Aurintricarboxylic Acid Is a Potent Inhibitor of Influenza A and B Virus Neuraminidases

Hashem, Anwar M.; Flaman, Anathea S.; Farnsworth, Aaron; Brown, Earl G.; Van Domselaar, Gary; He, Runtao; Li, Xuguang

The NA-StarH Influenza Neuraminidase Inhibitor Resistance Detection Kit (Applied Biosystems, Foster City, CA, USA) was used to measure the inhibition of NA activity as described previously [27, 28] . Briefly, serial dilutions of ATA, AH and NAA ranging from 2000 mg/ml to 0.002 mg/ml were prepared in NA-Star assay buffer, i.e. 26 Ten ml of NA-Star substrate diluted in assay buffer to a final concentration of 10 mM was added to each mixture in an opaque, solid-white 96-well plate. The reactions were incubated at 37uC for 30 min with gentle agitation, then 60 ml of NA-Star accelerator was added to each well and a chemiluminescent signal was measured at a rate of 1 sec/well in a Synergy TM 2 Multi-Mode Microplate Reader. Curves were constructed by plotting the percentage of NA activity (chemiluminescent signal) in the presence of inhibitors relative to the activity of controls (NA without inhibitors) against the concentration of inhibitors and used to determine the drug concentration required to reduce NA activity to 50% of control NA activity (IC 50 ).