The synthesis and antibacterial activity of totarol derivatives. part 3: modification of ring-B Original Research Article

Ring-B derivatization of totarol (1) afforded the series of compounds 2–22 which were screened in vitro against: β-lactamase-positive and high level gentamycin-resistant Enterococcus faecalis, penicillin-resistant Streptococcus pneumoniae, methicillin-resistant Staphylococcus aureus (MRSA), and multiresistant Klebsiella pneumoniae. Several of the derivatives retained much of the antibacterial activity of totatol against the first three of these organisms (all Gram-positive), but none was more active. The Gram-negative Klebsiella was resistant to all compounds examined. Totarol (1) was shown to uncouple oxidative phosphorylation in isolated mitochondria at 50 μM.