Anti-bacterial and anti-biofilm activities of hopea ferrea stembark extract against cariogenic bacterium

Dental caries, caused by enamel-adherent cariogenic bacteria breaking down sugars into acid, gradually demineralizes tooth structure. Cariogenic biofilms contribute significantly to antibiotic resistance, treatment failure, increased morbidity, and rising healthcare costs. Hence, research is exploring strategies to interrupt biofilm formation and bacterial communication, aiming to modify the microbial pathogenic cycle. This interest is supported by studies on Hopea ferrea's therapeutic potential due to its secondary compounds like flavonoids, phenols, and tannins. The main objective of the present study is to determine the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and anti-biofilm activity of H. ferrea extract against cariogenic bacteria namely Streptococcus mutans. This study used a Brain Heart Infusion (BHI) medium for growing bacterium S. mutans. Antimicrobial activity was tested by growing bacteria on agar plates and in broth cultures. Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) were determined following standard procedures. Biofilms were grown in 24-well plates, and their biomass was assessed using a crystal violet stain. Finally, data was analyzed using GraphPad Prism. The results showed that the MIC and MBC results of the H. ferrea extract against S. mutans were at of 2.5 mg/mL. Anti-biofilm activity of the extract using crystal violet assay showed significant reduction of the biomass at 2.5 and 1.25 mg/mL (p<0.01). However, biofilm reduction on the biomass was not significant on formed biofilm.