Define Hydroxybenzoic acid and Hydroxycinnamic acid?

Hydroxybenzoic acid: e.g. ellagic and gallic acids, which are hydrolyzable tannins, present in berries and nuts.

Hydroxycinnamic acid: e.g. caffeic and ferulic acids, which are heat-sensitive. Caffeic acid is a precursor of lignin. Caffeic with qunic acid gives chlorogenic acid. They occur in fruits, vegetables notably seeds, coffee beans, grains, sunflower seeds. Among these, curculnin and chlorogenic ncid have been studied more. Anticarcinogenic effects are attributed to caffeic and ferulic acid. They may act in two ways:

 a) Prevent formation of carcinogens from precursors, and

 b) Block reaction of carcinogens with critical cellular macroinolecules.