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  • 1
    Electronic Resource
    Electronic Resource
    Conjugation of copper-zinc superoxide dismutase with succinylated gelatin: Pharmacological activity and cell-lubricating function (1993)
    s.l. : American Chemical Society
    Bioconjugate chemistry 4 (1993), S. 490-498 
    Details
    ISSN: 1520-4812
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/bc00024a011
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  • 2
    Electronic Resource
    Electronic Resource
    In Vitro and In Vivo Evaluation of the Enhancing Activity of Glycyrrhizin on the Intestinal Absorption of Drugs (1999)
    Springer
    Pharmaceutical research 16 (1999), S. 80-86 
    Details
    ISSN: 1573-904X
    Keywords: dipotassium glycyrrhizinate ; glycyrrhetinylmonoglucuronide ; glycyrrhetinic acid ; salmon calcitonin ; absorption enhancer ; β-glucuronidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The enhancing activity of dipotassium glycyrrhizinate (Grz) on the intestinal absorption of drugs has been demonstrated in an in vitro study using Caco-2 cell monolayers and in an in vivo absorption study in rats. Methods. The hydrolysis of Grz by luminal content and mucosa of the rat colon was investigated. The absorption-enhancing activity of Grz and its hydrolysates was estimated by changes in transepithelial electrical resistance (TEER) and the permeation of sodium fluorescein (Flu-Na) in Caco-2 cell monolayers. It was further evaluated through the absorption of salmon calcitonin (sCT) in the rat colon. Results. Grz was not hydrolyzed to glycyrrhetinylmonoglucuronide (GrMG) and glycyrrhetinic acid (GA) by colonic mucosa, but, rather by the β-glucuronidase in colonic flora. The hydrolysis of Grz to GrMG was extremely slow and the GrMG produced was rapidly regenerated to GA. Grz and GrMG had no effect on TEER nor on the permeability of Flu-Na across Caco-2 cell monolayers. On the other hand, GA decreased TEER and increased the permeability of Flu-Na in a dose-dependent manner. However, Grz and GrMG enhanced the plasma calcium-lowering effect of sCT after administration in the rat colon. The coadministration of sCT and GA in the rat colon induced the strongest plasma calcium-lowering effect and the highest plasma concentration of sCT. Conclusions. The in vivo enhancing-activity of Grz in the absorption of drugs is dependent on GA, a hydrolysis product of Grz resulting from the action of β-glucuronidase in intestinal flora.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018822829302
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  • 3
    Electronic Resource
    Electronic Resource
    Interaction Between Two Dicarboxylate Endogenous Substances, Bilirubin and an Uremic Toxin, 3-Carboxy-4-Methyl-5-Propyl-2-Furanpropanoic Acid, on Human Serum Albumin (1999)
    Springer
    Pharmaceutical research 16 (1999), S. 916-923 
    Details
    ISSN: 1573-904X
    Keywords: human serum albumin ; uremic toxin ; bilirubin ; dicarboxylate ; electrostatic interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. Two dicarboxylate endogenous substances, bilirubin (BR) and 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid (CMPF), have a very high affinity to human serum albumin (HSA). This study was undertaken to clarify the existence of a dicarboxylate binding site on HSA. Methods. Chemical modification, pH dependent binding and X-ray crystallographic analysis were performed to characterize these dicarboxylate binding sites. Results. It was found the binding behavior for dicarboxylates was different from typical site I ligands such as warfarin (WF) and phenyl-butazone (PB) and that electrostatic interaction was an important factor for their binding to HSA. Moreover, His residues were considered to play an important role in pH dependent binding of dicarboxylic acids but in a different manner from the site I ligands. X-ray crystallography of CMPF and BR revealed the distances between the two carboxyl groups in their chemical structures were 5.854 Å and 9.979 Å, respectively. This difference may be reflected in pH dependent binding. Using fluorescent probe displacement, we attempted to identify the binding site for monocarboxylate derivatives of CMPF and investigated the role of individual carboxyl group in the recognition of the binding site. The results suggested two carboxyl groups were important for the specific binding of CMPF to site I. Conclusions. The binding site for dicarboxylic acids is located in subdomain IIA, which includes site I, on the HSA molecule. Electrostatic interaction is an important driving force for binding to HSA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018842506896
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  • 4
    Electronic Resource
    Electronic Resource
    Reversal of Signs of Induced Cotton Effects of Dicumarol-α1-Acid Glycoprotein Systems by Phenothiazine Neuroleptics Through Ternary Complexation (1992)
    Springer
    Pharmaceutical research 9 (1992), S. 845-849 
    Details
    ISSN: 1573-904X
    Keywords: α1-acid glycoprotein ; induced circular dichroism ; dicumarol ; phenothiazine derivatives ; ternary complex ; binding mode
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The interaction of dicumarol and phenothiazine neuroleptics binding to α1-acid glycoprotein (AGP) was investigated by circular dichroism (CD) and equilibrium dialysis. The induced CD spectra of the dicumarol–AGP complex were affected differently by the different substituents of the phenothiazine molecule. The sign of the induced Cotton effect of dicumarol bound to AGP was reversibly changed with the introduction of the propyldimethylamine substituent at position 10 or chloride group at position 2 of the phenothiazine molecule. Chlorpromazine, which contains both of these substituents reversed the sign of the induced Cotton effect with the highest intensity. The addition of trifluoperazine, fluphenazine, and promethazine containing neither of the two substituents generated a new negative CD band. However, the addition of opromazine, which contains sulfoxide at position 5, decreased the CD intensity of the dicumarol–AGP complex without changing the shape of the CD spectra. Equilibrium dialysis studies revealed that the interaction of dicumarol–AGP with phenothiazine derivatives occurred simultaneously, and the interaction followed a cooperative and anticooperative binding model. Further, among the six phenothiazine derivatives that reversed the signs of the induced Cotton effects of the dicumarol–AGP complex, a linear relationship was observed between coupling constants and the difference in the induced optical ellipticity. The opromazine and dicumarol interaction was competitive for a common binding site on the AGP molecule. Removal of sialic acid did not have any effect on this interaction. These data support the hypothesis that the acidic and the basic drug binding sites overlap each other.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015880327911
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  • 5
    Electronic Resource
    Electronic Resource
    Species Differences of Serum Albumins: II. Chemical and Thermal Stability (1998)
    Springer
    Pharmaceutical research 15 (1998), S. 449-454 
    Details
    ISSN: 1573-904X
    Keywords: serum albumin ; species difference ; thermal denaturation ; chemical denaturation ; conformational stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The chemical and thermal stability of five species of mammalian serum albumins (human, bovine, dog, rabbit, and rat) were investigated, and conformational stabilities were compared to obtain structural information about the different albumins. Methods. The chemical stability was estimated by using guanidine hydrochloride (GdnCl), and monitored by fluorometry and circular dichroism (CD). Thermal stability was evaluated by differential scanning calorimetry (DSC). Results. In human, bovine, and rat albumin, two transitions were observed when GdnCl-induced denaturation was monitored fluorometrically, indicating at least one stable intermediate, although, in dog and rabbit albumin, only one transition was observed. However, GdnCl denaturation, as monitored by the ellipticity, showed a two-state transition in all species used in this study. Since these proteins, showing two transitions, contained a conserved tryptophan residue within domain II, these structural changes might have occurred in domain II during intermediate formation. DSC measurements showed that human, bovine, and rat albumin exhibited single sharp endotherms and these were clearly consistent with a two-state transition, while the deconvolution analysis of broad thermograms observed for dog and rabbit albumin showed that the absorption peaks could be approximated by a two-component composition, and were consistent with independent transitions of two different cooperative blocks. Conclusions. These experimental results demonstrate that species differences exist with respect to the conformational stability and the mechanism of the unfolding pathway for mammalian albumin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011932516717
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  • 6
    Electronic Resource
    Electronic Resource
    Species Differences in Stereoselective Hydrolase Activity in Intestinal Mucosa (1998)
    Springer
    Pharmaceutical research 15 (1998), S. 626-631 
    Details
    ISSN: 1573-904X
    Keywords: O-acyl-propranolol ; stereoselective hydrolysis ; intestinal mucosa ; carboxylesterase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The aim of this study is to investigate species differences in the stereoselective hydrolysis for propranolol ester prodrugs in mammalian intestinal mucosa and Caco-2 cells. Methods. Hydrolase activities for propranolol prodrugs and p-nitro-phenylacetate in man (age: 51−71 years), the beagle dog (age: 4 years) and Wistar rat (age: 8 weeks) intestinal mucosa, and also in Caco-2 cells (passage between 60−70) were estimated by determining the rate of production of propranolol and p-nitrophenol, respectively. Results. The hydrolase activities for both propranolol prodrugs and p-nitrophenylacetate were in the order of man 〉 rat 〉〉 Caco-2 cells 〉 dog for intestinal microsomes, and rat 〉 Caco-2 cells = man 〉 dog for intestinal cytosol. Dog microsomes showed stereoselective hydrolysis for propranolol prodrugs, but not those from human or rat. Interestingly, both subcellular fractions of Caco-2 cells showed remarkable R-enantioselectivity except acetyl propranolol. Enzyme kinetic experiments for each enantiomer of butyryl propranolol in microsomes revealed that dog possesses both low and high affinity hydrolases. Both Km and Vmax values in rat were largest among examined microsomes, while Vmax/Km was largest in man. Finally, it was shown that the carboxylesterases might contribute to the hydrolysis of propranolol prodrug in all species by inhibition experiments. Conclusions. The hydrolase activities for propranolol prodrugs and p-nitrophenylacetate in intestinal mucosa showed great species differences and those in human intestine were closer to those of rat intestine than dog intestine or Caco-2 cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011946314416
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  • 7
    Electronic Resource
    Electronic Resource
    Interactions of Aldosterone Antagonist Diuretics with Human Serum Proteins (1997)
    Springer
    Pharmaceutical research 14 (1997), S. 522-526 
    Details
    ISSN: 1573-904X
    Keywords: spironolactone ; canrenone ; drug interaction ; human serum albumin ; α1-acid glycoprotein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The purpose of this study was to investigate the binding mechanism of aldosterone antagonist diuretics with human serum proteins, human serum albumin (HSA) and α1-acid glycoprotein (AGP), as well as to identify the binding sites of the drugs on these proteins. Methods. Binding activities of spironolactone (SP) and its pharmacologically active metabolite canrenone (CR) to serum and serum protein were examined by ultrafiltration and spectroscopic techniques. The data for the binding of these drugs to HSA were analyzed on the basis of a theoretical model of simultaneous binding of the ligands. Results. The binding percentages of antagonist diuretics SP and CR to human serum proteins were 88.0% and 99.2%, respectively, at therapeutic concentrations. SP bound strongly and almost equally to both HSA and AGP, but CR bound strongly only to HSA. In addition, the displacement results found using fluorescent probes and ultrafiltration methods demonstrated that SP bound to site I, particularly to the warfarin region on HSA, and to the basic binding site on AGP, while CR bound to the warfarin region on HSA. Conclusions. The limited results presented here stress the need for caution on coadministration of acidic drugs which bind to the warfarin region on HSA and basic drugs which bind to AGP with SP and its metabolite CR.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1012168020545
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  • 8
    Electronic Resource
    Electronic Resource
    Species Differences of Serum Albumins: III. Analysis of Structural Characteristics and Ligand Binding Properties During N-B Transitions (1998)
    Springer
    Pharmaceutical research 15 (1998), S. 592-598 
    Details
    ISSN: 1573-904X
    Keywords: serum albumin ; species difference ; N-B transition ; protein binding ; conformational stability ; chemical modification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The aim of this study was to investigate the characteristics of the structural transitions and changes in ligand binding properties of different albumins during the pH-dependent structural transition, often referred to as the N-B transition. Methods. Structural transitions were evaluated by means of spectrometry, differential scanning calorimetry and chemical modification. In addition, ligand binding properties were investigated using typical site-specific bound drugs (warfarin, phenylbutazone, ibuprofen and diazepam). Results. Conformational changes, including N-B transition, clearly occurred in albumins from all species used in this study. The conformational stabilities of all the albumins were clearly lost in the weakly alkaline pH range. This was probably the result of the destruction of salt bridges between domain I and domain III in the albumin molecule. In addition, the profiles of the ANS-induced fluorescence were different and could be classified into two patterns, suggesting that hydrophobic pockets in the albumin molecules were different for the different species. The data suggest that the amino acid residues responsible for the transitions were some of the His residues located in domain I. Further, the ligand binding properties of the albumins were slightly different but statistically significant. Conclusions. The overall mechanisms of the N-B transition may be similar for all the albumins, but its impact is considerably different among the species in terms of both structural characteristics and ligand binding properties. Furthermore, the transitions appear to be multi-step transitions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011986028529
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  • 9
    Electronic Resource
    Electronic Resource
    Interaction of Benzothiadiazides with Human Serum Albumin Studied by Dialysis and Spectroscopic Methods (1994)
    Springer
    Pharmaceutical research 11 (1994), S. 1452-1457 
    Details
    ISSN: 1573-904X
    Keywords: benzothiadiazides ; human serum albumin ; electrostatic interaction ; hydrophobic interaction ; binding site
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The interaction of a series of benzothiadiazides with human serum albumin (HSA) was investigated by equilibrium dialysis (ED) and spectroscopic methods including circular dichroism (CD). The primary binding site of benzothiadiazides was designated site II, the diazepam site on the HSA molecule, as indicated by displacement experiments using different site-selective probes. Tyrosine and lysine amino acid residues were probably involved in the binding site of these compounds to HSA. Both electrostatic and hydrophobic interactions were found to play a role in the binding of these compounds to HSA. Among the compounds tested, chlorothiazide had the highest affinity (K1 = 5.5 × 104M−1, K2 = 5.8 × 103 M−1).The primary binding affinity of the compounds for HSA was of the order: chlorothiazide 〉 cyclopenthiazide 〉 polythiazide 〉 ethiazide 〉 trichlormethiazide = methyclothiazde 〉 hydrochlorothiazide. Binding was insensitive to the N-B transition of HSA. The binding site is proposed to consist of a cationic site on the surface of the HSA molecule with a hydrophobic crevice to accommodate the aromatic ring of the compounds. Positions 3 and 7 of the benzothiadiazide molecule is thought to affect the binding affinity to HSA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018952108327
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  • 10
    Electronic Resource
    Electronic Resource
    The Controlled Release of Prednisolone Using Alginate Gel (1994)
    Springer
    Pharmaceutical research 11 (1994), S. 272-277 
    Details
    ISSN: 1573-904X
    Keywords: alginate ; gel beads ; controlled release ; prednisolone ; in vitro/in vivo correlation ; beagle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In a release study of alginate gel beads, swelling and erosion of the beads were observed at pH 6.8, whereas no swelling occurred at pH 1.2. The amount of released prednisolone (PL) was greater at pH 6.8 than at pH 1.2. The lower the ratio of mannuronic acid block to guluronic acid block in alginate, the slower the release of PL. An increase in loaded PL in the beads resulted in a slower release of PL. The decrease in bead size caused a rapid release of PL. The addition of sodium alginate propylene glycol ester elevated the extent of PL release. The plasma profile of PL showed sustained-release behavior after the oral administration of the beads to beagles. Furthermore, the correlation between in vitro release and in vivo absorption of PL for various alginate gel beads was evaluated using deconvolution and convolution methods. The in vivo absorption of PL was correlated with the PL release at pH 1.2, and it differed from that at pH 6.8. The release of PL from alginate gel beads in vivo appeared to occur under conditions that cause little swelling.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018963626248
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