Search results for "HYDROLYSIS"
showing 10 items of 632 documents
A hypotensive procyanidin-glycoside from Rhamnus lycioides ssp. lycioides.
1990
A lyophilized hot water extract of the aerial parts of Rhamnus lycioides L. (Rhamnaceae) produced a lowering of systemic arterial blood pressure in normotensive anaesthetized Wistar rats. An activity-guided fractionation of the methanolic extract led to the isolation of a tetrameric procyanidin-glycoside which produced a clear dose-dependent hypotensive response (1.5-6 mg/kg i.v.). This principle was characterized using acid hydrolysis, thiolytic degradation and spectroscopic methods. It consisted of four flavanol units with a 2,3-cis configuration and with a O-beta-d-glucosylpyranoside function on the epicatechin terminal unit. The interflavan linkage was (4-8).
MATRICES OF A HYDROPHOBICALLY FUNCTIONALIZED HYALURONIC ACID DERIVATIVE FOR THE LOCOREGIONAL TUMOUR TREATMENT
2015
A hyaluronic acid (HA) derivative bearing octadecylamine and acylhydrazine functionalities has been here employed for the production of a paclitaxel delivering matrix for locoregional chemotherapy. Through a strategy consisting in a powder compression and a plasticization with a mixture water/ethanol, a physically assembled biomaterial, stable in solutions with physiologic ionic strengths, has been produced. Two different drug loading strategies have been adopted, by using paclitaxel as chemotherapic agent, and obtained samples have been assayed in terms of release in enhanced solubility conditions and in vitro and in vivo tumoural cytotoxicity. In particular sample with the best releasing …
Controlled transdermal iontophoresis for poly-pharmacotherapy: Simultaneous delivery of granisetron, metoclopramide and dexamethasone sodium phosphat…
2015
Iontophoresis has been used to deliver small molecules, peptides and proteins into and across the skin. In principle, it provides a controlled, non-invasive method for poly-pharmacotherapy since it is possible to formulate and to deliver multiple therapeutic agents simultaneously from the anodal and cathodal compartments. The objective of this proof-of-principle study was to investigate the simultaneous anodal iontophoretic delivery of granisetron (GST) and metoclopramide (MCL) and cathodal iontophoresis of dexamethasone sodium phosphate (DEX-P). In addition to validating the hypothesis, these are medications that are routinely used in combination to treat chemotherapy-induced emesis. Two p…
The effects of phorbol esters on choline phospholipid hydrolysis in heart and brain
1990
The efflux of choline was determined in rat striatal slices, incubated chicken atria and perfused chicken hearts. 4 beta-Phorbol-12 beta,13 alpha-dibutyrate (PDB) and 4 beta-phorbol-12 beta-myristate, 13 alpha-acetate (PMA) were used to stimulate protein kinase C. The other phorbol esters, 4 beta-phorbol-13 alpha-acetate (PAc) and 4 alpha-phorbol-12 beta,13 alpha-didecanoate (4 alpha PDD), known to be inactive, were tested to evaluate the specificity of the responses. PDB markedly enhanced the efflux of choline in all of the three preparations. The PDB-evoked efflux of choline in incubated chicken atria was equal to the net production of choline and, therefore, was not caused by translocati…
Targeting metabolomics analysis of the sunscreen agent 2-ethylhexyl 4-(N,N-dimethylamino)benzoate in human urine by automated on-line solid-phase ext…
2011
The in vivo metabolism of the xenobiotic agent 2-ethylhexyl 4-(N,N-dimethylamino)benzoate (EDP), a UV filter commonly used in sunscreen cosmetic products, was studied by targeting metabolomics analysis in human urine. The metabolomic study involved the use of urine from male and female volunteers before and after application of an EDP-containing sunscreen cosmetic. The metabolism of EDP in urine was studied by using the triple quadrupole detector in a combination of Precursor Ion Scanning and Neutral Loss Scanning modes, with and without enzymatic hydrolysis. Detected metabolites were subsequently confirmed as glucuronide conjugates of 4-(N,N-dimethylamino)benzoic acid and 4-(N-methylamino)…
Intestinal transport of cefuroxime axetil in rats: absorption and hydrolysis processes.
2002
Studies were performed using three cefuroxime axetil solutions (11.8, 118 and 200 microM) in three selected intestinal segments and one cefuroxime axetil solution (118 microM) in colon of anaesthetized rats. First-order absorption rate pseudoconstants, k(ap) and effective permeability coefficients, P(eff), were calculated in each set. Absorption of cefuroxime axetil can apparently be described as a carrier-mediated transport, which obeys Michaelis-Menten and first order kinetics in the proximal segment of the small intestine and a passive diffusion mechanism in the mean and distal segments. The absorption kinetic parameters for cefuroxime axetil were obtained: Vm=0.613 (0.440) microM min-1;…
A Microassay for Measuring Glycogen in 96-Well-Cultured Cells
1996
Abstract This study describes a rapid, sensitive, and automated spectrophotometric enzymatic microassay that measures the intracellular glycogen of primary cultured hepatocytes and other cultured cells in 96-well plates and can be adapted for other samples that are transferred to these plates. The procedure involves in situ disruption of cells, followed by hydrolysis of glycogen into glucosyl units by fungal glucoamylase (exo-1,4-α- D -glucosidase, EC 3.2.1.3), and glucose determination with the glucose oxidase colorimetric method. The color intensity can be measured in conventional ELISA readers, and the data can be fed to an on-line computer for rapid processing. The advantages of this me…
Transdermal iontophoresis of dexamethasone sodium phosphate in vitro and in vivo: effect of experimental parameters and skin type on drug stability a…
2010
The aim of this study was to investigate the cathodal iontophoresis of dexamethasone sodium phosphate (DEX-P) in vitro and in vivo and to determine the feasibility of delivering therapeutic amounts of the drug for the treatment of chemotherapy-induced emesis. Stability studies, performed to investigate the susceptibility of the phosphate ester linkage to hydrolysis, confirmed that conversion of DEX-P to dexamethasone (DEX) upon exposure to samples of human, porcine and rat dermis for 7 h was limited (82.2+/-0.4%, 72.5+/-4.8% and 78.6+/-6.0% remained intact) and did not point to any major inter-species differences. Iontophoretic transport of DEX-P across dermatomed porcine skin (0.75 mm thic…
Mass spectrometric identification of the amino donor and acceptor sites in a transglutaminase protein substrate secreted from rat seminal vesicles.
1991
Four different transglutaminase-modified forms of a protein secreted by the rat seminal vesicles (SV-IV) were synthesized in vitro and characterized. FAB maps of both the native protein and its derivatives, produced by the purified guinea pig liver enzyme in the presence or absence of the polyamine spermidine, were obtained by mass spectrometric analysis after proteolytic digestions. Two differently derivatized SV-IV molecular forms, both possessing only one glutamine residue out of two (Gln-86) cross-linked to endogenous lysine residues, were produced when spermidine was omitted from the reaction mixture: (i) an insoluble homopolymer in which Lys-2, -4, -59, -78, -79, and -80 were involved…
A muramidase from Acremonium alcalophilum hydrolyse peptidoglycan found in the gastrointestinal tract of broiler chickens
2021
Abstract This study evaluates peptidoglycan hydrolysis by a microbial muramidase from the fungus Acremonium alcalophilum in vitro and in the gastrointestinal tract of broiler chickens. Peptidoglycan used for in vitro studies was derived from 5 gram-positive chicken gut isolate type strains. In vitro peptidoglycan hydrolysis was studied by three approaches: (a) helium ion microscopy to identify visual phenotypes of hydrolysis, (b) reducing end assay to quantify solubilization of peptidoglycan fragments, and (c) mass spectroscopy to estimate relative abundances of soluble substrates and reaction products. Visual effects of peptidoglycan hydrolysis could be observed by helium ion microscopy an…