Theaflavin monomers are transformed from
tea catechins through oxidation catalyzed by enzyme
and chemical condensation, which makes theaflavin
monomers more stable than EGCG. Some experiments
demonstrated that the theaflavins presented in
black tea have at least the same antioxidant potential
as catechins presented in green tea, and that the conversion
of catechins to theaflavins during black tea
production does not alter significantly their free
radical-scavenging activity (Leung et al., 2001).
More studies indicated that the synergistic anticancer
effects of AA and green tea extract on several cancer
cell lines in tissue culture were higher than those of
the individual nutrients (Roomi et al., 2006).