Major Degradation Products Research Articles

Electrochemical degradation of aromatic organophosphate esters: Mechanisms, toxicity changes, and ecological risk assessment

Aromatic organophosphate esters (AOPEs), including triphenyl phosphate (TPHP), tricresyl phosphate (TCP), and 2-ethylhexyl diphenyl phosphate (EHDPP), pose significant health and ecological risks. Electrochemical advanced oxidation process (EAOP) is effective in removing refractory pollutants. In this study, the degradation performance and detoxication ability of AOPEs by EAOP were investigated. Hydroxylation, oxidation, and bond cleavage products were identified as major degradation products (DPs) due to the reaction with ·OH and O₂·-. Toxicity assessments using ecological structure activity relationship (ECOSAR) model and flow cytometry (FCM) revealed the cytotoxicity and aquatic toxicity for DPs were significantly decreased. 16S rRNA gene sequencing of sediment exposure to AOPEs and DPs were applied to assess ecological toxicity, and results showed reduced bacterial richness and diversity with EHDPP and TCP, while TPHP slightly enhanced richness. AOPEs and DPs altered bacterial genera involved in carbon, nitrogen, sulfur cycling and organic compound degradation. Bacterial community assembly suggested elevated stochastic processes and reduced ecotoxicity, confirming AOPEs can be effectively detoxified by 10-min EAOP treatment. Molecular ecological network analysis indicated increased complexity and stability of bacterial communities with DPs. These findings comprehensively revealed the toxicity of AOPEs and their DPs and provided the first evidence of effective degradation and detoxification by EAOP from ecotoxicological perspective.

Field and laboratory perspectives on fentanyl and carfentanil decontamination

Abuse of the highly toxic compound fentanyl and its analogues is increasing, raising serious public health concerns due to their potency and availability. Therefore, there is a need for decontamination methodologies to safely remove fentanyl to avoid harmful exposure. In this study, the efficacy of commercial and in-house synthesized decontamination agents (Dahlgren Decon, RSDL (Reactive Skin Decontamination Lotion), FAST-ACT (First applied sorbent treatment against chemical threats), GDS2000, alldecont MED, bleach, Domestos Spray Bleach, Effekt Klor, MgO, TiO2-nanodiamond, and CeO2) were evaluated for the degradation of fentanyl and carfentanil under controlled laboratory conditions and on wooden floor surfaces. Liquid chromatography/mass spectrometry analysis showed that oxidative decontamination agents were the most effective, with N-oxides identified as major degradation products. The physiological effects of these N-oxides were also investigated regarding their ability to activate the µ-opioid receptor and their metabolism in human liver microsomes. The results provide empirical evidence that complements prior research findings on the degradation of fentanyl and carfentanil using a variety of decontamination agents.

A comprehensive study on the identification and characterization of major degradation products of synthetic liraglutide using liquid chromatography-high resolution mass spectrometry.

Liraglutide (LGT) is a synthetic glucagon-like peptide-1 analogue mainly used for the treatment of type-2 diabetes or obesity. Comprehensive stability testing is essential in the development and routine quality control of synthetic therapeutic peptide pharmaceuticals. The GLP-1 peptide drugs are usually formulated in aqueous-base solution, which can generate stability issues during manufacturing, storage or shipment. The current study endeavors to observe the chemical stability behavior of LGT by exposing the drug substance to oxidative and hydrolytic stress conditions. A simple liquid chromatography (LC) method was developed where sufficient resolution between LGT and the generated degradation products was achieved. In total, 19 degradation products (DPs) were separated under acidic, basic and oxidative stress conditions. Using LC-HRMS, MS/MS studies, the generated degradation products were identified and characterized. The mechanistic fragmentation pathway for all generated DPs were established and the plausible chemical structure for the identified DPs was predicted based on MS/MS data. The results strongly suggest that LGT is highly susceptible to degrade under oxidative and hydrolytic conditions. Furthermore, this study provides insights into the hydrolytic and oxidative stability of LGT, which can be implied during generic and novel formulation drug development and discovery in synthesizing relatively stable GLP-1 analogues.

Comparative analysis of additive decomposition using one-dimensional and two–dimensional gas chromatography: Part II - Irgafos 168 and zinc stearate

Plastic production has experienced a significant increase in the last sixty years due to its cost-efficiency and adaptable characteristics, leading to the extensive use of additives to improve its performance and longevity. Due to the high demand for plastic, plastic waste production has increased, contaminating the environment and living beings by leaching additives, among other substances. Pyrolysis stands out among recycling techniques because it can handle mixed polymer waste feedstock. However, understanding the pyrolyzates distribution of additives is fundamental to assessing pyrolysis process of plastic waste. This study investigated the pyrolysis product distributions of two commonly used antioxidants, namely, Irgafos 168 and zinc stearate (ZnSt), using one-dimensional gas chromatography equipped with a quadruple mass spectrometer (GC–MS) and two-dimensional gas chromatography coupled to flame ionization detector and time–of–flight mass spectrometer (GC×GC–FID/TOF–MS). While GC separation technique provided limited information on product distribution, GC×GC offered enhanced resolution and identification of the decomposition products. In the pyrolysis of Irgafos 168 at 550 °C, GC identified 18 products, while GC×GC identified 198 products, representing an increase of approximately 11-fold. Similarly, for ZnSt, GC identified 67 products, while GC×GC identified 434 products, representing a 6-fold increase. GC×GC identified decomposition products from 15 different chemical classes for Irgafos 168 and 16 chemical classes for ZnSt, compared to 4 and 11 chemical classes identified by GC, respectively. Phenols and their derivatives were the major chemical class in the decomposition products of Irgafos 168 with a yield of 9.51 wt.%. In contrast, olefinic products were the dominant ones for ZnSt, with a yield of 9.73 wt.%. The major decomposition product of Irgafos 168 and ZnSt was 2‑tert‑butyl‑methylphenol (C11H16O) and C6 olefin (C6H12) with yields of 3.88 wt.%, and 1.13 wt.%, respectively. Utilizing the GC×GC separation method improved the ability to identify decomposition products, which can ultimately lead to a better understanding of antioxidant degradation that occurs during the pyrolysis process. GC×GC also provided thorough characterization of minor and co-eluted products along with major antioxidant degradation products. Additionally, the decomposition product distribution of Irgafos 168 and ZnSt was also compared with the primary antioxidants, Irganox 1010, Irganox 1076, and BHT, studied in part 1. The analysis indicated that the olefinic chemical class was the predominant one in Irganox 1010, Irganox 1076, and ZnSt, while ketones were the major chemical class in the decomposition of BHT and phenolics had the highest yield in Irgafos 168.

Degradation mechanism of atrazine in water by permutit loaded Fe and Cu oxides in a multi-electrode dielectric barrier discharge reactor

In this paper, the degradation of ATZ (Atrazine) in water by a catalyst-filler synergistic multi-electrode DBD (Dielectric barrier discharge) reactor was investigated.The results showed that 1O2, ·O2- and ·OH played a major role in the degradation process of ATZ. The addition of catalyst filler accelerated the removal efficiency of ATZ, and the removal efficiency of ATZ in Fe2O3/Permutit+DBD, CuO/Permutit+DBD, and Permutit+DBD were 95.76 % at the input voltage, gas flow rate, dosing volume, and processing time of 34 kV, 100 L/h, 1 g, and 15 min, respectively, 94.85 % and 91.54 %, which was 15 min shorter than the processing time of DBD system alone. Eight major degradation products were detected by high-resolution mass spectrometry, and their possible degradation pathways were inferred by combining with the DFT, and their intermediate products were found to be less acutely toxic and less chronically toxic than the parent ATZ by the ECOSAR toxicity analysis software.

Biodegradable and biocompatible nonisocyanate polyurethanes synthesized from bio-derived precursors

Despite the enormous use of polyurethanes (PUs) in multiple aspects of modern lifestyle, the industrial scale manufacturing of PUs uses toxic chemicals like isocyanates, phosgene till today. In addition, the non-biodegradability and non-biocompatibility of PUs and their debris are serious cause of concerns for the environment. To deal with these challenges, in the current work, a new approach is reported in which bio-derived non-isocyanate polyurethanes were synthesized by exploiting viable amino acid-based diamines and biscyclocarbonates from sebacoyl chloride and diglycerol derivatives in a readily doable process. The newly designed polyhydroxyurethanes (PHUs) exhibited remarkable biodegradability and biocompatibility (cell viability) in comparison with commercial diamine based PHUs. A series of PHUs were synthesized in bulk and solvent free green synthetic route by polycondensing library of amino acids (such as glycine, alanine, valine, and isoleucine etc.) based diamines consisting of varying alkyl chain lengths and biscyclocarbonates like sebacic biscyclocarbonate and diglycerol biscyclocarbonate etc. All the synthesized PHUs were thoroughly characterised by IR, NMR and HRMS spectroscopic techniques. The impact of chain length and molecular structure of the synthesized PHUs were also evaluated using DSC, TGA, SEC, water contact angle measurements and hydrolytic degradation studies. The molar masses of the PHUs obtained from the SEC analysis are in the range of ∼17,000–24,000 Da. The current study demonstrated that amino acids is one of the major degradation products and are biocompatible in in-vitro conditions. The PHUs and their degradable products showed excellent cell viability when studied in HEK293T cells that were carried out using microgram to milligram concentration of PHUs. The outcome of this work in comparison to conventional PHUs and polyurethanes clearly demonstrated good biocompatibility and hence drawing attention to potential applications in bio-adhesives, bio-implants, drug delivery, and green coatings etc. in the near future.

Simultaneous knockout of cytosolic and plastidial disproportionating enzymes disrupts grain setting and filling in rice.

Rice (Oryza sativa) plants contain plastidial and cytosolic disproportionating enzymes (DPE1 and DPE2). Our previous studies showed that DPE2 acts on maltose, the major product of starch degradation in pollens, releasing one glucose to fuel pollen tube growth and fertilization, whereas DPE1 participates in endosperm starch synthesis by transferring maltooligosyl groups from amylose to amylopectin, and removing excess short maltooligosaccharides. However, little is known about their integrated function. Here, we report that the coordinated actions of DPE1 and DPE2 contribute to grain setting and filling in rice. The dpe1dpe2 mutants could not be isolated from the progeny of heterozygous parental plants but were obtained via anther culture. Unlike that reported in Arabidopsis (Arabidopsis thaliana) and potato (Solanum tuberosum), the dpe1dpe2 rice plants grew normally but only yielded a small number of empty, unfilled seeds. In the dpe1dpe2 seeds, nutrient accumulation was substantially reduced, and dorsal vascular bundles were also severely malnourished. Zymogram analyses showed that changes in activities of the major starch-synthesizing enzymes matched well with various endosperm phenotypes of mutant seeds. Mechanistically, DPE1 deficiency allowed normal starch mobilization in leaves and pollens but affected starch synthesis in endosperm, while DPE2 deficiency blocked starch degradation, resulting in substantially decreased levels of the sugars available for pollen tube growth and grain filling. Overall, our results demonstrate the great potential of DPE1-DPE2 as an important regulatory module to realize higher crop yields and present a promising target for regulating nutrient accumulation in cereal crop endosperm.

Glucose-montmorillonite hydrochar composite activating peroxymonosulfate for sulfentrazone rapid degradation and phytotoxicity alleviation to rice

Sulfentrazone is an excellent herbicide for the control of broad-leaved weeds and some grasses. However, its herbicidal residues pose potential risks to the environment. The use of carbonaceous materials as catalysts for activating peroxymonosulfate (PMS) for managing pesticide contamination has attracted considerable attention. Herein, the rapid degradation of sulfentrazone in water and the alleviation of sulfentrazone-induced phytotoxicity alleviation to rice were investigated using glucose-montmorillonite hydrochar (GM-HC) activating PMS. The findings revealed that the GM-HC/PMS system can rapidly degrade sulfamethoxazole and achieved 93.90% of removal efficiency in 24 h. Specifically, GM-HC activating PMS generated the active species, including sulfate radicals (SO4•–), singlet oxygens (1O2) and superoxide radicals (O2•−), which speeds up the degradation of sulfentrazone. Five major degradation products of sulfentrazone and two possible degradation pathways were proposed. The C-Cl and C-CH3 of sulfentrazone molecules are the initiation sites attacked by active species for degradation according to density functional theory (DFT) calculation. Additionally, after the sulfentrazone was degraded by GM-HC/PMS system, sulfentrazone-induced phytotoxicity to rice seeds and seedlings was significantly alleviated. This work presents a novel approach for addressing herbicide wastewater pollution.Graphical

Thermal degradation of polyamide 66 and its model compound

Thermal degradation of N, N'-dibutyladipamide and polyamide 66 (PA66) was carried out in a large-scale experimental setup with nitrogen sweeping in order to collect elusive degradation intermediates. At a high nitrogen flow rate, 1-butylazepane-2,7-dione was identified as a major degradation product from the thermal decomposition of N, N'-dibutyladipamide. Upon heating, 1-butylazepane-2,7-dione produced cyclopentanone and its derivatives, dibutylurea and a nitrile that constituted the majority of degradation products of N, N'-dibutyladipamide, proving that the 7-membered heterocycle compound is a crucial primary degradation product as well as a precursor for the secondary degradation products of N, N'-dibutyladipamide. Subsequently, chemistry concerning the generation and decomposition of 1-butylazepane-2,7-dione was developed for the thermal decomposition of DBA. On the other hand, hexamethylenediamine, 1,8-diazacyclotetradecane-2,7-dione, cyclopentanone and its derivatives were collected as important degradation products from the thermal decomposition of PA66. In view of the structural similarity between DBA and PA66 and their comparable degradation products, a mechanism centering on the generation and decomposition of a 7-membered ring has ultimately been established for thermal degradation of PA66.

Photo-metallo-immunotherapy: Fabricating Chromium-Based Nanocomposites to Enhance CAR-T Cell Infiltration and Cytotoxicity against Solid Tumors.

The infiltration and cytotoxicity of chimeric antigen receptor (CAR)-T cells are crucial for effective elimination of solid tumors. While metallo-immunotherapy is a promising strategy that can activate the antitumor immunity, its role in promoting CAR-T cell therapy remains elusive. The first single-element nanomaterial based on chromium nanoparticles (Cr NPs) for cancer photo-metallo-immunotherapy has been reported previously. Herein, an extended study using biodegradable polydopamine as a versatile carrier for these nanoparticles, enabling synergistic CAR-T cell therapy, is reported. The results show that these nanocomposites with or without further encapsulation of the anticancer drug alpelisib can promote the CAR-T cell migration and antitumor effect. Upon irradiation with near-infrared light, they caused mild hyperthermia that can "warm" the "cold" tumor microenvironment (TME). The administration of B7-H3 CAR-T cells to NOD severe combined immunodeficiency gamma mice bearing a human hepatoma or PIK3CA-mutated breast tumor can significantly inhibit the tumor growth after the induction of tumor hyperthermia by the nanocomposites and promote the secretion of serum cytokines, including IL-2, IFN-γ, and TNF-α. The trivalent Cr3+ ions, which are the major degradation product of these nanocomposites, can increase the CXCL13 and CCL3 chemokine expressions to generate tertiary lymphoid structures (TLSs) in the tumor tissues, facilitating the CAR-T cell infiltration.

A Simple Validated LC-UV Method for the Simultaneous Determination of Brimonidine and Brinzolamide in the Presence of Brinzolamide's Degradation Product (Major Metabolite) in Rabbit Aqueous Humor.

A sensitive, specific, reliable and low-cost LC-UV method has been developed and validated for simultaneous quantification of brimonidine tartrate (BM) and brinzolamide (BZ) in rabbit aqueous humor (AH) in the presence of N-desethyl-brinzolamide (NDBZ); BZ is a major degradation product, and it is also considered to be its major metabolite. Dorzolamide hydrochloride (DZ) was used as an internal standard (IS). The analytes were extracted from rabbit AH samples by a simple pre-treatment utilizing ZnSO4.7H2O as a deproteinizing agent. The analytes were separated on a cyanopropyl Waters column (4.6 × 200mm, 5μm) with an isocratic mobile phase consisting of 25mM ammonium acetate pH4.5 (adjusted with 85% phosphoric acid):methanol:acetonitrile (94:4.5:1.5, v/v) at a flow rate of 1.0mLmin-1. The detection was done at 254nm. The lower limit of quantification in rabbit AH was 100.0ngmL-1. The method was validated according to EMA guidelines. The method was confirmed to be accurate, precise and linear over a range of 100.0-1000.0ngmL-1 for BM and BZ. The method developed herein is simple, safe, eco-friendly, rapid and accurately applied for the quantification of BM and BZ, along with the successful separation of NDBZ, which is considered as a potential irritant degradation product of BZ.

Development and validation of stability-indicating assay method and identification of force degradation products of glucagon-like peptide-1 synthetic analog Exenatide using liquid chromatography coupled with Orbitrap mass spectrometer.

Exenatide is a synthetic glucagon-like peptide 1 analog, widely used in the management of type 2 diabetes mellitus. The stability of pharmaceutical products is significantly impacted by various environmental stress conditions. The present study reports the development of a validated reverse-phase high-performance liquid chromatography (RP-HPLC) stability-indicating method for the identification of force degradation products (DPs) of synthetic glucagon-like peptide-1 analog Exenatide using UHPLC-Orbitrap fusionTM mass spectrometer. Force degradation studies were performed by subjecting Exenatide to various stress conditions, such as hydrolytic, oxidative, photolytic and thermal to investigate the stability indicating ability of the method. Significant degradation was observed during acidic, oxidative, photolytic and thermal stress conditions. Exenatide and its major DPs identification and characterization were demonstrated by employing LC-HRMS and MS/MS method. In total, five major stress DPs were characterized, and their fragmentation pathway was proposed using MS/MS studies. Finally, the proposed RP-HPLC method was validated as per ICH guidance.

Degradation, transformation and cytotoxicity of triphenyl phosphate on surface of different transition metal salts in atmospheric environment

Triphenyl phosphate (TPhP) and transition metal elements have been ubiquitously detected in the atmosphere, which can participate in atmospheric chemical reactions and induce damage to human health. Currently the understanding of TPhP degradation, transformation and cytotoxicity on atmospheric particles surface are still limited. Therefore, this study used laboratory simulation methods to investigate the influence of irradiation time, transition metal salts, relative humidity (RH) to TPhP degradation, transformation and relative cytotoxicity. TPhP was coated on particle surfaces of four transition metal salts (MnSO4, CuSO4, FeSO4 and Fe2(SO4)3) in the experiment. Within 12 h irradiation, the significant TPhP photodegradation can be observed on all particles surface. Among these influence factors, the irradiation and RH were the crucial aspects to TPhP degradation, which primarily affect the OH concentration in the atmosphere. The transition metal elements only exhibited slightly catalytic effect to TPhP degradation. The mechanism study indicated that the major degradation products of TPhP are diphenyl hydrogen phosphate (DPhP) and OH-DPhP, which originated from the phenoxy bond cleavage and hydroxylation of TPhP induced by OH. As for the cytotoxicity to A549 cells, all the transition metal particles coated with TPhP can cause cellular injury, which was chiefly induced by the transition metal salt. The possible cytotoxicity mechanism of these particles to A549 cells can be attributed to the excessive reactive oxygen species (ROS) production. This study may provide a further understanding of TPhP degradation and related cytotoxicity with the coexistent transition metal salts in the atmosphere.

Identification of major degradation products of Clorsulon drug substance including its degradation pathways by high resolution mass spectrometry and NMR

Clorsulon is an effective anthelmintic drug substance extensively used in the treatment of parasitic infestations in both cattle and sheep. An in-depth investigation of Clorsulon’s degradation products (DPs) was carried out through forced degradation study to comprehend its degradation path. A total of eight degradation products were separated under various stress degradation conditions. Structural elucidation of these DPs was conducted using ultra-high performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS), and their fragmentation patterns were compared to that of the parent compound. Adequate amount of DP-4 was isolated and purified by semi-preparative high-performance liquid chromatography (HPLC) methods. Subsequently, it was examined in detail using both 1D and 2D NMR (nuclear magnetic resonance spectroscopy). Most probable mechanistic pathways for the formation of degradation products under various stress degradation conditions were proposed to better understand the degradation profile. Based on the results of the stress study, Clorsulon drug substance was found to be unstable under photolytic and oxidative conditions. Understanding Clorsulon's degradation pathway is essential for determining shelf-life prediction of the finished product, safety and efficacy assurance, and guiding the development of stable, high-quality formulations.

LC and LC-MS/MS Studies for the Separation and Identification of Impurities and Degradation Products of Betaxolol.

Betaxolol (Bx) is a selective β1 receptor blocker used in the treatment of hypertension and glaucoma. The aim of the present work was to demonstrate an approach involving use of liquid chromatography (LC) and liquid chromatography-electrospray ionization mass spectrometry (LC-ESI/MS) for the simultaneous separation, identification and characterization of impurities and of degradation products of betaxolol without their isolation from the reaction mixtures. At optimum condition, and according to ICH guidelines, the limit of detection (LOD) and limit of quantification (LOQ) for Bx are found to be 5.46 and 16.54μgmL-1, respectively. However, the LOD and LOQ for the major degradation product P6 were 2.15 and 6.53μgmL-1. Betaxolol was subjected to hydrolytic (acidic and basic) and oxidative, stress conditions according to International Conference on Harmonization (ICH) guideline Q1A (R2), and as results, the drug was found to be labile in acidic, basic and oxidative stress conditions. Based on LC-ESI/MS analysis, the found results revealed that Bx decomposes in acidic, basic and oxidizing environments. All degradation products were identified with the help of their fragmentation pattern and the masses obtained upon the MS analysis.

IDENTIFICATION, SEPARATION, AND CHARACTERIZATION OF DEGRADATION PRODUCTS OF TRIAMCINOLONE HEXACETONIDE USING LC AND LC-MS/MS

Objective: The study aimed to separate the forced degradation products of Triamcinolone hexacetonide using HPLC and characterize the degradation product by LC-MS/MS fragmentation pattern. Methods: Triamcinolone hexacetonide (THA) and its primary degradation products were identified using a liquid chromatography-mass spectrometry/Mass spectrometry (LC-MS/MS) approach. The degradation study was based on in-depth stress testing with acid, base, peroxide, heat, and light. A Zorbax SB C18 column and a greener mobile phase composed of methanol and 10 mmol ammonium acetate buffer in water at pH 3 were employed to accomplish separation and quantitation at a flow rate of 0.7 ml/min in an isocratic mode with a 239 nm detection wavelength. Results: A major degradation product of the drug was obtained in acidic and alkaline stress conditions. The drug was found to be stable for all other stress conditions. The LC-MS/MS analysis results of the active pharmaceutical ingredient and resulting product after degradation were interpreted to identify the novel degradation product and fragments. The developed method was validated as per International Council for Harmonization (ICH) guidelines. The square root of the correlation coefficients, which indicated linearity for THA in 50 to 150 % of the workload, was 0.99. Method Precision assay was performed on six different preparations, percentage relative standard deviation (% RSD) of assay value is 0.17 % and system precision is 0.30 %. In accuracy, overall % RSD of 50 %, 100 %, and 150 % in triplicate is 0.95. Conclusion: It is concluded that the drug is stable to all other stress conditions except for acidic and alkaline stress conditions and generates a novel degradation product. The developed LC (Liquid chromatography) method separates and identifies the degradation product.

Forced Degradation Products of Olmesartan Medoxomil and their In Vitro Genotoxicity Assessment by Comet Assay using HEK Cells

AbstractThis study designed to characterize major forced degradation products of Olmesartan Medoxomil (OM) and to perform genotoxicity profiling using acid, base, and hydrogen peroxide‐induced stress degradation studies. The isolation of degradation products was conducted on flash chromatography using FlashPure ECOFLEX C18 4 g column with gradient elution and diode array detection‐based fraction collection, and characterized by mass spectrometry. Three impurities (impurity‐1, 2, and 3) were identified with respective m/z values of 447.213, 461.229, and 463.208. The genotoxic potential of impurities was assessed by in silico prediction, and in vitro comet assay using HEK cells. The extent of DNA damage was analyzed using Comet Assay IV imaging software. For impurity‐1, head and tail lengths and their respective total intensities were significantly (p<0.001) larger than those of dimethyl sulfoxide (solvent) control and comparable to positive control. Other parameters such as mean grey level and total area of comet were statistically significant as compared with the solvent and positive controls. Overall, impurity‐1 was a possible genotoxic impurity and a known major degradation product in OM tablet dosage form. In silico prediction also revealed impurity‐1 as toxicity class 3, whilst impurities 2 and 3 were of toxicity class 4.

Degradation of several chlorophenols using advanced oxidative processes: Major and minor products

AbstractThis study focuses on finding direct evidence of oxidative degradation of chlorophenols. The aim of the study was distinguishing major and minor degradation products. Several chlorophenols with different numbers of chloride substituents (2‐chlorophenol, 2,4‐dichlorophenol, and 2,4,5‐trichlorophenol) were chosen for a thorough study. UV photolysis, Fenton, and photo‐Fenton processes were tested as advanced oxidative processes. Photo‐Fenton appeared to result in higher conversions of mono‐ and dichlorophenols. Conversions of trichlorophenol were comparable for all the processes under this study. Formic and acetic acids were shown to be the major products. Their formation was confirmed by 1H NMR spectroscopy. Other possible products are minor and are formed in negligible concentrations. The degradation methods can be considered harmless techniques of inactivating the chlorophenols, leading to the formation of products of low toxicity.

Identification of β-aspartic semialdehyde and homocysteine as major reaction products of riboflavin-sensitized photooxidation of peptide-bound methionine

Methionine is an essential amino acid for mammals and it is limiting for monogastric animals. It can be oxidized easily by UV light. This could influence the bioaccessibility and bioavailability of methionine. In this work, the photosensitized degradation of peptide-bound methionine in the presence of riboflavin was investigated in a model system. Capillary electrophoresis was employed to analyze the time course of the degradation. The products were identified by liquid chromatography coupled to mass spectrometry (LC–MS/MS). Benzoyl methionine was degraded by 50% during UV irradiation in the presence of riboflavin after 5.0 min with 10 mol% riboflavin and 6.4 min with 3 mol% riboflavin. Homocysteine (16–20 mol%) and β-aspartic semialdehyde (ca. 30 mol%) were found as major degradation products next to methionine sulfoxide (ca. 25 mol%). A smaller molar ratio of riboflavin led to a higher formation of aspartic semialdehyde. The formation of homocysteine was paralleled by the formation of formaldehyde. Furthermore, the experiment was transferred to small peptides, which showed the analogous degradation products of peptide-bound methionine.

Application of atmospheric cold plasma for zearalenone detoxification in cereals: Kinetics, mechanisms, and cytotoxicity analysis

IntroductionZearalenone (ZEN) is one of the most widely contaminated mycotoxins in world, posing a severe threat to human and animal health. Atmospheric cold plasma (ACP) holds great penitential in mycotoxin degradation. ObjectivesThis study aimed to investigate the degradation efficiency and mechanisms of ACP on ZEN as well as the cytotoxicity of ZEN degradation products by ACP. Additionally, this study also investigated the degradation efficiency of ACP on ZEN in cereals and its effect on cereal quality. MethodsThe degradation efficiency and products of ZEN by ACP was analyzed by HPLC and LC-MS/MS. The human normal liver cells and mice were employed to assess the cytotoxicity of ZEN degradation products. The ZEN artificially contaminated cereals were used to evaluate the feasibility of ACP detoxification in cereals. ResultsThe results showed that the degradation rate of ZEN was 96.18 % after 30-W ACP treatment for 180 s. The degradation rate was dependent on the discharge power, and treatment time and distance. Four major ZEN degradation products were produced after ACP treatment due to the oxidative destruction of CC double bond, namely C18H22O7 (m/z = 351.19), C18H22O8 (m/z = 367.14), C18H22O6 (m/z = 335.14), and C17H20O6 (m/z = 321.19). L02 cell viability was increased from 52.4 % to 99.76 % with ACP treatment time ranging from 0 to 180 s. Mice results showed significant recovery of body weight and depth of colonic crypts as well as mitigation of glomerular and liver damage. Additionally, ACP removed up to 50.55 % and 58.07 % of ZEN from wheat and corn. ConclusionsThis study demonstrates that ACP could efficiently degrade ZEN in cereals and its cytotoxicity was significantly reduced. Therefore, ACP is a promising effective method for ZEN detoxification in cereals to ensure human and animal health. Future study needs to develop large-scale ACP device with high degradation efficiency.