Pharmacological Evaluation of Bakuchiol From <i>Psoralea corylifolia</i> L. as Potent Antimicrobial Agent Against <i>Staphylococcus aureus</i>

The surge in multidrug resistance in Staphylococcus aureus is the pressing need to identify novel alternatives to combat antimicrobial resistance effectively. Bakuchiol is a bioactive prenylated phenolic meroterpene largely abundant in the seeds of Psoralea corylifolia. In this study, we present the biological assessment of bakuchiol derived from P. corylifolia as an antimicrobial agent. S. aureus, a significant opportunistic pathogen, attracts global concern for its biofilm formation and resilience against numerous antibiotics, escaping antibiotic pressure. The primary screening of bakuchiol as an antimicrobial agent against S. aureus delineated its potential as a strong bactericidal agent with a minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of 2 and 8 µg/mL, respectively. Importantly, bakuchiol also exhibited low toxicity against HepG2 cells, showing a favorable selectivity index (SI) of 14.4. Furthermore, bakuchiol demonstrated comparable activity (MIC = 2 µg/mL) against a laboratory-generated ciprofloxacin-resistant mutant of S. aureus. Bakuchiol could significantly inhibit the biofilm formation of S. aureus in a dose-dependent manner with minimum biofilm inhibitory concentration (MBIC)₅₀ of 0.956 µg/mL. Bakuchiol effectively inhibited DNA gyrase supercoiling activity at a concentration eight times the MIC, establishing DNA gyrase inhibition as the mechanism of action for bakuchiol. Our findings suggest bakuchiol as a potential therapeutic agent for S. aureus-mediated nosocomial infections.