METHODS: In this study, Pichia pastoris was used for the expression of recombinant TC-1. The microbroth dilution method was used to determine the minimum inhibitory concentration [MIC] and minimum bacterial concentration [MBC]. It tested against four main oral pathogens; Streptococcus mutans, Streptococcus salivarius, Streptococcus oralis, and Enterococcus faecalis. Moreover, the cytotoxicity analysis was done on gingival fibroblast cells by the MTT method. The data were analyzed using a two-way analysis of variance [ANOVA] and Tukey\'s HSD tests.
RESULTS: The most bactericidal effect of TC-1 was against S. salivarius, the highest bacteriostatic effect was against S. salivarius, and S. oralis had the lowest MIC value of 1.512 μg/ml. The Thrombocidin-1 peptide showed lower antibacterial properties against E. faecalis compared with CHX, unlike the stronger antimicrobial effect on examined streptococci. According to cytotoxicity examination, no concentration of TC-1 presented over 50% growth inhibition [IC50] of the fibroblasts cells.
CONCLUSIONS: Based on antimicrobial tests and cytotoxicity results, the Thrombocidin-1 peptide may be useful as a safe antibacterial agent against some oral pathogens in dental materials.