The leaves of Canarium album (Lour.) DC. suppresses influenza A virus replication and inflammation through modulation of PI3K-AKT pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: Canarium album (Lour.) DC. (Chinese olive, Ganlan), a traditional medicinal plant documented in medical classics, has been historically employed as heat-clearing and detoxicating herbs for warm disease treatment. While contemporary studies have validated its antiviral properties, its anti-inflammatory therapeutic potential against influenza virus infection remains largely unexplored.

AIM: This study explored the underlying mechanisms and active components of Canarium album (Lour.) DC. leaf extract (GLY) in combating H1N1 influenza.

METHOD: The antiviral and anti-inflammatory activities of GLY aqueous extract were systematically assessed using Influenza A Virus (IAV)-infected Madin-Darby Canine Kidney (MDCK) cells, A549 alveolar epithelial cells, and murine models, followed by Reverse Transcription Quantitative Real-Time Polymerase Chain Reaction (RT-qPCR), western blotting, and immunofluorescence. The active phytochemicals were explored through ultra-performance liquid chromatography coupled with Q-Exactive Orbitrap mass spectrometry (UPLC-Q-Orbitrap-MS) analysis on GLY-containing plasma. Mechanistic investigations involved network-based target prediction and subsequent experimental validation through Western blot analysis of critical signaling mediators. Molecular docking analysis assessed phytochemical-protein interactions, followed by evaluation of anti-influenza activity in MDCK cells.

RESULTS

Our study demonstrated the leaves of the Chinese olive, exerted great anti-influenza activities in the MDCK cell model with IC50 of 31.11-36.72 μg/mL. In IAV infected A549 cell and mouse model, GLY reduced viral proteins, cytokines and chemokines expressions. GLY at 2 g/kg/d could improve mouse survival rate and elongate mouse average survival days. The mechanism involved that GLY components had decent binding affinity for phosphoinositide 3-kinase (PI3K), protein Kinase B (AKT), and glycogen synthase kinase 3 beta (GSK3β) and inhibit phosphitylation of proteins in PI3K-AKT signal pathway to protect IAV infected cells and mice. Xanthotoxol, esculetin, isorhoifolin and nobiletin were first discovered to be absorbed into plasma as anti-flu agents and their in vitro activities were confirmed in this research.

CONCLUSIONS

This study revealed that GLY could potentially inhibit influenza A virus replication and inflammation by suppressing the PI3K/AKT signaling pathway. Notably, 20 active compounds including xanthotoxol, esculetin, isorhoifolin, and nobiletin were identified as key contributors to GLY's activity. These findings underscore the multi-component, multi-target advantages of GLY, offering a promising strategy for combating influenza and its complications.