Antimicrobial activity of ginsenoside Rh2 against Enterococcus faecalis and its biofilm

Enterococcus faecalis (E. faecalis) is frequently associated with persistent root canal infections and treatment failure, and effective strategies for its elimination remain limited. Plant-derived compounds may provide alternative antimicrobial strategies for endodontic treatment.

In the present study, we evaluated the antimicrobial activity of 20(S)-ginsenoside Rh2 (Rh2), a bioactive compound derived from ginseng, against planktonic and biofilm forms of E. faecalis. The effects of Rh2 on extracellular polysaccharide (EPS)-associated carbohydrate content and biofilm metabolic activity were evaluated using the phenol-sulfuric acid and MTT assays, respectively. Biofilm structural alterations were examined by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). The cytotoxicity of Rh2 toward L929 cells was assessed using an MTT assay, with sodium hypochlorite (NaClO) serving as the reference antimicrobial agent.

Rh2 exhibited antibacterial activity against planktonic E. faecalis, with a minimum inhibitory concentration (MIC) of 3.125 μg/mL and a minimum bactericidal concentration (MBC) of 6.250 μg/mL. Rh2 inhibited biofilm formation and reduced the biomass of established biofilms at 2 × MIC and 4 × MIC. Rh2 also markedly reduced EPS-associated carbohydrate content, altered biofilm architecture, and decreased the metabolic activity of biofilm-associated bacteria. Under the tested conditions, Rh2 exhibited favorable cellular compatibility at concentrations with antibacterial activity against E. faecalis.

These findings demonstrate the in vitro antibacterial and antibiofilm activities of Rh2 against E. faecalis and support further investigation of its potential as an intracanal antimicrobial agent.