scholarly journals Investigation of The Activity of Lipase Variants on Different 4-Nitrophenyl Esters by Spectrophotometric Assay

2021 ◽  
Author(s):  
Nurcan VARDAR YEL
Keyword(s):  
Spectrophotometric Assay

scholarly journals Suitability of the Cyclic Voltammetry Measurements and DPPH• Spectrophotometric Assay to Determine the Antioxidant Capacity of Food-Grade Oenological Tannins

Molecules ◽  
2019 ◽  
Vol 24 (16) ◽  
pp. 2925 ◽  
Author(s):  
Arianna Ricci ◽  
Giuseppina Paola Parpinello ◽  
Nemanja Teslić ◽  
Paul Andrew Kilmartin ◽  
Andrea Versari
Keyword(s):  
Cyclic Voltammetry ◽  
Colorimetric Assay ◽  
Radical Scavenging ◽  
Calibration Graph ◽  
Spectrophotometric Assay ◽  
Experimental Conditions ◽  
Fast Analysis ◽  
Cv Measurements ◽  
And Control ◽  
Analytical Approaches

Twenty commercially available oenological tannins (including hydrolysable and condensed) were assessed for their antiradical/reducing activity, comparing two analytical approaches: The 2,2-diphenyl-1-picrylhydrazyl (DPPH•) radical scavenging spectrophotometric assay and the cyclic voltammetry (CV) electrochemical method. Electrochemical measurements were performed over a −200 mV–500 mV scan range, and integrated anodic currents to 500 mV were used to build a calibration graph with (+)-catechin as a reference standard (linear range: From 0.0078 to 1 mM, R2 = 0.9887). The CV results were compared with the DPPH• assay (expressed as % of radical scavenged in time), showing high correlation due to the similarity of the chemical mechanisms underlying both methods involving polyphenolic compounds as reductants. Improved correlation was observed by increasing the incubation time with DPPH• to 24 h (R2 = 0.925), demonstrating that the spectrophotometric method requires a long-term incubation to complete the scavenging reaction when high-molecular weight tannins are involved; this constraint has been overcome by using instant CV measurements. We concluded that the CV represents a valid alternative to the DPPH• colorimetric assay, taking advantage of fast analysis and control on the experimental conditions and, because of these properties, it can assist the quality control along the supply chain.

scholarly journals Linking a rapid throughput plate-assay with high-sensitivity stable-isotope label LCMS quantification permits the identification and characterisation of low β-L-ODAP grass pea lines

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Peter M. F. Emmrich ◽  
Martin Rejzek ◽  
Lionel Hill ◽  
Paul Brett ◽  
Anne Edwards ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Internal Standard ◽  
High Sensitivity ◽  
Spectrophotometric Assay ◽  
Rapid Screening ◽  
Grass Pea ◽  
Stable Isotope Label ◽  
Tissue Samples ◽  
Plate Assay ◽  
Accurate Quantification

Abstract Background Grass pea (Lathyrus sativus) is an underutilised crop with high tolerance to drought and flooding stress and potential for maintaining food and nutritional security in the face of climate change. The presence of the neurotoxin β-L-oxalyl-2,3-diaminopropionic acid (β-L-ODAP) in tissues of the plant has limited its adoption as a staple crop. To assist in the detection of material with very low neurotoxin toxin levels, we have developed two novel methods to assay ODAP. The first, a version of a widely used spectrophotometric assay, modified for increased throughput, permits rapid screening of large populations of germplasm for low toxin lines and the second is a novel, mass spectrometric procedure to detect very small quantities of ODAP for research purposes and characterisation of new varieties. Results A plate assay, based on an established spectrophotometric method enabling high-throughput ODAP measurements, is described. In addition, we describe a novel liquid chromatography mass spectrometry (LCMS)-based method for β-L-ODAP-quantification. This method utilises an internal standard (di-13C-labelled β-L-ODAP) allowing accurate quantification of β-L-ODAP in grass pea tissue samples. The synthesis of this standard is also described. The two methods are compared; the spectrophotometric assay lacked sensitivity and detected ODAP-like absorbance in chickpea and pea whereas the LCMS method did not detect any β-L-ODAP in these species. The LCMS method was also used to quantify β-L-ODAP accurately in different tissues of grass pea. Conclusions The plate-based spectrophotometric assay allows quantification of total ODAP in large numbers of samples, but its low sensitivity and inability to differentiate α- and β-L-ODAP limit its usefulness for accurate quantification in low-ODAP samples. Coupled to the use of a stable isotope internal standard with LCMS that allows accurate quantification of β-L-ODAP in grass pea samples with high sensitivity, these methods permit the identification and characterisation of grass pea lines with a very low ODAP content. The LCMS method is offered as a new ‘gold standard’ for β-L-ODAP quantification, especially for the validation of existing and novel low- and/or zero-β-L-ODAP genotypes.

High-throughput spectrophotometric assay of reactive oxygen species in serum

2007 ◽  
Vol 631 (1) ◽  
pp. 55-61 ◽  
Author(s):  
Ikue Hayashi ◽  
Yukari Morishita ◽  
Kazue Imai ◽  
Masakazu Nakamura ◽  
Kei Nakachi ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
High Throughput ◽  
Reactive Oxygen ◽  
Spectrophotometric Assay ◽  
Oxygen Species

scholarly journals Experimental and Computational Evaluation of Chloranilic Acid as an Universal Chromogenic Reagent for the Development of a Novel 96-Microwell Spectrophotometric Assay for Tyrosine Kinase Inhibitors

Molecules ◽  
2021 ◽  
Vol 26 (3) ◽  
pp. 744
Author(s):  
Ibrahim A. Darwish ◽  
Hany W. Darwish ◽  
Nasr Y. Khalil ◽  
Ahmed Y. A. Sayed
Keyword(s):  
Tyrosine Kinase ◽  
Tyrosine Kinase Inhibitors ◽  
Kinase Inhibitors ◽  
Spectrophotometric Assay ◽  
Charge Transfer Complexes ◽  
Physical Parameters ◽  
Chloranilic Acid ◽  
Chromogenic Reagent ◽  
Computational Evaluation ◽  
Computational Calculations

The tyrosine kinase inhibitors (TKIs) are chemotherapeutic drugs used for the targeted therapy of various types of cancer. This work discusses the experimental and computational evaluation of chloranilic acid (CLA) as a universal chromogenic reagent for developing a novel 96-microwell spectrophotometric assay (MW-SPA) for TKIs. The reaction resulted in an instantaneous formation of intensely purple colored products with TKIs. Spectrophotometric results confirmed that the reactions proceeded via the formation of charge-transfer complexes (CTCs). The physical parameters were determined for the CTCs of all TKIs. Computational calculations and molecular modelling for the CTCs were conducted, and the site(s) of interaction on each TKI molecule were determined. Under the optimized conditions, Beer’s law correlating the absorbances of the CTCs with the concentrations of TKIs were obeyed in the range of 10–500 µg/well with good correlation coefficients (0.9993–0.9998). The proposed MW-SPA fully validated and successfully applied for the determination of all TKIs in their bulk forms and pharmaceutical formulations (tablets). The proposed MW-SPA is the first assay that can analyze all the TKIs on a single assay system without modifications in the detection wavelength. The advantages of the proposed MW-SPA are simple, economic and, more importantly, have high throughput.

HEMOLYTIC CRISES OF FAVISM IN SICILIAN FEMALES HETEROZYGOUS FOR G-6-PD DEFICIENCY

PEDIATRICS ◽  
1972 ◽  
Vol 49 (6) ◽  
pp. 854-859
Author(s):  
Giuseppe Russo ◽  
Florindo Mollica ◽  
Lorenzo Pavone ◽  
Gino Schilirò
Keyword(s):  
Clinical Signs ◽  
Spectrophotometric Assay ◽  
Red Cells ◽  
Enzyme Deficiency ◽  
Reduction Test ◽  
Female Children ◽  
Hemolytic Crisis ◽  
Selective Lysis ◽  
Individual Erythrocytes

Five female children who suffered hemolytic crises of favism were studied 10 to 20 months after crisis. Spectrophotometric assay of erythrocytic glucose-6-PD (G-6-PD) activity, methemoglobin reduction test, and three cytochemical methods of enzyme demonstration in individual erythrocytes were performed. The parents were also studied in the same way. Four girls were certainly heterozygotes for G-6-PD deficiency, and one was very probably a heterozygote. A relationship was found between severity of hemolytic crisis and degree of enzyme deficiency and percentage of enzyme devoid red cells. The G-6-PD levels during crisis were higher than out of crisis. Assumption of a selective lysis of enzymopenic red cells during crisis would seem justified. Heterozygotes with low percentages of enzymopenic red cells probably experience hemolytic processes without or with minimal clinical signs. Hence favism in females is probably more frequent than generally thought.

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