Isofloridoside: A Novel Inhibitor of Streptococcus mutans Biofilm Formation and Glucosyltransferase Activity

Isofloridoside, a galactose-containing heteroside derived from marine red algae, has potential applications as a sweetener because it can activate the sweet taste receptor taste 1 receptor members 2 and 3. This study investigated the effects of isofloridoside on the growth and sucrose-dependent biofilm formation of the cariogenic bacterium Streptococcus mutans. The results showed that S. mutans did not grow when isofloridoside was used as the sole carbon source. Isofloridoside inhibited sucrose-dependent biofilm formation by S. mutans in a concentration-dependent manner, similar to galactose and glucose, but unlike melibiose, galactose-containing disaccharides. Biofilm inhibition induced by isofloridoside was associated with the inhibition of glucosyltransferase activity. Isofloridoside exhibited biofilm inhibition comparable to that of xylitol, an alternative sugar known to inhibit biofilm formation. The differential effects of isofloridoside and melibiose on biofilm formation may be due to structural differences that affect their interactions with S. mutans enzymes. These findings highlight the potential of galactose and its polysaccharides as regulators of S. mutans biofilm formation and suggest that isofloridoside is a promising alternative sweetener for caries prevention. Further research is required to elucidate the detailed mechanism of action, potential for resistance acquisition, taste, safety, and economic feasibility of isofloridoside as a caries-preventive agent.