Polar surface area
Encyclopedia
Molecule
A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...
is defined as the surface sum over all polar atoms, primarily oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
and nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
, also including their attached hydrogens.
PSA is a commonly used medicinal chemistry
Medicinal chemistry
Medicinal chemistry and pharmaceutical chemistry are disciplines at the intersection of chemistry, especially synthetic organic chemistry, and pharmacology and various other biological specialties, where it is involved with design, chemical synthesis and development for market of pharmaceutical...
metric for the optimisation of a drug's ability to permeate cells. Molecules with a polar surface area of greater than 140 angstrom
Ångström
The angstrom or ångström, is a unit of length equal to 1/10,000,000,000 of a meter . Its symbol is the Swedish letter Å....
s squared tend to be poor at permeating cell membranes. For molecules to penetrate the blood-brain barrier
Blood-brain barrier
The blood–brain barrier is a separation of circulating blood and the brain extracellular fluid in the central nervous system . It occurs along all capillaries and consists of tight junctions around the capillaries that do not exist in normal circulation. Endothelial cells restrict the diffusion...
(and thus act on receptors in the central nervous system
Central nervous system
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
), a PSA less than 60 angstroms squared is usually needed.
See also
- Lipinski's Rule of FiveLipinski's Rule of FiveLipinski's Rule of Five is a rule of thumb to evaluate druglikeness or determine if a chemical compound with a certain pharmacological or biological activity has properties that would make it a likely orally active drug in humans. The rule was formulated by Christopher A...
- Biopharmaceutics Classification SystemBiopharmaceutics Classification SystemThe Biopharmaceutics Classification System is a guide for predicting the intestinal drug absorption provided by the U.S. Food and Drug Administration . The fundamental basis for the BCS was established by Dr...
- Implicit solvationImplicit solvationImplicit solvation is a method of representing solvent as a continuous medium instead of individual “explicit” solvent molecules most often used in molecular dynamics simulations and in other applications of molecular mechanics...
- CheminformaticsCheminformaticsCheminformatics is the use of computer and informational techniques, applied to a range of problems in the field of chemistry. These in silico techniques are used in pharmaceutical companies in the process of drug discovery...
- Chemistry Development KitChemistry Development KitThe Chemistry Development Kit is an open-source Java library for Chemoinformatics and Bioinformatics. It is available for Windows, Unix, and Mac OS...
- JOELibJOELibJOELib is a free software chemical expert system mainly used for converting chemical file formats. Because of its strong relationship to informatics, this program belongs more to the category cheminformatics than to molecular modelling. It is available for Windows, Unix and other systems supporting...
- Chemistry Development Kit