In vitro superoxide anion radical scavenging ability of honeybush tea (Cyclopia)

The superoxide anion radical (O-2(.)-) scavenging ability of aqueous extracts from honeybush tea, as affected by species and fermentation, and phenolic compounds from fermented C. intermedia, was evaluated. Unfermented C. sessili-flora showed the strongest O-2(.)- scavenging ability. Fermentation significantly (P less than or equal to 0.05) decreased the O-2(.)- scavenging ability of the different species. A strong structure-activity relationship was illustrated by the relative O-2(.)- scavenging efficacy of the phenolic compounds. The flavone luteolin and the flavanone eriodictyol showed excellent O-2(.)- scavenging activity compared to the flavanones, hesperidin and hesperetin. The isoflavone formononetin and coumestan medicagol were not effective scavengers of this radical.