Charushin and coworkers have synthesized a series of fifteen pyrimidine derivatives and evaluated their antituberculosis activity against a clinical isolated MDR-TB strain resistant to RMP and INH. Compound (9) (Figure 3) has shown the most promising activity with MIC90 of 0.7 μM. Mice acute toxicity revealed a median lethal dose (LD50) of 315 mg/kg for this molecule . Additional studies performed by this same research group have described other pyrimidine derivatives with similar antituberculosis activity. The most promising compound (10) (Figure 3) exhibited an MIC90 value of 1.95 μM against a clinically isolated MDR-TB strain and LD50 of 600 mg/kg in acute toxicity using mice . Quinolizidine-related compounds have also been reported with antituberculosis activity in a study involving fifteen derivatives. The series was evaluated against several MDR-TB strains. Compound (11) (Figure 3) was the most active in the series with MIC90 of 0.86 μM. In addition, this compound exhibited low cytotoxicity against VERO cells with IC50 of 68 μM. .