Chemical composition, antibacterial properties, and mechanism of Smilax china L. polyphenols

This work aimed at investigating the chemical composition, antibacterial properties, and effect mechanism of Smilax china L. polyphenols (SCLP). SCLP was extracted and purified, and then, its eighteen polyphenolic compounds were identified by LC-MS/MS analysis. SCLP exhibited antibacterial activity against five bacteria (Salmonella typhimurium, Listeria monocytogenes, Staphylococcus aureus, Bacillus subtilis, and Escherichia coli) with minimum inhibitory concentration in a range of 195.31 to 781.25 mu g/mL. Escherichia coli and Staphylococcus aureus showed a higher sensitivity to SCLP. Notably, when combined with antibiotics, the SCLP-thiamphenicol and SCLP-gatifloxacin combinations showed additional properties against Escherichia coli and Staphylococcus aureus, while SCLP-streptomycin and SCLP-penicillin combinations exhibited dramatically synergistic effects. In addition, the changes in permeability and integrity of the cell membrane and cell wall were observed by measuring UV absorption, extracellular AKP concentration, FTIR spectroscopy, and scanning electron microscopy. It is speculated that the mechanism of action of SCLP on bacteria may be described as destruction of bacterial cell wall and cell membrane. In conclusion, SCLP was a potential natural antimicrobial substance with strong antimicrobial activity, which may reduce the use of antibiotics or combat drug-resistant bacteria through synergistic combination with antibiotics.