Tetrandrine Derivatives as Promising Antibacterial Agents

This work reports on the antibacterial activity of twotetrandrinederivatives, with acridine (MAcT) and anthracene (MAnT) units, against Gram-positive and Gram-negative bacteriaof clinical importance by the broth microdilution method as well astheir antioxidant activity against ABTS(& BULL;+) and DPPH & BULL;+ radicals. Unlike natural tetrandrine, its derivativesinhibited bacterial growth, showing selectivity against Staphylococcus aureus with notable activity of MAnT (MIC = 0.035 & mu;g/mL); this compound also has goodactivity against the ABTS(& BULL;+) radical (IC50 = 4.59 & mu;g/mL). Cell membrane integrity studies and reactiveoxygen species (ROS) detection by fluorescent stains helped to understandpossible mechanisms related to antibacterial activity, while electrophoreticmobility assays showed that the derivatives can bind to bacterialDNA plasmid. The results indicate that MAnT can inducea general state of oxidative stress in S. aureus and Escherichia coli, while MAcT induces an oxidative response in S. aureus. Complementary electrochemical studies were included.

Automated summary

This study reports on the antibacterial and antioxidant activities of two tetrandrine derivatives against clinically important bacteria. The derivatives showed selective activity against Staphylococcus aureus and exhibited good antioxidant activity against ABTS(·+) radical. The mechanisms involved in antibacterial activity were investigated through studies on cell membrane integrity, reactive oxygen species, and binding to bacterial DNA plasmid.