Investigating the Antibacterial Activity of Biphenylthiazoles against Methicillin- and Vancomycin-Resistant Staphylococcus aureus (MRSA and VRSA).

Phenylthiazoles were reported previously as a new scaffold with antibacterial activity against an array of multidrug-resistant staphylococci. However, their promising antibacterial activity was hampered in large part by their short half-life due to excessive hepatic clearance. Close inspection of the structure-activity-relationships (SARs) of the phenylthiazoles revealed two important structural features necessary for antibacterial activity (a nitrogenous and a lipophilic component). Incorporating the nitrogenous part within a pyrimidine ring resulted in analogues with a prolonged half-life, while the biphenyl moiety revealed the most potent analogue 1b. In this study, advantageous moieties have been combined to generate a new hybrid scaffold of 5-pyrimidinylbiphenylthiazole with the objective of enhancing both anti-MRSA activity and drug-like properties. Among the 37 tested biphenylthiazoles, piperazinyl-containing derivatives 10, 30, and 36 were the most potent analogues with MIC values as low as 0.39 μg/mL. Additionally, 36 exhibited significant improvement in stability to hepatic metabolism.