scholarly journals Computational modeling of distribution coefficients and their correlations with pharmacokinetic properties of 17α-picolyl and 17(E)-picolinylidene androstane derivatives

2019 ◽  
pp. 123-133
Author(s):  
Strahinja Kovacevic ◽  
Milica Karadzic-Banjac ◽  
Sanja Podunavac-Kuzmanovic ◽  
Jovana Ajdukovic
Keyword(s):  
Computational Modeling ◽  
Ph Value ◽  
Living Organism ◽  
Distribution Coefficients ◽  
Skin Permeability ◽  
Anticancer Activities ◽  
Drug Candidates ◽  
Brain Barrier Permeability ◽  
Androstane Derivatives

The present study describes the computational modeling of distribution coefficient (logD) of 17?-picolyl and 17(E)-picolinylidene androstane derivatives, as a group of compounds with significant anticancer activities. The determination of logD is practically important for estimation and prediction of pharmacokinetic and pharmacodynamic behavior of compounds in a living organism and it is related to blood-brain barrier permeability, skin permeability, gastrointestinal absorption, binding to plasma proteins, etc. These features are crucial for the determination of potential drug candidates as well. The results presented in this study include determination of pH versus logD profiles, pH versus molecular charge profiles and determination of isoelectric point of eleven 17?- picolyl androstane derivatives and thirteen 17(E)-picolinylidene androstane derivatives. Since the pH of the organism differs depending on the organ (for example, the pH of the blood is significantly different from the pH of the stomach), these profiles are significant because they indicate in what form the molecule will exist and how it will be distributed between different phases at certain pH value. The influence of tautomerization and resonance was taken into account during the modeling of logD parameters. Eventually, the correlations between logD values and specific absorption, distribution, metabolism, and excretion (ADME) properties, such as human intestinal absorption (HIA) and permeability of heterogeneous human epithelial colorectal adenocarcinoma cells (Caco-2), were determined.

Determination of the Potential of Drug Candidates to Cause Severe Skin Disorders Using Computational Modeling

2013 ◽  
Vol 32 (3) ◽  
pp. 303-312
Author(s):  
Yuye He ◽  
Frederica Hui Ting Chong ◽  
Junianti Lim ◽  
Rina Jia Tien Lee ◽  
Chun Wei Yap
Keyword(s):  
Computational Modeling ◽  
Skin Disorders ◽  
Drug Candidates

Atomic absorption determination of Hg (II), Cd (II), and As (III) in natural and waste water after preliminary group preconcentration

2019 ◽  
Vol 85 (2) ◽  
pp. 12-16
Author(s):  
I. V. Saunina ◽  
E. N. Gribanov ◽  
E. R. Oskotskaya
Keyword(s):  
Waste Water ◽  
Atomic Absorption ◽  
High Sensitivity ◽  
Distribution Coefficients ◽  
Neutral Medium ◽  
Atomic Absorption Determination ◽  
Absorption Determination ◽  
Relative Standard ◽  
Preliminary Group

The sorption of Hg (II), Cd (II), and As (III) by natural aluminosilicate is studied. It is shown that the mineral absorbs those toxicants in a rather wide pH range, quantitative extraction of analytes being achieved in a neutral or close to neutral medium (pH values range within 7.0 - 8.0; 6.3 - 7.5; 7.4 - 8.5 for Hg (II), As (III), and Cd (II), respectively). The effect of the time of phase contact on the degree of extraction of elements is shown. The sorption capacity of the mineral in optimal conditions of the medium acidity (0.06 mmol/g for mercury, 0.31 mmol/g for cadmium, and 0.52 mmol/g for arsenic) is determined. The distribution coefficients attain values of aboutnX 103-nX 104. A new combined method for determination of Hg (II), Cd (II), and As (III) in natural and waste water is developed and tested. The method consists in a preliminary group sorption concentration of the analytes by aluminosilicate, desorption of the analytes from the surface of the mineral and their subsequent atomic absorption determination. The correctness of the method is verified in analysis of spiked samples. The method is easy to use and exhibits high sensitivity, reproducibility and accuracy of analyte determination. The relative standard deviation does not exceed 0.13. Economic availability and possibility of using domestic sorption materials are the important advantages of the proposed procedure which can be used in the practice of laboratories monitoring the quality and safety of environmental objects.

Optimization of sol-gel based fibre-optic cholinesterase biosensor for the determination of organophosphorus pesticides

2000 ◽  
Vol 42 (7-8) ◽  
pp. 283-290 ◽  
Author(s):  
H.-C. Tsai ◽  
R.-A. Doong
Keyword(s):  
Fiber Optic ◽  
Ph Value ◽  
Rapid Determination ◽  
Organophosphorus Pesticides ◽  
Sol Gel ◽  
Neutral Red ◽  
Fluorescent Indicators ◽  
Low Leakage ◽  
Fiber Optic System

A sol-gel based fiber-optic biosensor with acetylcholinesterase as the biorecognition element has been developed for the rapid determination of organophosphorus pesticides. Nine fluorescent indicators, acridine, acridine orange, neutral red, DAPI, rhodamine B, fluorescein, umbelliferone, FITC on celite and FITC-dextran, have been examined to optimize the fiber-optic system. Results showed that acridine and FITCs were sensitive to the change of pH value caused by the enzyme-substrate catalysis reaction. However, the sensitivity of acridine was 260 times lower than that of FITCs. Higher toxicity of acridine to acetylcholinesterase than FITC was also observed. Moreover, the high-molecular-weight FITC-dextran showed low leakage rate when immobilizing using sol-gel technology, showing that the FITC-dextran was a suitable pH sensitive fluorescent indicator for the OPPs biosensor. The response of the fiber-optic biosensor to the substrate, acetylcholine, was highly reproducible (RSD=3.5%). A good linearity of acetylcholine in the range from 0.5 to 20 mM was also obtained (R2=0.98). Furthermore, a 30% inhibition can be achieved in 30min when 152 ppb paraoxon was added into the system. The results show the possibility for real-time determination of organophosphorus pesticides by using the biosensor developed in this study.

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