Polar surface area

The Polar Surface Area (PSA) is defined as the surface sum over all polar atoms, (usually oxygen and nitrogen), including also attached hydrogens.

PSA is a commonly used medicinal chemistry metric for the optimisation of cell permeability. Molecules with a polar surface area of greater than 140 angstroms squared are usually believed to be poor at permeating cell membranes. For molecules to penetrate the blood-brain barrier (and thus acting on receptors in the central nervous system), PSA should be less than 60 angstroms squared.

ee also

* Lipinski's Rule of Five
* Biopharmaceutics Classification System
* Implicit solvation
* Cheminformatics
** Chemistry Development Kit
** JOELib

External links

* [http://www.molinspiration.com/cgi-bin/properties Interactive Polar Surface Area calculator]
* [http://depth-first.com/articles/2007/09/19/easily-calculate-tpsa-descriptors-from-smiles-strings-using-ruby-cdk/ Free, Programmable TPSA Calculator]

References

* Ertl, P., Rohde, B., Selzer, P. Fast calculation of molecular polar surface area as a sum of fragment based contributions and its application to the prediction of drug transport properties. "J. Med. Chem." 2000, "43", 3714-3717. (DOI|10.1021/jm000942e)