Antibacterial constituents of Fructus Chebulae Immaturus and their mechanisms of action

Background To extract, purify, and identify the effective constituents of aqueous extract of Fructus Chebulae Immaturus , and analyze the bactericidal effects of total tannins. Methods Preparative thin layer chromatography and semi-preparative high performance liquid chromatography were used to isolate and purify the total tannin fraction. 1 H- and 13 C- NMR spectroscopy were used to elucidate compound structures. The antibacterial activities of total tannins and ethyl gallate on Klebsiella pneumoniae (KP) and Staphylococcus aureus (SA) were determined through minimum inhibitory concentration and minimum bactericidal concentration assays. Their antibacterial mechanisms of action were explored by transmission electron microscopy and scanning electron microscopy. Results Five compounds were isolated: ellagic acid, ethyl gallate, arjugenin, β-sitosterol, and tri-n-butyl chebulate. Tri-n-butyl chebulate is a newly-reported compound. Total tannins and ethyl gallate both had favorable bactericidal effects against KP and SA. Conclusion In vivo and in vitro pharmacodynamic experiment demonstrated that the effective components of Fructus Chebulae Immaturus possessed significant antibacterial effects, and were nontoxic and safe. Trial registration No results of a health care intervention on human participants