Cinnamic acid is a central intermediate in the biosynthesis of myriad natural products include lignolsto lignin and lignocellulose), flavonoids, isoflavonoids, coumarins, aurones, stilbenes, catechin, and phenylpropanoids. Its biosynthesis is performed by action of the enzyme phenylalanine ammonia-lyase (PAL) on phenylalanine. Cinnamic acid is a precursor for the synthesis of a huge number of plant substances, including lignin, tannins, flavonoids, pigments, many of the flavor components of spices, and various alkaloids, such as morphine and colchicine.