Antimicrobial activity and mechanism of Magnolia officinalis root extract against methicillin-resistant Staphylococcus aureus based on mannose transporter

Magnolia officinalis root extract was obtained by high-pressure-assisted extraction, and the yield of honokiol (HNK) was 86.97 ± 1.05 mg/g dry power. The purified extracts and HNK inhibited the growth of methicillin-resistant Staphylococcus aureus (MRSA). Assays for alkaline phosphatases , proteins, nucleic acids leakage, and electrical conductivity, along with scanning and transmission electron microscopy measurements, confirmed the damaging effects of HNK on the cell wall and membrane of MRSA. Intake of sugar, protein production, molecular docking , and dynamic simulations revealed that HNK interfered with the transport of mannose-based carbohydrates by binding to VAL196, ILE291, ALA293, PRO294, and MET214 on the mannose transporter (ManP) in the phosphotransferase system, and thereby inhibited the carbohydrate metabolism of MRSA. These results indicated that HNK prevented MRSA from using carbohydrates by cutting off its nutritional process, and ultimately caused bacterial rupture and lysis. Therefore, ManP may be a potential target for HNK to combat MRSA infections.