Theaflavin 3,3'-digallate (TF-3) is a potent Zika virus (ZIKV) protease inhibitor with an IC50 of 2.3 μM. Theaflavin 3,3'-digallat directly binds to ZIKVpro (Kd=8.86 μM) and inhibits ZIKV replication. Theaflavin 3,3'-digallat inhibits the activity of gp41 and NS2B-3 protease and has antiviral activity against HSV and HIV-1. Theaflavin 3,3'-digallate, the typical pigment in black tea, is a potent antitumor agent.