## 3 Results and Discussion  
Our initial efforts were to probe the effect of alteration and modification of the phenethylaniline moiety around a fixed quinazoline core. This was done by syntheses of 10 compounds and screening against _M. bovis_ BCG and Mtb strains (H37 Rv and N0145) to assess activity against mycobacterial cyt-_bd_ (Table 1). A representative compound from this set (7a) served as the foundation toward the design of a second set of 11 compounds that focused on modification of the quinazoline core and were subsequently screened for cyt-_bd_ activity (Table 2). \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Compound**} & \multirow{2}{*}{**Clog**\(p\)**} & \multirow{2}{*}{**Mol. Wt.**} & \multicolumn{2}{c}{**BCG**} & \multicolumn{2}{c}{**Replicating ATP IC\({}_{50}\) (uM)**} & \multirow{2}{*}{**N0145**} \\  & & & \multicolumn{2}{c}{**-Q203**} & & \multicolumn{2}{c}{**+Q203**} & \multicolumn{2}{c}{**-Q203**} & \multicolumn{2}{c}{**+Q203**} \\ \hline
**16a** & 5.19 & 351.3 & \(>\)25 & 13.1 \(\pm\) 0.651 & \(>\)25 & 28.8 \(\pm\) 5.054 & \(>\)25 & 7.1 \(\pm\) 0.207 \\
**17a** & 5.51 & 347.33 & \(>\)25 & 7.5 \(\pm\) 0.580 & \(>\)25 & 22.3 \(\pm\) 5.796 & \(>\)25 & 3.4 \(\pm\) 0.559 \\
**18a** & 5.41 & 363.33 & \(>\)25 & 26.9 \(\pm\) 1.231 & \(>\)25 & \(>\)25 & \(>\)25 & 17.1 \(\pm\) 0.220 \\
**19a** & 5.19 & 351.3 & \(>\)25 & 0.8 \(\pm\) 0.077 & \(>\)25 & 7.6 \(\pm\) 1.079 & \(>\)25 & 0.2 \(\pm\) 0.057 \\
**20a** & 5.76 & 367.75 & \(>\)25 & \(>\)25 & \(>\)25 & \(>\)25 & \(>\)25 & \(>\)25 \\
**21a** & 5.91 & 412.21 & \(>\)25 & 6.7 \(\pm\) 0.591 & \(>\)25 & 19.5 \(\pm\) 2.356 & \(>\)25 & 4.9 \(\pm\) 0.226 \\
**22a** & 5.95 & 401.31 & \(>\)25 & \(>\)25 & \(>\)25 & \(>\)25 & \(>\)25 & \(>\)25 \\
**23a** & 5.41 & 363.33 & \(>\)25 & \(>\)25 & \(>\)25 & \(>\)25 & \(>\)25 & \(>\)25 \\
**24a** & 5.51 & 347.33 & 12.2 \(\pm\) 0.737 & 3.1 \(\pm\) 0.369 & 7.5 \(\pm\) 1.025 & 11.7 \(\pm\) 1.252 & 8.2 \(\pm\) 0.654 & 2.9 \(\pm\) 0.140 \\
**25a** & 5.95 & 373.37 & 8.5 \(\pm\) 1.529 & 4.0 \(\pm\) 0.604 & 7.6 \(\pm\) 1.026 & 11.7 \(\pm\) 1.036 & 7.3 \(\pm\) 1.052 & 2.1 \(\pm\) 0.347 \\
**26a** & 5.69 & 365.32 & 27.6 \(\pm\) 9.513 & 6.5 \(\pm\) 0.751 & 23.6 \(\pm\) 7.807 & 16.9 \(\pm\) 3.822 & 32.7 \(\pm\) 2.700 & 4.6 \(\pm\) 0.219 \\
**2** & 6.69 & 381.36 & \(>\)25 & 0.7 \(\pm\) 0.103 & \(>\)25 & 6.3 \(\pm\) 0.349 & \(>\)25 & 0.3 \(\pm\) 0.049 \\
**BDQ** & 7.25 & 555.52 & 0.17 \(\pm\) 0.019 & 0.11 \(\pm\) 0.026 & 0.06 \(\pm\) 0.019 & 0.04 \(\pm\) 0.024 & 0.05 \(\pm\) 0.003 & 0.03 \(\pm\) 0.001 \\
**Aurachin D** & 6.79 & 363.55 & \(>\)25 & 2.9 \(\pm\) 0.317 & 5.5 \(\pm\) 1.107 & 7.3 \(\pm\) 1.973 & \(>\)25 & 1.5 \(\pm\) 0.065 \\ \hline \hline \end{tabular} IC\({}_{50}\) values were determined by ATP depletion in the presence and absence of Q203 (see Section 2.2 for details). IC\({}_{50}\) values were determined using GraphPad Prism 9. The values given in the table represent the average and standard deviation, which were calculated from the IC\({}_{50}\) values of replicates from two experimental repeats. cLogP was calculated by Perkin Elmer ChemDraw Professional 16.0. Bedaquiline (BDQ), ND-11992 (**2**) and aurachin D were used as positive control compounds.  
\end{table} 
Table 1: In vitro activity of phenethyl-quinazolin-4-yl-amines **(3, 6a–15a)** and control compounds bedaquiline (BDQ), ND-11992 (**2**), and aurachin D against three mycobacterial strains (_M. bovis_ BCG, _M. tuberculosis_ H37 Rv, and _M. tuberculosis_ N0145). \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Compound**} & \multirow{2}{*}{**Clog**\(p\)**} & \multirow{2}{*}{**Mol. Wt.