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This work demonstrates facile synthesis of Tb-doped ZnO nanoparticles and investigates their structural, optical, electrochemical, photocatalytic, and antibacterial performance. XRD patterns of undoped and doped ZnO nanoparticles confirm a hexagonal wurtzite structure. TEM and SAED reveals that the particle size is 14–38 nm. SEM images show that ZnO and Tb-doped ZnO nanoparticles have smooth surfaces, and elemental composition was confirmed by EDX analysis. UV–Visible spectrophotometry studies, reveals that the band gap narrows with increasing Tb concentration. Photoluminescence spectra at room temperature showed a band at 538 nm, indicating zinc vacancies and green emission. Tb-doped ZnO with x = 0.075 exhibited the highest photocatalytic activity for degrading Rose Bengal dye compared to other photocatalysts. The electrochemical behaviour of Catechol (CC), Hydroquinone (HQ), and Bisphenol-A (BPA) at Tb–ZnO/MCPE was studied. The modified electrode process for CC and BPA was adsorption-controlled, and simultaneous recognition of CC, HQ, and BPA was achieved, showing an increase in current. Electro polymerization of poly (Congo red) on Tb–ZnO/MCPE confirmed clean deposition on the surface, enhancing electrocatalytic activity. The antibacterial efficacy was tested using the traditional disc diffusion method, showing effective inactivation of bacterial strains, including pathogens such as S. aureus (G+) and E. coli (G-). [Display omitted] • This work demonstrates the facile synthesis of ZnO and Tb doped nanoparticles via chemical co-precipitation process. • The XRD pattern appearance hexagonal wurtzite structure. TEM and SAED reveal particle sizes of 14–38 nm. SEM and EDX confirm morphology and elemental composition. • Higher Tb doping exhibit the highest photocatalytic activity in degrading Rose Bengal dye. And the antibacterial activity, tested via disc diffusion, effectively inactivates S. aureus (G+) and E. coli (G−) bacterium. • The sweep rate confirms that the modified electrode process of CC and BPA at the PCRTZO/MCPE was adsorption controlled. Tb–ZnO/MCPE electrode simultaneously detects CC, HQ and BPA with distinct current increases. • Electro polymerization of poly (Congo red) on Tb–ZnO/MCPE confirms Congo red deposition on the electrode surface. [ABSTRACT FROM AUTHOR]

The reaction center-light-harvesting complex 1 (RC-LH1) plays an essential role in the primary reactions of bacterial photosynthesis. Here, we present high-resolution structures of native monomeric and dimeric RC-LH1 supercomplexes from Rhodobacter (Rba.) blasticus using cryo-electron microscopy. The RC-LH1 monomer is composed of an RC encircled by an open LH1 ring comprising 15 aß heterodimers and a PufX transmembrane polypeptide. In the RC-LH1 dimer, two crossing PufX polypeptides mediate dimerization. Unlike Rhodabacter sphaeroides counterpart, Rba. blasticus RC-LH1 dimer has a less bent conformation, lacks the PufY subunit near the LH1 opening, and includes two extra LH1 aß subunits, forming a more enclosed S-shaped LH1 ring. Spectroscopic assays reveal that these unique structural features are accompanied by changes in the kinetics of quinone/quinol trafficking between RC-LH1 and cytochrome bc1. Our findings reveal the assembly principles and structural variability of photosynthetic RC-LH1 supercomplexes, highlighting diverse strategies used by phototrophic bacteria to optimize light-harvesting and electron transfer in competitive environments. [ABSTRACT FROM AUTHOR]

Here we illustrate the use of dimethylglyoximate (DMG) as shape directing agent for the synthesis of nickel oxide nanowires (NiONWs) via hydrothermal process followed by calcination at elevated temperature. As-prepared NiONWs were characterized through scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) techniques and Fourier Transform Infra-red (FTIR) spectroscopy. The surface area of 27 m2 g–1 and pore diameter of 22 nm was true for the product. The prepared NiONWs were drop casted over the active surface of glassy carbon electrode (GCE) to apply it for the electrochemical sensing of hydroquinone based on cyclic voltammetry (CV) and amperometry techniques. The phosphate buffer solution (PBS) of pH 5.8 was used for the measurement of hydroquinone during electrochemical investigation. The developed sensor displayed a wide linear range of 0.5 to 11 µM for hydroquinone detection with sensitivity of 200 µA mM–1 cm–2 and limit of detection (LOD) equal to 0.01 µM. The sensor was further examined and found to be highly stable and extremely selective for the oxidation of hydroquinone. The sensor was successfully applied for amperometric detection of hydroquinone from water samples. [ABSTRACT FROM AUTHOR]

Electrochemical reduction of dioxygen (O2) in the presence of benzene‐1,4‐diol (hydroquinone) in N,N‐dimethylformamide (DMF) was examined using cyclic voltammetry and digital simulation techniques. The presence of hydroquinone modified the quasi‐reversible cyclic voltammograms (CV) of O2, resulting in formation of a superoxide radical anion (O2•−), which was scavenged by hydroquinone to form quinone radical anion and hydroperoxide. This reaction proceeded via a two‐proton‐coupled electron transfer (2PCET) mechanism with superior reaction kinetics. Digital simulations of the CVs elucidated the details of the 2PCET process, which involved heterogeneous electrochemical reactions and homogeneous solution reactions between the electrogenerated O2•− and hydroquinone. The thermodynamic and kinetic parameters of 2PCET were obtained from simulation analyses, which included three elementary steps: (i) formation of the prereactive complex from the free reactants, (ii) intracomplex 2PCET forming the product complex via a transition state, and (iii) dissociation of the product complex yielding free products. These parameters provide essential information for the development of artificial electron‐transfer catalysts and electron transfer carriers using hydroquinone derivatives. [ABSTRACT FROM AUTHOR]

Effectively detecting catechol (CC) and hydroquinone (HQ) simultaneously is crucial for environmental protection and human health monitoring. In the study presented herein, a novel electrochemical sensor for the sensitive simultaneous detection of CC and HQ was constructed based on an electrochemically reduced graphene oxide (ERGO)-modified multi-walled carbon nanotube paste electrode (MWCNTPE). Scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy and electrochemical techniques were utilized to characterize the sensing interface and investigate the sensing mechanism. Under the optimal detection conditions, the oxidation peak currents of CC and HQ show a good linear relationship with their concentrations in the range of 0.4–400 μM with a detection limit of 0.083 μM for CC and 0.028 μM for HQ (S/N = 3). Moreover, the sensor exhibits good performance and can be applied successfully in the simultaneous detection of CC and HQ in tap water samples and urine samples with satisfactory results, indicating its promising application prospects. [ABSTRACT FROM AUTHOR]

This study shows that incorporating taro carbon (TC) into a glassy carbon electrode (GCE) significantly enhanced surface charge transfer characteristics and conductivity and successfully separated the hydroquinone (HQ) and catechol (CT). Moreover, TC on the GCE surface reduced the overpotential of HQ and CT oxidation. Using X‐ray diffraction (XRD) analysis, field‐emission scanning electron microscopy (FESEM), and energy dispersive spectroscopy (EDS), the surface morphology and elemental composition of TC was investigated. The enhanced electron transfer process at TC‐GCE was studied using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) investigation. Scan rate analysis revealed that HQ and CT exhibited a higher oxidation affinity at TC‐GCE, with diffusion‐regulated anodic processes. Quantitative analysis showed a linear detection range of 5–200 μM for both HQ and CT, with LOD values of 0.47 μM for HQ and 0.51 μM for CT respectively. The modified electrode showed excellent selectivity, stability, and high recovery rates for detecting HQ and CT in tap water. [ABSTRACT FROM AUTHOR]

Post inflammatory hyperpigmentation (PIH) affects all skin types with a heightened predilection for darker skin tones. Its course is chronic once developed and treatment is often difficult. This systematic review aims to summarize the treatment outcomes for PIH with a focus on skin of colour (SOC) individuals. A literature search was conducted using MEDLINE (from 1946), Embase (from 1974), PubMed, and Cochrane in adherence to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guideline. Results from 48 studies summarized 1356 SOC individuals. The mean age was 29 years (n = 1036) and 78% were female (n = 786). The ethnic prevalence was 70% Black, 27% Asian, and 3% Latin. Overall, 20% were Fitzpatrick skin type (FST) III, 40% FST IV, 34% FST V, and 6% FST VI. Most cases were precipitated by inflammatory conditions (89%) and localized to the face (83%). The most frequently reported interventions were topical retinoids (22%) and laser therapy (17%). Partial improvement was seen in 85% and 66% of participants, respectively. Laser was the only intervention that offered complete resolution in a subgroup of patients (26%); however, there were reported cases of PIH exacerbation following treatment. Chemical peels (9%) and hydroquinone (7%) were among other treatments with less effective outcomes. PIH and its persistence is a prevalent issue, significantly affecting many affected individuals with darker skin tones. Our results show a lack of robust efficacy across all treatment modalities. There is considerable room for improvement in interventions for at-risk populations. [ABSTRACT FROM AUTHOR]

Abiotic humification, dominated by catalytic oxidation, is one of the critical mechanisms for organic carbon preservation in nature. However, the effects of biochar catalysis on abiotic humification have not yet been elucidated. This study investigated the catalytic power of biochar from walnut shells at different temperatures (300 °C, 600 °C, and 900 °C) for the abiotic transformation of hydroquinone (HQ) as a representative polyphenol. All the biochar samples catalyzed HQ polymerization, resulting in the formation of humic polymers such as fulvic acids (FAs) and humic acids (HAs). Light and oxygen promoted HA formation. HO• was detected in the BC600–HQ reaction system, and HO• quenching resulted in a 41.22% decrease in HA production, indicating that HO• plays a major role in the oxidative polymerization. In the proposed pathway for the abiotic humification, biochar active sites and generated reactive oxygen species accept an electron from HQ, resulting in oxidation to (semi)quinone radicals, which subsequently undergo cleavage or a coupling reaction to form the oligomerized products. Under BC600 catalysis, the weight-average molecular weight (Mw) of the reaction products of HQ, glucose, and glycine reached 14,449 Da. These findings provide new insights into the application potential of biochar for promoting soil carbon sequestration. [ABSTRACT FROM AUTHOR]

Background: There is controversy on the efficacy and safety of chemical peels used to treat Hispanic women with melasma. Studies evaluating superficial peels for melasma are limited due to lack of controls, blinding or objective assessment tools, poor inclusion of darker phototypes, and small sample number. Objectives: We sought to evaluate the safety and efficacy of trichloroacetic acid (TCA) peels when added to hydroquinone and tretinoin in the treatment of melasma in Hispanic women. Methods: A single blinded, prospective, split-face trial of superficial TCA peels was performed on Hispanic women with melasma. Topical hydroquinone and tretinoin were used on both sides. A total of four monthly peels were performed on one side. The relative reduction of melasma severity was evaluated using narrowband reflectance spectrophotometry (NRS), Modified Melasma Area and Severity Index (mMASI), and Global Melasma Severity Assessment (GMSA). Adverse events were monitored. Results: Thirty-three patients completed the study. Pigment intensity was reduced on both sides based on all measures. A greater improvement of mMASI and GMSA was achieved on the peeled side. Limitations: Limitations include the single-center study design with one blinded investigator. Conclusion: Based on our results, TCA peels appear to be safe and effective in augmenting treatment response on melasma patients with phototypes III and IV treated with hydroquinone and tretinoin. [ABSTRACT FROM AUTHOR]

Objective: Melasma is a multifactorial, chronic, acquired skin disorder of hyperpigmentation. Terminalia chebula Retz. (T. chebula) has shown antioxidant, anti-inflammatory and tyrosinase enzyme inhibitory activities. So, the present study was designed to evaluate the efficacy of T. chebula 5% cream compared to hydroquinone 2% cream in treating patients with melasma. Materials and Methods: The formulation of T. chebula 5% cream was prepared. The stability and release study of the cream were performed. In this randomized, controlled, triple-blind clinical trial, participants with facial melasma were randomly assigned to receive T. chebula 5% cream or hydroquinone 2% cream at bedtime for 12 weeks. Modified Melasma Area and Severity Index (mMASI) scores were recorded for all the participants at the baseline and 4, 8, and 12 weeks after initiating the study. Results: No statistically significant differences regarding mMASI scores were detected between T. chebula and hydroquinone groups at each time point. The reduction in mMASI scores was statistically significant (p<0.05) in T. chebula group 4, 8, and 12 weeks after initiating the study. However, it reached statistical significance (p<0.05) in hydroquinone group 8, and 12 weeks after the study initiation. The frequencies of side effects especially skin irritation were significantly (p<0.05) lower in T. chebula group. Conclusion: T. chebula 5% cream could be as effective as hydroquinone 2% cream in treating melasma with fewer side effects. [ABSTRACT FROM AUTHOR]

Fly ash, poses environmental risks if not managed responsibly, potentially causing soil, air, and water pollution. However, within a circular economy framework, the reuse of fly ash can mitigate these issues. In this investigation, fly ash (FA) sourced from thermal power plants has been employed following alkaline activation to improve the activity of carbon paste electrode (CPE) toward the detection of bisphenol A (BPA). The initial phase involved characterizing both FA and the modified FA (MFA) using scanning electron microscopy (SEM), X-ray Fluorescence (XRD), and X-ray diffraction (XRD) techniques. Afterwards, the cost-effective electrochemical sensor (MFA/CPE) was utilized for the bisphenol A (BPA) detection in water samples. Several parameters influencing the anodic striping voltammetric (ASV) response of BPA have been carefully optimized. In particular the MFA/CPE ratio, the pH of the medium as well as the time and the deposition potential. The optimum amount of activated FA (MFA) used in carbon paste modification, exhibiting the best electrocatalytic activity for BPA oxidation, was 2.5%. Under optimal experimental conditions, the calibration plot exhibits linearity within the concentration range of 2.5 to 125 µM. Furthermore, the developed sensor demonstrated low detection limits of 0.31 µM and quantification capability at approximately 1.02 µM, improving its sensitivity for the detection of BPA. Interference experiments show that Hydroquinone (HQ) and Catechol (CC) do not exert any impact on the accuracy of BPA determination. [ABSTRACT FROM AUTHOR]

Background: Clobetasol has demonstrated remarkable results in treating melasma within a short time frame; however, its use is limited because of the risk of local side effects. To date, there is no controlled trial on sequential clobetasol/hydroquinone for melasma. This study aimed to investigate the tolerability and efficacy of 0.05% clobetasol followed by 4% hydroquinone (CLOB‐HQ) in comparison to the isolated use of 4% hydroquinone (HQ). Methods: A double‐blinded, randomized clinical trial involving 50 women with facial melasma was performed. They were directed to apply 0.05% clobetasol every night for 14 days, followed by 4% hydroquinone for 46 days (CLOB‐HQ group), or the use of hydroquinone for 60 days (HQ group). Evaluations were carried out at inclusion, and after 14 and 60 days of treatment, measuring modified Melasma Area and Severity Index (mMASI), Melasma Quality of Life scale (MELASQoL), and colorimetry. The Global Aesthetic Improvement Scale (GAIS) was assessed by a blinded evaluator. Results: There was no difference in the main outcomes at D14 and D60 (P > 0.1). For CLOB‐HQ, the mean (CI 95%) reduction in mMASI was 13.2% (5.1–21.3%) and 43.1% (32.2–54.0%) at D14 and D60, and for HQ, they were 10.6% (5.9–27.5%) and 44.8% (33.2–52.3%). The MELASQoL, colorimetric luminosity, and GAIS showed a progressive improvement for both groups despite no difference between them. No severe side effects were identified. No cases of telangiectasias, atrophy, or perioral dermatitis were associated with the use of CLOB. Conclusion: The sequential CLOB‐HQ regimen was safe and well tolerated, even though its efficacy was not different from HQ after 14 or 60 days of treatment. Based on these findings, the use of clobetasol 14 days before hydroquinone is not advisable for the treatment of melasma. [ABSTRACT FROM AUTHOR]

This study reports the degradation of hydroquinone using lab-scale hydrodynamic cavitation approach (aswirl-type micro-nano bubble reactor), which is considered a green and effective method. The effects of inlet pressure, gas flow rate, pH and initial hydroquinone concentration on hydroquinone degradation were analysed based on experimental research. After experiments investigation, it was concluded that with pH 7.38, hydroquinone concentration of 50 mg/L, and int pressure of 0.2 MPa, the degradation efficiency of hydroquinone reached 91.25% in wastewater. Furthermore, this study also investigated the degradation effect of hydroquinone wastewater by hydrodynamic cavitation combined with persulfate oxidation (HC + PS). The kinetics of hydroquinone degradation by HC or PS oxidation alone and HC + PS oxidation were also examined. Compared with the degradation method alone, the degradation of hydroquinone by HC + PS was more pronounced, and the enhancement factor was 4.55, which indicates that HC greatly enhances the oxidation capacity of PS. In additon, from viewpoint of energy consumption and operating cost, the synergy of HC + PS (1.05 mM) is also the most promising combination. Based on the detection results of the Gas chromatography-mass spectrometry (GC-MS) the possible degradation pathways of hydroquinone were analysed: under the action of ·OH and the high temperature and pressure by cavitation process, the hydroquinone molecule undergoes dehydrogenation and ring-opening reaction, demethylation and decarboxylation reaction to produce intermediate products, which are finally converted into CO2 and H2O in micro-nano bubble cavitation process. [ABSTRACT FROM AUTHOR]

BACKGROUND: The present work describes the facile, fast and economic base‐catalyzed acylation of benzenediols with vinyl acetate. The Hirshfeld surface analysis of benzene‐1,4‐diol O,O′‐diacetate is also described. NaOH, KOH and K2CO3 were the bases used for the catalysis of the acylation of benzene‐1,x‐diols (x = 2, 3, 4) with vinyl acetate to obtain the corresponding O,O′‐diacetyl derivatives. RESULTS: The yields were quite good, up to 99% under solvent‐free conditions. This method represents an alternative 'green' process for the preparation of O‐acetyl derivatives of hydroxyaryls. The benzene‐1,4‐diol O,O′‐diacetate crystal structure was obtained and described using Hirshfeld surface analysis. A noticeable contribution of the C⋯H contacts is shown (16.7%), despite the insignificant area of the Hirshfeld surface occupied by the carbon atoms (9.4%). By using two‐dimensional fingerprint plots, it was proved that C⋯H contacts were due to the presence of π‐stacking. The O⋯H contacts (41.4%) were the most numerous ones, relating mainly to typical hydrogen bonds (de + di ≈ 2.6 Å). The high saturation of the C⋯H and O⋯H contacts (enrichment ratios (E) = 1.30 and 1.36, respectively), despite their smaller contribution to the overall surface as compared to the H⋯H contacts (E = 0.84), is shown. CONCLUSION: The novelty of this work is the development of a method based on an inexpensive, safe and easy‐to‐use catalyst (K2CO3). This method is fast with high yields. Besides, it may be used for acylation at an industrial scale. © 2024 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

Prolonged exposure to hydroquinone (HQ), a metabolite of benzene, can cause severe haematologic disorders in humans. However, the mechanism is still unclear. In the present study, we investigated whether HQ can induce haematological diseases through ferroptosis, which is another form of cell death apart from apoptosis. The results showed that HQ inhibited the viability of Jurkat cells in a dose-dependent and time-dependent manner. The half inhibitory concentrations (IC50s) of HQ-treated Jurkat cells for 12 h, 24 h and 48 h were 107.16 μmol/L, 33.29 μmol/L, and 14.78 μmol/L. The exposure of Jurkat cells to HQ increased intracellular Fe 2 + , malondialdehyde (MDA) and lipid reactive oxygen species (ROS) levels and down-regulated glutathione (GSH) levels. We used erastin-treated cells as a positive control and cells treated with HQ combined with deferoxamine mesylate (DFO) and ferrostain-1 (Fer-1)-treated cells as the negative controls. DFO and Fer-1 partially restored the degradation of cell viability and GSH content and the accumulation of Fe 2 + , MDA and lipid ROS caused by HQ. In addition, we found that cellular mitochondria in the HQ-treated group showed a decrease in volume, an increase in the density of the bilayer membrane and a decrease or disappearance of mitochondrial cristae. Changes in the erastin-treated group were similar to those in the HQ-treated group. We inferred that HQ induces ferroptosis in Jurkat cells. Subsequently, we found that HQ up-regulated the levels of transferrin receptor 1 (TFRC) mRNA and protein expression and down-regulated FTH1, SLC7A11 and synthetic substrate of antioxidant enzyme 4 (GPX4) mRNA levels and protein expression levels. However, the exposure of Jurkat cells to HQ with DFO and Fer-1 alleviated these changes. Notably, the activation of TFRC and the inhibition of FTH1 and System X c − (cystine–glutamate reverse transporter protein) /GPX4 were associated with HQ-induced ferroptosis. These results provide novel insights into how HQ exacerbates haematopoietic cytotoxicity and provide potential targets for the prevention of HQ-induced diseases. [ABSTRACT FROM AUTHOR]

An electrochemical analysis of Hydroquinone (HDQ) and Catechol (CTL) was analyzing in a 0.2 M phosphate buffer solution (PBS) using a modest constructing electrochemically polymerized (EP) L-Alanine (ALN) modified carbon nanotube paste electrode (EP(ALN)MCNTPE). The electrochemical, structural, resistive, and conductive properties of both the EP(ALN)MCNTPE and bare carbon nanotube paste electrode (BCNTPE) surfaces were studied by cyclic voltammetry (CV), Differential pulse voltammetry (DPV), scanning electron microscopy (SEM) and electrochemical impedance Spectroscopy (EIS) techniques. The EP(ALN) presented electrode surface exhibits significantly enhanced peak currents compared to BCNTPE. The optimizing experimental parameters, including PBS in pH, scan rate and concentration variation, also constructed to achieving high selectivity and sensitivity for the analysis of HDQ. The oxidation and reduction peak currents of HDQ exhibited improvement with increasing concentrations ranging from 0.2 µM to 4.0 µM. The achieved lower limit of detection (LOD) and lower limit of quantification (LOQ) were 0.174 µM and 0.582 µM, alone and it shows good analytical responses. The EP(ALN)MCNTPE shows good stability, reproducibility, and repeatability for HDQ. The electrochemically developed sensor proved applicable for both quantitative and qualitative analysis of HDQ in a cosmetic sample. [ABSTRACT FROM AUTHOR]

The microsomal metabolism of phenol (11 °C) over an annual reproductive cycle from June to December was studied using fall spawning adult brook trout (Salvelinus fontinalis). Hepatic microsomes were isolated from three male and three female fish each month. Incubations were optimized for time, cofactor concentration, pH, and microsomal protein concentration. The formation of phase I ring-hydroxylation metabolites, i.e., hydroquinone (HQ) and catechol (CAT), was quantified by HPLC with dual-channel electrochemical detection. Sample preparation and chromatographic conditions were optimized to achieve the separation and sensitivity required for the analysis of these labile products. Biotransformation of phenol over a range of substrate concentrations (1 to 150 mM) was quantified for the calculation of Michaelis–Menten constants (Km and Vmax) for each month. Results indicate a nearly equal production of HQ and CAT among males and females in late June. At the peak of maturity in October, there was an approximate ten-fold greater production of ring-hydroxylation metabolites noted in females in comparison with males on a total liver basis. In vitro phase II biotransformation of phenol glucuronidation was assessed by determining the Michaelis–Menten constants (Km, Vmax) using brook trout hepatic microsomes over a range of substrate concentrations (1 to 60 mM). Initially, there were no significant differences in the glucuronide rate of formation (pmol/min/mg protein) or total capacity (nmol/min/liver) between females and males. At the peak of maturation, the maximum rate of glucuronide formation was 4-fold less in females; however, the total capacity was 2-fold less in females due to the increased liver size in the females. The alterations in biotransformation coincided with increases in the hepatic and gonadal somatic indices and with changes in plasma hormone concentrations. These experiments provide insight into the metabolic deactivation of xenobiotics and to provide data for the prediction of altered hepatic biotransformation rates and pathways during the reproductive cycle. [ABSTRACT FROM AUTHOR]

We describe two operating modes for the same potentiostat, where the redox processes of hydroquinone in a hydrochloric acid medium are contrasted for cyclic voltammetry (CV) as functions of a digital/staircase scan and an analogue/linear scan. Although superficially there is not much to separate the two modes of operation as an end user, differences can be seen in the voltammograms while switching between the digital and analogue modes. The effects of quantization clearly have some impact on the measurements, with the outputs between the two modes being a function of the equivalent-circuit model of the electrochemical system under investigation. Increasing scan rates when using both modes produces higher peak redox currents, with the differences between the analogue and digital modes of operation being consistent as a function of the scan rate. Differences between the CV loops between the analogue and digital modes show key differences at certain points along the scans, which can be attributed to the nature of the electrolyte affecting the charging and discharging processes and consequently changing the peak currents of the redox processes. The faradaic processes were shown to be independent of the scan rates. Simulations of the equivalent-circuit behaviour show differences in the responses to different input signals, i.e., the step and ramp responses of the system. Both the voltage and current steps and ramp responses showed the time-domain behaviour of distinct elements of the equivalent electrochemical circuit model as an approximation of the applied digital and analogue CV input signals. Ultimately, it was concluded that similar parameters between the two modes of operation available with the potentiostat would lead to different output voltammograms and, despite advances in technology, digital systems can never fully emulate a true analogue system for electrochemical applications. These observations showcase the value of having hardware capable of true analogue characteristics over digital systems. [ABSTRACT FROM AUTHOR]

The development of an efficient, precise, and reliable method for identifying hazardous substances in environmental samples has drawn a lot of attention in the current research environment. The process of electrochemical polymerization produces conducting and non-conducting polymers from electroactive monomers on the electrode surface. By adjusting specific interactions between the functional groups on the polymer and the electrode surface, the electrodes modified by electropolymers can be tuned for a particular usage. Here we present an easy, sensitive, and straightforward method for the electro-polymerization of 4-amino-6-chloro-1,3-benzene disulfonamide on a graphite electrode, which allows for the simultaneous determination of hydroquinone (HQ) and catechol (CC). The electrochemical activity of ACBSA-modified pencil graphite electrode (PGE) towards the analytes in contrary to other reported polymer-based sensors is dramatically enhanced in terms of the concentration range and detection limit. The fabricated sensor has a lower detection value of 3.15 μM for CC and 0.6 μM for HQ. The polymer can act as a versatile medium for the electrochemical determination of catechol and hydroquinone in water samples with distinct oxidation peaks. [ABSTRACT FROM AUTHOR]

Nanozymes constitute a category of nanomaterials presenting the potential to replace natural enzymes. Nonetheless, weak catalytic activity becomes the biggest barrier hindering their practical applications. In this study, we fabricated a montmorillonite (MMT)‐supported ruthenium (Ru)‐doped CuBi2O4 nanozyme (Ru/CuBi2O4‐MMT) with robust peroxidase (POD)‐like activity by hydrothermal method and studied its application in determination of hydroquinone (HQ). Specifically, the CuBi2O4 material is brought into nanozyme field for the first time. MMT‐supported CuBi2O4 material possesses smaller size and larger surface area than pure CuBi2O4. Ru‐doped exhibits significantly higher POD‐like activity in comparison to CuBi2O4 due to the increase of defect sites. Both of strategies synergistically enhance the POD‐like activity of CuBi2O4 material. The POD‐like activity of nanozyme originates from the photogenerated holes (h+) and superoxide radicals (•O2−) produced during the catalytic decomposition of H2O2. Ru/CuBi2O4‐MMT nanozyme can be successfully applied for HQ colorimetric detection by redox reaction. Our newly developed nanozyme exhibits exceptional POD‐like activity by introducing support and element doping strategies, holding great potential for detecting pollutants in practical applications. [ABSTRACT FROM AUTHOR]

Katiragum dialdehyde‐tryptophan Schiff base (KGDT) is developed for selective and efficient detection of Cd2+ ion and hydroquinone (HQ) in the aqueous medium by electrochemical method. KGDT is synthesized by selectively oxidizing the C2‐C3 bond of katiragum with sodium meta periodate (NaIO4) to obtain katiragum dialdehyde (KGD), followed by condensation between KGD and an α‐amino acid (L)‐tryptophan. KGD and KGDT are characterized by 1HNMR, HRMS, and FESEM with EDAX analysis. The electrochemical experiment is carried out by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods. The electrochemical sensing toward the Cd2+ ion in the DPV method is found to be better compared to the CV method. In the CV method, the limit of detection (LOD) values of Cd2+ ion and HQ are calculated as 8.84 nm and 15.91 nm, respectively. In the DPV method, the LOD values of Cd2+ ion and HQ are found to be 7.24 nm and 15.29 nm, respectively. The proposed sensor, KGDT/GCE, shows satisfactory results in the stability and reproducibility test and also shows excellent practical applicability in real sample analysis. [ABSTRACT FROM AUTHOR]

Because of their unique physical, chemical, and biological characteristics, conductive nanomaterials have a lot of potential for applications in materials science, energy storage, environmental science, biomedicine, sensors/biosensors, and other fields. Recent breakthroughs in the manufacture of carbon materials, conductive polymers, metals, and metal oxide nanoparticles based electrochemical sensors and biosensors for applications in environmental monitoring by detection of catechol (CC) and hydroquinone (HQ) are presented in this review. To achieve this goal, we first introduced recent works that discuss the effects of phenolic compounds and the need for accurate, inexpensive, and quick monitoring, and then we focused on the use of the most important applications of nanomaterials, such as carbon-based materials, metals, and metal oxides nanoparticles, and conductive polymers, to develop sensors to monitor catechol and hydroquinone. Finally, we identified challenges and limits in the field of sensors and biosensors, as well as possibilities and recommendations for developing the field for better future applications. Meanwhile, electrochemical sensors and biosensors for catechol and hydroquinone measurement and monitoring were highlighted and discussed particularly. This review, we feel, will aid in the promotion of nanomaterials for the development of innovative electrical sensors and nanodevices for environmental monitoring. Research Highlights: The most commonly used procedures to prepare electroechemical sensors for catechol and hydroquinone monitoring are described. The electroanalytical techniques have been compared and evaluated. The essential carbon based materials used to fabricate sensitive and selective electrodes are discussed. Prominent applications of nanomaterials combinations for electrochemical sensors are presented. The potential of novel green synthesis procedures for the future development of electrochemical sensors is outlined. [ABSTRACT FROM AUTHOR]

Liquid crystalline polyarylates (LCPs) have excellent thermal stability and mechanical properties, widely used in cutting-edge fields such as aerospace and electronics industries, but the existing LCPs still face the processing problems caused by high melting point (tm >350 °C). Liquid crystal polyarylate thermosets (LCTs) with excellent overall performance are obtained using the reactive end-group phenynyl to encapsulate the main chain of LCPs, effectively regulating the molecular weight and lowering the melting point of the polymers without destroying the liquid crystallinity. The thermal properties of LCTs can be further regulated by modulating the main chain structure. LCTs consisting of p-hydroxybenzoic acid (HBA), terephthalic acid (TA), hydroquinone (HQ), 4,4'-dihydroxybenzophenone (DHBP) and 2, 6-naphthalene dicarboxylic acid (NDA) were synthesized by one-pot melt polycondensation reaction. A series of LCTs were synthesized by adjusting the ratio of HQ to DHBP to further study the relationship between ketone carbonyl groups and LCTs. The results show that the prepared LCTs have high thermal stability (td,5% > 470 °C), typical nematic schlieren textures and oriented microfiber morphology. The addition of ketone carbonyl groups affected the regularity of molecular chain and the proportion of soft and hard segments. With the increase of ketone carbonyl groups content, the glass transition temperature of LCTs decreased. [ABSTRACT FROM AUTHOR]

Trianthema portulacastrum L. is an alien naturalized noxious summer weed belonging to Aizoaceae. Our field observations revealed that it was the dominant weed in the fields planted with maize and other summer crops, and on roadsides of wastelands and farmlands. This study was conducted to evaluate the potential allelopathic effects of the aqueous shoot extracts and mulching with different rates of air-dried shoots of T. portulacastrum collected from maize fields on two associating weeds namely, Corchorus olitorius and Euphorbia heterophylla. Seed germination and seedling growth of the test weeds decreased with increasing concentrations of the aqueous extract. The seeds bioassay experiments confirmed the autotoxicity of T. portulacastrum. We have found that the allelopathic effects of the target species on the two weeds, and the autotoxic effects on itself were mainly attributed to the presence of allelochemicals and not to the osmotic potential of the aqueous extracts. Mulching had inhibitory effects on the percentage of dry matter allocations and the growth parameters of the test weed species. The relative growth rate, the net assimilation rate, and the leaf area ratio of the non-mulched weeds were higher than those of mulched ones. The phytochemical screening of the dry shoots of T. portulacastrum indicated the presence of phenolic compounds, flavonoids, tannins, and alkaloids. The high concentration of alkaloids in the shoot deserves further research. The high-performance liquid chromatography confirmed the presence of 14 phenolic substances, which included 12 phenolic compounds, and 2 flavonoids. Evaluation of seed bioassay and mulching experiments revealed that the aqueous extract concentrations of 4 and 6 % of T. portulacastrum inhibited the germination of E. heterophylla, while the mulched plants showed tolerance at the juvenile-flowering stage. We conclude that tolerance to allelopathic stress varied among the tested weed species and the growth stages of the same species. The suitability of using either aqueous shoot extract or mulch of T. portulacastrum as a potential bioherbicide deserves further monitoring under field conditions. [ABSTRACT FROM AUTHOR]

Melasma is a chronic pigmentary disorder that results in hyperpigmented patches in sun-exposed areas. Tranexamic acid (TXA) and microneedling are potential treatment options for individuals with melasma. The objective of our systematic review was to review 12 randomized controlled trials and clinical trials on the use and efficacy of TXA with microneedling for melasma. The combination of TXA and microneedling was found to be more effective at improving melasma lesions than either treatment alone; TXA alone was equally effective at reducing melasma lesions vs the standard treatment of hydroquinone. [ABSTRACT FROM AUTHOR]

Melasma, also known as chloasma and the "mask of pregnancy", is a common acquired pigmentary disorder characterized by irregular, hyperpigmented brown-to-grey patches primarily situated on the face. It typically affects women of reproductive age, especially those exhibiting Fitzpatrick skin types III to V. The precise etiopathogenesis of melasma is complex and has not been fully elucidated; however, ultraviolet radiation, hormonal factors, and genetic predispositions significantly contribute to the melanin production increase associated with this condition. Due to the multifactorial aetiology, resistance to various therapeutic options, and high recurrence rate, treating melasma is challenging. Hydroquinone has long been considered a gold standard in melasma treatment due to its ability to inhibit tyrosinase; however, it has faced scrutiny after concerns about its adverse effects. Current treatment strategies include various topical and systemic therapies, procedural interventions, as well as combinations of these methods. For optimal results, both photoprotection and a treatment plan that targets different pathogenic mechanisms should be used. Additionally, treatment should be tailored to patient characteristics, such as skin type, the severity of the condition, and compliance. This review summarises current treatment options, focusing on long-term therapy and the latest advancements in managing this challenging condition. [ABSTRACT FROM AUTHOR]

Mayla Barbosa,1 Rebecca Perez de Amorim,1 Daniel Cassiano,2 Marina Dias,1 Ana Flávia de Abreu,1 Edileia Bagatin,2 Hélio Amante Miot,1 Ana Cláudia Cavalcante Espósito1 1Department of Dermatology, Faculdade de Medicina de Botucatu (UNESP), Botucatu, SP, Brazil; 2Department of Dermatology, Universidade Federal de São Paulo (UNIFESP), São Paulo, SP, BrazilCorrespondence: Ana Cláudia Cavalcante Espósito, Department of Dermatology, Faculdade de Medicina de Botucatu, UNESP Medical School, Botucatu, SP, Brazil, Email anaclaudiaesposito@gmail.comBackground: Nicotinamide has demonstrated efficacy in the treatment of melasma. Topical antioxidants and humectants may enhance its performance. Currently, there is no controlled trial on the combination of 10% nicotinamide, 5% magnesium ascorbyl phosphate, and 5% hyaluronic acid, a dermo-cosmetic compound, in comparison to 4% hydroquinone for the treatment of melasma. This study aimed to explore the tolerability and efficacy of the association of the combined product versus hydroquinone.Methods: A randomized, double-blind trial involving women with facial melasma was conducted. Participants were instructed to apply the combined product (NIC group) twice daily or 4% hydroquinone for 60 days (HQ group) at night and placebo in the morning. Evaluations were performed at inclusion, after 14 and 60 days of treatment, measuring the modified Melasma Area and Severity Index (mMASI), Melasma Quality of Life Scale (MELASQoL), and colorimetric luminosity. The Global Aesthetic Improvement Scale (GAIS) was assessed by a blinded evaluator.Results: Both interventions led to a progressive improvement in mMASI, MELASQoL, and GAIS, without a difference between them on D14 and D60 (p> 0.2). For NIC, the mean reduction (95% CI) in mMASI was 16% (8– 24%) on D14 and 32% (23– 41%) on D60, while for HQ, it was 10% (7– 24%) on D14 and 43% (34– 52%) on D60. Reduction in colorimetric luminosity was greater in the HQ group at D60 (p=0.01). No serious side effects were identified. Of the initially included 50 patients, one was lost to follow-up in the HQ group on D60, and one withdrew consent from the NIC group, both unrelated to treatment.Conclusion: The association of 10% nicotinamide, 5% magnesium ascorbyl phosphate, and 5% hyaluronic acid was safe and well-tolerated, although its overall clinical efficacy was numerically inferior to 4% hydroquinone. This regimen can be considered for patients with poor tolerability to hydroquinone.Clinical Trial Registration: &num;RBR-4mkfmr8.Keywords: melasma, hyperpigmentation, nicotinamide, hydroquinone, antioxidants

Background: The mainstay of treatment for melasma is topical hydroquinone or preparations containing hydroquinone. In recent years, cysteamine cream has gained popularity in the treatment of hyperpigmentation disorders. Objectives: This study aimed to compare the efficacy of combined hydroquinone/betamethasone to cysteamine in the treatment of melasma. Methods: Eighteen patients had completed this open-label controlled trial. Subjects received either 5% cysteamine cream or a combination of 4% hydroquinone cream and 0.06% betamethasone valerate for 12 weeks according to standardized protocols. Patients were assessed at recruitment, 4 weeks, and 12 weeks after treatment for Melasma Area and Severity Index (MASI) scores. Other parameters relating to skin complexions and patient satisfaction were also assessed. Results: Patients treated with hydroquinone (n = 7) and cysteamine (n = 11) both showed significant decreases in MASI score at week 12: 33.1% (P = 0.009) and 37.9% (P = 0.009), respectively. There was no statistically significant difference between the two treatment groups (P = 0.236). Melanin content at week 12 decreased by 8.8% (P = 0.016) in the hydroquinone group and 11.5% (P = 0.046) in the cysteamine group, with no significant difference between the groups (P = 0.253). No significant differences were observed between the groups for other parameters or patient satisfaction. Conclusion: Cysteamine cream may provide an alternative treatment option for individuals with melasma, offering fewer side effects while delivering comparable results.

Herein, a reliable and selective photoelectrochemical (PEC) sensor for hydroquinone quantitative determination is achieved by combining 0D CdS nanoparticle/3D flower-like ZnIn 2 S 4 microsphere nanocomposite with molecular imprint polymer (MIP) technology. [Display omitted] A novel photoelectrochemical (PEC) sensor was developed for the ultra-sensitive and highly selective detection of hydroquinone (HQ), featuring a composite structure that combines 0D CdS nanoparticles with a 3D flower-like ZnIn 2 S 4 microsphere. The sensor, termed rMIP/CdS/ZnIn 2 S 4 , employed molecularly imprinted polymers (MIPs) to achieve specific recognition of HQ. An p-phenylenediamine (pPD) polymer film was electrochemically polymerized onto the surface of the CdS/ZnIn 2 S 4 composite-coated glassy carbon electrode (GCE). Through hydrogen bonding, HQ molecules were imprinted onto the polymer film. Subsequent elution removed these molecules, leaving behind specific recognition sites, enabling selective detection of HQ. The unique spatial structure and heterojunction properties of the 0D CdS nanoparticle/3D flower-like ZnIn 2 S 4 composite, combined with molecular imprinting, significantly enhanced the photocurrent response and increased the selectivity and sensitivity for HQ detection. Under optimal conditions, the rMIP/CdS/ZnIn 2 S 4 sensor demonstrated a low detection limit (0.7 nmol·L−1, S/N=3) over a wide linear range of 1–1200 nmol·L−1. The sensor was successfully applied to detect HQ in real water samples, showing promise for environmental pollution control applications. [ABSTRACT FROM AUTHOR]

Background: Response to the current available treatments of melasma, dermal type, in particular, is usually gradual and can result in possible side effects. Aim and Objectives: In this study, we aim to evaluate the efficacy of the combination of plasma rich in growth factors (PRGF) and topical 4% hydroquinone (HQ) in comparison with monotherapy using topical 4% HQ alone in the treatment of dermal type of melasma. Materials and Methods: This is a single-blinded, randomized, split-face clinical trial on twenty female patients with dermal type of melasma. Patients were asked to apply topical 4% HQ on both sides of their face at night for 6 months. In each participant, one side of the face was randomly chosen to receive monthly intradermal injections of PRGF for 3 sessions. Efficacy of the treatment was assessed using hemi melasma area and severity index (MASI) score, physician’s global assessment (PGA), and patients’ global assessment (PtGA). Results: Both groups revealed significant improvement in hemi-MASI score during the treatment course. Mean percentage of improvement at the end of study was 40.38 ± 6.04% and 33.42 ± 3.23% in the combination therapy and monotherapy groups, respectively (P = 0.31). PGA demonstrated excellent-to-marked improvement in melasma in 25% and 5% of patients in the combination therapy and monotherapy groups, respectively (P = 0.31). PtGA showed high levels of satisfaction in 15% of patients in the combination therapy group (vs. 0% in the monotherapy group) (P = 0.05). Conclusion: Differences between the two treatment groups in terms of hemi-MASI and PGA scores were not statistically significant; however, patients demonstrated higher satisfaction with combination of PRGF and topical 4% HQ compared with topical HQ alone. Thereby, combination of PRGF and topical 4% HQ can be suggested as a safe alternative therapeutic approach and may hold promise in the development of future therapeutic options for dermal type of melasma.

As a critical step in advancing the simulation of photosynthetic complexes, we present the Martini 3 coarse-grained (CG) models of key cofactors associated with light harvesting (LHCII) proteins and the photosystem II (PSII) core complex. Our work focuses on the parametrization of beta-carotene, plastoquinone/quinol, violaxanthin, lutein, neoxanthin, chlorophyll A, chlorophyll B, and heme. We derived the CG parameters to match the all-atom reference simulations, while structural and thermodynamic properties of the cofactors were compared to experimental values when available. To further assess the reliability of the parameterization, we tested the behavior of these cofactors within their physiological environments, specifically in a lipid bilayer and bound to photosynthetic complexes. The results demonstrate that our CG models maintain the essential features required for realistic simulations. This work lays the groundwork for detailed simulations of the PSII-LHCII super-complex, providing a robust parameter set for future studies. [ABSTRACT FROM AUTHOR]

The in vitro biotransformation of phenol at 11 °C was studied using pre-spawn adult rainbow (Oncorhynchus mykiss) (RBT), brook (Salvelinus fontinalis) (BKT), and lake trout (Salvelinus namaycush) (LKT) hepatic microsomal preparations. The incubations were optimized for time, cofactor concentration, pH, and microsomal protein concentration. Formation of Phase I ring-hydroxylation and Phase II glucuronidation metabolites was quantified using HPLC with dual-channel electrochemical and UV detection. The biotransformation of phenol over a range of substrate concentrations (1 to 180 mM) was quantified, and the Michaelis–Menten kinetics constants, Km and Vmax, for the formation of hydroquinone (HQ), catechol (CAT), and phenylglucuronide (PG) were calculated. Species differences were noted in the Km values for Phase I enzyme production of HQ and CAT, with the following rank order of apparent enzyme affinity for substrate: RBT > BKT = LKT. However, no apparent differences in the Km for Phase II metabolism of phenol to PG were detected. Conversely, while there were no apparent differences in Vmax between species for HQ or CAT formation, the apparent maximum capacity for PG formation was significantly less in LKT than that observed for RBT and BKT. These experiments provide a means to quantify metabolic activation and deactivation of xenobiotics in fish, to compare activation and deactivation reactions across species, and to act as a guide for future predictions of new chemical biotransformation pathways and rates in fish. These experiments provided the necessary rate and capacity (Km and Vmax) inputs that are required to parameterize a fish physiologically based toxicokinetic (PB-TK) model for a reactive chemical that is readily biotransformed, such as phenol. In the future, an extensive database of these rate and capacity parameters on important fish species for selected chemical structures will be needed to allow the effective use of predictive models for reactive, biotransformation chemicals in aquatic toxicology and environmental risk assessment. [ABSTRACT FROM AUTHOR]

Background: Response to the current available treatments of melasma, dermal type, in particular, is usually gradual and can result in possible side effects. Aim and Objectives: In this study, we aim to evaluate the efficacy of the combination of plasma rich in growth factors (PRGF) and topical 4% hydroquinone (HQ) in comparison with monotherapy using topical 4% HQ alone in the treatment of dermal type of melasma. Materials and Methods: This is a single‑blinded, randomized, split‑face clinical trial on twenty female patients with dermal type of melasma. Patients were asked to apply topical 4% HQ on both sides of their face at night for 6 months. In each participant, one side of the face was randomly chosen to receive monthly intradermal injections of PRGF for 3 sessions. Efficacy of the treatment was assessed using hemi melasma area and severity index (MASI) score, physician’s global assessment (PGA), and patients’ global assessment (PtGA). Results: Both groups revealed significant improvement in hemi‑MASI score during the treatment course. Mean percentage of improvement at the end of study was 40.38 ± 6.04% and 33.42 ± 3.23% in the combination therapy and monotherapy groups, respectively (P = 0.31). PGA demonstrated excellent‑to‑marked improvement in melasma in 25% and 5% of patients in the combination therapy and monotherapy groups, respectively (P = 0.31). PtGA showed high levels of satisfaction in 15% of patients in the combination therapy group (vs. 0% in the monotherapy group) (P = 0.05). Conclusion: Differences between the two treatment groups in terms of hemi‑MASI and PGA scores were not statistically significant; however, patients demonstrated higher satisfaction with combination of PRGF and topical 4% HQ compared with topical HQ alone. Thereby, combination of PRGF and topical 4% HQ can be suggested as a safe alternative therapeutic approach and may hold promise in the development of future therapeutic options for dermal type of melasma. [ABSTRACT FROM AUTHOR]

The article discusses efforts to expand education on skin lightening products. Topics include how skin lightening products are marketed in the U.S., impact of the Coronavirus Aid, Relief, and Economic Security (CARES) Act on over-the-counter (OTC) skin lightening products, and factors that drive the consumer motivation to use skin lightening products.

A successful approach for the construction of steroid dimers with a hydroquinone linker under PBu3/TMAD/Et3N/toluene conditions is described. This study provided a new one‐step methodology for the design and synthesis of bis‐steroidal 1,4‐phenylene diethers using mild and effective reagents. [ABSTRACT FROM AUTHOR]

The water-soluble part of the EtOH extract of Rhodiola rosea L. [Sedum roseum (L.) Scop., Crassulaceae] contained 15 compounds including six new glycosides 1–6. UV and NMR spectroscopic and mass spectrometric data and chemical transformations determined the structures of the new compounds as hydroquinone 1-O-(6′-O-α-L-arabinopyranosyl)-β-D-glucopyranoside (rhodirosin I, 1), hydroquinone 1-O-(6′-O-α-Larabinofuranosyl)-β-D-glucopyranoside (rhodirosin J, 2), tyrosol 1-O-(6′-O-α-L-arabinofuranosyl)-β-Dglucopyranoside (rhodirosin K, 3), tyrosol 1-O-(2′-O-acetyl)-β-D-glucopyranoside (rhodirosin L, 4), tyrosol 1-O-(2′,6′-di-O-acetyl)-β-D-glucopyranoside (rhodirosin M, 5), and rosiridol 1-O-(2′,6′-di-O-acetyl)-β-D-glucopyranoside (rhodirosin N, 6). [ABSTRACT FROM AUTHOR]

Sensitive and selective detection of hydroxylamine (HX) in environmental samples, particularly in the presence of phenol, is of significant importance. Herein, we present an electrochemical sensor based on a carbon paste electrode (CPE) modified with magnesium oxide (MgO) nanoparticles (NPs) and 3,4-dihydroxy benzaldehyde, 2-(Phenyl) hydrazine (DHP), for the simultaneous determination of hydroxylamine and phenol. Employing voltammetric techniques, we investigated the electrocatalytic oxidation of hydroxylamine using the DHP/MgO NPs/CPE electrode. Under optimized conditions (pH = 7), the sensor exhibited a low detection limit of 1.7 μM and a wide linear range of 5.0–650.0 μM for hydroxylamine. The results revealed that the modified electrode significantly enhanced the oxidation activity of HX, resulting in a notable increase in current response compared to the bare electrode. The altered electrode demonstrated satisfactory stability, selectivity, and sensitivity for the detection of hydroxylamine. Furthermore, the developed electrode was successfully utilized for the determination of hydroxylamine in real drinking water samples. The satisfactory recoveries for HX (98.0–102.2%) indicated the high performance and reliable of the proposed method for the assessment of hydroxylamine in water samples. Distinct anodic peaks were observed in the differential pulse voltammetry responses of hydroxylamine and phenol at the surface of the proposed electrode, indicating the feasibility of simultaneous determination of these two compounds. In conclusion, the electrochemical sensor, using MgO NPs and DHP modification, detects hydroxylamine with precision and enables environmental monitoring and water quality assessment. [ABSTRACT FROM AUTHOR]

Boldine ((S)-2,9-dihydroxy-1,10-dimethoxy-aporphine) has been defined as the major alkaloid in Chilean boldo tree. Besides its diverse pharmacological activities, e.g. neuroprotective, cytoprotective, anti-inflammatory activities, boldine also exhibits tyrosinase-inhibiting effect. Tyrosinase [EC 1.14.18.1] is well known as a bifunctional enzyme that is responsible for the melanin biosynthesis. Considering the diphenolic structural feature of the alkaloid, which is associated with its tyrosinase inhibitory properties, herein we first modified the boldine core and then linked it with the natural phenolic antioxidants such as: caffeic-, ferulic- and sinapic acids. Furthermore, the newly amides were tested in vitro on the mushroom tyrosinase. Our results indicated, that amongst the tested boldine derivatives, caffeoyl- and feruloylamides have shown the anti-tyrosinase activity closely correlated with a hydroquinone, used as a standard. [ABSTRACT FROM AUTHOR]

Background: Q‐switched (QS) Nd: YAG laser is one of the treatment options for solar lentigines (SLs). However, the incidence of post‐inflammatory hyperpigmentation (PIH) is a common complication, especially in dark‐complexioned skin. Isobutylamido thiazolyl resorcinol (ITR) has been reported as a preventive modality for ultraviolet B (UVB)‐induced hyperpigmentation. Aims: This study aims to evaluate the efficacy and safety of ITR for the prevention of laser‐induced PIH. Patients/Methods: A randomized, evaluator‐blinded study including 24 subjects with SLs was conducted. Three SLs of each patient were randomized into three groups, which were to apply ITR twice daily, once daily, and no application for 2 weeks. Thereafter, 532‐nm QS Nd: YAG laser was performed. Incidence of laser‐induced PIH, relative melanin index (RMI), mean luminance score (L*), hyperpigmentation score, and adverse events were recorded for 2 months post‐laser. Results: The incidence of PIH at the 4th week after laser treatment was significantly lower in the ITR twice‐daily group compared to the no‐application group (20.83% vs. 50%, p = 0.028). There was no statistically significant difference in RMI, mean L*, and hyperpigmentation score between treatments at all visits. No serious adverse events were reported regarding ITR application and laser treatment. Conclusion: Two‐week application of ITR prior to QS: Nd YAG laser treatment may potentially reduce the incidence of PIH. A longer duration of application, including after the laser procedure, may be more beneficial for the prevention of laser‐induced PIH. [ABSTRACT FROM AUTHOR]

Background Through the use of sustainable and green chemistry concepts, scientists need to decrease waste, conserve energy, and develop safe substitutes for hazardous compounds, all for protecting and benefiting society and the environment. Objective Four novel eco-friendly ion selective electrodes (ISE) were generated to determine Ethamsylate (ETM) in bulk powder and different pharmaceutical formulations. The present electrodes were fabricated to clearly distinguish ETM from a variety of inorganic, organic ions, sugars, some common drug excipients and the degradation product, hydroquinone (HQ) of ETM, and thus used for stability-indicating methods. Methods The electrodes fabrication was based on 2-nitrophenyl octyl ether (NPOE) that was employed as a plasticizer in electrodes 1, 2, and 3 within a polymeric matrix of polyvinyl chloride (PVC) except for electrode 4, in which dibutyl sebacate was used as a plasticizer. Electrodes 1 and 2 were fabricated using tetradodecylammonium bromide as an anionic exchanger, adding 4-sulfocalix-8-arene as an ionophore only to electrode 2 and preparing electrode 1 without incorporation of an ionophore. The fabrication of electrodes 3 and 4 was based on ethamsylate–tetraphenylborate (ETM–TPB) as an ion-association complex in a PVC matrix. The environmental sustainability was assessed using the green analytical procedure index (GAPI), and analytical greenness metric for sample preparation (AGREEprep). Results Electrodes 1 and 2 had linear dynamic ranges of 10−1–10−5 mol/L and 10−1–10−4 mol/L, respectively, with a Nernstian slope of 49.6 and 53.2 mV/decade, respectively. Electrodes 3 and 4 had linear dynamic ranges of 10−1–10−4 mol/L, with a Nernstian slope of 43.9 and 40.2 mV/decade, respectively. Conclusion The electrodes' selectivity coefficients showed good selectivity for ETM. The utility of 4-sulfocalix-8-arene as an ionophore had a significant influence on increasing the membrane sensitivity and selectivity of electrode 2 compared to other electrodes. Highlights Four novel eco-friendly ISEs were used for determination of ETM in bulk powder and different pharmaceutical formulations. Different experimental parameters were performed to optimize the determination conditions such as solvent mediators, dynamic response time, effect of pH, and temperature. Stability-indicating measurement of ETM in the presence of its degradate HQ and co-formulated drug tranexamic acid. Using new ecological assessment tools to determine whiteness and greenness profiles. [ABSTRACT FROM AUTHOR]

In this work, the glassy carbon electrode was modified by multi-walled carbon nanotubes, β -cyclodextrin, reduced graphene oxide, and gold nanoparticle nanocomposites GC/MWCNTs/ β -CD-rGO@Au). The GC/MWCNTs/ β -CD-rGO@Au electrode was utilized for simultaneous monitoring of catechol (CC) and hydroquinone (HQ). The modified electrode has a clear pair of voltammetric peaks for CC and HQ, which makes it an appropriate tool for the simultaneous determination of the two isomers. Under optimized conditions, the oxidation peak currents of CC and HQ at GC/MWCNTs/ β -CD-rGO@Au were increased linearly in the 1–173 μ M and 2–80 μ M concentration range with the limit of detection (LOD) (based on S/N = 3) of 0.17 μ M and 0.26 μ M. The GC/MWCNTs/ β -CD-rGO@Au exhibits adequate stability, repeatability, and recovery in analyzing two dihydroxybenzenes isomers. [ABSTRACT FROM AUTHOR]

Apigenin (APG) is a plant-based flavonoid that possesses antioxidants, anti-inflammatory, and modulates P38 MAPK as well as tyrosinase. Hydroquinone (HQ), a phenolic compound was used to induce vitiligo in C57BL/6 mice. The present study was performed to check the therapeutic potential of apigenin in HQ-induced vitiligo via targeting P38 MAPK pathway. In the present study, 41 C57BL/6 mice were divided into six groups containing seven animals per group except normal group. (I) normal group, (II) HQ group, (III) to (IV) APG with (1%, 2.5%, 5%), and (VI) tacrolimus (TAC) group. Topical application of HQ was performed from day 1 to day 20 to, (II), (III) to (IV) APG with (1%, 2.5%, 5%), (VI) tacrolimus (TAC) group, and then APG; tacrolimus (TAC) was applied from day 21 to day 60 after removing the hair. In the case of (I) normal group and (II) HQ group, we smeared them with water for 60 days and HQ for 20 days in their individual group. On day 61 after anesthesia, a part of the target skin was peeled and blood serum was taken to check the level of malondialdehyde, cholinesterase, catalase, tyrosinase, pro-inflammatory cytokines, and expression of P38 MAPK, histology of melanin containing hair follicles and depigmentation evaluation. Applying HQ topically had a noticeable impact on depigmentation, inflammatory indicators, oxidative stress, and lowered tyrosinase activity. Further HQ reduced melanin containing hair follicles and increased expression of P38 MAPK was confirmed by histopathology and immunohistochemistry. Furthermore, application of APG and TAC after day 21 to 60 significantly reduced depigmentation, inflammatory markers, oxidative stress, and increased tyrosinase. Furthermore, APG increased melanin containing hair follicles and decreased expression of non-phosphorylated P38 MAPK, as confirmed by histopathology and immunohistochemistry. Our finding demonstrated that APG significantly prevented HQ-induced vitiligo by acting as an anti-inflammatory, increasing tyrosine, and reducing the expression of non-phosphorylated P38 MAPK. [ABSTRACT FROM AUTHOR]

Organic redox molecules have attracted considerable attention because of their abundant availability and excellent design flexibility. For practical applications, these molecules must be anchored onto scaffolds such as polymers to prevent crystallization and elution into the electrolyte. In this study, we explore the use of polyhedral oligomeric silsesquioxane (POSS) derivatives as scaffolds for anthraquinone (AQ) and hydroquinone. We investigated the cage structure of POSS and the number of redox units incorporated. Notably, a corner‐opened POSS (CO‐POSS) variant with three AQ units exhibited reversible redox behavior under neutral, acidic, and basic conditions. Furthermore, we examined the air‐battery performance of AQ‐modified CO‐POSS as an anode‐active material. [ABSTRACT FROM AUTHOR]

This study offers a simple voltammetric method for quantifying hydroquinone using a poly(valine)-modified carbon paste electrode (PVLMCPE). Differential pulse voltammetry, cyclic voltammetry, electrochemical impedance spectroscopy, and scanning electron microscopy were utilized to assess the performance of the developed sensor. The oxidation peak current of hydroquinone at the PVLMCPE surface significantly increased in contrast to the bare carbon paste electrode, and overpotentials decreased. Using response surface methodology, a methodical investigation of the electrochemical response of hydroquinone electro-oxidation was carried out, taking potential, pH, polymerization cycle, and scan rate into consideration as important variables. At pH 6.5, phosphate buffer solution produced the best results. In perfect circumstances, the linear detection range showed a high correlation coefficient of 0.920, ranging from 20 to 150 μM. The results showed that the limit of detection and limit of quantification were 0.092 μM and 0.027 μM, respectively. A successful assessment of the results with those obtained using the official method was necessary for validation. Additionally, the created sensor demonstrated a remarkable sensitivity in detecting hydroquinone even in the presence of common interference molecules such as resorcinol. The modified electrode exhibits notable recovery rates and can be used for accurate determination of hydroquinone in real samples due to its broad linear range, high sensitivity, and excellent reproducibility. [ABSTRACT FROM AUTHOR]

N-doped hollow carbon spheres loaded with Cu single atoms (Cu SAs/N-CSs) were prepared via an in situ hard-template method. As an electrode catalyst, the Cu SAs/N-CSs electrochemical-sensing properties to hydroquinone (HQ) and catechol (CC) were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV), and the linear detection ranges of HQ and CC were 1–324 and 1–123 μM, respectively; the detection limits are 0.33 and 0.17 μM, respectively. The experimental and DFT calculation results show that Cu SAs/N-CSs have stronger adsorption strength and more effective affinity for CC and HQ due to the synergistic effect of dispersed Cu SAs and N-CSs, thus improving the electrocatalytic and sensing properties of CC and HQ. Furthermore, the prepared electrode has been successfully applied to the simultaneous determination of HQ and CC in practical water samples with satisfactory results. [ABSTRACT FROM AUTHOR]

Background: β-Arbutin, a hydroquinone glucoside found in pears, bearberry leaves, and various plants, exhibits antioxidant, anti-inflammatory, antimicrobial, and anticancer effects. β-Arbutin has wide applications in the pharmaceutical and cosmetic industries. However, the limited availability of high-performance strains limits the biobased production of β-arbutin. Results: This study established the β-arbutin biosynthetic pathway in C. glutamicum ATCC13032 by introducing codon-optimized ubiC, MNX1, and AS. Additionally, the production titer of β-arbutin was increased by further inactivation of csm and trpE to impede the competitive metabolic pathway. Further modification of the upstream metabolic pathway and supplementation of UDP-glucose resulted in the final engineered strain, C. glutamicum AR11, which achieved a β-arbutin production titer of 7.94 g/L in the optimized fermentation medium. Conclusions: This study represents the first successful instance of de novo β-arbutin production in C. glutamicum, offering a chassis cell for β-arbutin biosynthesis. [ABSTRACT FROM AUTHOR]

To ensure edible oil quality and safety, herein, superior hybrid magnetic nanocomposites with an enhanced peroxidase-like activity were demonstrated, which exhibited electrochemical detection of TBHQ in edible oil. Gold nanoparticles (AuNPs) and magnetic Fe3O4 NPs were embedded in an organic framework by a simple self-assembly method to fabricate Fe3O4@Au/MOF nanocomposites validated through various characterization techniques. The effective combination of Fe3O4 NPs, AuNPs and Cu-MOF exhibited high electrocatalytic activity of Fe3O4@Au/MOF, promoting charge transfer and more sensing sites. Due to its enhanced peroxidase-like activity, Fe3O4@Au/MOF catalyzes H2O2 to generate oxidatively active radicals. On the basis of these results, the redox reaction of TBHQ can be further promoted and the accurate quantitative detection of TBHQ can be achieved. Results displayed that Fe3O4@Au/MOF employed for electrochemical sensing of TBHQ exhibited a low detection limit of 0.3323 μM (S/N = 3) in the concentration range of 1–100 M. Moreover, the results of the electrochemical assays proposed to measure TBHQ in five common edible oils show a good correlation with the actual amount added. The nanocomposite demonstrated good stability, repeatability, reproducibility and sensitivity in real samples, which ensures its practical applicability in edible oil antioxidant analysis as an electrochemical sensor. [ABSTRACT FROM AUTHOR]

In this study, we explored anti-inflammatory compounds from the brown alga Dictyopteris polypodioides and isolated 7 meroterpenoids. Their anti-inflammatory activities were evaluated using the lipopolysaccharide-stimulated mouse macrophage cell line, RAW264. Yahazunol (1) exhibited similar nitric oxide (NO) production inhibitory activity as zonarol (2), which has previously been shown to be an anti-inflammatory compound. Yahazunol (1), zonarol (2), and isozonarol (3) inhibited not only NO production but also inducible nitric oxide synthase, interleukin-6, and C-C motif chemokine ligand 2 mRNA expression in RAW264 cells. The structure-activity relationships of the 11 compounds, including their synthetic analogs, revealed the significance of the hydroquinone moiety in the anti-inflammatory activity of these sesquiterpenoids in RAW264 cells. Diacetylated zonarol (9) exhibited an activity comparable to that of zonarol as a result of intracellular deacetylation. These results provide new insights into the anti-inflammatory activity of hydroquinone-containing natural products. [ABSTRACT FROM AUTHOR]