Polar Surface Area

Polar Surface Area (PSA) is formed by polarized atoms of a molecule. It is a descriptor that shows good correlation with passive molecular transport through membranes, and allows estimation of transport properties of drugs. Estimation of Topoligical Polar Surface Area (TPSA) is based on the method described in Ertl et al. The method gives results that are practically identical with the 3D PSA, while calculating TPSA is approximately 100 times faster. This method is more suitable for fast bioavailability screening of large virtual libraries. The TPSA value can be calculated both for the neutral form of the molecule and for the major microspecies at a given pH. The Polar Surface Area Plugin (2D) calculates the descriptor described above.