Relationships between structure and high-throughput screening permeability of diverse drugs with artificial membranes: application to prediction of Caco-2 cell permeability.

To evaluate the absorption of drugs with diverse structures across a membrane via the transcellular route, their permeability was measured using the parallel artificial membrane permeation assay (PAMPA). The permeability coefficients obtained by PAMPA were analyzed using a classical quantitative structure-activity relationship (QSAR) approach with simple physicochemical parameters and 3D-QSAR, VolSurf. We formulated correlation equations for diverse drugs similar to the equation obtained for peptide-related compounds in our previous study.

Metabolic flux analysis of the phenylpropanoid pathway in elicitor-treated potato tuber tissue.

The effects of beta-1,3-oligosaccharide elicitor on the metabolism of phenylpropanoids in potato tuber were analyzed quantitatively, by monitoring the time-dependent changes in the levels of seven compounds. The elicitor treatment caused an increase in the pool size of octopamine and tyramine amides (N-p-coumaroyloctopamine, N-feruloyloctopamine, N-p-coumaroyltyramine and N-feruloyltyramine), as well as a decrease in that of chlorogenic acid and putrescine amides (caffeoylputrescine and feruloylputrescine). An analysis of metabolic flux using stable isotope labeling and liquid chromatography-spectrometry (LC-MS) detection clearly demonstrated that the changes in the pool size of these compounds were correlated with the changes in their flux for biosynthesis (Jin) upon elicitor treatment.

[High throughput screening of pharmacokinetics and metabolism in drug discovery (III)--investigation on in- silico model for membrane permeability and CYP1A2 inhibition].

Pharmacokinetic and metabolic screening plays an important role in the optimization of a lead compound in drug discovery. Since those screening methods are time-consuming and labor intensive, in silico models would be effective to select compounds and guide derivatization prior to the screening. We investigated in silico models for permeability in Caco-2 cells, brain distribution and cytochrome P450 (CYP) inhibition using molecular weight, lipophilicity (clog D(7.

[High throughput screening of pharmacokinetics and metabolism in drug discovery (II)--investigation on in vitro and in vivo correlation in drug metabolism screening].

Metabolic screening using liver microsomes of rats and humans is an indispensable tool to optimize a lead structure and to select compounds for in vivo study. Elucidating the relationship between in vitro intrinsic clearance (CL(int, app)) and in vivo clearance (CL(b)) is a prerequisite for screening. We investigated the relationship between CL(int, app) in rat liver microsomes and CL(b) after intravenous administration in rats in eight projects.

[High throughput screening of pharmacokinetics and metabolism in drug discovery (I)--establishment of assessment system for absorption to compounds with a wide diversity of physical properties].

The application of combinatorial chemistry and high-throughput screening to biological targets has led to efficient identification of lead compounds in wide therapeutic areas. However, the physicochemical properties of some lead compounds are lipophilic with low water soluble. Since these parameters determine in vivo absorption, we established robust screening methods for solubility and Caco-2 membrane permeability which are applicable to our screening strategy based on the structure-pharmacokinetic parameter relationship (SPR).

Relationships between structure and high-throughput screening permeability of peptide derivatives and related compounds with artificial membranes: application to prediction of Caco-2 cell permeability.

To evaluate absorption of compounds across the membrane via a transcellular route, the permeability of peptide derivatives and related compounds was measured by the parallel artificial membrane permeation assay (PAMPA). The permeability coefficients by PAMPA were analyzed quantitatively using classical QSAR and Volsurf approaches with the physicochemical parameters. The results from both approaches showed that hydrogen bonding ability of molecules in addition to hydrophobicity at a particular pH were significant in determining variations in PAMPA permeability coefficients.

Relationship between structure and permeability of dipeptide derivatives containing tryptophan and related compounds across human intestinal epithelial (Caco-2) cells.

The permeability of dipeptide derivatives containing tryptophans and indole derivatives through Caco-2 cells was used as an in vitro intestinal absorption model in order to clarify structural factors which influence their intestinal epithelial permeation and metabolism. Most peptide derivatives were hydrolysed not only by the cytosolic enzymes in Caco-2 cells during permeation but also by enzymes released to the apical solution before cell permeation. The N-terminal blocked dipeptides were more resistant to hydrolases expressed in the Caco-2 cells and indole derivatives were not entirely degraded.

Relationship between structure and permeability of tryptophan derivatives across human intestinal epithelial (Caco-2) cells.

L-Trp and its derivatives were used as model compounds to clarify structural factors which influence the intestinal epithelial permeation and metabolism of amino-acid derivatives. Permeability of model compounds through Caco-2 cells was used as an in vitro absorption model for human intestinal epithelial cells. The influence of compound concentration, the effects of various transporter substrates on permeability coefficients, and pH dependency of permeability coefficients were investigated.