Kyllinga nemoralis is an ignored plant distributed in tropical, subtropical, and warm temperature regions around the world. K. nemoralis plant is rich with bioactive molecules exhibiting antiherpetic properties. This study determined the antiviral activities of K. nemoralis stem with leaves aqueous extract against herpes simplex virus type 1 (HSV-1). The stem with leaves of K. nemoralis plant was extracted using aqueous extraction method. The cytotoxicity of K. nemoralis extract was evaluated using a cell viability assay. Plaque reduction assays were carried out to estimate the antiviral activity of K. nemoralis extract against HSV-1. Antiviral studies consisted of post-treatment, pre-treatment, and virucidal assay. Cell viability assay revealed K. nemoralis stem with leaves aqueous extract is non-toxic toward Vero cells. K. nemoralis stem with leaves aqueous extract inhibited HSV-1 replication in Vero cells with 50% effective concentration (EC50) = 0.004 mg/mL and selective index (SI) = 14 when given after adsorption to the cells. The EC50 against HSV-1 was 0.013 mg/mL and SI = 4.31 when cells were treated 24 h before virus infection. K. nemoralis stem with leaves aqueous extract exhibited direct virucidal activity against HSV-1 with EC50 = 0.0065 mg/mL and SI = 8.62. The results presented the potential of K. nemoralis as an anti-HSV-1 agent by the following modes: direct damage to viral particle, interruption of virus attachment, and suppression of viral replication cycle.
Key words: Kyllinga nemoralis, antiviral, herpes simplex virus, plaque reduction assay, cytotoxicity, virucidal.
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