Abstract
Tea is one of the most popular beverages in Japan. We unexpectedly found that green tea immobilized cholera vibrios within several seconds and agglutinated them. Therefore, we examined the biologic functions of tea and catechin.
Tea and catechin possesed antibacterial and bactericidal activities against various bacteria that cause food poisoning and diarrheal and respiratory diseases and also possessed fungicidal activities against Trichophyton. Catechin damaged the lipid bilayer of bacterial cell membranes. Catechin also caused morphologic changes in T. mentagrophytes evident on scanning and transmission electron microscopy. We also found that in the presence of catechin oxacillin had antibacterial activity against methicillin resistant Staphylococcus aureus at concentrations less than its minimum inhibitory concentration. Tea and catechin also inhibited the toxic activities of Vibrio parahemolyticus thermostable direct hemolysin (Vp-TDH), S. aureus a -toxin, cholera hemolysin, and cholera toxin. They had protected against V. cholerae O1 in animal models. Tea and catechin inhibited the infectivity of both influenza virus A and B in vitro. Black tea prevented influenza virus infection in mice. Furthermore, gargling with black tea significantly inhibited influenza infection in volunteers. Catechin also had mitogenic activity on B cells.
These findings suggest that tea and catechin might be applied as prophylactic and therapeutic agents against infectious diseases.
