Antibacterial and anti-adherent effect of Mimosa tenuiflora and Myrciaria cauliflora on dental biofilm bacteria

The use of plants in the prevention and treatment of oral infectious and as an antibiofilm agent continues to be valued in many parts of the world. The aim of study is to evaluate in vitro antimicrobial action of the plant extracts of barks Mimosa tenuiflora (Willd.), Poir. (jurema preta) and leaf and stem of Myrciaria cauliflora Berg. (jabuticabeira) against dental biofilm bactéria. The oral bacteria were used to determine the minimum inhibitory concentration (MIC) and minimum inhibitory concentration of adherence (MICA): Streptococcus mitis, Streptococcus mutans, Streptococcus sanguinis, Streptococcus oralis, Streptococcus salivarius and Lactobacillus casei. Each assay was carried out in duplicate and the positive control (0.12% chlorhexidine digluconate) was subjected to the same procedure. Results were analyzed by Student t test or Mann-Whitney test, with the level of significance set at 5%. The extract of M. tenuiflora showed inhibition halos ranging from 10 to 25 mm in diameter, presenting an average performance superior to chlorhexidine digluconate, being statistically significant only at the concentration of 1:128 (3.9 mg/mL). The leaf and stem extracts of M. cauliflora were found to have inhibition halos varying from 10 to 18 mm in diameter and presented a significantly lower average performance in relation to chlorhexidine digluconate in crude extract (500 mg/mL) concentration; 1:2 (250 mg/mL) and 1:4 (125 mg/mL) and crude extract (500 mg/mL), 1:2 (250 mg/mL), 1:4 (125 mg/mL) and 1:8 (62 mg/mL), respectively. All extracts studied were effective in the inhibition of adherence, especially the stem extract of M. cauliflora (1:64/ 7.81 mg/mL). Conclusively, the extracts of M. tenuiflora and M. cauliflora produced a significant bactericidal activity and in vitro anti-adherent effect on the bacteria forming the dental biofilm, which suggests the use of these substances as an alternative and economically viable means for the control of infections in dentistry.