关键词: 毛秔子梢, 化学成分, 神经氨酸酶抑制剂, 流感病毒

Influenza is and remains a disease to reckon with. Seasonal epidemics around the world kill several hundred thousand people every year. Development of effective drugs for the treatment or prevention of epidemic and pandemic influenza is important in order to reduce its impact. Neuraminidase inhibitors is a class of anti-influenza drugs available for influenza therapy currently. However, emergence of resistance to these drugs has been detected, which raises concerns regarding their widespread use. Therefore, the search for low toxic natural neuraminidase inhibitor is one of the route for finding new anti-influenza virus drugs. In current study, the classical MUNANA-based NA activity assay was established to assess the neuraminidase inhibitory activities of compounds isolated from Campylotropis hirtella. The bioassay guided separation of 95% ethanol extract of the dried root of C. hirtella has led to the isolation of ten compounds, and their structures were elucidated on the basis of spectroscopic methods, with special emphasis on 1D and 2D NMR techniques. Compounds 1～4 are new compounds and these are two chromones, an isoflavone and a glycosides. Compounds 5～10 were isolated from C. hirtella for the first time. All compounds were assesses for their inhibitory activities against influenza A1(H1N1) virus NA. Compounds 1, 2, 3, 5 showed good and dose dependent inhibitory effects against NA enzyme. Among them, compound 1 had the best NA inhibitory activity with the IC₅₀ at 16.76 μmol/L. Although, compound 1 is less active than Tamiflu, however, the results from the study demonstrated that isoflavone and chromone could be potent neuraminidase inhibitor. Since the structure of compound 1 is very similar to Hirtellanine B, an isoflavonoid isolated from the same herb with potent antiproliferative effects in cancer cells, the biosynthetic pathway of both compound 1 and Hirtellanine B were proposed.

Key words: Radix Campylotropis hirtella, chemical constituent, NA inhibitors, influenza virus