In vitro Investigation of Hydro-alcoholic Extract of Helichrysum leucocephalum on the Inhibition of Streptococcus Mutans Growth

Statement of Problem: Indiscriminate use of antibacterial agents increases the antibiotic resistance, which consequently necessitates seeking alternatives such as herbal remedies. Objectives: The aim of this study was to evaluate the antimicrobial effect of hydroalcoholic extract of Helichrysum leucocephalum (H.leucocephalum) on Streptococcus mutans (S. mutans) growth as a major cause of dental caries. Materials and Methods: In this study, hydroalcoholic extract of H. leucocephalum was prepared. The antibacterial effects, minimal inhibitory concentration (MIC), and minimal bactericidal concentration (MBC) of hydroalcoholic extract of H. leucocephalum and penicillin were assessed. Agar well diffusion method and micro broth dilution assay were used on bacterial suspension adjusted to a 0.5 McFarland standard (equivalent to 1.5×108 CFU/mL).Each test was repeated four times to minimize lab errors. Results: In this study, the inhibitory zone of hydroalcoholic extract of H.leucocephalum in concentration of 100 mg/mL was 34±0.1 mm and for penicillin was 10 mm. The MIC and MBC of H.leucocephalum hydroalcoholic extract were 5.6±6.25, 21.6±6.25 mg/mL, respectively. Conclusions: Hydroalcoholic extract of H. leucocephalum have antibacterial effect on S.mutans at a concentration of 12.5mg/mL, indicating possible application of this extract in prevention of dental caries; however, future researches are necessary.