Antiviral Effect of Crude Aqueous Extracts from Ten Philippine Medicinal Plants against Zika Virus

Abstract

Objective. This study aimed to determine the antiviral activity of ten Philippine medicinal plants against Zika virus (ZIKV).
Methods. Lyophilized aqueous plant extracts were used for cell cytotoxicity and virus inhibition assays. The therapeutic index was computed from the 50% cytotoxic concentration (CC50) and 50% effective concentration (EC50) values. Plant metabolites were also identified using mass spectroscopy. An in-silico screening of these metabolites was done using ZIKV enzymes and the Axl protein in human microglial cells as target proteins, followed by the ranking of binding energy scores to generate a hypothesis on the possible mechanism of antiviral action.
Results. The plants that demonstrated the highest therapeutic index were Momordica charantia, Psidium guajava, Vitex negundo, and Blumea balsamifera. The majority of the metabolites present in the aqueous extracts were saponin, terpenes and terpenoids, and anthocyanin. Further, in-silico docking results showed a higher binding affinity for viral replication proteins compared to the viral envelope protein.
Conclusion. The crude aqueous extracts of M. charantia, P. guajava, V. negundo, and B. balsamifera were the most potent candidate antiviral therapies against ZIKV among the ten plants tested. Meanwhile, the in-silico results suggested that the metabolites possibly employ an intracellular mechanism for the observed antiviral activity.