Anti-herpes simplex virus type 1 activity of the Rohdea chinensis (Baker) N. Tanaka aqueous extracts

Herpes simplex virus type 1 (HSV-1) is a prevalent neurotropic pathogen that establishes lifelong latency in the peripheral nervous system, posing substantial clinical challenges due to its recurrent infections and emerging drug resistance. Rohdea chinensis (Baker) N. Tanaka, a traditional Chinese herbal medicine, has been historically used for heat-clearing, detoxifying, wind-dampness dispelling, blood-stasis removing, and pain-relieving properties. Despite its common folk use in Leshan, Sichuan Province, for treating herpes simplex infections, the chemical composition and antiviral activity of Rohdea chinensis remain largely uninvestigated.

The aim of this study was to clarify the chemical composition and antiviral activity of the Rohdea chinensis aqueous extract (RCAE), and preliminarily speculate the possible mechanism of its antiviral effect.

The chemical profile of RCAE was characterized using UPLC-Q-TOF-MS/MS, identifying 9 major compounds. The antiviral effects of RCAE were assessed through in vitro and in vivo models, including direct virucidal assays, HSV-1 adhesion inhibition, and a mouse model of flank scratch HSV-1 infection. Immunomodulatory effects were evaluated by analyzing dendritic cell (DC) maturation, CD8⁺ T cell differentiation, and cytokine expression. Additionally, HSV-1 latent reactivation models were established to assess RCAE's impact on viral persistence in the dorsal root ganglion (DRG). Molecular docking studies were conducted to determine potential interactions between RCAE bioactive compounds and HSV-1 glycoprotein D (gD).

The overall anti-HSV-1 effect of RCAE on Vero cells was determined and the EC₅₀ value was 7.994 μg/mL. RCAE directly killed HSV-1 and inhibited HSV-1 adhesion in vitro (P < 0.001, 30 μg/mL RCAE treated groups vs HSV-1 group), and alleviated viral infection and inflammation of the skin involving the NF-κB pathway (P < 0.001, different doses of RCAE treated groups vs HSV-1 group), as well as anti-viral infection of the brain and DRG in HSV-1-induced mice (P < 0.05, 0.6 g/mL RCAE treated groups vs HSV-1 group). Interestingly, RCAE played an antiviral role by increasing the maturation of DC in mice, enhancing the antigen presentation ability of DC, promoting the differentiation of CD8⁺T cells and the secretion of CXCL1 and IFN-γ, and inhibiting the immune escape of HSV-1 virus (P < 0.05, 0.6 g/mL RCAE treated groups vs HSV-1 group). Besides, RCAE prevented the reactivation of HSV-1 in vitro (P < 0.001, 0.6 g/mL RCAE treated groups vs HSV-1 group). HSV gD is a critical viral glycoprotein that plays a central role in viral attachment to host cells, intercellular spread, and entry into host cells. To clarify the anti-HSV-1 mechanism of RCAE, molecular docking was employed to preliminarily confirm stable interactions between RCAE compounds (notably compound 9, with a binding energy of -10.5 kcal/mol) and HSV-1 gD. In vitro and in vivo experiments showed that RCAE reduced the expression of gD gene (P < 0.001, different doses of RCAE treated groups vs HSV-1 group) and protein in skin tissues of HSV-1-infected mice, as well as the gD mRNA levels (P < 0.001, different doses of RCAE treated groups vs HSV-1 group) in HSV-1-treated HaCaT cells. These findings suggest that the anti-HSV-1 effect of RCAE may be associated with the inhibition of gD function.

Our results indicate that RCAE has multi-target antiviral effects, including direct virus-killing activity, inhibition of viral replication, immune regulation, and inhibition of latent reactivation of HSV-1 in preclinical models. Integrating traditional Chinese medicine principles (heat-clearing, detoxifying, and blood-stasis-removing properties) with modern pharmacological activities (antiviral, anti-inflammatory, and immunomodulatory effects), RCAE demonstrates potential as a natural product candidate for addressing HSV-1 infection. Given RCAE's complex and undefined composition, future studies are needed to identify key antiviral components and their in vivo efficacy and mechanisms.