11 - Xanthones and Anthranoids from the Medicinal Plants of Africa

Xanthones or xanthen-9H-ones (dibenzo-gamma-pirone) comprise an important class of oxygenated heterocycles whose role is well known in medicinal chemistry. The biological activities of this class of compounds are associated with their tricyclic scaffold but vary depending on the nature and/or position of the different substituents. In this chapter, the biosynthetic pathways of xanthones and anthrones (or anthronoids) are examined, and we summarize the occurrence of these two classes of compounds in African plants, together with their biological/pharmacological activities. It appears that most xanthones identified so far in plants of the continent were isolated from the family Guttiferae. The present literature review revealed 97 compounds (86 xanthones and 11 anthranoids), of which 46 were reported for the first time. The biological activity reported for such compound includes antimicrobial, cytotoxic, and enzyme inhibitory effects.