The polar surface area (PSA) or topological polar surface area (TPSA) of a
molecule
A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bio ...
is defined as the surface sum over all
polar atoms or molecules, primarily
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as we ...
and
nitrogen
Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at seve ...
, also including their attached hydrogen atoms.
PSA is a commonly used
medicinal chemistry
Medicinal or pharmaceutical chemistry is a scientific discipline at the intersection of chemistry and pharmacy involved with designing and developing pharmaceutical drugs. Medicinal chemistry involves the identification, synthesis and developme ...
metric for the optimization of a drug's ability to permeate cells. Molecules with a polar surface area of greater than 140
angstrom
The angstromEntry "angstrom" in the Oxford online dictionary. Retrieved on 2019-03-02 from https://en.oxforddictionaries.com/definition/angstrom.Entry "angstrom" in the Merriam-Webster online dictionary. Retrieved on 2019-03-02 from https://www.m ...
s squared (Å
2) tend to be poor at permeating cell membranes.
For molecules to penetrate the
blood–brain barrier (and thus act on receptors in the
central nervous system
The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all p ...
), a PSA less than 90 Å
2 is usually needed.
See also
*
Biopharmaceutics Classification System
*
Cheminformatics
**
Chemistry Development Kit
**
JOELib
*
Implicit solvation
*
Lipinski's rule of five
References
*
*
*
*
* Ertl, P
Polar Surface Area in ''Molecular Drug Properties'', R. Mannhold (ed), Wiley-VCH, pp. 111–126, 2007
*
External links
Interactive Polar Surface Area calculatorFree, Programmable TPSA Calculator
Cheminformatics
Medicinal chemistry
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