Catechins and Proantocyanidins : naturally occurring O-Heterocycles with antimicrobial activity

Pharmacological interest in drug discovery has increased in recent years. Accordingly, an increasing part of the scientific body has thus far studied several thousands of compounds of natural and synthetic origin to ascertain their biological activity. The occurrence in plant tissues of secondary metabolites characterized by a O-heterocyclic structure and exhibiting antimicrobial properties is a well-known phenomenon. Among them, catechins and proanthocyanidins are two classes of compounds that exhibit antiviral or antimicrobial properties towards prokaryotic and eukaryotic microorganisms. Yet, despite the profusion of studies published so far, the real potentialities and limitations presented by the use of the above-mentioned class of molecules as antiviral or antimicrobial agents have not been critically evaluated. The present chapter represents an overview of the recent literature regarding the antiviral and antimicrobial properties exhibited by this class of compounds. Their mode of action as well as their synergy with currently used antibiotic molecules are also reviewed. In addition, their potentialities and the causes that have hampered their pharmaceutical exploitation so far are discussed. Antibacterial activity - Antimycotic activity - Antiprotozoal activity - Antiviral activity - Cathechins - Proanthocyanidins