Effect of Terminalia chebula Retz. extraction with water on Staphylococcus epidermidis activity and its biofilm formation

Background: Based on modern pharmacological studies, Terminalia chebula Retz. exhibits antimicrobial activity against a variety of bacteria. Previously, we found Terminalia chebula Retz. exhibited excellent antibacterial activity against Malassezia restricta. Methods: We determined the minimal inhibitory concentration (MIC) and minimum bactericidal concentration of Terminalia chebula Retz. extraction with water (TRW) against Staphylococcus epidermidis (including Staphylococcus epidermidis 1-15) using the microdilution method. Staphylococcus epidermidis 1 (SE11), which was the most sensitive to TRW, was selected as the test bacterium for subsequent experiments. The time-kill curve of TRW on SE11 was generated using the viable count method. Further, an in vitro biofilm model of SE11 was constructed using the 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-((phenylamino)carbonyl)-2H-tetrazolium hydroxide test, semi-quantitative crystal violet experiment, and scanning electron microscopy. The effects of TRW on the total amount of biofilm formation, the number of viable biofilm bacteria, and biofilm microstructure of SE11 were also determined using a semi-quantitative crystal violet experiment, viable count method, and scanning electron microscopy. Finally, the electrical conductivity and soluble protein content of the SE11 suspensions were determined. Results: The average MIC of TRW against SE11 was 0.75 +/- 1.09 mg/mL. TRW (1/2MIC and 2MIC) and zinc pyrithione (1/2MIC and 2MIC) had no significant effect on total biofilm inhibition in the adhesion stage (P > 0.05) and the aggregation stage (P > 0.05). Further, TRW (1/2MIC and MIC) and zinc pyrithione (1/2MIC and MIC) had no significant effect on viable biofilm bacteria in the adhesion stage (P > 0.05) and aggregation stage (P > 0.05). TRW destroyed the integrity of the SE11 cell membrane, resulting in leakage of intracellular substances. Conclusion: TRW inhibits SE11 biofilm formation and is similar to zinc pyrithione in the adhesion and aggregation stages, which provides a theoretical basis for its application in the field of antimicrobial additives.