Human rhinoviruses (HRVs) are a major cause of the
common cold and until now there is no registered clinically effective
antiviral chemotherapeutic agent for treatment of diseases caused by HRVs. Our previous report showed that
gallic acid from Woodfordia fruticosa flowers possessed
antioxidant activity. Many studies reported that
antioxidants possess
antiviral activities against various viruses. Therefore, we examined
antiviral activity of
gallic acid against HRVs and mode of its actions by observing the effect of
gallic acid on HRV-induced cytopathic effect (CPE) and the infectivity of HRV particles, and then carried out a time-addition study. As a result,
gallic acid actively inhibited HRV2 and -3 replications with
antiviral activity more than 55% without cytotoxicity in human epitheloid
carcinoma cervix (HeLa) cells at a concentration of 100 mug/mL. Also,
ribavirin showed lower anti-HRV3 activity than
gallic acid and similar anti-HRV3 activity to it. The addition of
gallic acid to HRV-infected HeLa cells directly reduced the formation of a visible CPE. Furthermore,
gallic acid did directly interact or activate with HRV particles. Collectively, we concluded that the inhibition of HRV production by
gallic acid is mainly due to a general action as an
antioxidant and the mode of action derived from the inhibition of virus absorption.