Evaluation of the antimicrobial and anti-biofilm effects of St. John’s wort oil (Hypericum perforatum) extract on common pathogens of periodontitis

Abstract

Abstract Introduction: Antibiotics are commonly used to treat periodontitis cases. The many side effects of synthetic drugs and the spread of drug resistance have led to the desire for antimicrobial substances of natural origin such as plants. In this study, we investigated the antibacterial and anti-biofilm effect of St John's wort oil extract on common pathogens that cause periodontitis. Materials and Methods: In this research work, which is a laboratory study, the oil extract of St John's wort produced by Keroya company was prepared and purchased. Disc diffusion, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) methods were used to determine antimicrobial effects. To determine the anti-biofilm effects, the amount of bacterial biofilm formation was determined by the microtiter plate method, and then the anti-biofilm effects were determined by determining the minimum biofilm inhibitor concentration (MBIC). The results were reported as descriptive indices. The Shapiro-Wilk test was used to check the normality of the units. To compare MIC and MBC between control and intervention groups, non-parametric Mann-Whitney test was used, and non-parametric Kruskal-Wallis test was used to compare the groups simultaneously. Also, non-parametric Kruskal-Wallis test was used to compare the non-growth halo diameter and biofilm formation and MBIC between groups. SPSS version 25 software was used for data analysis. A probability value of less than 0.05 was considered as a significant level. Results: Examining the antimicrobial effect of pure extract, 50% extract and antibiotic disks showed that pure extract and 50% extract both had antimicrobial effects. In comparing the effect of St John's wort oil extract between the study group and the control group (which only used antibiotics), our results showed that there is no significant difference between the groups and this extract is effective. MIC, MBC, and MBIC values were respectively reported 64, 256, and 512 μg/mL for Staphylococcus aureus; 128, 256 and 512 μg/mL for Streptococcus mutans; 256, 512 and 256 μg/mL for Escherichia coli; 32, 128 and 512 µg/mL for Enterococcus faecalis and 64, 128 and 256 µg/mL for Porphyromonas gingivalis. Conclusions: According to our results, this substance has anti-bacterial properties against common bacteria in periodontitis, which can prevent the growth of bacteria, prevent the formation of biofilm, and cause bacterial removal. The largest diameter of the non-growth halo observed around Escherichia coli. Also, the strongest inhibitory effect on bacterial growth and bactericidal effect was achieved in Enterococcus faecalis.