In Vitro and In Silico Evaluation of Melissa officinalis Terpenoids as Potential Antibacterial Agents Against Dental Caries Associated Bacteria

Background and Objective: The growing prevalence of antibiotic-resistant oral pathogens has increased interest in medicinal plants as alternative sources of antimicrobial agents. Melissa officinalis L. (lemon balm) is rich in bioactive phytochemicals, particularly terpenoids, known for their antimicrobial potential. This study aimed to evaluate the antibacterial activity of M. officinalis extracts and isolated terpenoids against dental plaque–associated bacteria and to investigate their inhibitory mechanisms against penicillin-binding protein (PBP) and β-lactamase using in vitro and in silico approaches. Methods: This study conducted during a period ۲۰ June to ۱st. Novmber ۲۰۲۵. at the Laboratories of Harem Private Hospital, Sulaimanya City, Iraq.  M. officinalis extracts and terpenoids were tested against Streptococcus viridans, Porphyromonas gingivalis, Prevotella intermedia, and Aggregatibacter actinomycetemcomitans. Antibacterial efficacy was assessed using inhibition zone assays, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC), with amoxicillin as a reference drug. Molecular docking was conducted to analyze the binding interactions of ursolic acid and amoxicillin with consensus-modeled PBP and β-lactamase proteins. Results: Both crude extracts and terpenoids exhibited strong antibacterial activity, producing large inhibition zones and low MIC and MBC values compared with amoxicillin. S. viridans displayed greater resistance, with MIC and MBC values approximately twice those of other bacteria. Docking analysis demonstrated that terpenoids had stronger binding affinities and higher specificity toward β-lactamase and PBP, forming stable protein–ligand complexes. Conclusion: Melissa officinalis terpenoids represent promising natural inhibitors of PBP and β-lactamase and may serve as alternative antimicrobial agents for controlling dental plaque–associated infections.

کلیدواژه ها:

Melissa officinalis ، terpenoids ، PBP ، β-lactamase ، Dental caries ، Antibacteria