Topic 23.3

Structural Requirements for Biological Activity of Abscisic Acid

The features shown to be essential for biological activity include the carboxyl group, the tertiary hydroxyl group, the 2-cis, 4-trans-pentadienoic side chain, a 4′-ketone, and a double bond in the cyclohexane ring. Catabolic products of ABA that are present in the tissue and are missing any of these groups are biologically inactive.