Anti-MRSA activities of cycloberberine derivatives with a novel chemical scaffold

Using CBBR as the parent core constructed in our lab, we designed and synthesized 15 novel compounds with diverse structures for evaluation of anti-bacterial activities. Structure activity relationship studies revealed that ① ring C was essential for the activity; ② 7,8-or 8,13-disubstituted CBBR derivatives showed ideal activities, weaker or similar to those corresponding to 7-, 8-, or 13-monosubstituted CBBR derivatives. Among those, compound 9a showed the most potential activity against MRSA/VISA isolates with MIC values of 1-2 μg·mL^-1, much better than Lev. 9a also displayed higher stability in the plasma and liver microsomes. Molecular docking indicated that 9a might target bacterial DNA Topo IV ParE subunit, indicating a mode of action distinct from current antibacterial drugs on market. The results provided key scientific evidence for developing such compounds into a new family of anti-MRSA drugs.