Lipophilicity similarity matrices

The use of lipophilicity similarity matrices for the quantitative description of nonlinear lipophilicity-activity relationships is discussed in chapter 9.4. 

However, despite the simplicity of the analyses and the good correlations obtained in these studies, a ligand interaction-based model like the CoMFA method should not be used to model nonlinear effects arising from transport and distribution no reasonable results can be expected for sets of compounds which are no homologous series. Better and theoretically more consistent alternatives would be the addition of suitably weighted log P values to the CoMFA table, the use of lipophilicity similarity matrices (chapter 9.4), or the correlation with log P values in the classical manner, applying either the parabolic or the bilinear model. 

Table 31. Nonlinear lipophilicity-activity relationships. Comparison of the bilinear model (r values are given instead of r values) with results from PLS analyses, using lipophilicity similarity matrices a,j= -llogPi-logPjl [1013]...

Theoretically, a chemical enhancer, which has a lipophilicity similar to the PSA matrix, will have the highest affinity for the adhesive matrix, thus having the lowest skin absorption. This would often happen with the same concentration of enhancers, but shows the different enhancing effects in the different PSA matrices. Table 6 shows the different enhancing effects of IPM in various acrylic adhesives with different lipo-philicities. Here, the concentration of FB is saturated in every adhesive, and the amount of IPM is fixed to be 38% in acrylic copolymers. In relation to be the... 

To demonstrate the utility of a, plots of enzyme activity vs. contain similar shapes and optimal values for a variety of different solvents. - (However, for a given value, the activity for lipophilic solvent is higher than for polar solvent, as discussed above.) Inconsistent trends exist when enzyme activity is plotted against water concentration in solvent rather than In addition, a ,-activity profiles for enzyme preparations that differ only in matrix material have similar shapes and maxima. Exceptions to the commonality of fl ,-enzyme activity profiles include... 

Another common practice in HPLC enantioseparation is the use of organic solvents of low polarity as mobile phase components. Although, from the point of view of lipophilic-ity, the organic material bonded or coated onto the chromatographic matrix makes CSPs similar to C8, C18, or phenyl standard stationary phases, normal phase mode is often preferred over reversed-phase conditions. The use of a lipophilic solvent in a lipophilic environment favors dipolar interactions such as hydrogen bonding, dipole-dipole interactions, and ir-stacking, while nonselective van der Waals interactions are minimized. As a result, the selective association CS-enantiomer is favored. 

All plasticizers used in this study are commonly used for the application of polymer coatings as well as for matrix systems [31-33,45-47]. TEC is the standard plasticizer for Eudragit RS with a maximum water solubility of 5%, underlining its hydrophilic character. ATBC was chosen due to its structural similarity compared to TEC, but with an increased lipophilic character. The third plasticizer, the double butylated decanedicarboxy acid (DBS), has a similar lipophilic character as ATBC, but the different molecular structure allows for an additional testing of our computational method. 

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