Menu
Home
People
Places
Arts
History
Plants & Animals
Science
Life & Culture
Technology
Reference.org
Structure–activity relationship
open-in-new
<p>The structure–activity relationship (SAR) is the relationship between the <a href="/facts/Chemical_structure/r5rT1Lj4">chemical structure</a> of a molecule and its <a href="/facts/Biological_activity/jJ14jyvc">biological activity</a>. This idea was first presented by <a href="/facts/Alexander_Crum_Brown/14K2CVU4">Alexander Crum Brown</a> and <a href="/facts/Thomas_Richard_Fraser/U6Sy03F4">Thomas Richard Fraser</a> at least as early as 1868. </p><p>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 <a href="/facts/Potency_(pharmacology)/D38FDyPh">potency</a> of a <a href="/facts/Bioactive_compound/pCpWaBbr">bioactive compound</a> (typically a drug) by changing its chemical structure. <a href="/facts/Medicinal_chemistry/SLNHz1hb">Medicinal chemists</a> use the techniques of <a href="/facts/Chemical_synthesis/3KXsVVwC">chemical synthesis</a> to insert new chemical groups into the biomedical compound and test the modifications for their biological effects. </p><p>This method was refined to build mathematical relationships between the chemical structure and the biological activity, known as <a href="/facts/Quantitative_structure%E2%80%93activity_relationship/6RDyCQDD">quantitative structure–activity relationships</a> (QSAR). A related term is structure affinity relationship (SAFIR). </p>