Analysis of Inhibitory Mechanism of Reyanning Mixture Combined with Linezolid Against MRSA and Its Biofilm Based on Metabonomics / 中国实验方剂学杂志

Objective:To investigate the inhibitory effects and mechanism of Reyanning mixture （RYN） combined with linezolid （LNZ） against methicillin-resistant <italic>Staphylococcus aureus</italic> （MRSA） and its biofilm. Method:The minimum inhibitory concentrations （MICs） of RYN and LNZ against MRSA were determined by microdilution assay. The microplate method was used to detect the changes in viable count before and after MRSA administration at four time points （0， 6， 12， 24 h） in the process of biofilm growth. The morphological changes of MRSA after 24 h were observed by scanning electron microscope. Metabonomic technique was applied to analyze the changes in terminal metabolites of endogenous small molecules from MRSA treated by the two drugs at four time points. Result:The MICs of RYN and LNZ were 1/2 of the stock solution concentration and 4 mg·L^-1， respectively. The inhibitory effect of LNZ （2 mg·L^-1） against viable bacteria at 0 h was better than that of 1/16 RYN. At 6， 12， 24 h， 1/16 RYN was superior to LNZ in inhibiting MRSA. The inhibitory effects of RYN combined with LNZ were better than those of RYN or LNZ alone at the four time points. RYN combined with LNZ caused more severe damages to the morphological structure of MRSA biofilm at 24 h than RYN or LNZ alone. Cyclic adenosine monophosphate （cAMP）， adenosine diphosphate （ADP）-<italic>D</italic>-ribose and 2-methylbutanoyl-coenzyme A （2M-CoA）， as the metabolites related to biofilm formation， were immune to LNZ， but 2M-CoA and ADP-<italic>D</italic>-ribose were influenced by RYN at 12 h and 24 h. The combined use of RYN and LNZ interfered with the three metabolites at 24 h. <italic>L</italic>-tryptophan， phenylpyruvic acid， cytidine and sebacic acid were the pharmacometabolic markers of LNZ， and the related biological pathways were phenylalanine， tyrosine and tryptophan biosynthesis and phenylalanine metabolism. Four metabolites such as<italic> L</italic>-histidine， uric acid， and <italic>L</italic>-lysine were the pharmacometabolic markers of RYN， with phenylalanine metabolism and aminoacyl-transfer ribonucleic acid （tRNA） biosynthesis confirmed as the related biological pathways. Nine metabolites such as <italic>L</italic>-tryptophan，<italic> L</italic>-lysine， and sphingosine-1-phosphate were responsible for the efficacy of RYN combined with LNZ. The related biological pathways involved aminoacyl-tRNA biosynthesis， phenylalanine， tyrosine and tryptophan biosynthesis， novobiocin biosynthesis， and tyrosine metabolism. Conclusion:RYN combined with LNZ better exerts the inhibitory effects against MRSA at each time point of its biofilm formation， which is attributed to cAMP metabolism. The synergistic effect resulted from aminoacyl-tRNA biosynthesis and phenylalanine， tyrosine and tryptophan biosynthesis. RYN combined with LNZ can serve as a potentially effective solution to MRSA infection.