Background: Streptococcus mutans are involved in caries by forming biofilm polysaccharides through their glucosyltransferase enzymes. Natural plant extracts can inhibit glucosyltransferase production and bacterial activity. Endophytic fungi inside plant tissues can produce bioactive compounds similar to those produced by their host plants.
Aim:Compare the inhibitory effect of rosemary endophytic fungal extract on S.mutans glucosyltransferase to rosemary and chlorhexidine and their effect on enamel microhardness.
Methods: Glucosyltransferase was purified from S.mutans. The ability of the total metabolites and endophytic fungi extracted from rosemary to inhibit the purified glucosyltransferase compared to chlorhexidine and artificial saliva.13crowns of human molars were subdivided into 4 equal parts giving 4groups for microhardness and biofilm evaluation. The microhardness was evaluated at baseline and after treating the four subgroups using the rosemary extract, chlorhexidine, artificial saliva and endophytic fungal extract for 24and72h.The biofilm inhibition was tested using SEM after 24and72h.
Results:Nine endophytic fungal strains were recovered from rosemary. Chaetomium globosum, Alternaria alternata and Aspergillus niger extracts showed positive inhibitory effect on glucosyltransferase 96.25%, 90.9%and81.74% respectively. While, those of rosemary extract, chlorhexidine and artificial saliva were 36.19%, 86.38%and0.27%. Chaetomium globosum extract showed the highest inhibitory effect on biofilm formation in comparison to chlorhexidine and rosemary extract after 24and72h.The highest microhardness value for all groups was at baseline then microhardness decreased after24 and72h except for Chaetomium globosum and rosemary extract where microhardness increased after72h to be higher than that after24h.
Conclusion:Endophytic fungal extract of rosemary can inhibit S.mutans glucosyltransferase and its biofilm formation where it can remineralize initial carious lesions.