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. 2015 May;43(5):725–734. doi: 10.1124/dmd.114.062539

Fig. 2.

Fig. 2.

(A) MRP4: PCA of the training and test set compounds (257 in total) were selected such that they occupy similar areas of the PCA plot. The PCA among the training and test set compounds was generated with the following properties: ALogP, molecular weight, molecular fractional polar surface area, number of rings, aromatic rings, rotatable bonds, hydrogen bond acceptors, and hydrogen bond donors. The first principal component explains 0.366 of total variance, and the second principal component explains 0.272 of total variance. When combined, these explain 0.638 of total variance. The principal components are linear combinations of original descriptors. The dominate descriptors in the principal components are determined by the product of the descriptor coefficient while accounting for the magnitude of the descriptor. The first principal component is dominated by molecular weight, number of hydrogen bond acceptors, and number of rotatable bonds. The second principal component is dominated by the molecular fractional polar surface area. Component 1 = −3.8514 + 0.17609 * [ALogP] + 0.0029942 * [Molecular_Weight] + 0.19241 * [Num_H_Donors] + 0.12966 * [Num_H_Acceptors] + 0.11058 * [Num_RotatableBonds] + 0.21601 * [Num_Rings] + 0.26649 * [Num_AromaticRings] − 0.91018 * [Molecular_FractionalPolarSurfaceArea]. Component 2 = −0.91763 − 0.22028 * [ALogP] + 0.00060715 * [Molecular_Weight] + 0.30038 * [Num_H_Donors] + 0.1113 * [Num_H_Acceptors] + 0.0097512 * [Num_RotatableBonds] − 0.15452 * [Num_Rings] − 0.34347 * [Num_AromaticRings] + 4.3042 * [Molecular_FractionalPolarSurfaceArea]. (B) BSEP: PCA analysis of the training and test sets. The first and second principal components accounted for 0.391 and 0.344 of total variance, respectively. Together, they explain 0.735 of total variance. The first principal component (x-axis) is governed by the number of hydrogen bond donors/acceptors and number of rings, whereas the second principal component (y-axis) is governed by lipophilicity and the number of aromatic rings. Both principal components are strongly influenced by the fractional polar surface area. Component 1 = −4.0005 + 0.035399 * [ALogP] + 0.0031256 * [Molecular_Weight] + 0.16608 * [Num_H_Donors] + 0.14138 * [Num_H_Acceptors] + 0.11881 * [Num_RotatableBonds] + 0.23456 * [Num_Rings] + 0.23836 * [Num_AromaticRings] + 0.48987 * [Molecular_FractionalPolarSurfaceArea]. Component 2 = −0.12988 + 0.2367 * [ALogP] + 0.00047919 * [Molecular_Weight] − 0.20734 * [Num_H_Donors] − 7.2971e-002 * [Num_H_Acceptors] + 0.019248 * [Num_RotatableBonds] + 0.16242 * [Num_Rings] + 0.31811 * [Num_AromaticRings] − 3.6221 * [Molecular_FractionalPolarSurfaceArea]. PCA analysis comparing the training set of MRP4 (C) and BSEP (D) to the DrugBank database of U.S. Food and Drug Administration–approved drugs.