Exploration of the mechanisms of Callicarpa nudiflora Hook. et Arn against influenza A virus (H1N1) infection.

• C. nudiflora can inhibit the replication stage of H1N1. • C. can suppress the increase of inflammatory cytokines caused by H1N1 infection in mice, reducing lung damage. • C. nudiflora exhibits immunomodulatory effects on H1N1-infected mice. • C. nudiflora can regulate the toll-like receptor and STAT signaling pathway in H1N1-infected mice. In our preliminary research on screening traditional Chinese medicine extracts for anti-H1N1 activity, we discovered that the 75 % ethanol extract of Callicarpa nudiflora Hook. & Arn (C. nudiflora) exhibited promising anti-H1N1 infection activity. However, the underlying active components and mechanism of action remain to be elucidated. This experiment further explores the potential active components and mechanisms of action of C. nudiflora against H1N1. In this study, the composition of the C. nudiflora was determined using UPLC-Q-Orbitrap-MS/MS. The inhibitory effect of C. nudiflora on H1N1 was investigated using a Madin-Darby canine kidney (MDCK) cell model infected with H1N1, and the protective effect of C. nudiflora on H1N1-infected mice was examined using a Balb/c mouse model infected with H1N1. The potential mechanisms of action were demonstrated at the mRNA and protein levels. A total of 21 compounds were detected in C. nudiflora , which was found to act on the replication stages of H1N1. Moreover, C. nudiflora improved the survival rate of H1N1-infected mice, enhanced the organ index, alleviated the trend of weight loss, reduced lung viral load, mitigated lung tissue damage, and regulated CD4/CD8 and Th1/Th2 immune balance. Molecular mechanism studies revealed that C. nudiflora can regulate the expression of key genes in the toll-like receptor and STAT signaling pathway. C. nudiflora can inhibit H1N1 replication. It also can exert a regulatory effect on the immune response of H1N1-infected mice, and mitigate inflammatory damage by modulating the expression of key genes in the toll-like receptor and STAT signaling pathways, indicating its potential for development as an anti-H1N1 drug. [ABSTRACT FROM AUTHOR]