Physiological Roles of Phenolic Compounds Isolated from Medicinal Plants of Tropical Origin

In this paper, Phytochemicals also known as secondary metabolites were reviewed. They are plant secondary metabolites, and they have an important role as defensive agents in biological systems.  Polyphenols exhibit various properties that are indispensable to humans. Most phenolic compounds are known to have antimicrobial,  cytotoxicity,  anti-inflammatory  properties as  well  as  antitumor  activities,  but the best-described property of virtually every group of polyphenols is their capacity to act as powerful antioxidants  which  can  protect  the human  body from  free  radicals  and  reactive  oxygen  species(ROS). For this reasons, phenolic compounds and their biological roles have become a subject of intense scrutiny.  Basically, structural classification, sources, chemical composition and biological activity of phenolic compounds such as tannins, saponins, Alkaloids, flavonoids, coumarins and chalcones were discussed.