Combined network pharmacology and biological verification to investigate anti-influenza A virus effect and potential mechanism of Pudilan Xiaoyan Oral Liquid

Influenza is a common respiratory disease affecting human health and life. Pudilan Xiaoyan Oral Liquid (PDL) has frequently been used to treat respiratory infections such as COVID-19, pharyngitis, and tonsillitis. However, its efficacy against influenza A virus (IAV) infection remains unclear. This study aimed to investigate the anti-IAV activity and potential mechanism of action of PDL. The in vitro anti-IAV activity was investigated in a virus-infected MDCK (Madin-Darby canine kidney) cell model. The in vivo protective effect on AIV infection was evaluated in a virus-infected mice model. qRT-PCR was performed to examine the anti-inflammatory effects of the PDL. A network pharmacology method was used to investigate the underlying mechanism of PDL against IAV. Western blotting was performed to confirm the antiviral mechanism of PDL against IAV. Our findings indicated that PDL had a broad-spectrum anti-IAV effect in vitro and exhibited an excellent protective effect against IAV infection by significantly increasing the survival rate, extending the survival time, and reducing pathological lung tissue damage. Moreover, PDL effectively inhibited the mRNA expression of inflammatory factors in lung tissue. GO analysis revealed that the potential targets were primarily associated with defense response regulation, positive regulation of cytokine production, and positive regulation of responses to external stimulation. PPI analysis indicated that Sarcoma (SRC), signal transducer and activator of transcription 3 (STAT3), mitogen-activated protein kinase1 (MAPK1), phosphatidylinositol 3-kinase regulatory subunit alpha (PIK3R1), and epidermal growth factor receptor (EGFR) might be potential PDL targets against IAV infection. Mechanistically, inhibition of the Toll-like receptor 3 (TLR3)/myeloid differentiation primary response gene (88) (MyD88) signaling pathway to attenuate an excessive inflammatory response might be one of the primary mechanisms of PDL against IAV. PDL efficiently suppressed in vitro IAV replication and provided protection against lethal influenza virus infection in vivo . Network pharmacology analysis revealed that the key PDL targets against influenza might be highly associated with biological processes, such as regulation of defense responses, cytokine production, and the Toll-like receptor signaling pathway. Mechanistically, regulating the TLR3/MyD88 signaling pathway may be one of the primary mechanisms of PDL against influenza virus infection. These findings indicate that PDL could be a potential therapeutic option for the clinical treatment of influenza viral infections.