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Approaches for Identification and Validation of Antimicrobial Compounds of Plant Origin: A Long Way from the Field to the Market
Published in Mahendra Rai, Chistiane M. Feitosa, Eco-Friendly Biobased Products Used in Microbial Diseases, 2022
Lívia Maria Batista Vilela, Carlos André dos Santos-Silva, Ricardo Salas Roldan-Filho, Pollyanna Michelle da Silva, Marx de Oliveira Lima, José Rafael da Silva Araújo, Wilson Dias de Oliveira, Suyane de Deus e Melo, Madson Allan de Luna Aragão, Thiago Henrique Napoleão, Patrícia Maria Guedes Paiva, Ana Christina Brasileiro-Vidal, Ana Maria Benko-Iseppon
Some techniques allow to infer the secondary structure, such as circular dichroism spectroscopy that identifies changes in the secondary structure when determining the percentage of alpha-helix, beta sheet and turns. X-ray crystallography and nuclear magnetic resonance reveal the tertiary structure and the interaction of the protein with ligands. Fluorimetric methods indicate changes in the hydrophobic environment, while thermodynamic measurements reveal regions of the protein that differ in stability (Nelson and Cox 2014).
Granulation of Poorly Water-Soluble Drugs
Published in Dilip M. Parikh, Handbook of Pharmaceutical Granulation Technology, 2021
Albert W. Brzeczko, Firas El Saleh, Hibreniguss Terefe
The stability constant and stoichiometry can be determined using the method of continuous variations, also known as Job Plots [37,38], and monitoring band shifts with different analytical methods such as nuclear magnetic resonance and circular dichroism spectroscopy [38]. Also, the phase-solubility diagrams [38,39]isotherms are often used for the same purpose. For this, Eq. (4) could be rewritten as Eq. (5) [36] and used to calculate the Kc for 1:1 complexes based on the slope and intercept (D0) of a regression line passing through the linear part of the phase-solubility diagram, in which both axes are expressed as Mol/L:
Structure-Function Elucidation of Flavonoids by Modern Technologies
Published in Dilip Ghosh, Pulok K. Mukherjee, Natural Medicines, 2019
Ritu Varshney, Neeladrisingha Das, Rutusmita Mishra, Partha Roy
Various other methods for elucidating structures include ultraviolet–visible spectroscopy (UV–Vis spectroscopy), circular dichroism spectroscopy and colorimetric analysis. Previously, UV–Vis spectroscopy was routinely used to determine flavonoid structures for two characteristics. These polyphenolic compounds provide two characteristic peaks at 240–285 nm (arising from the A-ring) and 300–550 nm (arising from the B-ring). The use of UV–Vis spectroscopy in predicting structures has diminished after the technical advancement in NMR, along with modern spectroscopic techniques. However, it is now mostly used for quantitative analyses of the flavonoids. UV–Vis spectroscopy is also widely used in the analysis of anthocyanins, which frequently change their colour with respect to pH (Melo et al. 2000; Giusti and Wrolstad 2001; Moncada et al. 2004). As far as circular dichromism is concerned, it is mainly used to determine the optical properties of the flavonoids. The principle behind dichromism is that when a polarized light is passed through a substance containing chiral molecules, the direction of the polarization can be altered (Berova et al. 2000). This technique is mainly used to define the stereochemistry of the flavonoids having a stereogenic centre or chiral molecule.
In silico identification and experimental validation of cellular uptake and intracellular labeling by a new cell penetrating peptide derived from CDN1
Published in Drug Delivery, 2021
Xiangli Guo, Linlin Chen, Lidan Wang, Jingping Geng, Tao Wang, Jixiong Hu, Jason Li, Changbai Liu, Hu Wang
We also used the PPM server and CellPM server to predict the interaction between the peptide and cell membrane. Residues 12, 15-16, 18 and 24 of peptide P2 may embed into lipid bilayers (Figure S4(A)), and the transfer energy ΔG(z) of a peptide from water to DOPC bilayer is shown in Figure S4(B). This peptide-membrane interaction prediction suggested that the optimal translocation pathway of the peptide is through the lipid bilayer, which reflects peptide P2’s affinity to different membrane regions. Circular dichroism spectroscopy was also performed to further validate the secondary structure of peptide P2 (Figure S5(A)), although a weak α‐helix structure was formed in a low concentration of phosphate-buffered saline. Lastly, the aggregation propensity of peptide P2 was characterized by native PAGE, a single band of P2 and without apparent aggregation was observed in Figure S5(B).
The problem of racemization in drug discovery and tools to predict it
Published in Expert Opinion on Drug Discovery, 2019
Andrew Ballard, Stefania Narduolo, Hiwa O. Ahmad, David A. Cosgrove, Andrew G. Leach, Niklaas J. Buurma
Finally, experimental studies might be required to confirm a prediction or when the computational methods do not provide consistent predictions. Following racemization by following deuterium incorporation in deuterated buffers can use 1H NMR or mass spectrometry. Care must be taken to correct for any other side-reactions (typically hydrolyses) and to investigate the influence of buffer concentration. Alternatively, the reaction can be followed directly by circular dichroism spectroscopy.