The major phenolic compounds in the leaves of Cyclopia species (honeybush tea)

The phenolic compounds of the leaves of Cyclopia species (tribe Podalyrieae) are of both chemotaxonomic and commercial interest, as the leaves are used to brew a herbal drink known as honeybush tea. Despite the commercial importance of Cyclopia, virtually nothing was known about the chemistry of the leaves prior to the present work. Methanolic extracts from leaves of 22 species were screened for the presence and distribution of phenolic compounds. Three major constituents of the leaves were identified as mangiferin (a xanthone) and glycosides of the flavanones hesperitin and isosakuranetin. The combination of these three compounds is a unique character for Cyclopia, as none of them are present in any of the other genera of the tribes Podalyrieae and Liparieae. Various combinations of the three compounds occur in the different infrageneric groups, but the species are remarkably similar. These results are thus of chemotaxonomic significance at the generic rather than infrageneric level.