| 1. |
- Bergström, Christel, et al.
(author)
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Poorly soluble marketed drugs display solvation limited solubility
- 2007
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In: Journal of Medicinal Chemistry. - : American Chemical Society (ACS). - 0022-2623 .- 1520-4804. ; 50:23, s. 5858-5862
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Journal article (peer-reviewed)abstract
- We determined the intrinsic aqueous solubility of 15 poorly soluble drugs with solubilities ranging from 2.9 nM to 1.1 μM. We then analyzed the data from a physicochemical perspective, using experimentally determined solid-state properties and easily interpretable two-dimensional molecular descriptors, to better understand the factors underlying poor solubility. The analysis shows that poorly soluble drugs that have reached the market are solubility limited by solvation rather than by their solid state.
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| 2. |
- Bose, Partha Pratim, et al.
(author)
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In vitro ADMET and physicochemical investigations of poly-N-methylated peptides designed to inhibit Aβ aggregation
- 2010
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In: Bioorganic & Medicinal Chemistry. - : Elsevier BV. - 0968-0896 .- 1464-3391. ; 18:16, s. 5896-5902
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Journal article (peer-reviewed)abstract
- N-Methylation is a common strategy for improving oral bioavailability of peptide-based lead structures. Herein, we present a detailed study on how the degree of N-methylation affects the absorption-distribution-metabolism-excretion-toxicity (ADMET) properties such as solubility, membrane transport, proteolytic stability, and general cell toxicity of the investigated peptides. As representative structures we chose hexapeptides 1-8. These peptides, corresponding to N-methylated analogues of residues 16-21 and 32-37 of the Abeta-peptide, pathological hallmark of Alzheimer's disease (AD), have previously been shown to inhibit aggregation of Abeta fibrils in vitro. This study suggests that poly-N-methylated peptides are non-toxic and have enhanced proteolytic stability over their non-methylated analogues. Furthermore, solubility in aqueous solution is seen to increase with increased degree of N-methylation, while membrane transport was found to be low for all investigated hexapeptides. The present results, together with those reported in the literature, suggest that poly-N-methylated peptides, especially shorter or equal to six residues, can be suitable candidates for drug design.
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| 3. |
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| 4. |
- Hubatsch, Ina, et al.
(author)
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Beta- and gamma-di- and tripeptides as potential substrates for the oligopeptide transporter hPepT1
- 2007
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In: Journal of Medicinal Chemistry. - : American Chemical Society (ACS). - 0022-2623 .- 1520-4804. ; 50:21, s. 5238-5242
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Journal article (peer-reviewed)abstract
- The hPepT1-mediated transport properties of a series of 11 synthesized beta- and gamma-peptides have been studied in Caco-2 cells. The results show that several of the compounds interact with the peptide transporter, but only two beta-dipeptides act as substrates and are transported across the cell monolayers. These two are less-efficient substrates than alfa-peptides. Larger derivatives than beta-dipeptides do not act as hPepT1 substrates, but instead, they appear to be substrates for P-glycoprotein efflux.
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| 5. |
- Hubatsch, Ina, et al.
(author)
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Determination of drug permeability and prediction of drug absorption in Caco-2 monolayers
- 2007
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In: Nature Protocols. - : Springer Science and Business Media LLC. - 1754-2189 .- 1750-2799. ; 2:9, s. 2111-2119
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Journal article (peer-reviewed)abstract
- Permeability coefficients across monolayers of the human colon carcinoma cell line Caco-2, cultured on permeable supports, are commonly used to predict the absorption of orally administered drugs and other xenobiotics. This protocol describes our method for the cultivation, characterization and determination of permeability coefficients of xenobiotics (which are, typically, drug-like compounds) in the Caco-2 model. A few modifications that have been introduced over the years are incorporated in the protocol. The method can be used to trace the permeability of a test compound in two directions, from the apical to the basolateral side or vice versa, and both passive and active transport processes can be studied. The permeability assay can be completed within one working day, provided that the Caco-2 monolayers have been cultured and differentiated on the permeable supports 3 weeks in advance.
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| 6. |
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| 7. |
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| 8. |
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| 9. |
- Lazorova, Lucia, et al.
(author)
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Structural Features Determining the Intestinal Epithelial Permeability and Efflux of Novel HIV-1 Protease Inhibitors
- 2011
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In: Journal of Pharmaceutical Sciences. - : Elsevier BV. - 0022-3549 .- 1520-6017. ; 100:9, s. 3763-3772
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Journal article (peer-reviewed)abstract
- The primary aim of this study was to identify structural features that alter the intestinal epithelial permeability and efflux in a series of novel HIV-1 protease inhibitors (PIs). Eleven PIs were selected containing a tertiary alcohol in a transition-state mimicking scaffold, in which two substituents (R1 and R2) were varied systematically. Indinavir was selected as a reference compound. The apical-to-basolateral permeability was investigated in 2/4/A1 and Caco-2 monolayers. In addition, the basolateral-to-apical permeability was investigated in the Caco-2 monolayers and the efflux ratios were calculated. The absence of active drug transport processes in 2/4/A1 cells allowed identification and modeling of structural elements affecting the passive permeability. For instance, small aromatic R1 substituents and a small (bromo-) R2 substituent were associated with a high passive permeability. Efflux studies in Caco-2 cells indicated that amide-substituted neutral hydrophobic amino acids, such as valine and leucine, in the R1 position, reduced the apical-to-basolateral transport and enhanced the efflux. We conclude that our investigation revealed structural features that alter the intestinal epithelial permeability and efflux in the series of PIs and hope that these results can contribute to the synthesis of PIs with improved permeability and limited efflux properties.
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| 10. |
- Poliakov, Anton, et al.
(author)
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Expression and purification of recombinant full-length NS3 protease-helicase from a new variant of Hepatitis C virus
- 2002
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In: Protein Expression and Purification. - 1046-5928 .- 1096-0279. ; 25:3, s. 363-371
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Journal article (peer-reviewed)abstract
- Viral mRNA extracted from the serum of a patient infected with HCV strain I a was used for cloning, expression, and purification of full-length Hepatitis C NS3 protein. Sequencing of the protease gene identified the virus to be a new variant closely related to strain H77, differing in 15 out of 631 amino acids in the NS3 protein, none of which were predicted to be directly involved in catalysis, binding of substrate, or cofactor. A pBAD expression system was used to express the enzyme with an N-terminal tag in Escherichia coli. Purification from the soluble cellular fraction was achieved by Ni2(+)-IMAC and PolyU Sepharose affinity chromatography. The dependence of the proteolytic activity of the full-length NS3 protein on ionic strength, glycerol concentration, and a peptide corresponding to the activating region of NS4A was analyzed and used to design an activity assay that is suitable for inhibition studies. The kinetic constants (k(cat) and K-M) for catalysis and the inhibitory potencies (IC50 and K-i) of five product-based hexapeptide inhibitors were comparable to those reported for the truncated NS3 protein. Detailed kinetic and inhibition studies using this variant of full-length NS3 can increase the understanding of the enzymatic characteristics of NS3, reveal the importance of the substituted amino acids and the significance of the genetic variability for design of effective inhibitors of the virus, and is thus of relevance for drug discovery.
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| 11. |
- Zwart, Peter, et al.
(author)
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Structural Basis for Substrate Specificity Differences of Horse Liver Alcohol Dehydrogenase Isozymes
- 2000
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In: Biochemistry. - : American Chemical Society (ACS). - 0006-2960 .- 1520-4995. ; 39:42, s. 12885-12897
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Journal article (peer-reviewed)abstract
- A structure determination in combination with a kinetic study of the steroid converting isozyme of horse liver alcohol dehydrogenase, SS-ADH, is presented. Kinetic parameters for the substrates, 5β-androstane-3β,17β-ol, 5β-androstane-17β-ol-3-one, ethanol, and various secondary alcohols and the corresponding ketones are compared for the SS- and EE-isozymes which differ by nine amino acid substitutions and one deletion. Differences in substrate specificity and stereoselectivity are explained on the basis of individual kinetic rate constants for the underlying ordered bi-bi mechanism. SS-ADH was crystallized in complex with 3α,7α,12α-trihydroxy-5β-cholan-24-acid (cholic acid) and NAD+, but microspectrophotometric analysis of single crystals proved it to be a mixed complex containing 60-70% NAD+ and 30-40% NADH. The crystals belong to the space group P21 with cell dimensions a = 55.0 Å, b = 73.2 Å, c = 92.5 Å, and β = 102.5. A 98% complete data set to 1.54-Å resolution was collected at 100 K using synchrotron radiation. The structure was solved by the molecular replacement method utilizing EE-ADH as the search model. The major structural difference between the isozymes is a widening of the substrate channel. The largest shifts in Cα carbon positions (about 5 Å) are observed in the loop region, in which a deletion of Asp115 is found in the SS isozyme. SS-ADH easily accommodates cholic acid, whereas steroid substrates of similar bulkiness would not fit into the EE-ADH substrate site. In the ternary complex with NAD+/NADH, we find that the carboxyl group of cholic acid ligates to the active site zinc ion, which probably contributes to the strong binding in the ternary NAD+ complex.
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