Antiviral activities of coffee extracts in vitro

Both hot water extracts of coffee grinds and instant coffee solutions inhibited the multiplication of herpes simplex virus type 1, a representative enveloped DNA virus, when they were added to the culture medium of the virus-infected cells at a dose of one fifth the concentration suitable for drinking. The antiherpetic activity was independent of the suppliers (companies) of the coffee grinds and of the locations where the coffee beans were produced. Further characterization revealed that there are two different mechanisms, by which the coffee extracts exert inhibitory activities on the virus infection; (1) a direct inactivation of the infectivity of virus particle (i.e., a virucidal activity) and (2) the inhibition of progeny infectious virus formation at the late stage of viral multiplication in the infected cells. Caffeine, but not quinic acid and chlorogenic acid, inhibited the virus multiplication to some extent, but none of them showed the virucidal activity, suggesting that other component(s) in the coffee extracts must play a role in the observed antiviral activity. In addition, the coffee extracts inhibited the multiplication of poliovirus, a non-enveloped RNA virus, but showed no virucidal effect on this virus.