WIRKUNG VON 1,2α-METHYLEN-6-CHLOR-Δ4,6-PREGNADIEN-17α-OL-3,20-DION (CYPROTERON) AUF DIE BIOGENESE VON C19-STEROIDEN IN RATTENTESTES

1968 ◽  
Vol 57 (4) ◽  
pp. 623-638 ◽  
Author(s):  
W. Hoffmann ◽  
H. Breuer
Keyword(s):  
Mixed Type ◽  
Kinetic Studies ◽  
Final Concentration ◽  
Polar Fraction ◽  
Enzyme Kinetic ◽  
Experimental Conditions ◽  
Enzyme Systems

ABSTRACT The effect of 1,2α-methylene-6-chloro-pregna-4,6-dien-17α-ol-3,20-dione (Cyproterone) on the formation of C19-steroids from 17α-hydroxyprogesterone was studied in the 20 000 × g supernatants and the microsomal fractions obtained from the testis of young (5 weeks ± 5 days) and old (5 months ± 14 days) rats. Under the experimental conditions chosen, cyproterone (final concentration 2.7-27 μmoles/1) inhibited the biogenesis of C19-steroids to an extent of 20–80%. On the basis of enzyme-kinetic studies, cyproterone belongs to the class of »mixed type inhibitors«. The investigation of the pattern of the C19-steroid metabolites showed that, after the addition of cyproterone, the formation of testosterone, androst-4-ene-3,17-dione and the »polar« fraction was inhibited, whereas the androsterone fraction mostly increased. These results suggest that cyproterone affects not only the activity of the desmolase, but also the activities of the enzymes involved in the metabolism of C19-steroids. The experiments reported are, to a large extent, in agreement to the already known fact that the activity of the desmolase depends upon the age of rats. However, the biogenesis of C19-steroids from C21-steroids is greatly influenced by the preparation of the relevant enzyme systems and by the experimental conditions.

Cellular Regulation of the Metabolism of Androgens in Rat Oral Mucosa. III. Activation of Δ4-3-ketosteroid-5α-A Ring Reductase Enzyme System by 5,5-Diphenylhydantoin

1979 ◽  
Vol 58 (2) ◽  
pp. 642-645 ◽  
Author(s):  
Jozef Vittek ◽  
Gary G. Gordon ◽  
Sydney C. Rappaport ◽  
A. Louis Southren
Keyword(s):  
Oral Mucosa ◽  
Enzyme System ◽  
Kinetic Studies ◽  
In Vitro Assay ◽  
Enzyme Kinetic ◽  
Cellular Regulation ◽  
Vitro Assay ◽  
Allosteric Mechanism

Systemic pretreatment of rats with diphenylhydantoin (DPH) or its addition into an in vitro assay increases 5α-reduction of testosterone by the oral mucosa. Enzyme kinetic studies showed that DPH binds to the enzyme and probably activates it by an allosteric mechanism.

scholarly journals Recent advances in the use of benzimidazoles as corrosion inhibitors

BMC Chemistry ◽  
2019 ◽  
Vol 13 (1) ◽  
Author(s):  
Maria Marinescu
Keyword(s):  
Mixed Type ◽  
Corrosion Inhibitors ◽  
Benzimidazole Derivatives ◽  
Theoretical Studies ◽  
Cathodic Reaction ◽  
Electrochemical Studies ◽  
Salt Solutions ◽  
Acidic Media ◽  
Experimental Conditions ◽  
Pure Metals

Abstract Background Benzimidazole, a key heterocycle in therapeutic chemistry, and its derivatives, are recently mentioned in the literature as corrosion inhibitors for steels (CS, MS), pure metals (Fe, Al, Cu, Zn) and alloys. Benzimidazoles are good corrosion inhibitors for extremely aggressive, corrosive acidic media such as 1 M HCl, 1 M HNO3, 1.5 M H2SO4, basic media, 0.1 M NaOH or salt solutions. Benzimidazole derivatives act as mixed type inhibitors, exhibiting stronger inhibitive effect on the cathodic reaction than on the anodic one. Conclusion These review highlights recent research in the field of benzimidazole compounds that their role as corrosion inhibitors, the structure of the compounds, electrochemical studies, the experimental conditions, the proposed mechanisms as well as the quantum theoretical studies that predict the structure of the compounds with inhibition properties.

scholarly journals Optimization, equilibrium and kinetic studies of Zn2+ and Ni2+ adsorption from aqueous solutions using composite adsorbent

2018 ◽  
Vol 67 (3) ◽  
pp. 279-290 ◽  
Author(s):  
Haider M. Zwain ◽  
Mohammadtaghi Vakili ◽  
Irvan Dahlan
Keyword(s):  
Contact Time ◽  
Coal Fly Ash ◽  
Sol Gel ◽  
Freundlich Isotherm ◽  
Kinetic Studies ◽  
Isotherm Models ◽  
Experimental Conditions ◽  
Palm Oil Fuel Ash ◽  
Composite Adsorbent ◽  
Oil Fuel

Abstract A novel RHA/PFA/CFA composite adsorbent was synthesized from rice husk ash (RHA), palm oil fuel ash (PFA), and coal fly ash (CFA) by modified sol-gel method. Effect of different parameters such as adsorbent dosage, contact time, and pH were studied using batch experiment to optimize the maximum zinc (Zn2+) and nickel (Ni2) adsorption conditions. Results showed that the maximum adsorption condition occurred at adsorbent amount of 10 g/L, contact time of 60 min, and pH 7. At this condition, the removal efficiencies were 81% and 61% for Zn2+ and Ni2+, in which the adsorption capacities (qmax) were 21.74 mg/g and 17.85 mg/g, respectively. Adsorption behavior of RHA/PFA/CFA composite adsorbent was studied through the various isotherm models at different adsorbent amounts. The results indicated that the Freundlich isotherm model gave an excellent agreement with the experimental conditions. Based on the results obtained from the kinetic studies, pseudo-second-order was suitable for the adsorption of Ni2+ and Zn2+, compared to the pseudo-first-order model. The results presented in this study showed that RHA/PFA/CFA composite adsorbent successfully adsorbed Zn2+ and Ni2.

scholarly journals Be Aware of Aggregators in the Search for Potential Human ecto-5′-Nucleotidase Inhibitors

Molecules ◽  
2018 ◽  
Vol 23 (8) ◽  
pp. 1876 ◽  
Author(s):  
Lucas Viviani ◽  
Erika Piccirillo ◽  
Arquimedes Cheffer ◽  
Leandro de Rezende ◽  
Henning Ulrich ◽  
...  
Keyword(s):  
Drug Discovery ◽  
Kinetic Studies ◽  
Enzyme Concentration ◽  
Experimental Conditions ◽  
Time Aggregation ◽  
Compound C ◽  
Promising Target ◽  
Ic50 Values ◽  
Potential Inhibitors ◽  
Triton X

Promiscuous inhibition due to aggregate formation has been recognized as a major concern in drug discovery campaigns. Here, we report some aggregators identified in a virtual screening (VS) protocol to search for inhibitors of human ecto-5′-nucleotidase (ecto-5′-NT/CD73), a promising target for several diseases and pathophysiological events, including cancer, inflammation and autoimmune diseases. Four compounds (A, B, C and D), selected from the ZINC-11 database, showed IC50 values in the micromolar range, being at the same time computationally predicted as potential aggregators. To confirm if they inhibit human ecto-5′-NT via promiscuous mechanism, forming aggregates, enzymatic assays were done in the presence of 0.01% (v/v) Triton X-100 and an increase in the enzyme concentration by 10-fold. Under both experimental conditions, these four compounds showed a significant decrease in their inhibitory activities. To corroborate these findings, turbidimetric assays were performed, confirming that they form aggregate species. Additionally, aggregation kinetic studies were done by dynamic light scattering (DLS) for compound C. None of the identified aggregators has been previously reported in the literature. For the first time, aggregation and promiscuous inhibition issues were systematically studied and evaluated for compounds selected by VS as potential inhibitors for human ecto-5′-NT. Together, our results reinforce the importance of accounting for potential false-positive hits acting by aggregation in drug discovery campaigns to avoid misleading assay results.

scholarly journals Effect of bicarbonate on growth of the oleaginous microalga Botryococcus braunii

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Giovanna Salbitani ◽  
Carmela M.A. Barone ◽  
Simona Carfagna
Keyword(s):  
Inorganic Carbon ◽  
Algal Growth ◽  
Botryococcus Braunii ◽  
Final Concentration ◽  
Time Intervals ◽  
Experimental Conditions ◽  
Co2 Gas ◽  
Inorganic Carbon Source ◽  
Doubling Times

The effect of bicarbonate, produced by the enzymatic hydration of CO2 from postcombustion fumes, was investigated on Botryococcus braunii growth. The NaHCO3, supplied to cultures in the role of inorganic carbon source is proposed as a more eco-sustainable alternative to gaseous CO2. The salt was provided to the cultures at the final concentration of 0.5-1.5-2.5 g L- 1. The growth rate was considered for specific time intervals (T0-T5, T5-T10 and T0- T10) showing values significantly higher in the culture supplemented with 2.5 g L-1 bicarbonate. The doubling times were also considered in all experimental cultures showing a faster doubling for the period T0÷T5. The increase in pH drives the increase in growth in the experimental conditions in which the salt was added. The results suggest that bicarbonate is able to promote the algal growth, therefore it can be considered a valid alternative to CO2 gas.

KINETIC STUDIES ON ACID PHOSPHATASE IN TRIBOLIUM CONFUSUM DUVAL

1964 ◽  
Vol 42 (12) ◽  
pp. 1769-1775 ◽  
Author(s):  
K. D. Chaudhary ◽  
S. Moorjani ◽  
A. Lemonde
Keyword(s):  
Kinetic Studies ◽  
Final Concentration ◽  
Tribolium Confusum ◽  
Metallic Ions ◽  
Optimal Conditions ◽  
Optimum Temperature ◽  
Apparent Effect ◽  
Michaelis Constant ◽  
Optimum Ph ◽  
Zero Order Reaction

The biochemical characteristics of acid phosphomonoesterase in Tribolium confusum homogenate have been determined. Zero-order reaction occurs for 30 minutes, with 10−3 M final concentration of phenyl phosphate at an optimum pH of 6.4. Michaelis constant (Km) under the optimal conditions is 6.34 × 10−3 M. Maximum enzyme activity is obtained at 40 °C, and the activation energy (ΔE) is 13,000 cal/mole, within the limits of optimum temperature. Inorganic phosphate inhibits competitively and Ki value is 3.45 × 10−3 M. Partial inhibition by fluoride is shown. Apparent effect of metallic ions also has been demonstrated.Comparison of these results with those reported in the literature for several other species of insects, as well as with those in certain mammalian systems, has been discussed.

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