Zika virus (ZIKV) is an emerging vector-borne virus that is associated with severe congenital cerebral anomalies in fetuses and paralytic Guillain-Barre syndrome in adults. In the current global health crisis, there are no vaccines or therapeutics available for the treatment of ZIKV infection. In the present study, we evaluated the efficacy of the protoberberine alkaloid, palmatine, in inhibiting ZIKV and Japanese encephalitis virus (JEV). Palmatine was shown to bind to restricted viruses, inhibit ZIKV infection, and resist ZIKV-induced cytopathic effects. Palmatine was also shown to inhibit JEV infection in multiple cell lines. Overall, the effects of palmatine in disrupting ZIKV binding, entry, and stability indicate that this small molecule would be a good starting point for the development of treatments aimed at inhibiting ZIKV infection. (C) 2019 Elsevier Inc. All rights reserved.