Elucidation Of Degradation Pathways Research Articles

Forced Degradation Studies, Elucidation of Degradation Pathways and Degradation Kinetics of Xylopic Acid via LC and LC-MS/MS Analyses

Stability studies of active pharmaceutical ingredients (APIs) remain an essential quality requirement of the pharmaceutical industry. Stability data of an API could guide in the choice of its processing technique, packaging method and storage conditions. Here, we sought to determine the stability or otherwise of xylopic acid (XA) under various stress conditions as stipulated by the International Conference on Harmonization (ICH). XA is a diterpene kaurene isolate of the African spice, Xylopia aethiopica (Annonaceae) that is credited with diverse biological activities. XA was subjected to various stress conditions (hydrolytic, oxidative, photolytic and thermal) and its degradation products characterized. Seven degradation products were identified and tentatively characterized by LC-MS/MS analysis. The probable degradation pathways for the seven degradation products were then predicted. Using a simple and validated UHPLC-DAD method, the degradation kinetics of XA under the different stress conditions were comprehensively assessed. The degradation of XA under all the stress conditions followed the first order reaction kinetics. XA was found to be less stable in strongly acidic or strongly basic solutions as well as in an oxidizing agent (hydrogen peroxide). The stability of XA was also found to be pH- and temperature-dependent. Its stability was however not affected by UV-light irradiation.

Optimizing the malathion degrading potential of a newly isolated Bacillus sp. AGM5 based on Taguchi design of experiment and elucidation of degradation pathway

Malathion, a pesticide used to control pests in crops, vegetables, fruits, and livestock. Its widespread and indiscriminate usage has ensued in different ecological issues, thus, it's vital to remediate this insecticide. Malathion degrading bacterium Bacillus sp. AGM5, isolated from pesticide contaminated agricultural field was cultured in presence of different malathion concentrations under aerobic and energy restrictive conditions and was found effective at malathion degradation. Recovered malathion was extracted based on QuEChERS approach and then analyzed by UHPLC. About 39.5% of malathion biodegradation was observed at 300µlL-1 after 96h of incubation with the tested bacteria which increased to 58.5% and 72.5% after 240, and 360h of incubation, respectively. To further enhance malathion biodegradation, the effects of co-substrates, pH, temperature, initial malathion concentration, agitation (rpm), and inoculum size were evaluated using Taguchi methodology. Taguchi DOE's ability to predict the optimal response was established experimentally via optimised levels of these factors (glucose-0.1%, yeast extract-0.1%, inoculum size-2%wv-1, malathion concentration 300 µlL-1, rpm-150, pH-7, temperature 40°C), whereby biodegradation rate was enhanced to 95.49% after 38h. Confirmation of malathion biodegradation was performed by UHPLC, Q-TOF-MS, GC-MS analysis and a possible degradation pathway was proposed for malathion biodegradation. First order kinetic model was appropriate to describe malathion biodegradation. The Taguchi DOE proved to be viable tool for optimizing culture conditions and analysing the interactions between process parameters in order to attain the best feasible combination for maximum malathion degradation. These results could influence the development of a bioremediation strategy.

Forced Degradation Studies, Elucidation of Degradation Pathways and Degradation Kinetics of Xylopic Acid via LC and LC-MS/MS Analyses

Forced Degradation Studies, Elucidation of Degradation Pathways and Degradation Kinetics of Xylopic Acid via LC and LC-MS/MS Analyses

Optimization of triazo Acid Black 210 dye degradation by Providencia sp. SRS82 and elucidation of degradation pathway

The current work is aimed to evaluate the degradation of triazo textile dye Acid Black 210 (AB210) by Providencia sp. SRS82 that degrade 100mg/L dye within 90min under optimum conditions and was also found tolerant to as high as 2000ppm of dye AB210. Optimum conditions for decolourization and degradation of AB210 with the isolate were viz. temperature 30°C, pH 8, NaCl concentration 2.5% (w/v) and initial cell load of 8×108 cells/mL under static condition. Induction of intracellular and extracellular lignin peroxidase, intracellular laccase and tyrosinase, azoreductase, and DCIP reductase indicated their contribution in the biodegradation of AB210. The products obtained from Providencia sp. SRS82 degradation was monitored through UV–Vis spectrophotometer and were characterized by FTIR, HPTLC, HPLC, GC/MS and LCMS. The proposed metabolic pathway for the biodegradation of AB210 is elucidated for the first time, which showed production of 4 molecules of benzene, one of naphthalene and 4-aminophenyl-N-(4-amino phenyl) benzene sulphonamide. Microbial toxicity and cytotoxicity studies revealed the comparatively less toxic nature of metabolites generated after degradation of AB210. Providencia sp. SRS82 was found competent to degrade actual effluent and diverse dyes that could be present in textile industry effluent showing usefulness of the organism for possible commercial application.

Assessment of pyrolysis polygeneration of biomass based on major components: Product characterization and elucidation of degradation pathways

The pyrolysis behaviors of biomass components (cellulose, hemicellulose and lignin) were studied at various temperatures and the evolution mechanisms of the pyrolytic products were investigated with variant approaches. Anhydro-saccharides, light oxygenates and phenols were the main compounds in pyrolytic bio-oil from cellulose, xylan and lignin, respectively. The subsequent degradation of saccharides involved was the fragmentation to generate gaseous and light oxygenates, and these compounds formed competitively against the generation of phenols and aromatics. CO released from cellulose originated from the decomposition of saccharides while that from xylan was more likely to derive from the decarbonylation of ketones and decarboxylation of acids. H2, CH4 and light hydrocarbons formed during aromatization when exceeded 650°C. Cellulose was the main contributor to the porosity of biomass chars and lignin was the main contributor for the mass of biomass chars. Furthermore, a new pathway for the pyrolysis of biomass and insights into how biomass materials used more efficiently and comprehensively, were provided.

Efficient decolorization/degradation of aqueous azo dyes using buffered H2O2 oxidation catalyzed by a dosage below ppm level of chloroperoxidase

The decolorization/degradation of aqueous azo dyes generated by textile photography industries are a main issue in wastewater treatment. Despite many significant efforts and numerous systems have been exploited, the problem is still unsolved due to intrinsically low activity or use of non-convenient chemical reagents. Biodegradation appears to be one of the most efficient ways, however, the initial step of biotransformation usually involves a reductive cleavage of the azo bond, which under anaerobic conditions leads to the formation of aromatic amines known to be carcinogenic. This study shows that applying an oxidative process of H2O2 catalyzed by chloroperoxidase (CPO) for decolorization/degradation of aqueous azo dyes (Orange G and Sunset Yellow) in buffer solution is a very efficient system. The effect of initial pH, dosage of enzyme, H2O2 concentration, reaction temperature and time, and suitable initial dye concentration on the decolorization efficiency were investigated in detail and optimized accordingly. At optimum reaction condition, the decolorization efficiency of Orange G reached 98.72% in 5min, and 77.25% in 10min for Sunset Yellow. The dosage of CPO was below ppm level. This enzymatic reaction is an ideal potential alternative for application on decolorization/degradation of aqueous azo dyes.Furthermore, the elucidation of degradation pathways is of special interest considering healthy and environmental priorities. In this work, LC–MS was used to determine the structures of intermediates arising from Orange G by CPO–H2O2 oxidation. Eight transformation products were identified and two types of cleavage were proposed for the degradation pathway.

Mechanism of enzymatic degradation of the azo dye Orange II determined by ex situ 1H nuclear magnetic resonance and electrospray ionization-ion trap mass spectrometry

Removal of azo dye effluents generated by textile photography industries is a main issue in wastewater treatment. Enzymatic treatment of dyes appears to be one of the most efficient processes for their degradation. The elucidation of degradation pathways is of special interest considering health and environmental priorities. Ex situ nuclear magnetic resonance (NMR) spectroscopy and electrospray ionization (ESI)-ion trap mass spectrometry performed directly on incubation medium have been used for the first time to follow kinetics of sulfonated azo dye Orange II enzymatic degradation. Nine transformation products were identified using these complementary analyses performed ex situ without any prior treatment. Three types of cleavage are proposed for the degradation pathway: (i) a symmetrical splitting of the azo linkage that leads to the formation of 4-aminobenzenesulfonate (and 1-amino-2-naphthol, not detected); (ii) an asymmetrical cleavage on the naphthalene side that generates 1,2-naphthoquinone and 4-diazoniumbenzenesulfonate as products, with the latter one being transformed into 4-hydroxybenzensulfonate; and (iii) a third degradation pathway that leads to 2-naphthol and 4-hydroxybenzenesulfonate. Moreover, three other intermediates have been identified. This study, which constitutes the first concomitant use of 1H NMR spectroscopy and ESI-ion trap mass spectrometry in this field, illustrates the indubitable interest of the ex situ approach.