Definition of QSAR

What is QSAR?

See Quantitative Structure-Activity Relationships.

Quantitative Structure-Activity Relationships (QSAR)

Quantitative structure-activity relationships are mathematical relationships linking chemical structure and pharmacological activity in a quantitative manner for a series of compounds. Methods which can be used in QSAR include various regression and pattern recognition techniques.


A receptor is a molecule or a polymeric structure in or on a cell that specifically recognizes and binds a compound acting as a molecular messenger (neurotransmitter, hormone, lymphokine, lectin, drug, etc.).

Receptor mapping

Receptor mapping is the technique used to describe the geometric and/or electronic features of a binding site when insufficient structural data for this receptor or enzyme are available. Generally the active site cavity is defined by comparing the superposition of active to that of inactive molecules.

Second messenger

A second messenger is an intracellular metabolite or ion increasing or decreasing as a response to the stimulation of receptors by agonists, considered as the "first messenger". This generic term usually does not prejudge the rank order of intracellular biochemical events.

Site-specific delivery

Site-specific delivery is an approach to target a drug to a specific tissue, using prodrugs or antibody recognition systems.

Soft drug

A soft drug is a compound that is is degraded in vivo to predictable non-toxic and inactive metabolites, after having achieved its therapeutic role.


See Structure-property correlations.

Structure-activity relationship (SAR)

Structure-activity relationship is the relationship between chemical structure and pharmacological activity for a series of compounds.

Structure-based design

Structure-based design is a drug design strategy based on the 3D structure of the target obtained by X-ray or NMR.

Structure-property correlations (SPC)

Structure-property correlations refers to all statistical mathematical methods used to correlate any structural property to any other property (intrinsic, chemical or biological), using statistical regression and pattern recognition techniques.


Systemic means relating to or affecting the whole body.


A teratogen is a substance that produces a malformation in a foetus.

Three-dimensional Quantitative Structure-Activity Relationship (3D-QSAR)

A three-dimensional quantitative structure-activity relationship is the analysis of the quantitative relationship between the biological activity of a set of compounds and their spatial properties using statistical methods.

Topliss tree

A Topliss tree is an operational scheme for analog design.

Transition-state analog

A transition-state analog is a compound that mimics the transition state of a substrate bound to an enzyme.


A xenobiotic is a compound foreign to an organism (xenos [greek] = foreign).

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