Insights into Inhibitory Effects of Lapachol against Zika Virus

The reemergence of Zika virus (ZIKV) in 2015 and its association with severe neurological manifestations highlighted the urgent need for effective antiviral therapies, which, despite extensive efforts, remain unavailable. Lapachol, a 1,4-naphthoquinone compound abundant in Brazilian plant species, seems to be a promising candidate as an antiviral agent since its activity against other RNA viruses, as well as other human pathogens, including reported activity against Epstein-Barr virus and inhibition of herpes simplex virus type 1 by a lapachol-derived compound. Here, we investigated the activity of lapachol in inhibiting ZIKV replication by employing the wild-type strain ZIKV_PE243. Lapachol exhibited potent inhibition of ZIKV with an EC₅₀ of 3 μM and selectivity index of 50. Mechanistic assays suggest that its main action is exerted through postentry inhibition of viral replication, possibly through the blockage of the catalytic sites of NS2B-NS3 protease and NS5 polymerase. Biochemical enzymatic assays confirmed that lapachol inhibits NS2B-NS3 protease and NS5 polymerase activities, being complemented by molecular docking analyses. A protective effect was noted when cells were treated prior to infection, and lapachol was found to induce ROS formation in vitro, indicating that several antiviral mechanisms may be involved, including the initiation of an oxidative stress response that can affect viral particles. Overall, these findings shed light on the potential of lapachol to be used for the development of ZIKV inhibitors, especially targeting postentry stages of virus replication.