Synthetic cajaninstilbene acid derivatives eradicate methicillin-resistant Staphylococcus aureus persisters and biofilms.

ABSTRACT

The Staphylococcus aureus can switch to a transient genotype-invariant dormancy, known as a persister, to survive treatment with high doses of antibiotics. This transient persister is an important reason underlying its resistance. There is an urgent need to find new antibacterial agents capable of eradicating methicillin-resistant S. aureus (MRSA) persisters. In this study, 37 new derivatives of cajaninstilbene acid (CSA) were designed and synthesized, and their biological activity against MRSA persisters was evaluated. Most of the newly synthesized derivatives exhibit more potent antimicrobial properties against S. aureus and MRSA than CSA itself, and 23 of the 37 derivatives show a tendency to eradicate MRSA persisters. A representative compound (A6) was demonstrated to target bacterial cell membranes. It eradicated the adherent biofilm of MRSA in a concentration dependent manner, and showed a synergistic antibacterial effect with piperacilin. In a model mouse abscess caused by MRSA persisters, A6 effectively reduced the bacterial load in vivo. These results indicate that A6 is a potential candidate for treatment of MRSA persister infections.