Nicotinic acid from Bubali Cornu alleviates H1N1-induced acute lung injury via dual antiviral and anti-inflammatory actions: A bioactivity-driven discovery.

ETHNOPHARMACOLOGICAL RELEVANCE

Bubali Cornu (BC) has a long history of use in traditional Chinese medicine for the treatment of various conditions, including high fever, hemoptysis, epistaxis, and infections. Despite its historical use, the active components responsible for its therapeutic effects, particularly in viral pneumonia, remain poorly understood.

AIM OF THE STUDY

The objective of this study was to identify the active compounds in BC with antiviral activity against H1N1 and to evaluate their therapeutic potential in alleviating inflammation in H1N1-infected acute lung injury (ALI) mice.

MATERIALS AND METHODS

The antiviral components of BC were isolated using silica gel column chromatography and high-performance liquid chromatography (HPLC) according to a bioactive guided separation strategy. Then, the protective effects of these components in H1N1-induced ALI mice were evaluated. To explore the potential mechanisms, network pharmacology (NP) analysis and qPCR were used to screen the related signaling pathways or proteins. Finally, the functions of the most effective compound were verified in H1N1-infected RAW264.7 macrophages, focusing on its regulatory effects on key proteins.

RESULTS

The ethyl acetate fraction (EAF) of BC had a protective effect against ALI induced by H1N1 in mice. Subsequently, 13 compounds were isolated from EAF of BC, of which nicotinic acid (NA) showed the best antiviral activity in vitro. In vivo studies showed that NA treatment of ALI mice infected with H1N1 significantly reduced lung index and inflammation, and improved lung tissue morphology. Flow cytometry analysis revealed that NA reduced the over-recruitment of macrophages and neutrophils to alleviate the inflammatory storm. As verified by NP and qPCR, NA reduced the mRNA levels of NOS2 and NOX1 in the lungs of mice with viral pneumonia, but Western blot analysis only showed that NA inhibited the expression of NOS2. Finally, NA significantly inhibited the expression of NOS2 in RAW264.7 cells infected with H1N1, suggesting that NA might alleviate ALI induced by H1N1 by inhibiting NOS2 expression in pulmonary macrophages.

CONCLUSION

The present study demonstrated that NA isolated from BC exhibited significant antiviral and anti-inflammatory properties in H1N1-induced ALI. NA might alleviate the progression of H1N1 pneumonia by inhibiting virus replication, reducing the over-recruitment of macrophages and neutrophils, and inhibiting the expression of NOS2. These findings provided valuable insights into the potential of BC in the treatment of viral infections, and highlighted the importance of exploring traditional animal-derived TCM in modern antiviral applications.