ABSTRACT
In the present investigation we report the antibacterial activity of halistanol sulfate A isolated from the sponge Petromica ciocalyptoides, as well as of rodriguesines A and B isolated from the ascidian Didemnum sp., against the caries etiologic agent Streptococcus mutans. The transcription levels of S. mutans virulence genes gtfB, gtfC and gbpB, as well as of housekeeping genes groEL and 16S, were evaluated by sqRT-PCR analysis of S. mutans planktonic cells. There were no alterations in the expression levels of groEL and 16S after antimicrobial treatment with halistanol sulfate A and with rodriguesines A and B, but the expression of the genes gtfB, gtfC and gbpB was down-regulated. Halistanol sulfate A displayed the most potent antimicrobial effect against S. mutans, with inhibition of biofilm formation and reduction of biofilm-associated gene expression in planktonic cells. Halistanol sulfate A also inhibited the initial oral bacteria colonizers, such as Streptococcus sanguinis, but at much higher concentrations. The results obtained indicate that halistanol sulfate A may be considered a potential scaffold for drug development in Streptococcus mutans antibiofilm therapy, the main etiologic agent of human dental caries. .
ABSTRACT
This study aimed to develop a low cost in vitro viable microbiological model to produce biofilms to be used in dental researches. Single and multi-species biofilms of S. mutans, S. sobrinus, S. mitis, S. salivarius, S. cricetus and S. sanguinis were grown on bovine enamel slabs during 10 days, in a sterile brain-heart infusion broth, containing 5% sucrose and incubated at 37ºC in an atmosphere of 10% CO2. The slabs were transferred to a fresh medium at every 6, 12 or 24 hours. After the experimental period, enamel volume percent mineral was determined by cross-sectional microhardness. Caries-like lesions were found in all bacterial groups when compared with the control group. No statistical significant differences were found between S. mutans and S. sobrinus with respect of their cariogenicity or among the periods of medium change. However, it was found a statistical significant difference among the cariogenicity of S. salivarius and S. sanguinis (ANOVA followed by Tukey test). This model has successfully developed caries-like lesion on enamel and the medium can be changed at every 24 hours utilizing either S. mutans or S. sobrinus.