The inhibitory activity of compound 1 and its analogues.^a

aThe NAT activity was measured by the NAT-inhibition assay using 150 µM HLZ and 120 µM Ac-CoA as substrates. The level of enzyme inhibition was measured in the presence of 50 µM inhibitor and compared to the un-inhibited control. The antimycobacterial activity against M. bovis BCG and M. tuberculosis were determined. Inhibition curves were obtained by non-linear fitting of the % inhibition and the inhibitor concentration (µM) using the Log(inhibitor) vs. response module of GraphPad Prism 5.0. The time-dependent assay kobs values were obtained from the slope of the semilogarithmic plots of the residual activity vs incubation time at 11.9 µM, except for 3 (5.9 µM). The results are presented as the mean ± S.D. of triplicate measurements at 24°C. t1/2 is the apparent inactivation half-life calculated from kobs (t1/2 = 0.693/kobs). ND is not determined. bSee Methods for further experimental details.