Nicotinamide could reduce growth and cariogenic virulence of <i>Streptococcus mutans</i>

Abstract

Dental caries is among the most prevalent chronic oral infectious diseases. <i>Streptococcus mutans</i>, a major cariogenic bacterial species, possesses several cariogenicity-associated characteristics, including exopolysaccharides (EPS) synthesis, biofilm formation, acidogenicity, and aciduricity. Nicotinamide (NAM), a form of vitamin B3, is a non-toxic, orally available, and inexpensive compound. The present study investigated the inhibitory effects of NAM on the cariogenic virulence factors of <i>S. mutans in vitro</i> and <i>in vivo</i>. NAM inhibited the growth of <i>S. mutans</i> UA159 and the clinical isolates. In addition, there was a decrease in the acid production and acid tolerance ability, as well as biofilm formation and EPS production of <i>S. mutans</i> after NAM treatment. Global gene expression profiling showed that 128 and 58 genes were significantly downregulated and upregulated, respectively, in NAM-treated <i>S. mutans</i> strains. The differentially expressed genes were mainly associated with carbohydrate transport and metabolism, glycolysis, acid tolerance. Moreover, in a rat caries model, NAM significantly reduced the incidence and severity of smooth and sulcal-surface caries <i>in vivo</i>. NAM exhibited good antimicrobial properties against <i>S. mutans</i>, indicating its potential value for antibiofilm and anti-caries applications.