Fractionated ethanolic red ginger extract as antibacterial agent against Aggregatibacter actinomycetemcommitans and Porphyromonas gingivalis: In silico and in vitro studies

Background Periodontitis is a chronic inflammatory disease associated with oral microbiome dysbiosis, where Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis contribute through adhesion, biofilm formation, and tissue-destructive virulence factors. Although chlorhexidine is widely used as an adjunctive antimicrobial agent, its long-term use is limited by adverse effects, highlighting the need for safer natural alternatives. Red ginger ( Zingiber officinale var. rubrum) exhibits antibacterial potential; however, data on fractionated extracts and their interaction with specific virulence proteins remain limited. Objective To evaluate the antibacterial activity of fractionated ethanolic red ginger extract against A. actinomycetemcomitans and P. gingivalis using integrated in silico and in vitro approaches. Methods Twenty-two bioactive compounds identified from the fractionated extract were analyzed via molecular docking against cytolethal distending toxin (Cdt) of A. actinomycetemcomitans and fimbrial protein Mfa5 of P. gingivalis , with chlorhexidine as reference. In vitro assays determined minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), bacterial adherence, biofilm formation, and viability. Results Docking analysis showed that cyclooctacosane and gamma-sitosterol demonstrated binding affinities comparable to chlorhexidine toward both target proteins. The extract exhibited MIC/MBC values of 0.062/0.125 mg/mL for A. actinomycetemcomitans and 0.031/0.062 mg/mL for P. gingivalis . Significant reductions in bacterial adherence, biofilm formation, and viability were observed at concentrations of 0.031–0.125 mg/mL. Conclusion Fractionated ethanolic red ginger extract demonstrates promising antibacterial activity against key periodontal pathogens by targeting virulence mechanisms related to adhesion and biofilm formation, supporting its potential as a natural adjunct in periodontal therapy.