Antibacterial Activity of Fruiting Body Extracts from Culinary-Medicinal Winter Mushroom, Flammulina velutipes (Agaricomycetes) against Oral Pathogen Streptococcus mutans

The edible medicinal mushroom Flammulina velutipes (enokitake) has many applications as food and medicine, but its application in dentistry is unknown. This study aims to investigate the inhibitory effect of fruiting body extracts from F velutipes on the growth and adhesion of Streptococcus mutans, the main cause of human caries, in vitro. Of the four extracts (named TGO1 from water, TGO2 from 95% ethanol, TGO3 from 50% ethanol, and TGO4 from ethyl acetate), TGO3 had significant antibacterial activity (MIC = 10 mg/mL; MBC = 20 mg/mL). Planktonic growth and biofilm formation in S. mutans was repressed by TGO3 at 5 mg/mL and above. Meanwhile, cytotoxicity analysis showed that TGO3 was not toxic to human oral keratinocyte cells. IEPLC-QQQ-MS analysis showed that the TGO3 extract contained a large amount of arabitol, a sucrose substitute that reduces the development of caries. Thus, E velutipes extracts can effectively inhibit the growth of the oral pathogen S. mutans without cytotoxicity against human oral keratinocytes. Therefore, F velutipes is a good candidate for the development of oral hygiene agents to control dental caries.