Development of new and effective anti-influenza drugs is critical for the treatment of influenza virus infection. The polymerase basic 2 (PB2) subunit as a core subunit of influenza A virus RNA polymerase complex is considered to be an attractive drug target for anti-influenza drug discovery. Dihydromyricetin, as a natural flavonoid, has a wide range of biological activities, but its anti-influenza A virus activity is ambiguous. Here, we found dihydromyricetin could inhibit the replication of a variety of influenza A virus strains. Mechanism studies demonstrated that dihydromyricetin reduced viral polymerase activity via selective inhibition of viral PB2 subunit, and decreased relative amounts of viral mRNA and genomic RNA during influenza A virus infection. The binding affinity and molecular docking analyses revealed that dihydromyricetin interacted with the PB2 cap-binding pocket, functioned as a cap-binding competitor. Interestingly, dihydromyricetin also reduced cellular immune injury by inhibiting TLR3 signaling pathway. Additionally, combination treatment of dihydromyricetin with zanamivir exerted a synergistic anti-influenza effect. Altogether, our experiments reveal the antiviral and anti-inflammatory activities of dihydromyricetin in vitro against influenza virus infection, which provides a new insight into the development of novel anti-influenza drugs.

开发新型有效的抗流感药物对于治疗流感病毒感染至关重要。作为甲型流感病毒RNA聚合酶复合物的核心亚基的聚合酶碱性2（PB2）亚基被认为是抗流感药物发现的有吸引力的药物靶标。二氢杨梅素作为一种天然的类黄酮，具有广泛的生物学活性，但其抗甲型流感病毒的活性却模棱两可。在这里，我们发现二氢杨梅素可以抑制多种甲型流感病毒株的复制。机制研究表明，二氢杨梅素通过选择性抑制病毒PB2亚基降低了病毒聚合酶的活性，并降低了甲型流感病毒感染期间病毒mRNA和基因组RNA的相对量。结合亲和力和分子对接分析表明，二氢杨梅素与PB2帽结合口袋相互作用，起着帽结合竞争者的作用。有趣的是，二氢杨梅素还通过抑制TLR3信号通路减少了细胞免疫损伤。另外，二氢杨梅素与扎那米韦的联合治疗发挥了协同抗流感作用。总之，我们的实验揭示了二氢杨梅素的抗病毒和抗炎活性体外抗流感病毒感染，这为新型抗流感药物的开发提供了新见识。