The Ghose-Crippen-Viswanadhan octanol-water partition coefficient (ALogP) is calculated from a regression equation based on the hydrophobicity contribution of 120 atom types [A.K. Ghose and G.M. Crippen, J. Comput. Chem. 1986, 7, 565-577; V.N. Viswanadhan et al., J. Comput. Chem. 1993, 14, 1019-1026]. Each atom in every structure is classified into one of the 120 atom types. Then, estimated logP for any compound is given by:

 

AlogP = å niai

 

where ni is the number of atom of type i and ai is the corresponding hydrophobicity constant.

The list of the atom types with the corresponding hydrophobicity contributions is given under List of atom-centred fragments.

The model coefficients are taken from Ghose et al, J.Phys.Chem. A 1998, 102, 3762-3772. They have been estimated by using a training set of 8364 compounds. 

 

The statistical parameters of the AlogP model are: r = 0.95; s = 0.55; predictive r2 = 0.90.

 

The AlogP estimates are provided only for compounds having C, H, O, N, S, Se, P, B, Si, and halogens.

 

The AlogP model implemented in DRAGON has been evaluated on a set of 3568 compounds with known experimental logP taken from the NCI Open DataBase. The resulted correlation coefficient r was 0.931. Moreover, on our internal logP data set constituted by 9834 compounds the correlation coefficient r between experimental and calculated logP was 0.932.