Figure 2.

Prediction of the permeability of artificial lipid bilayers to organic molecules. (A) Comparison of experimental $\left(\text{log}{P}_{\text{exp}}^{\text{BLM}}\right)$ and calculated $\left(\text{log}{P}_{\Sigma }^{\text{BLM}}\right)$ permeability coefficients across unilamellar lipid bilayers of 58 un-ionized (black circles) and 20 ionized in water (open circles) organic molecules. The corresponding data values are from Tables S1 and S2. (B) Plot of experimental BLM permeability coefficients $\left(\text{log}{P}_{\text{exp}}^{\text{BLM}}\right)$ vs the calculated ones $\left(\text{log}{P}_{\text{calc }}^{\text{BLM}}\right)$ for 78 organic molecules. Dashed lines indicate ideal line and residual line limits (using a cutoff of |3.1| that corresponds to 2.0 rmse for ionized molecules). Predicted permeability coefficients, $\text{log}{P}_{\text{calc }}^{\text{BLM}}$, in B were calculated using eq 15. The $\text{log}{P}_{\Sigma }^{\text{BLM}}$ values were calculated using eq 6. For ionized species, the integral $\text{log}{P}_{\text{m}\Sigma }^{\text{BLM}}$ accounted for the deionization penalty of ionizable groups at the specified pH. The number of molecules “n” is indicated in parentheses.