Lignans and Stilbenes from African Medicinal Plants

Lignans and stilbenes are two groups of related secondary metabolites widely distributed in the plant kingdom. They have been found in roots, rhizomes, stems, bark, leaves, seeds, and fruits of more than 100 species of African medical plants belonging to various families. Lignans are biosynthesized by oxidative dimerization of two phenylpropanoid units; they possess an enormous structural diversity originating from various linkage patterns. Stilbenes are also biosynthesized from phenylpropanoids that can be further oxidized to form oligomers. Both lignans and stilbenes from African medicinal plants have attracted intense interest because of their structural diversity and biological functions, specifically for their anticancer, antiplasmodial, and antibacterial properties. This is exemplified by many clinical studies that have been performed on the use of schweinfurthins, combretastatins, and steganolides to treat cancer. This chapter provides information on the biosynthesis, subclasses, and structural diversity of lignans and stilbenes, as well as their biological activity. Selected data are presented for those molecules with biological information