The structure–activity relationship (SAR) is the relationship between the
chemical structure
A chemical structure determination includes a chemist's specifying the molecular geometry and, when feasible and necessary, the electronic structure of the target molecule or other solid. Molecular geometry refers to the spatial arrangement of at ...
of a molecule and its
biological activity
In pharmacology, biological activity or pharmacological activity describes the beneficial or adverse effects of a drug on living matter. When a drug is a complex chemical mixture, this activity is exerted by the substance's active ingredient or ...
. This idea was first presented by Crum-Brown and Fraser in 1865.
The analysis of SAR enables the determination of the chemical group responsible for evoking a target biological effect in the organism. This allows modification of the effect or the
potency
Potency may refer to:
* Potency (pharmacology), a measure of the activity of a drug in a biological system
* Virility
* Cell potency, a measure of the differentiation potential of stem cells
* In homeopathic dilutions, potency is a measure of how ...
of a
bioactive compound
A bioactive compound is a compound that has an effect on a living organism, tissue or cell, usually demonstrated by basic research in vitro or in vivo in the laboratory. While dietary nutrients are essential to life, bioactive compounds have not ...
(typically a drug) by changing its chemical structure.
Medicinal chemists use the techniques of
chemical synthesis
As a topic of chemistry, chemical synthesis (or combination) is the artificial execution of chemical reactions to obtain one or several products. This occurs by physical and chemical manipulations usually involving one or more reactions. In moder ...
to insert new chemical groups into the biomedical compound and test the modifications for their biological effects.
This method was refined to build mathematical relationships between the chemical structure and the biological activity, known as
quantitative structure–activity relationship
Quantitative structure–activity relationship models (QSAR models) are regression or classification models used in the chemical and biological sciences and engineering. Like other regression models, QSAR regression models relate a set of "predic ...
s (QSAR). A related term is structure affinity relationship (SAFIR).
Structure-biodegradability relationship
The large number of synthetic organic chemicals currently in production presents a major challenge for timely collection of detailed environmental data on each compound. The concept of structure biodegradability relationships (SBR) has been applied to explain variability in persistence among organic chemicals in the environment. Early attempts generally consisted of examining the degradation of a homologous series of structurally related compounds under identical conditions with a complex "universal"
inoculum
In biology, inoculum refers to the source material used for inoculation. ''Inoculum'' may refer to:
* In medicine, material that is the source of the inoculation in a vaccine
* In microbiology, propagules: cells, tissue, or viruses that are used t ...
, typically derived from numerous sources. This approach revealed that the nature and positions of substituents affected the apparent
biodegradability
Biodegradation is the breakdown of organic matter by microorganisms, such as bacteria and fungi. It is generally assumed to be a natural process, which differentiates it from composting. Composting is a human-driven process in which biodegradati ...
of several chemical classes, with resulting general themes, such as halogens generally conferring persistence under aerobic conditions. Subsequently, more quantitative approaches have been developed using principles of QSAR and often accounting for the role of
sorption
Sorption is a physical and chemical process by which one substance becomes attached to another. Specific cases of sorption are treated in the following articles:
; Absorption: "the incorporation of a substance in one state into another of a dif ...
(bioavailability) in chemical fate.
See also
*
Combinatorial chemistry Combinatorial chemistry comprises chemical synthetic methods that make it possible to prepare a large number (tens to thousands or even millions) of compounds in a single process. These compound libraries can be made as mixtures, sets of individua ...
*
Congener
*
Conformation activity relationship
Conformation generally means structural arrangement and may refer to:
* Conformational isomerism, a form of stereoisomerism in chemistry
** Carbohydrate conformation
** Cyclohexane conformation
** Protein conformation
** Conformation activity rela ...
*
Quantitative structure–activity relationship
Quantitative structure–activity relationship models (QSAR models) are regression or classification models used in the chemical and biological sciences and engineering. Like other regression models, QSAR regression models relate a set of "predic ...
*
Pharmacophore
300px, An example of a pharmacophore model.
A pharmacophore is an abstract description of molecular features that are necessary for molecular recognition of a ligand by a biological macromolecule. IUPAC defines a pharmacophore to be "an ensemble o ...
References
External links
Molecular Property ExplorerQSAR World
{{DEFAULTSORT:Structure-activity relationship
Medicinal chemistry