Peroxide Degradation Research Articles

Physiological response of diverse halophytes to high salinity through ionic accumulation and ROS scavenging

Salt stress induced modulations in different ionic ratios and ROS system were studied in ten halophytic species, namely Atriplex lentiformis, Tamarix aphylla, Sporobolus marginatus, Suaeda nudiflora, Urochondra setulosa, Arundo donax, Aeluropus lagopoides, Heliotropium ramossimum, Atriplex nummularia, Leptachloa fusca at salinity level of ECe ∼ 30 dSm−1 (≈300 mM NaCl) to explore their possible role in salt tolerance ability of these halophytes. These halophytes were categorized for their salt tolerance levels based on the ratios of Na+/K+, Na+/Ca2+, Na+/Cl− and Na + Cl/K + Ca. Variable responses were observed among all halophytes where Atriplex lentiformis had lowest leaf Na+/K+ (0.44) which is one of the best indicator of salt tolerance, Heliotropium ramossimum had lowest Na+/Ca2+ and Na+/Cl− (0.97 and 0.18), whereas Sporobolus marginatus had lowest Na + Cl/K + Ca (0.79). Specific enzymes activities of ascorbate peroxidase (APX), superoxide dismutase (SOD), catalase (CAT) and peroxidase (POX) were also assessed to get better comprehension of the ROS scavenging system under salinity in these halophytes. Urochondra setulosa showed highest APX and SOD activity followed by Atriplex lentiformis. Most efficient enzyme in degrading hydrogen peroxide i.e. CAT showed highest activity in Suaeda nudiflora followed by Atriplex nummularia and Urochondra setulosa, whereas Atriplex nummularia and Atriplex lentiformis showed higher POX activity. Significant variability in H2O2 and MDA content was also observed. These results possibly suggest higher inbuilt genetic potential of these halophytes to combat high salinity induced oxidative stress via higher antioxidant activities. Novelty statement: Halophytic plant adopt different strategies to cope up with the toxic ions and our studies show that the induction of antioxidant defense system to scavenge ROS, alongwith structural modifications in terms of lipid peroxidation and compartmentalization of toxic ions are the main strategies for tighter control of ion fluxes in the studied halophytes.

Degradation of diclofenac sodium using Fenton-like technology based on nano-calcium peroxide

A nano-calcium peroxide (nCaO2) powder with a purity of 89.1% was prepared using an improved traditional method. Then, the as-prepared nCaO2 was used as the source of hydrogen peroxide (H2O2) for the Fenton-like degradation of diclofenac sodium (DCF). The results showed that nCaO2 performed better for DCF removal when compared to nCaO2 prepared by a conventional method and commercial calcium peroxide (CaO2). Further experimental results indicated that 97.5% of DCF could be removed in 180 min at a nCaO2/Fe2+-EDTA/DCF molar ratio of 16/8–8/1, which was more efficient than in the H2O2/EDTA-Fe2+/DCF and nCaO2/Fe2+/DCF systems. The best removal rate of DCF was at pH 6.0, unlike previous claims that stated that the lower the pH in the buffer system, the better the degradation of DCF. In addition, the influence of water quality parameters, such as Cl−, NO3−, SO42−, HCO3−, and humic acid (HA), on DCF removal were evaluated. A free radical masking experiment revealed the existence of hydroxyl radical (OH), superoxide radical (O2−) and singlet oxygen (1O2), and indicated that the degradation of DCF was mainly due to oxidation caused by OH. Electron paramagnetic resonance (EPR) studies for different systems and different active oxygen species were carried out, and it was further confirmed that OH radicals have high intensity in the Fenton-like system based on nCaO2. EPR results also showed that the addition of EDTA can promote the production of OH. According to the identification of the dominant reactive species and GC–MS, the possible theoretical DCF degradation pathways were proposed.

Oxidative degradation profile studies of tavaborole by a validated stability indicating RP-UPLC method: Isolation and characterization of novel degradant using 2D-NMR and HRMS.

The current research work reports a study on the degradation profile of tavaborole, which is an oxaborole antifungal drug used to treat infections in the toenails. This work also reports the chemical stability of tavaborole in different stress conditions along with the isolation and characterization of degradation products by high-resolution mass spectrometry and two-dimensional nuclear magnetic resonance techniques. A sensitive and reproducible stability-indicating ultra-performance liquid chromatography method was developed and validated for quantification of tavaborole bulk drug in the presence of degradation products. Significant degradation was observed during oxidative stress conditions using H2 O2 . It was observed that the drug was highly unstable under oxidation stress conditions and thus degradation profiles with various oxidizing reagents were studied. One unknown impurity (DP-1) was formed during peroxide degradation, which was isolated by reverse-phase preparative chromatography. The structure of this degradant was characterized by high-resolution mass spectrometry and multidimensional nuclear magnetic resonance techniques. The structure of this novel impurity DP-1 was identified as [4-fluoro-2-(hydroxymethyl)phenol], which was not reported as a degradant in the literature. An Acquity BEH C18 , 100 × 2.1 mm, 1.7 μm column was used to achieve the desired separation within a shorter runtime of 4.0 min. The method was validated for specificity, precision, linearity and accuracy over the concentration range of 5.0-400 μg ml-1 (r2 -0.9999) and limit of quantitation 5.0 μg ml-1 . This method is compatible with LCMS analysis which enables to identify the unknown impurities formed in the process.

VALIDATION OF A DEVELOPED ANALYTICAL METHOD FOR DETERMINATION OF NATEGLINIDE AND METFORMIN HCL IN PURE AND PHARMACEUTICAL DOSAGE FORM BY REVERSED-PHASE HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY AND ITS DEGRADATION STUDIES

Objective: The objective of the study was to develop a versatile analytical method and validate according to International Council for Harmonization guidelines for simultaneous estimation of nateglinide and metformin HCl by reversed-phase high-performance liquid chromatography (RP-HPLC) in active pharmaceutical ingredient and in tablet dosage form.
 Methods: Analytes, metformin and nateglinide, are separated and eluted from stationary phase luna phenyl hexyl column (150 mm ×4.6 mm, 3.5 μm) (micrometer) using polar mobile phase composed of acetonitrile:1% orthophosphoric acid 30:70 v/v, with flow rate of 1 ml/min for 8 min at ambient column temperature, at 221 nm (nanometer) detection. Acid, base, peroxide, thermal, and photolytic-induced degradation studies were performed on nateglinide and metformin.
 Results: Through isocratic flow, both metformin and nateglinide are detected at retention times of 2.79 min and 5.13 min, respectively, at 221 nm. The linearity and range of analytical method for nateglinide and metformin were 0.61–9.15 μg/ml and 7.5–75.15 μg/ml, respectively. The R2 value for nateglinide was 0.9998 and for metformin HCl was 0.9991. The limit of detection and limit of quantification for nateglinide were 0.21 μg/ml and 0.63 μg/ml and for metformin were 4.8 μg/ml and 14.6 μg/ml, respectively. The % relative standard deviation for method precision was found to be 0.22% and 0.64% for both nateglinide and metformin, respectively. The mean %recovery for nateglinide and metformin was 99.88% and 99.21%, respectively. The %thermal degradation was identified as 17.7% and 17.5% for nateglinide and metformin, respectively.
 Conclusion: The developed chromatographic (RP-HPLC) method was selective, specific, economic, precise, and accurate. Hence, it can be one of the preferred analytical methods of choice for the estimation of nateglinide and metformin by RP-HPLC in pure and in tablet dosage form.

Isocratic RP-UHPLC method development and validation of stability-indicating for simultaneous determination of teneligliptin and metformin in fixed-dose combination

The pharmaceutical combination of Teneligliptin Hydrobromide hydrate (TEN) and Metformin Hydrochloride (MET) drugs is used in the treatment of type 2 diabetes mellitus. A new analytical method: QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe) has been developed for the quantification of Teneligliptin (TEN) and Metformin (MET) in bulk and tablet dosage forms. The analysis was performed on Agilent symmetry analytical column Eclipse plus C18 (150 mm × 4.6 mm, 5 μm) ultra- performance liquid chromatography-Diode Array Detectors (UHPLC-DAD), while the detection was performed on 233 nm using Diode Array Detectors. Buffer and acetonitrile (65:35 v/v) were the mobile phase, run at a flow rate of 0.7 mL min−1 for isocratic elution. The buffer used in the mobile phase contained 50 mM potassium di-hydrogen phosphate, pH adjusted to 3.5±0.02 with orthophosphoric acid. The mean values of recovery were found to be 100.50% and 99.81%. The proposed method could be ideal for quantitative evaluation in pharmaceutical preparations of these drugs and also for their quality control in bulk manufacturing. Stress test covers: acid, base, peroxide, thermal and photolytic degradation; were conducted to show the specificity of the method and degradation.

Catalytic wet peroxide degradation of acrylonitrile wastewater by ordered mesoporous Ag/CeO2: synthesis, performance and kinetics.

Ordered mesoporous Ag/CeO2 catalysts have been successfully synthesized by a microwave assisted soft template method. The morphology, structure and chemical composition of the catalyst were characterized by XRD, N2 adsorption–desorption, SEM, EDS, TEM and XPS. The study of catalytic performance and reaction kinetics of organic matter degradation in acrylonitrile wastewater was performed in a catalytic wet peroxide (CWPO) system. The degradation pathways of organic matter in acrylonitrile wastewater were elucidated by temporal evolution of intermediates and final products detected by GC/MS analysis along with a continuous flow experiment study. The results show that the Ag/CeO2 has an ordered mesoporous structure, the specific surface area is 91.4–118.2 m2 g−1 and the average pore size is 12.63–16.86 nm. 0.4-Ag/CeO2 showed the best catalytic performance, the COD removal rate reached 94.6%, which was 30% higher than that of CeO2. The degradation is in accordance with the second-order reaction kinetics of the Arrhenius empirical model and Langmuir–Hinshelwood kinetic model. However the latter fits better, and the linear correlation coefficient R2 is more than 0.98, which describes the adsorption catalytic mechanism of Ag/CeO2. According to the analysis by GC/MS, the organic compounds in acrylonitrile wastewater oxidized into intermediate compounds and other small compounds, then are further oxidized into carbon dioxide and water. The catalytic activity of Ag/CeO2 was the result of the combination of Lewis acid–base position of CeO2 and redox cycle of Ce3+/Ce4+.

In-situ utilization of piezo-generated hydrogen peroxide for efficient p-chlorophenol degradation by Fe loading bismuth vanadate

Piezocatalysis has emerged as a promising technology for environmental applications due to its capability to produce highly oxidative species by converting mechanical force into chemical energy. In this work, Fe-loaded bismuth vanadate (Fe/BVO) was developed as a catalyst for piezo-generation and in-situ utilization of hydrogen peroxide (H2O2). The piezoelectricity of Fe/BVO is confirmed by piezo-response force microscopy, and Fe displays a mixed valence (Fe(II) and Fe(III)). Fe/BVO piezocatalysis can achieve 86% p-CP degradation with ultrasonic treatment (120 W and 40 kHz) for 120 min, which is twice that of BVO piezocatalysis. While Fe loading decreases H2O2 concentration from 199.9 to 67.3 μmol/L due to the enhanced in-situ H2O2 utilization efficiency. Based on Mott-Schottky tests, Fe loading increases the charge carrier density, and accordingly leads to the improved piezocatalytic activity for H2O2 production and activation. In the Fe/BVO piezocatalytic system, H2O2 is generated by oxygen reduction via piezo-induced electrons and activated though Fe(II)/Fe(III) cycles. Meanwhile, quenching and fluorescence tests confirm that OH serve as the main active species for p-CP removal. This study is expected to provide a further understanding on the mechanism of piezo-Fenton processes and give some new insights for the design of piezocatalysts for in-situ H2O2 utilization.

A regular fucan sulfate from Stichopus herrmanni and its peroxide depolymerization: Structure and anticoagulant activity

Marine sulfated polysaccharides have aroused widespread concern for their various structures and bioactivities. Peroxide depolymerization is a common strategy in analysis of structures and structure-activity relationships of polysaccharides. However, confirming the depolymerization process and exact structures of the degradation products is still a considerable challenge. This study reported the structures of a fucan sulfate (FS) from sea cucumber Stichopus herrmanni and its depolymerized products (dFS) prepared by peroxide degradation. The FS was elucidated with a highly regular structure, {-3)-L-Fuc2S-(α1-}n. Structure analysis of oligosaccharides purified from dFS suggested that peroxide degradation involved in cleavage of glycosidic bonds and oxidative modification of reducing end of sugar residue, while no break in sugar ring was observed. Both FS and series of dFSs exhibited significant anticoagulant activities due to their anti-thrombin effects in presence of heparin cofactor II and their potencies were related to their molecular sizes, dFS with ∼ 20 kDa showed the strongest activity.

Nanocatalytic Medicine of Iron-Based Nanocatalysts

Iron can be found in all mammalian cells and is of critical significance to diverse cellular activities within human bodies. Widespread applications and the underlying chemical and biological funda...

Phycoremediation of tetracycline via bio-Fenton process using diatoms

The presence of antibiotics in wastewater poses serious environmental and health risks. As common wastewater treatment technologies are not effective in antibiotic removal from wastewaters, techniques such as ozonation, photo-Fenton process, and adsorption have been employed. However, studies are relatively scarce on the bio-Fenton process, in which aquatic plants have been used for the successful removal of pollutants. Many aquatic phytoplankton are capable of producing hydrogen peroxide (H2O2). Hence, in this study we identified the bio-Fenton reaction in diatoms: degradation of hydrogen peroxide produced by diatom cells to the hydroxyl radical in the presence of different iron particles like FeSO4, colloidal iron, and zeolite iron. Hydroxyl radicals produced have the potential to degrade complex organic molecules. The production of hydroxyl radicals was indicated by the fluorescence produced as a result of the cleavage of aminophenyl rings in aminophenyl fluorescine (APF). The capability of diatoms to degrade the tetracycline antibiotic was also demonstrated in batch experiments and three consecutive runs of the sequence batch reactor. Batch experiments showed that the main removal mechanism is the bio-Fenton process; adsorption and iron complex formation also contributed to the overall removal of tetracycline by the diatoms.

Preparation, characterization, and application of high-whiteness agar bleached with hydrogen peroxide

Agar that has been extracted via traditional alkaline pretreatment always appears yellowish because it contains pigments. This characteristic adversely affects the food and biotechnological applications of agar. In this work, agar was bleached with hydrogen peroxide. The whiteness of high-whiteness agar reached 74.4%, which was 32% higher than that of raw agar (56.48%). The high-whiteness agar bleached with hydrogen peroxide exhibited several other excellent qualities over raw agar. These characteristics included, low sulfate content (0.67%), low ash content (1.01%), and high transparency (64.4%). In particular, the transparency of the high-whiteness agar was 13% higher than that of raw agar (56.8%). By contrast, the gel strengths of the two agars did not significantly differ. The structures of raw and high-whiteness agar were characterized by using thermogravimetric (TG)–differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). TG–DSC analysis indicated that the high-whiteness agar had better thermal stability, hygroscopicity, and water-holding capacity than raw agar. SEM images showed that the surface of the high-whiteness agar had imperfections or fissures that were caused by the oxidative degradation of hydrogen peroxide. The diversified application of the high-whiteness agar was explored on the basis of the promotion of agar quality. Results indicated that the visual appearance of the jelly prepared with the high-whiteness agar was better than that of the jelly prepared with raw agar. Moreover, the high-whiteness agar medium was easier to observe and use for colony counting than biochemical medium.

Proteins involved in oxidative stress in leiomyoma tissues treated with ulipristal acetate.

Uterine leiomyoma presents the highest incidence among benign tumors of the female reproductive tract. The present study compared the proteome of leiomyoma treated with ulipristal acetate with that of untreated leiomyoma to investigate protein expression patterns in relation to oxidative stress. Paired tissue samples from seven treated and untreated leiomyomas were collected and the proteome was analyzed by two‑dimensional gel electrophoresis(2‑DE). Western blotting was used to validate the results of 2‑DE, and mass spectrometry was used to identify proteins. The tissue expression of 30 proteins was markedly affected by treatment with ulipristal acetate. Bioinformatics analysis revealed that several of the differentially expressed proteins were involved in the degradation of hydrogen peroxide and the synthesis of reactive oxygen species. The present study suggested the involvement of oxidative stress as a novel mechanism of action of ulipristal acetate. These findings require further investigations to understand the role of ulipristal acetate in the treatment of the leiomyoma.

Reactive oxygen species-responsive silk sericin microcapsules used for antioxidative stress damage.

Silk sericin microcapsules loaded with horseradish peroxidase (HRP) are prepared through protein self-assembly in a green environment containing enzymes to protect liver cells from alcohol damage. Load content and release dynamics of HRP in sericin microcapsules are investigated. The role of HRP-loaded microcapsules in hydrogen peroxide (H2 O2 ) degradation is demonstrated using electrochemical method. Furthermore, the effect of the HRP-loaded microcapsules on cells and intracellular reactive oxygen species (ROS) level is evaluated using an alcohol damage model in vitro. Results show that HRP can be loaded effectively in the sericin microcapsules and can be released ROS-responsively from microcapsules. Cell survival rate increases after suffering from alcohol damage due to the presence of HRP-loaded microcapsule, and the active oxygen content in cells is maintained at a stable level even when it remained in an environment with high alcohol concentration. We believe that the internalized sericin microcapsules maintain HRP activity intracellularly, allow controlled HRP release within a host cell, and show excellent ability in antioxidative stress injury.

Fast Degradation of Hydrogen Peroxide by Immobilized Catalase to Enable the Use of Biosensors in Extraterrestrial Bodies

Hydrogen peroxide has been postulated to be present on the surface of Europa and Enceladus. While it could represent a potential source of energy for possible life-forms, H2O2 may also interfere with a number of current detection technologies, including biosensors. To take advantage of the selectivity and portability of these devices, simple and reliable routes to degrade the potential H2O2 present should be developed and implemented to prepare for this possibility. Unfortunately, most of the current approaches for removing H2O2 are slow, may affect the sample, or could interfere with the performance of biosensors. To address these limitations, catalase was immobilized onto silica particles and used as a means to selectively decompose H2O2 prior to the analysis of common biomarkers with a biosensor. For these experiments, glucose, l-leucine, and lactic acid were used as representative examples of biomolecules such as carbohydrates, amino acids, and organic acids, respectively, which could be used as biomarkers on extraterrestrial bodies. While the decomposition reaction between catalase and H2O2 is well known, to our knowledge this is the first instance where catalase has been used in combination with a microfluidic paper-based analytical device (μPAD) to implement selective sample pretreatment.

Antioxidant and anti-inflammatory activities of Prussian blue nanozyme promotes full-thickness skin wound healing

Excessive reactive oxygen species (ROS) and unresolved inflammations are the major causes of impaired wound healing as they overwhelm the cellular antioxidant system and impede the healing process. In this study, we examined the application of Prussian blue (PB) nanozyme as a novel material for cutaneous wound healing through the alleviation of excessive ROS and inflammation modulation. The PB nanoparticles not only exhibited hydrogen peroxide (H2O2) degradation activity but also showed strong superoxide scavenging ability. PB nanozyme mitigated the intracellular ROS at a high oxidative stress environment, resulting in a pronounced cytoprotective effect. Moreover, PB nanozyme also displayed significant anti-inflammatory activity, as evident from the suppression of inflammatory mediators in the lipopolysaccharide (LPS) induced macrophage cells. Encouraged by the in vitro results, we evaluated the in vivo therapeutic efficacy of PB nanozyme in a full-thickness cutaneous wound model combined with LPS treatment to mimic bacterial infection. The beneficial effects of topically applied PB nanozyme on wound healing and tissue regeneration were evident compared to the control. The periodical administration of a low amount (50 μg × 4) of PB nanoparticles exhibited faster wound closure as well as collagen deposition, maturation, and organization. Moreover, the PB treatment effectively induced the differentiation of keratinocytes, enhanced the neovascularization, and reduced macrophage burden in the entire wound site. Thus, PB nanozyme not only accelerated the healing process in an infection-mimicking cutaneous wound model but also exhibited tissue regeneration characteristics owing to the synergistic effect of ROS-scavenging and anti-inflammatory activities.

Profiling the phyto-constituents of Punica granatum fruits peel extract and accessing its in-vitro antioxidant, anti-diabetic, anti-obesity, and angiotensin-converting enzyme inhibitory properties.

This context was investigated to assess the in vitro antioxidant, anti-diabetic, anti-obesity, and angiotensin-converting enzyme (ACE) inhibition traits of Punica granatum fruits peel extract. Initially, among various extracts tested, aqueous and ethanolic peel extracts depicted the presence of diverse phytoconstituents. In vitro antioxidative properties of peel extracts were determined using standard methodologies. Results showed that aqueous and ethanolic extracts had IC50 values of 471.7 and 509.16 μg/mL, respectively in terms of 1,1,diphenyl 2,2,picrylhydrazyl scavenging. Likewise, IC50 values of aqueous and ethanol extract were obtained as 488.76 and 478.47 μg/mL towards the degradation of hydrogen peroxide. The ethanolic extract exhibited the highest inhibition of α-glucosidase by showing activity of 53.34 ± 2.0 to 15.18 ± 1.4 U/L in a dose dependent manner (100–1000 µg/mL). Ethanolic extract was reported as the most active inhibitor of lipase with an IC50 value of 603.50 µg/mL. Ethanolic extract showed increased inhibition of ACE in a concentration dependent manner (100–1000 µg/mL) with IC50 value of 519.45 µg/mL. Fourier transform-infrared spectrum revealed the availability of various functional groups in the ethanolic extract of peel. Gas chromatography-mass spectrometry chromatogram of peel extract illustrated 23 diversified chemical constituents including 1,2,3,4-butanetetrol, Dimethyl sulfone, 9-octadecenamide, and Pentadecanoic acid as predominant compounds. In summary, P. granatum fruits peel extract revealed promising antioxidant, anti-diabetic, anti-obesity, and anti-hypertensive properties.

Stability-indicating Reversed Phase-Ultra Performance Liquid Chromatography Method Development and Validation for Simultaneous Determination of Encorafenib and Binimetinib in Formulation

A simple, accurate and precise stability indicating method was developed for the simultaneous estimation of the encorafenib (ECRB) and binimetinib (BMTB) in a dosage form by UPLC. Chromatographic elution was processed through a HSS C18 (100 x 2.1 mm, 1.8m) reverse phase column and the mobile phase composition of 0.01N KH2PO4 buffer (3.5 pH) and acetonitrile in the proportion of 55:45 was processed thru a column at a flow rate of 1.0 ml/min. Temperature of the column oven was kept at 30.0°C and the wavelength maximum of detection system was set to 294 nm. Retention times of ECRB and BMTB were found to be 0.767 min and 1.130 min respectively. Repeatability of the method was determined in the form of %RSD and findings were 0.3 and 0.6 for ECRB and BMTB respectively. The percentage recovery of the method was found to be 99.59% and 99.70% for ECRB and BMTB respectively. LOD, LOQ values obtained from regression equations of ECRB and BMTB were 0.51, 1.55mg/ml and 1.47, 4.44 mg/ml respectively. Regression equation of ECRB was y = 6684.x + 18102 and BMTB was y = 13118x + 2159. Two analytes were subjected for acid, peroxide, photolytic, alkali, neutral and thermal degradation studies and the results shown that the percentage of degradation was found between 0.76% and 6.88%. Retention times and total run time of two drugs were decreased and the developed method was simple and economical. So, the developed method can be adopted in industries as a regular quality control test for the quantification of ECRB and BMTB.

Cysteine sulfenylation by CD36 signaling promotes arterial thrombosis in dyslipidemia

AbstractArterial thrombosis in the setting of dyslipidemia promotes clinically significant events, including myocardial infarction and stroke. Oxidized lipids in low-density lipoproteins (oxLDL) are a risk factor for athero-thrombosis and are recognized by platelet scavenger receptor CD36. oxLDL binding to CD36 promotes platelet activation and thrombosis by promoting generation of reactive oxygen species. The downstream signaling events initiated by reactive oxygen species in this setting are poorly understood. In this study, we report that CD36 signaling promotes hydrogen peroxide flux in platelets. Using carbon nucleophiles that selectively and covalently modify cysteine sulfenic acids, we found that hydrogen peroxide generated through CD36 signaling promotes cysteine sulfenylation of platelet proteins. Specifically, cysteines were sulfenylated on Src family kinases, which are signaling transducers that are recruited to CD36 upon recognition of its ligands. Cysteine sulfenylation promoted activation of Src family kinases and was prevented by using a blocking antibody to CD36 or by enzymatic degradation of hydrogen peroxide. CD36-mediated platelet aggregation and procoagulant phosphatidylserine externalization were inhibited in a concentration-dependent manner by a panel of sulfenic acid–selective carbon nucleophiles. At the same concentrations, these probes did not inhibit platelet aggregation induced by the purinergic receptor agonist adenosine diphosphate or the collagen receptor glycoprotein VI agonist collagen-related peptide. Selective modification of cysteine sulfenylation in vivo with a benzothiazine-based nucleophile rescued the enhanced arterial thrombosis seen in dyslipidemic mice back to control levels. These findings suggest that CD36 signaling generates hydrogen peroxide to oxidize cysteines within platelet proteins, including Src family kinases, and lowers the threshold for platelet activation in dyslipidemia.

DEVELOPMENT AND VALIDATION OF STABILITY INDICATING RP-UPLC METHOD FOR THE QUANTIFICATION OF BALOXAVIR MARBOXIL IN TABLET FORMULATION

Objective: Aim of the present work is to develop a simple, accurate and precise stability-indicating method for the quantification of baloxavir marboxil (BLMX) in tablet dosage form by UPLC.
 Methods: Chromatographic elution was processed through a HSS C18 (100 x 2.1 mm, 1.8 mm) reverse phase column and the mobile phase composition of buffer 0.1% orthophosphoric acid and acetonitrile in the ratio of 50:50 was processed through a column at a flow rate of 0.3 ml/min. Column oven temperature was maintained at 30 °C and the detection wavelength was processed at 240 nm.
 Results: Retention time of BLMX was found to be 0.87 min. Repeatability of the method was determined in the form of %RSD and the value was 0.2. The percentage mean recovery of the method was found to be 99.47%. LOD, LOQ values obtained from the regression equation of BLMX were 0.69 and 2.10 mg/ml, respectively. Regression equation and correlation coefficient values of BLMX were y = 16994x+7179.2 and 0.9996. Drug was subjected for acid, peroxide, photolytic, alkali, neutral and thermal degradation studies and the results shown that the percentage of degradation was found between 5.96% and 9.55%.
 Conclusion: Retention time and total run time of the drug was decreased and the developed method was simple and economical. So, the developed method can be adopted in industries as a regular quality control test for the quantification of BLMX.

Bovine serum albumin decorated gold nanoclusters: A fluorescence-based nanoprobe for detection of intracellular hydrogen peroxide

Gold nanoclusters are well studied due to their facile synthesis, biocompatibility, limited photobleaching, and bright fluorescence properties. Monitoring the reactive oxygen species (ROS) level in mammalian cells is required to assess the healthy metabolism of oxygen, cell signaling, and homeostasis. ROS are also known to cause several human diseases including cancer, neurodegenerative disease, diabetes, and cardiovascular disorders, therefore, following the ROS status could provide important information about the critical pathophysiology of the diseased cells/tissues. Among different ROS, hydrogen peroxide is a well-reported stable oxidative stress biomarker for several diseases. In this work, we report the synthesis of BSA coated AuNCs (BSA-AuNCs) displaying bright red fluorescence (Ex./Em. 511/651 nm), which utilized for the degradation of hydrogen peroxide with concomitant loss of fluorescence of BSA-AuNCs. The fluorescence property of this nanoprobe was used for the detection of hydrogen peroxide levels in liver cells (WRL-68). The accumulation of hydrogen peroxide in WRL-68 cells was artificially induced by 3-amino-1,2,4-triazole (catalase inhibitor) treatment, which leads to a decrease in the fluorescence intensity of BSA-AuNCs to enable fluorescence-based sensing of hydrogen peroxide. Thus, the synthesized fluorescent BSA-AuNCs could be used for the detection of intracellular hydrogen peroxide.