scholarly journals Mesoporous silica microparticles gated with a bulky azo derivative for the controlled release of dyes/drugs in colon

2018 ◽  
Vol 5 (8) ◽  
pp. 180873 ◽  
Author(s):  
Daniel Ferri ◽  
Pablo Gaviña ◽  
Margarita Parra ◽  
Ana M. Costero ◽  
Jamal El Haskouri ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
High Performance ◽  
External Surface ◽  
Sodium Dithionite ◽  
Ph Values ◽  
Silica Microparticles ◽  
Safranin O ◽  
Hydrolysis Of ◽  
Chemical Integrity

Mesoporous silica microparticles were prepared, loaded with the dye safranin O ( M-Saf ) or with the drug budesonide ( M-Bud ) and capped by the grafting of a bulky azo derivative. Cargo release from M-Saf at different pH values (mimicking those found in the gastrointestinal tract) in the absence or presence of sodium dithionite (a reducing agent mimicking azoreductase enzyme present in the colon) was tested. Negligible safranin O release was observed at pH 6.8 and 4.5, whereas a moderate delivery at pH 1.2 was noted and attributed to the hydrolysis of the urea bond that linked the azo derivative onto the external surface of the inorganic scaffold. Moreover, a marked release was observed when sodium dithionite was present and was ascribed to the rupture of the azo bond in the molecular gate. Budesonide release from M-Bud in the presence of sodium dithionite was also assessed by ultraviolet-visible spectroscopy and high performance liquid chromatography measurements. In addition, preliminary in vivo experiments with M-Saf carried out in mice indicated that the chemical integrity of the microparticles remained unaltered in the stomach and the small intestine, and safranin O seemed to be released in the colon.

Influence of C-ANF receptor and neutral endopeptidase on pharmacokinetics of ANF in rats

1991 ◽  
Vol 260 (1) ◽  
pp. R208-R216 ◽  
Author(s):  
P. J. Chiu ◽  
G. Tetzloff ◽  
M. T. Romano ◽  
C. J. Foster ◽  
E. J. Sybertz
Keyword(s):  
High Performance ◽  
Fold Increase ◽  
Neutral Endopeptidase ◽  
Volume Of Distribution ◽  
Fourfold Increase ◽  
Control Value ◽  
Enzymatic Pathways ◽  
Hydrolysis Of

The role of C-atrial natriuretic factor (ANF) receptors and neutral endopeptidase (NEP) in the pharmacokinetics and hydrolysis of 125I-labeled ANF was evaluated in rats by using C-ANF and SCH 39370 to block the nonenzymatic and enzymatic pathways, respectively. After a bolus injection of 125I-ANF, the resulting area under the plasma concentration curve (AUC) with C-ANF treatment was seven times the control value with regard to trichloroacetic acid-precipitable (TCA-ppt) radioactivity (intact ANF). SCH 39370 tended to increase AUC, but the changes were not significant. Nevertheless, SCH 39370 suppressed the appearance of TCA-soluble radioactivity (hydrolytic products), indicating that in vivo inhibition of ANF degradation had occurred. SCH 39370 plus C-ANF produced a 15-fold increase in AUC for TCA-ppt radioactivity and a reduction in plasma TCA-soluble radioactivity. High-performance liquid chromatography (HPLC) analysis confirmed that combination treatment increased intact ANF and reduced hydrolytic products in the plasma. SCH 39370 reduced clearance (C) without altering volume of distribution in steady state (Vss) and half-life (t1/2). C-ANF decreased both C and Vss leading to a fourfold increase in t1/2, which was further prolonged by SCH 39370 (7.5 times control). Bilateral nephrectomy caused a proportionally similar decrease in Vss and C without changing t1/2, suggesting significant extrarenal metabolism of ANF. SCH 39370 systemically inhibits ANF hydrolysis; the resulting increase in ANF, however, is masked by the great capacity of ANF clearance receptors but can be revealed with excess C-ANF, suggesting that the plasma ANF concentrations are determined by the interplay of the C-ANF receptor and NEP systems.

scholarly journals Towards 99mTc- and Re-Based Multifunctional Silica Platforms for Theranostic Applications

Inorganics ◽  
2019 ◽  
Vol 7 (11) ◽  
pp. 134 ◽  
Author(s):  
Michel A. Wuillemin ◽  
Michael J. Reber ◽  
Thomas Fox ◽  
Bernhard Spingler ◽  
Dominik Brühwiler ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
External Surface ◽  
High Potential ◽  
Medical Applications ◽  
Pore Surface ◽  
Radio Imaging ◽  
Radiation Properties ◽  
Silica Microparticles ◽  
Theranostic Applications

Taking advantage of the radiation properties of 99mTc and 186/188Re and the photophysical characteristics of the {M(CO)3}+ moiety (M = Re), we developed a multifunctional silica platform with the theranostic pair 99mTc/Re with high potential for (nano)medical applications. Starting with a general screening to evaluate the most suitable mesoporous silica construct and the development of appropriate chelate systems, multifunctional mesoporous silica microparticles (SBA-15) were synthesized. These particles act as a model towards the synthesis of the corresponding nanoconstructs. The particles can be modified at the external surface with a targeting function and labeled with the {M(CO)3}+ moiety (M = 99mTc, Re) at the pore surface. Thus, a silica platform is realized, whose bioprofile is not altered by the loaded modalities. The described synthetic procedures can be applied to establish a target-specific theranostic nanoplatform, which enables the combination of fluorescence and radio imaging, with the possibility of radio- and chemotherapy.

Different pH-Values of Release Medium Influence the Drug Release from PTX-PCL Microspheres

2012 ◽  
Vol 482-484 ◽  
pp. 2605-2608 ◽  
Author(s):  
Li Li Ruan ◽  
Da Xin Wang ◽  
You Wei Zhang ◽  
Jiong Xin Zhao ◽  
Xiu Fang Zhang ◽  
...  
Keyword(s):  
Drug Release ◽  
Sustained Release ◽  
High Performance ◽  
Drug Loading ◽  
In Vitro Release ◽  
Buffer Solution ◽  
Ph Values ◽  
Sustained Release Microspheres

In this paper we study in vitro release of paclitaxel-loade polycaprolactone sustained-release microspheres. Different pH values release medium is used to simulate pH conditions in different parts of body, and determination the paclitaxel in Microspheres by High Performance Liquid Chromatography according Chinese Pharmacopoeia 2010. The experimental results indicate that the microspheres release rates of same drug loading content in buffer solution of pH 7.35 is the fastest, and in the pH 1.2 is the slowest. The drug release behavior according to the first-order model and it is not affected by drug loading rate of microspheres. The prepared paclitaxel-loade polycaprolactone sustained-release microspheres has good sustained release effect in different release media, and the results can provide references for further study of in vivo release.

scholarly journals Influence of Potassium and pH on the PG-mediated Hydrolysis of Pectin in Tomato Fruit Cell Wall

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 478C-478
Author(s):  
Jong-Pil Chun ◽  
Donald J. Huber
Keyword(s):  
Cell Wall ◽  
Tomato Fruit ◽  
In Vitro Assays ◽  
Ph Values ◽  
Ph Range ◽  
Hydrolysis Of ◽  
Ionic Effects ◽  
Catalytic Capacity

The catalytic capacity of tomato polygalacturonase (PG) toward soluble pectic polymers is in excess of activity expressed in vivo; however, in vitro assays of PG have traditionally been performed under conditions (pH 4.0 to 4.5, 150 mM NaCl) that likely do not reflect the apoplastic environment of ripening tomato fruit. In this study, hydrolysis of pectin by purified tomato PG (isozyme 2) was examined in response to K+ (the predominate apoplastic cation) and over the pH range from 3.0 to 6.0. In the presence of K+, PG activity toward polygalacturonic acid measured reductometrically increased nearly 3.5-fold from pH 4.0 to pH 5.5. In the presence of Na+, activity decreased 90% over the same pH range. PG-mediated degradation of cell wall from mature-green fruit showed divergent hydrolytic patterns in response to pH and K+. At pH 4.5 in the presence of K+ (as KCl), catalysis resulted in both solubilization and extensive depolymerization of cell wall pectin, with oligomers accounting for a significant portion of the hydrolysis products. At pH 5.5, the total quantity of wall pectin released in response to PG2 was similar to that at pH 4.5; however, oligomer production was strongly suppressed at the higher pH. At pH values favoring extensive depolymerization, low mol mass products were produced at 5 mM K+ and increased to a maximum at 100 mM K+. At higher pH, hydrolysis patterns were not affected by [K+]. pH and ionic effects may contribute to the distinctive patterns of pectin hydrolysis observed for different fruits.

Click Chemistry Expedited Radiosynthesis: Sulfur [18F]fluoride Exchange of Aryl Fluorosulfates

2019 ◽  
Author(s):  
Qinheng Zheng ◽  
Hongtao Xu ◽  
Hua Wang ◽  
Wen-Ge Han Du ◽  
Nan Wang ◽  
...  
Keyword(s):  
Click Chemistry ◽  
High Performance ◽  
Isotopic Exchange ◽  
Tumor Imaging ◽  
Radiochemical Yield ◽  
Exchange Method ◽  
Molar Activity ◽  
Positron Emission ◽  
Sulfur Fluoride

The lack of simple, efficient [<sup>18</sup>F]fluorination processes and new target-specific organofluorine probes remains the major challenge of fluorine-18-based positron emission tomography (PET). We report here a fast isotopic exchange method for the radiosynthesis of aryl [<sup>18</sup>F]fluorosulfate based PET agents enabled by the emerging sulfur fluoride exchange (SuFEx) click chemistry. The method has been applied to the fully-automated <sup>18</sup>F-radiolabeling of twenty-five structurally diverse aryl fluorosulfates with excellent radiochemical yield (83–100%) and high molar activity (up to 281 GBq µmol<sup>–1</sup>) at room temperature in 30 seconds. The purification of radiotracers requires no time-consuming high-performance liquid chromatography (HPLC), but rather a simple cartridge filtration. The utility of aryl [<sup>18</sup>F]fluorosulfate is demonstrated by the <i>in vivo</i> tumor imaging by targeting poly(ADP-ribose) polymerase 1 (PARP1).

Evaluation of New 99mTc(CO)3 + Radiolabeled Glycylglycine In Vivo

2019 ◽  
Vol 19 (11) ◽  
pp. 1382-1387
Author(s):  
Ahmet M. Şenışık ◽  
Çiğdem İçhedef ◽  
Ayfer Y. Kılçar ◽  
Eser Uçar ◽  
Kadir Arı ◽  
...  
Keyword(s):  
High Performance ◽  
The Body ◽  
Biological Behavior ◽  
In Vivo Evaluation ◽  
Radiolabeled Peptides ◽  
Tumor Bearing ◽  
Biodistribution Data ◽  
Good Accordance ◽  
Rapid Clearance

Background: Peptide-based agents are used in molecular imaging due to their unique properties, such as rapid clearance from the circulation, high affinity and target selectivity. Many of the radiolabeled peptides have been clinically experienced with diagnostic accuracy. The aim of this study was to investigate in vivo biological behavior of [99mTc(CO)3(H2O)3]+ radiolabeled glycylglycine (GlyGly). Methods: Glycylglycine was radiolabeled with a high radiolabeling yield of 94.69±2%, and quality control of the radiolabeling process was performed by thin layer radiochromatography (TLRC) and High-Performance Liquid Radiochromatography (HPLRC). Lipophilicity study for radiolabeled complex (99mTc(CO)3-Gly-Gly) was carried out using solvent extraction. The in vivo evaluation was performed by both biodistribution and SPECT imaging. Results: The high radiolabelling yield of 99mTc(CO)3-GlyGly was obtained and verified by TLRC and HPLRC as well. According to the in vivo results, SPECT images and biodistribution data are in good accordance. The excretion route from the body was both hepatobiliary and renal. Conclusion: This study shows that 99mTc(CO)3-GlyGly has the potential to be used as a peptide-based imaging agent. Further studies, 99mTc(CO)3-GlyGly can be performed on tumor-bearing animals.

Phytochemical, Analytical and Medicinal Studies of Holoptelea integrifolia Roxb. Planch - A Review

2019 ◽  
Vol 5 (4) ◽  
pp. 270-277 ◽  
Author(s):  
Vijay Kumar ◽  
Simranjeet Singh ◽  
Ragini Bhadouria ◽  
Ravindra Singh ◽  
Om Prakash
Keyword(s):  
Liquid Chromatography ◽  
Thin Layer ◽  
Thin Layer Chromatography ◽  
High Performance ◽  
Biologically Active ◽  
Toxicological Studies ◽  
Wide Range ◽  
Layer Chromatography

Holoptelea integrifolia Roxb. Planch (HI) has been used to treat various ailments including obesity, osteoarthritis, arthritis, inflammation, anemia, diabetes etc. To review the major phytochemicals and medicinal properties of HI, exhaustive bibliographic research was designed by means of various scientific search engines and databases. Only 12 phytochemicals have been reported including biologically active compounds like betulin, betulinic acid, epifriedlin, octacosanol, Friedlin, Holoptelin-A and Holoptelin-B. Analytical methods including the Thin Layer Chromatography (TLC), High-Performance Thin Layer Chromatography (HPTLC), High-Performance Liquid Chromatography (HPLC) and Liquid Chromatography With Mass Spectral (LC-MS) analysis have been used to analyze the HI. From medicinal potency point of view, these phytochemicals have a wide range of pharmacological activities such as antioxidant, antibacterial, anti-inflammatory, and anti-tumor. In the current review, it has been noticed that the mechanism of action of HI with biomolecules has not been fully explored. Pharmacology and toxicological studies are very few. This seems a huge literature gap to be fulfilled through the detailed in-vivo and in-vitro studies.

Preparation of Organized Mesoporous Silica from Sodium Metasilicate Solutions in Alkaline Medium Using Nonionic Surfactants

2003 ◽  
Vol 68 (10) ◽  
pp. 2019-2031 ◽  
Author(s):  
Markéta Zukalová ◽  
Jiří Rathouský ◽  
Arnošt Zukal
Keyword(s):  
Mesoporous Silica ◽  
Ethylene Oxide ◽  
Sodium Metasilicate ◽  
Spherical Particles ◽  
Structure Directing Agent ◽  
Inorganic Species ◽  
Poly Ethylene Oxide ◽  
Acidic Conditions ◽  
Poly Ethylene ◽  
Hydrolysis Of

A new procedure has been developed, which is based on homogeneous precipitation of organized mesoporous silica from an aqueous solution of sodium metasilicate and a nonionic poly(ethylene oxide) surfactant serving as a structure-directing agent. The decrease in pH, which induces the polycondensation of silica, is achieved by hydrolysis of ethyl acetate. Owing to the complexation of Na+ cations by poly(ethylene oxide) segments, assembling of the mesostructure appears to occur under electrostatic control by the S0Na+I- pathway, where S0 and I- are surfactant and inorganic species, respectively. As the complexation of Na+ cations causes extended conformation of poly(ethylene oxide) segments, the pore size and pore volume of organized mesoporous silica increase in comparison with materials prepared under neutral or acidic conditions. The assembling of particles can be fully separated from their solidification, which results in the formation of highly regular spherical particles of mesoporous silica.

Studies on the mechanism of acute inhibition of thyroglobulin hydrolysis by iodine

1985 ◽  
Vol 108 (4) ◽  
pp. 511-517 ◽  
Author(s):  
Nandalal Bagchi ◽  
Birdie Shivers ◽  
Thomas R. Brown
Keyword(s):  
Time Course ◽  
Period 2 ◽  
Iodotyrosine Deiodinase ◽  
Rate Of Hydrolysis ◽  
Underlying Mechanisms ◽  
Excess Iodide ◽  
Sites Of Action ◽  
Hydrolysis Of

Abstract. Iodine in excess is known to acutely inhibit thyroidal secretion. In the present study we have characterized the time course of the iodine effect in vitro and investigated the underlying mechanisms. Labelled thyroid glands were cultured in vitro in medium containing mononitrotyrosine, an inhibitor of iodotyrosine deiodinase. The rate of hydrolysis of labelled thyroglobulin was measured as the proportion of labelled iodotyrosines and iodothyronines recovered at the end of culture and was used as an index of thyroidal secretion. Thyrotrophin (TSH) administered in vivo acutely stimulated the rate of thyroglobulin hydrolysis. Addition of Nal to the culture medium acutely inhibited both basal and TSH-stimulated thyroglobulin hydrolysis. The effect of iodide was demonstrable after 2 h, maximal after 6 h and was not reversible upon removal of iodide. Iodide abolished the dibutyryl cAMP induced stimulation of thyroglobulin hydrolysis. Iodide required organic binding of iodine for its effect but new protein or RNA synthesis was not necessary. The inhibitory effects of iodide and lysosomotrophic agents such as NH4C1 and chloroquin on thyroglobulin hydrolysis were additive suggesting different sites of action. Iodide added in vitro altered the distribution of label in prelabelled thyroglobulin in a way that suggested increased coupling in the thyroglobulin molecule. These data indicate that 1) the iodide effect occurs progressively over a 6 h period, 2) continued presence of iodide is not necessary once the inhibition is established, 3) iodide exerts its action primarily at a post cAMP, prelysosomal site and 4) the effect requires organic binding of iodine, but not new RNA or protein synthesis. Our data are consistent with the hypothesis that excess iodide acutely inhibits thyroglobulin hydrolysis by increasing the resistance of thyroglobulin to proteolytic degradation through increased iodination and coupling.

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