Antiviral Effect of Polyphenolic Substances in Geranium wilfordii Maxim against HSV-2 Infection Using in vitro and in silico Approaches

Abstract

Background. Herpes simplex virus type 2 (HSV-2) infestation was the most widespread STD (sexually transmitted diseases) among humans and was the leading cause of infectious recurrent genital herpes. Existing therapies against HSV-2 did incompletely restrain the comeback of activated HSV-2 infestation. Geranium wilfordii Maxim had long been used as traditional Chinese medicine for treating the diseases owing to its anti-inflammatory and antiviral effects. Herein, the study was designed to investigate the antiviral activity of G.wilfordii and its potential effect in regulating the host’s immune response. Methods. To identify the stage of infection at which the compounds inhibited HSV-2, we performed virucidal, therapeutic, and prophylactic assays. The antiviral efficacy was evaluated by the analysis of viral components HSV-2 gD and VP16. The antiviral activities of these compounds were also evaluated by phenotypic analysis, such as cell proliferation and apoptosis. Molecular docking studies on candidate compounds were done to indicate binding interactions between the compounds and adopted compound targets. Results. Quercetin, corilagin, and geraniin inhibited the replication of HSV-2, with geraniin showing greater TI. The obtained IC50 value of quercetin was 204.7 μM and TI (IC50/EC50) was 5.1, whereas the obtained IC50 value of corilagin was 118.0 μg/ml and TI was 4.05. Geraniin exhibited prominent antiviral activity with an IC50 of 212.4 μM and an EC50 of 18.37 μM, resulting in a therapeutic index (TI) of 11.56. Geraniin showed important in vitro virucidal activity through blocking viral attachment. Compared with the virus group, the apoptosis rates in quercetin-, corilagin-, and geraniin-treated groups were significantly decreased ( $p<0.001$ ).The expressions at the transcription genes of virus own replication key factors (including HSV-2 gD and VP16) and cytokines (including TBK1) of infected cells treated with quercetin, corilagin, and geraniin were inhibited. The in silico approaches demonstrated a high number of potential strong intermolecular interactions as hydrogen bonds between geraniin, corilagin, and the activity site of HSV-2 gD. Molecular docking studies demonstrated the effects of corilagin by targeting TBK1. Conclusions. Together, these results highlighted the importance of G.wilfordii treatment in HSV-2 infection and underscored its therapeutic potential. However, additional in vitro and in vivo research was required to validate our findings.