Phenylpropanoids (or phenolic compounds) are a large class of plant secondary metabolites with important functions in plants as antibiotics, natural pesticides, signal molecules for the interaction of symbiotic rhizobia with plant roots, attractants for pollinators, protective agents against UV light, and structural material for plant stability. On the other hand, phenolic compounds are the most widespread dietary antioxidants with positive effects on human health.
These compounds play an important role in removing of harmful by-products (reactive oxygen species) formed during normal aerobic cell respiration and especially in oxidative stress under pathological conditions. Beneficial health effects of less known phenolic compounds such as chlorogenic acid and caffeic acid are discussed.