In Vitro and in Vivo Studies of the Inhibitory Effects of Emodin Isolated from Polygonum cuspidatum on Coxsakievirus B(4)

The lack of effective therapeutics for Coxsackievirus B(4) (CVB(4)) infection underscores the importance of finding novel antiviral compounds. Emodin (1,3,8-trihydroxy-6-methylanthraquinone) is one of the natural anthraquinone derivatives obtained from the root and rhizome of Polygonum cuspidatum. In the present study, the possibility of using emodin as a potential antiviral to treat CVB(4) infection was explored in vitro and in mice. Emodin reduced CVB(4) entry and replication on Hep-2 cells in a concentration- and time-dependent manner, with a 50% effective concentration (EC(50)) of 12.06 μM and selectivity index (SI) of 5.08, respectively. The inhibitory effect of emodin for CVB(4) entry and replication was further confirmed by a quantitative real time PCR (qPCR) assay. The results further showed that the mice orally treated with different dosages of emodin displayed a dose dependent increase of survival rate, body weight and prolonged mean time of death (MTD), accompanied by significantly decreased myocardial virus titers and pathologic scores/lesions. Moreover, emodin could inhibit CVB(4)-induced apoptosis in vitro and in vivo. Our results indicated that emodin could be used as potential antiviral in the post-exposure prophylaxis for CVB(4) infection.