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 a ...
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 of a
bioactive compound (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 mo ...
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 relationships (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 to ...
, typically derived from numerous sources. This approach revealed that the nature and positions of substituents affected the apparent
biodegradability 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 (bioavailability) in chemical fate.
See also
*
Combinatorial chemistry
*
Congener
*
Conformation activity relationship
*
Quantitative structure–activity relationship
*
Pharmacophore
References
External links
Molecular Property ExplorerQSAR World
{{DEFAULTSORT:Structure-activity relationship
Medicinal chemistry