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Human DOPA Decarboxylase: Catalysis and Involvement in Pharmacological Treatments for Parkinson’s Disease and Aromatic Amino Acid Decarboxylase Deficiency
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2020
Mariarita Bertoldi, Giada Rossignoli
In the first approach, a series of structure-based searches have been performed by bioinformatics methods in order to identify a class of compounds that have structural requirements and are predicted to behave as inhibitors. They have in common some structural constraints that led them to interact with essential active site residues (Daidone et al., 2012). Their effectiveness in inhibiting DDC has been tested and their affinity values are in the range of 0.5-1 µM, underlying the promising properties of these molecules to be further refined to build a specific DDC inhibitor. The second approach exploits some interesting properties of molecules present in vegetal extracts of medicinal plants. They have IC50 values in the micromolar range and are able to inhibit recombinant DDC and also endogenous DDC in HepG2 cell lines. In addition, given their polar chemical nature, they could not cross the blood-brain barrier and could thus exclusively inhibit peripheral DDC (Ren et al., 2014). Finally, chemical modifications of a natural quaternary benzophenanthridine alkaloid has been performed given the ability of this natural alkaloid to inhibit DDC (Drsata et al., 1996). The newly synthesized molecules are endowed with an IC50 value in the micro-to-millimolar range (Cheng et al., 2014). Altogether these compounds are either commercially available or not but, in any case, no proper investigations regarding their efficacy in vivo or their pharmacokinetic or toxicological properties have been carried out. They are interesting candidates and need further optimization and validation.
Modeling Risks from Water Contaminants: The Application of Concentration-Response Models
Published in Rhoda G.M. Wang, Water Contamination and Health, 2020
A. John Bailer, Christopher J. Portier
Alternatives to safety factor approaches for assessing the toxicity of effluents have also been proposed. Norberg-King (25) suggested an alternative to the ChV for examining reproductive toxicity in a Ceriodaphnia dubia. This alternative is the 50% inhibition concentration (IC50), which corresponds to the concentration of a toxin required to reduce the number of young produced in three broods to 50% of the control number. This method proceeds by identifying the concentration with average total young immediately above 50% of the control reproduction rate and the concentration immediately below 50% of the control rate. The IC50 is calculated using linear interpolation between these two concentrations. Inhibition concentration for other levels of inhibition are calculated similarly. A dose-response model-based analog of the IC50 has been proposed by Bailer and Oris (26). They suggest modeling the number of young produced as an exponential function of some polynomial of the concentrations, such as y. = ebo+btdi+b2d? + error As an initial suggestion, these authors propose using a Poisson model for the response distribution. An estimate of the concentration that leads to a specified level of productive inhibition can be obtained from the parameter estimates of b¡ and b2. The extension of this work to low-dose risk estimation has not been addressed.
Biomedical Imaging
Published in Mohammad E. Khosroshahi, Applications of Biophotonics and Nanobiomaterials in Biomedical Engineering, 2017
At the lowest concentration value of DMNP, 10 μg/mL, the cell viability was 62.69% and 59.79% for MCF7 and L929, respectively which can imply their high toxicity. By increasing the concentrations from 10 to 500 μg/mL, the cell viabilities were reduced for DMNP, which means that DMNP is no longer biocompatible. Thus, for in vivo applications, one should coat them suitably to prevent the toxic, hence the adverse effects, for example, by coating them by Polyethylene Glycol (PEG). But the test results for FDMNP showed a less toxicity. As its concentration increased from 10 to 500 μg/mL the amount of viability was reduced from 70% to 66% and 99.88% to 87%, respectively for MCF7 and L929 cells. The IC50 and IC20 represent the corresponding concentrations at which 50% and 20% of cell viability was inhibited. The results are given in Table 13.3.
Green and eco-friendly synthesis of silver nanoparticles by Quercus infectoria galls extract: thermal behavior, antibacterial, antioxidant and anticancer properties
Published in Particulate Science and Technology, 2022
Marzieh Khatamifar, S. Jamilaldin Fatemi, Masoud Torkzadeh-Mahani, Meisam Mohammadi, Mehdi Hassanshahian
The antioxidant activity of the Q. infectoria galls extract and AgNPs was determined on the basis of the scavenging activity of the stable 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical. 1 ml of each concentration of galls extract and AgNPs, ranging from 6.25 to 400 µg/mL, was added to 3 mL of DPPH methanolic solution (0.1 mM). Samples were placed in the dark place at room temperature for 30 min. Absorbance values were determined at 517 nm by using Elisa reader. The percentage of inhibition activity for each concentration was calculated with the following relation: where A0 is the absorbance of the negative control compound (blank, without samples) and A1 is the absorbance in the presence of samples. The experiment was repeated four times. The percentage of inhibition activity was calculated then calibration curves were drawn to obtain the IC50. IC50 values denote the concentration of sample, which is required to scavenge fifty percent of DPPH free radicals (Ansar et al. 2020).
Phytotoxic effects of biosynthesized ZnO nanoparticles using Betonica officinalis extract
Published in Environmental Technology, 2021
Renata Dobrucka, Marcin Szymanski, Robert Przekop
This work has assessed the phytotoxicity of ZnO nanoparticles biosynthesized using Zn(NO3)2 and Betonica officinalis extract. In toxicity studies, it is important to determine the IC50 coefficient, which means the concentration of a toxic substance that inhibits growth by a certain percent (50%) compared to the control sample. The IC50 coefficient (i.e. the concentration at which the growth of the test plant was inhibited by 50%) for Stachys officinalis extract as regards flax seeds and garden cress seeds was calculated on the basis of the equation: Awz = a*(C) + b. For Zn(NO3)2 solution and biosynthesized ZnO nanoparticles, both as regards flax seeds and garden cress seeds, the equation was Awz = a*ln(C) + b. The IC50 coefficient of biosynthesized ZnO nanoparticles could not be determined because the solutions did not exhibit a sufficient toxic effect at the studied range of concentrations. During the study, there was established a nominal equation y = ax2 + bx + c with a high R2 correlation coefficient. Figure 5 shows a chart depicting the dependence of growth activity on the concentration of biosynthesized ZnO nanoparticles for (A) flax seeds (B) Chia seeds, (C) garden cress seeds, (D) corn seeds.
Antimicrobial Activity of Ozone against Pathogenic Oral Microorganisms on Different Denture Base Resins
Published in Ozone: Science & Engineering, 2020
Yeliz Hayran, Sule Tugba Deniz, Ali Aydın
IC50 is the half maximal inhibitory concentration of an agent that kills 50% of the microorganisms which is a common indicator of the efficacy of disinfectants. The MTT assay outcome was stated as the test substances’ viability percent. The IC50 of the test compounds was calculated through these viability data percent through XLfit5 software (IDBS) and indicated in µg/ml at 95% confidence intervals.