Influenza viruses cause respiratory diseases in humans and animals with high morbidity and mortality rates. Conventional anti-influenza drugs are reported to exert side effects and newly emerging viral strains tend to develop resistance to these commonly used agents. Fritillaria thunbergii (FT) is traditionally used as an expectorant for controlling airway inflammatory disorders. Here, we evaluated the therapeutic effects of FT extracts against influenza virus type A (H1N1) infection in vitro, in ovo, and in vivo. In the post-treatment assay, FT extracts showed high CC50 (7,500 µg/ml), indicating low toxicity, and exerted moderate antiviral effects compared to oseltamivir (SI 50.6 vs. 222) in vitro. Antiviral activity tests in ovo revealed strong inhibitory effects of both FT extract and oseltamivir against H1N1 replication in embryonated eggs. Notably, at a treatment concentration of 150 mg/kg, only half the group administered oseltamivir survived whereas the FT group showed 100% survival, clearly demonstrating the low toxicity of FT extracts. Consistent with these findings, FT-administered mice showed a higher survival rate with lower body weight reduction relative to the oseltamivir group upon treatment 24 h after viral infection. Our collective results suggest that FT extracts exert antiviral effects against influenza H1N1 virus without inducing toxicity in vitro, in ovo or in vivo, thereby supporting the potential utility of FT extract as a novel candidate therapeutic drug or supplement against influenza.

中文翻译：

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贝母提取物在体外、卵内和体内对人类流感病毒 H1N1 (PR8) 的抗病毒活性。

流感病毒在人类和动物中引起具有高发病率和死亡率的呼吸道疾病。据报道，传统的抗流感药物会产生副作用，而新出现的病毒株往往会对这些常用药物产生耐药性。贝母(FT) 传统上用作控制气道炎症的祛痰药。在这里，我们评估了 FT 提取物在体外、卵内对甲型流感病毒 (H1N1) 感染的治疗效果, 和体内。在处理后测定中，FT 提取物显示出高 CC50 (7,500 µg/ml)，表明毒性低，并且与奥司他韦（SI 50.6 对 222）相比具有适度的抗病毒作用。卵内抗病毒活性测试显示 FT 提取物和奥司他韦对含胚卵中 H1N1 病毒复制具有强烈的抑制作用。值得注意的是，在 150 mg/kg 的治疗浓度下，接受奥司他韦治疗的组中只有一半存活下来，而 FT 组的存活率为 100%，这清楚地证明了 FT 提取物的低毒性。与这些发现一致，在病毒感染后 24 小时治疗时，与奥司他韦组相比，FT 给药的小鼠显示出更高的存活率和更低的体重减轻。在卵内或体内，从而支持 FT 提取物作为新型候选治疗药物或抗流感补充剂的潜在用途。