Table 1: Chemical structures of compounds 5–14 and their inhibitory activities against sialidase of three different strains of influenza A virus (A/PR/8/34 virus [H1N1], A/Memphis/1/71 virus [H3N2], and A/Duck/313/78 virus [H5N3]).

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Viral sialidase inhibition (IC50, μM)aHuman sialidase inhibition (IC50, μM)a
RH1N1H3N2H5N3NEU1NEU2NEU3NEU4

2DANA1911143436174
5Methyl22349758>1000>1000580
6Phenyl>1000>1000>1000
7Cyclopentyl850>1000>1000
8Cyclopropyl91698680>1000>1000825
9Propyl97559>1000
102-Methylpropyl59>1000>1000
11Isopropyl54680>1000
12n-Butyl34159>1000
13tert-Butyl78770>1000
142-Ethylpropyl698>1000>1000

aIC50 values of human sialidases are citied from [39].