Authors M. M. Cowan
The use of and search for drugs and dietary supplements derived from plants have accelerated in recent years. While 25 to 50% of current pharmaceuticals are derived from plants, none are used as antimicrobials. Plants are rich in a wide variety of secondary metabolites, such as tannins, terpenoids, alkaloids, and flavonoids, which have been found in vitro to have antimicrobial properties. Plants have an almost limitless ability to synthesize aromatic substances, most of which are phenols or their oxygen-substituted derivatives, In many cases, these substances serve as plant defense mechanisms against predation by microorganisms, insects, and herbivores. Some, such as terpenoids, give plants their odors; others (quinones and tannins) are responsible for plant pigment.
