Illustrated Glossary of Organic Chemistry

Quantitative structure-activity relationship (QSAR): A structure-activity relationship in which a drug's biological properties are quantitatively correlated with its molecular structure. The mathematical correlation is often in form of a linear equation.

QSAR equation for the biological activity of thyroid hormones: logBA =1.35π_X + 1.34π_Y - 1.32[Y- size I] - 0.36π_Z - 0.66σ_Y,Z - 0.89D - 2.836. BA is a measure of a certain type of activity. π and σ are parameters related to the substituents X, Y, and Z.