Theaflavin 3,3'-digallate (TF3), the typical pigment in black tea, is a good antitumor agent. Theaflavin 3,3'-digallate is generally regarded as the effective component for the inhibitory effects against carcinogenesis without adverse side effects by affecting multiple signal transduction pathways, such as upregulating p53 and p21, inhibiting phosphorylation of the cell survival protein Akt and MAPK pathway, downregulation of NF-κB, shifting the ratio between pro-/antiapoptotic proteins. Theaflavin 3,3'-digallate causes a rapid and sustained decrease in phospho-ERK1/2 and -MEK1/2 protein expression. Theaflavin 3,3'-digallate inhibits HCT116 cell growth with an IC₅₀ of 17.26 μM^[1].