterial activity of green synthesized α-Mn2O3 nanoparticles was investigated by using the broth microdilution method towards Enterococcus faecalis ATCC 29212 (Gram-positive), Staphylococcus aureus ATCC 29213 (Gram-positive), Salmonella typhimurium ATCC 14028 (Gram-negative), Klebsiella pneumoniae ATCC 7881 (Gram-negative), Escherichia coli ATCC 25922 (Gram-negative), Proteus mirabilis ATCC 7002 (Gram-negative), and Pseudomonas aeruginosa ATCC 27853 (Gram-negative) bacterial strains.

In situ NADES microwave‐mediated extraction of bioactive compounds from Beta vulgaris L. var. rubra waste

SummaryThe research focused on the recovery of bioactive compounds from beetroot waste (fresh stalks) using an innovative and microwave‐mediated (mw) procedure that could allow the simultaneous eutectic solvent preparation and matrix extraction (in situ mw NADES extraction), as a simplification of more conventional NADES (natural deep eutectic solvents) extractions. The main goal was to propose a fast and simple “one‐pot” extractive approach to obtain and screen non‐toxic, bioactive ready‐to‐use ingredients, potentially useful in food, cosmetic and pharmaceutical fields, meanwhile converting beetroot residues, from worn‐out plant matrices to recycled sources with significant added values. With this purpose, several eutectic mixtures of natural food‐grade hydrogen bond donors (choline chloride or betaine) and hydrogen bond acceptors (fructose, urea, citric acid, and glycerol) were selected and investigated (in opportune ratios) under microwave activation, considering time, temperature, and solvent‐to‐matrix ratio as the influencing variables and the total phenols content recovery as the response. By the in situ NADES microwave method developed, the best results were obtained within 5 min at 70 °C with recoveries of around 0.5 mg of polyphenols for gram of fresh stalks, assessed by the Folin–Ciocalteu test. The suitability of the NADES‐based extractives, as radical scavenging agents, was evaluated using the DPPH assay, which highlighted their good antioxidant activity; moreover, monitoring the betacyanin content by means of UV–vis spectrophotometric analyses, it was evident that NADES provide a relevant stability to the new complexes (up to 3 months) compared to water (24 h). The new in situ process proposed could be also useful for preliminary screenings of different organic matrices, simplifying workup, streamlining the procedures, and reducing costs.

Development and Validation of Derivatization Method for Simultaneous Quantitation of Asteracantha longifolia (L.) Nees Phytoconstituents by Liquid Chromatography–Electrospray Ionization–Mass Spectrometry/Mass Spectrometry

ABSTRACT Background: Betulin, lupeol, stigmasterol, and β-sitosterol are the active phytoconstituents accountable for the practical application of Asteracantha longifolia (L.) Nees in ayurvedic treatments as antitumor, hypoglycemic, aphrodisiac, antibacterial, free radical scavenging, lipid peroxidation, and hepatoprotective agent. As an essential medicinal plant in modern and traditional medicine, regularly checking raw material’s quality attributes and quantifying the phytoconstituents is indispensable. Aim: The aim of this study was to optimize derivatization conditions of these four essential phytoconstituents with p-toluenesulfonyl isocyanate (PTSI) reagent and the development of a liquid chromatography–electrospray ionization (ESI)–mass spectrometry (MS)/MS method that aids in the simultaneous detection of these four phytoconstituents. Objective: Thus, derivatization enhances sensitivity for detection in the negative mode with an electron spray ionization source and tandem mass spectroscopy. Further, the sensitive and rapid analytical method for simultaneous quantitation of betulin, lupeol, stigmasterol, and β-sitosterol is subsequently validated in line with the guidelines by ICH and used to quantify the phytoconstituents in two over-the-counter herbal formulations and one plant extract isolated at laboratory scale under batch analysis. Materials and Methods: PTSI reagent of purity <98% procured from TCI and other chromatography reagents of MS grade were utilized in the optimization of an analytical method. Results: The developed LC-ESI-MS/MS-based method demonstrated specificity for the targeted phytoconstituents, with LOD and LOQ values of < 0.13 ng/mL and 0.4 ng/mL, respectively. Linearity was established with a correlation coefficient ≥ 0.998 over a concentration range of 0.2 ng/mL to 6 ng/mL. Precision, expressed as %RSD for peak response, was ≤ 5%. The method showed satisfactory recovery for betulin (98.5%-108.3%), lupeol (95.0%-109.3%), stigmasterol (101.9%-117.0%), and β-sitosterol (99.1%-116.2%). Conclusion: The reagent PTSI reacts rapidly and forms stable derivatives. The derivatization of active phytoconstituents betulin, lupeol, stigmasterol, and β-sitosterol has enhanced the detection sensitivity of the analytical method.

Non-destructively incorporating ceria in Nafion membrane as hydroxyl radical scavenging agent for long-term PEMFC application

Aiming at enhancing the long-term operation of proton exchange membrane fuel cell (PEMFC), Nafion as a typical example of perfluorosulfonic acid proton exchange membrane is non-destructively modified by sulfonated ceria (CeO2-DS) nanoparticles via a swelling-filling strategy. CeO2-DS nanoparticles in Nafion matrix can not only act as radical scavenging agent to improve the durability of Nafion, but also assist the re-construction of the efficient proton conduction channel in the composite Nafion membrane. Both oxidative stability and proton conductivity of the Nafion membrane are therefore remarkably improved with the great mechanical and thermal stability of Nafion maintained. PEMFC equipped with the modified Nafion membrane therefore outperforms that with the pristine Nafion membrane in terms of both power output and durability. Specifically, the maximum power density of the PEMFC equipped with modified Nafion after Fenton accelerated degradation test was significantly improved by ca. 25 % compared with that of the pristine Nafion membrane. This work hence provides a facile way to improve the durability of the PEMFC for practical applications.

Effect and mechanism of phosphate enhanced sulfite activation with cobalt ion for effective iohexol abatement.

Sulfate radical (SO4•-)-based advanced oxidation processes (AOPs) from sulfite activation have recently received attention for abatement of microorganic pollutants in the aquatic environments. Trace-level Co(II) has been demonstrated to be effective for promoting sulfite activation (simplified as the Co(II)/sulfite system) and the corresponding radical formation, yet this process is challenged by the limited valence inter-transformation of Co(II)/Co(III). In order to enhance this valence inter-transformation, a novel Co(II)/HPO42-/sulfite system is developed in this work, because HPO42-, as a typical radical scavenging agent, has the advantage of complexing with Co(II) without quenching effect. In this work, complexation of Co(II) with HPO42- can regulate the electronic structure of Co(II), accelerate electron transfer, and promote valence inter-transformation of Co(II)/Co(III) during the sulfite activation process. The Co(II)/HPO42-/sulfite system exhibits superior iohexol abatement performance under circumneutral conditions. For pH 8.0 and Co(II) dose of 1 μM, the iohexol abatement efficiency is as high as 98%, which is considerably higher than that of the Co(II)/sulfite system (50%). SO4•- is identified as the predominant reactive radical contributing to iohexol abatement. The presence of HPO42- broadens the pH adaptability of the Co(II)/sulfite system for iohexol abatement. In addition, the coexisting Cl- exerts an inhibitory effect on iohexol abatement while the other cations and anions show negligible effect. The Co(II)/HPO42-/sulfite system displays good reusability and adaptability towards various organic pollutants. This study highlights the important role of complexation of Co(II) with HPO42- in sulfite activation and provides a feasible idea for abatement of the microorganic pollutants.

An Analysis of Antioxidant Therapies for COVID‐19

AbstractOxidative stress and inflammation are observed in critically ill patients with severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2). As oxidative stress is due to free radicals, free radical scavenging agents, such as vitamin C, are used in the hope of mitigating the severity of COVID‐19. In this paper an analytical model of free radical encounters within a cell is derived. It computes the effectiveness of free radical scavenging and the subsequent reduction in oxidative damage due to therapeutic intervention of exogenous antioxidants. Various publications make claims of success, albeit modest, treating critically ill COVID‐19 patients with high doses of vitamin C. The findings cast doubt on these claims and challenge the notion that any benefits attributed to vitamin C are due to free radical scavenging.

Coaxial 3D printing of hierarchical structured hydrogel scaffolds for on-demand repair of spinal cord injury.

After spinal cord injury (SCI), endogenous neural stem cells (NSCs) near the damaged site are activated, but few NSCs migrate to the injury epicenter and differentiate into neurons because of the harsh microenvironment. It has demonstrated that implantation of hydrogel scaffold loaded with multiple cues can enhance the function of endogenous NSCs. However, programming different cues on request remains a great challenge. Herein, a time-programmed linear hierarchical structure scaffold is developed for spinal cord injury recovery. The scaffold is obtained through coaxial 3D printing by encapsulating a dual-network hydrogel (composed of hyaluronic acid derivatives and N-cadherin modified sodium alginate, inner layer) into a temperature responsive gelatin/cellulose nanofiber hydrogel (Gel/CNF, outer layer). The reactive species scavenger, metalloporphyrin, loaded in the outer layer is released rapidly by the degradation of Gel/CNF, inhibiting the initial oxidative stress at lesion site to protect endogenous NSCs; while the inner hydrogel with appropriate mechanical support, linear topology structure and bioactive cues facilitates the migration and neuronal differentiation of NSCs at the later stage of SCI treatment, thereby promoting motor functional restorations in SCI rats. This study offers an innovative strategy for fabrication of multifunctional nerve regeneration scaffold, which has potential for clinical treatment of SCI. STATEMENT OF SIGNIFICANCE: Two major challenges facing the recovery from spinal cord injury (SCI) are the low viability of endogenous neural stem cells (NSCs) within the damaged microenvironment, as well as the difficulty of neuronal regeneration at the injured site. To address these issues, a spinal cord-like coaxial scaffold was fabricated with free radical scavenging agent metalloporphyrin Mn (III) tetrakis (4-benzoic acid) porphyrin and chemokine N-cadherin. The scaffold was constructed by 3D bioprinting for time-programmed protection and modulation of NSCs to effectively repair SCI. This 3D coaxially bioprinted biomimetic construct enables multi-factor on-demand repair and may be a promising therapeutic strategy for SCI.

Doped Graphene Quantum Dots as Biocompatible Radical Scavenging Agents.

Oxidative stress is proven to be a leading factor in a multitude of adverse conditions, from Alzheimer's disease to cancer. Thus, developing effective radical scavenging agents to eliminate reactive oxygen species (ROS) driving many oxidative processes has become critical. In addition to conventional antioxidants, nanoscale structures and metal-organic complexes have recently shown promising potential for radical scavenging. To design an optimal nanoscale ROS scavenging agent, we have synthesized ten types of biocompatible graphene quantum dots (GQDs) augmented with various metal dopants. The radical scavenging abilities of these novel metal-doped GQD structures were, for the first time, assessed via the DPPH, KMnO4, and RHB (Rhodamine B protectant) assays. While all metal-doped GQDs consistently demonstrate antioxidant properties higher than the undoped cores, aluminum-doped GQDs exhibit 60-95% radical scavenging ability of ascorbic acid positive control. Tm-doped GQDs match the radical scavenging properties of ascorbic acid in the KMnO4 assay. All doped GQD structures possess fluorescence imaging capabilities that enable their tracking in vitro, ensuring their successful cellular internalization. Given such multifunctionality, biocompatible doped GQD antioxidants can become prospective candidates for multimodal therapeutics, including the reduction of ROS with concomitant imaging and therapeutic delivery to cancer tumors.

Chemical Profile and Bioactivity Evaluation of Salvia Species from Eastern Europe.

The Salvia genus comprises about 1000 species endowed with medicinal, aromatic, cosmetic, and ornamental applications. Even though the genus is one of the most-studied taxa of the Lamiaceae family, data on the chemical composition and biological properties of certain locally used Salvia species are still scarce. The present work aimed to evaluate the phytochemical profile and antimicrobial, antioxidant, and cytotoxic potential of ten Salvia species that grow in Eastern Europe (e.g., the Republic of Moldova). LC-HRMS/MS metabolite profiling allowed for the annotation of 15 phenolic and organic acids, 18 flavonoids, 19 diterpenes, 5 sesterpenes, and 2 triterpenes. Multivariate analysis (e.g., principal component analysis, hierarchical cluster analysis) revealed that S. austriaca, S. nutans, and S. officinalis formed individual clusters, whereas the remaining species had a similar composition. S. officinalis showed the highest activity against Staphylococcus aureus and Streptococcus pneumoniae (MIC = 0.625 mg/mL). As evaluated in DPPH, ABTS, and FRAP assays, S. officinalis was one of the most potent radical scavenging and metal-reducing agents (CE50 values of 25.33, 8.13, and 21.01 μg/mL, respectively), followed by S. verticillata, S. sclarea, S. kopetdaghensis, S. aethiopis, and S. tesquicola. Pearson correlation analysis revealed strong correlations with rosmarinic acid, luteolin-O-glucuronide, and hydroxybenzoic acid. When the cytotoxic activity was evaluated in human breast carcinoma MCF-7 and MDA-MB-231 cells, no significant reduction in cell viability was observed over the concentrations ranging from 25 and 100 μg/mL. The results confirm the potential use of understudied Salvia species as promising sources of antioxidant compounds for developing novel pharmaceutical, nutraceutical, or cosmeceutical products.

Fabrication of Highly Thermally Resistant and Self-Healing Polysiloxane Elastomers by Constructing Covalent and Reversible Networks.

The fabrication of self-healing elastomers with high thermal stability for use in extreme thermal conditions such as aerospace remains a major challenge. A strategy for preparing self-healing elastomers with stable covalent bonds and dynamic metal-ligand coordination interactions as crosslinking sites in polydimethylsiloxane (PDMS) is proposed. The added Fe (III) not only serves as the dynamic crosslinking point at room temperature which is crucial for self-healing performance, but also plays a role as free radical scavenging agent at high temperatures. The results show that the PDMS elastomers possessed an initial thermal degradation temperature over 380°C and a room temperature self-healing efficiency as high as 65.7%. Moreover, the char residue at 800°C of PDMS elastomer reaches 7.19% in nitrogen atmosphere, and up to 14.02% in air atmosphere by doping a small amount (i.e., 0.3 wt%) of Fe (III), which is remarkable for the self-healing elastomers that contain weak and dynamic bonds with relatively poor thermal stability. This study provides an insight into designing self-healing PDMS-based materials that can be targeted for use as high-temperature thermal protection coatings.

Novel Virus Air Sampler Based on Electrostatic Precipitation and Air Sampling of SARS-CoV-2.

The assessment of airborne viruses in air is a critical step in the design of appropriate prevention and control measures. Hence, herein, we developed a novel wet-type electrostatic air sampler using a viral dissolution buffer containing a radical scavenging agent, and verified the concentration of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in the air of hospital rooms inhabiting coronavirus disease 2019 (COVID-19) patients and public areas. RNA damage caused by corona discharge was negligible when Buffer AVL was used as the collecting electrode. The viral RNA concentration in the air of the room varied by patient: 3.9 × 103 copy/m3 on the 10th day after onset in a mild case and 1.3 × 103 copy/m3 on the 18th day in a severe case. Viral RNA levels were 7.8 × 102 and 1.9 × 102 copy/m3 in the air of the office and food court, respectively, where people removed their masks when eating and talking, but it remained undetected in the station corridor where all the people were wearing masks. The assessment of airborne SARS-CoV-2 RNA using the proposed sampler can serve as a basis for the safe discontinuation of COVID-19 isolation precautions to identify exposure hotspots and alert individuals at increased infection risks.

Free radical scavenging activity, pancreatic lipase and a-amylase inhibitory assessment of ethanolic leaf extract of Phyllanthus amarus

Oxidative stress is associated with the pathogenesis of diabetes and obesity. The key enzymes involved in the carbohydrate and lipid metabolisms are a-amylase and pancreatic lipase respectively. The phytochemicals present in medicinal plants are known to be potent free radical scavenging agents and great inhibitors of metabolizing enzymes. Phyllanthus amarus leaves have antioxidant, anti-diabetic, and anti-obesity properties. This research is aimed at elucidating the carbohydrate and lipid metabolism inhibitory activities of P. amarus leaves through in-vitro screening. The phytochemical screening revealed that P.amarus is having high phenolic, flavonoid, tannin, and saponin content. The total protein content of P.amarus showed 2.720±0.001 mg BSAE/g. Diphenyl-2-picrylhydrazyl (DPPH) assay showed 0.0001mg/mL, Nitric oxide assay revealed 0.452 mg/mL, Ferric Reducing Antioxidant Power (FRAP) assay showed a value of 0.132±0.010 mg RE/g, Total antioxidant capacity (TAC) indicated a value of 2.217±0.002 mg GAE/g and 2,2-azino-bis(3-ethylbenzotiazoline)-6-sulfonic acid (ABTS) inhibitory activity at the peak concentration (1.2 mg/mL) was 40.29%. The enzyme inhibitory assessment showed a decrease in a-amylase activity as the concentration increased while there was a slight decrease in a-lipase activity but a slight increase at 18.75 mg/mL.

Novel Hybrid Indole-Based Caffeic Acid Amide Derivatives as Potent Free Radical Scavenging Agents: Rational Design, Synthesis, Spectroscopic Characterization, In Silico and In Vitro Investigations

Antioxidant small molecules can prevent or delay the oxidative damage caused by free radicals. Herein, a structure-based hybridization of two natural antioxidants (caffeic acid and melatonin) afforded a novel hybrid series of indole-based amide analogues which was synthesized with potential antioxidant properties. A multiple-step scheme of in vitro radical scavenging assays was carried out to evaluate the antioxidant activity of the synthesized compounds. The results of the DPPH assay demonstrated that the indole-based caffeic acid amides are more active free radical scavenging agents than their benzamide analogues. Compared to Trolox, a water-soluble analogue of vitamin E, compounds 3a, 3f, 3h, 3j, and 3m were found to have excellent DPPH radical scavenging activities with IC50 values of 95.81 ± 1.01, 136.8 ± 1.04, 86.77 ± 1.03, 50.98 ± 1.05, and 67.64 ± 1.02 µM. Three compounds out of five (3f, 3j, and 3m) showed a higher capacity to neutralize the radical cation ABTS•+ more than Trolox with IC50 values of 14.48 ± 0.68, 19.49 ± 0.54, and 14.92 ± 0.30 µM, respectively. Compound 3j presented the highest antioxidant activity with a FRAP value of 4774.37 ± 137.20 μM Trolox eq/mM sample. In a similar way to the FRAP assay, the best antioxidant activity against the peroxyl radicals was demonstrated by compound 3j (10,714.21 ± 817.76 μM Trolox eq/mM sample). Taken together, compound 3j was validated as a lead hybrid molecule that could be optimized to maximize its antioxidant potency for the treatment of oxidative stress-related diseases.

UV and Zero-Valent Iron (ZVI) Activated Continuous Flow Persulfate Oxidation of Municipal Wastewater

Currently, sulfate-radical-based advanced oxidation processes are promising candidates to become viable post-treatment processes for wastewater purification. In this work, a continuous flow UV light/persulfate (PS)/zero-valent iron (ZVI) system has been applied for wastewater treatment for the first time. The influence of certain photo-Fenton-like process parameters, such as space time, PS concentration, and PS to ZVI molar ratio, on the removal of total organic carbon (TOC), was examined using the Box–Behnken design. First, synthetic municipal wastewater was used for the experiments, and the polynomial regression model was constructed utilizing the real data by using the response surface methodology (RSM). The adequacy of the RSM model was assessed by analysis of variance, which showed that the model was reliable and could be applied to improve the process parameters for TOC removal. Moreover, both synthetic and real municipal wastewater were spiked with carbamazepine (CBZ), which is commonly prescribed as an antiepileptic drug, to investigate its fate in the UV/PS/ZVI system. With a space time of 60 min, PS concentration of 60 mM, and PS to ZVI molar ratio of 15, it was possible to remove 71% of TOC and completely remove CBZ from the synthetic municipal wastewater, whereas a 60% TOC removal and complete removal of CBZ were achieved at a space time of 50 min, PS concentration of 50 mM, and PS/ZVI molar ratio of 15 for the real municipal wastewater. This difference in TOC removal could possibly be linked to the complex matrix of the real wastewater and the presence of radical scavenging agents.

Copper oxide nanoparticles using Mentha spicata leaves as antibacterial, antibiofilm, free radical scavenging agent and efficient photocatalyst to degrade methylene blue dyes

In this findings, CuO NPs were made by an easy, eco-friendly, and economical approach using the leaf extract of M. spicata . The prepared Ms-CuO NPs exhibited characteristic absorbance peak at 320 nm with a band gap of 3.87 eV. XRD revealed the presence of crystalline particle with size of 11.28 nm as determined by the Scherrer equation. FTIR revealed the role of various functional molecules in the bio-reduction of copper salts to copper ions (Cu 2+ ). The spherical shaped particles with the mean size of 36 nm were visualized through TEM microscopic image. EDX analysis also confirmed the elemental signals of Cu (91.58%) and O (8.42%) respectively. The biosynthesized Ms-CuO NPs displayed a significant inhibition of Gram-positive Streptococcus pyogenes and Staphylococcus aureus at all tested concentrations. The inhibition size against S. pyogenes and S. aureus was 27.5 ± 0.5 mm and 26.2 ± 0.2 mm at 100 µg mL −1 respectively. On the other hand, the inhibition against K. pneumoniae and E. coli was 17.4 ± 0.6 mm and 18.2 ± 0.1 mm at 100 µg mL −1 respectively. Moreover, a significant inhibition of H 2 O 2 (84%) at 100 µg mL −1 demonstrates the free radical scavenging activity of Ms-CuO NPs. Furthermore, the Ms-CuO NPs have shown excellent degradation potential for industrial dyes i.e., Methylene blue (MB) and was noticed by the gradual decrease in the absorbance (at 460 nm) within 7 h of reaction. The percentage of MB dye degraded was 34% at 1 h which was substantially increased to 98% after 7 h. This study suggests that the Ms-CuO NPs may serve as a promising bactericidal, antibiofilm and antioxidant agent. Also, Ms-CuO NPs could be effectively used in the purification of water bodies contaminated with harmful industrial dyes to reduce toxicity. • M. spicata leaf extract based CuO NPs were synthesized and characterized. • Ms-CuO NPs have shown significant antibacterial and antibiofilm effects. • Ms-CuO NPs have shown H 2 O 2 radical scavenging activity. • Ms-CuO NPs efficiently degraded the methylene blue dye.