Virtual Screening for Molecular Targets of Emodin Against Red Complex Pathogens

Objective: Periodontitis is a chronic inflammatory disease affecting teeth' supporting tissues. It is caused by specific bacterial species, including Porphyromonas gingivalis (Pg), Tannerella forsythia (Tf), and Treponema denticola, known as the "red complex" group. These bacteria manipulate the immune response and promote tissue destruction, making them key players in periodontal pathogenesis. The present study aims to identify the potential molecular targets of Emodin against the red complex pathogens. Method: The interaction between the phytocompound Emodin and red complex pathogens was identified using the STITCH tool. The proteins identified were then classified into functional categories using the VICMPred. The virulent proteins identified were then subjected to Bepired prediction, which provided information about the epitopes in the virulent proteins. Finally, the subcellular location of the proteins was demonstrated with the pSORTb tool. Results: Carbamoyl-phosphate synthase is a large subunit identified as a virulence protein in Pg and Tf. DNA topoisomerase IV subunit A was found to be the common virulence protein for Pg and Td. The DNA gyrase subunit A and ATPase/histidine kinase/DNA gyrase B/HSP90 domain-containing protein were found to be identified in Td and Tf. It was the only protein predicted to be in the cytoplasmic membrane, while others were found in the cytoplasm. The four virulent proteins targeted by Emodin were found to harbor multiple epitopes. Conclusion: Emodin was found to interact with all three pathogens of the red complex group. However, further experimental validation is warranted to prove the antimicrobial effect of Emodin against periodontal pathogens.