We aimed to evaluate the antimicrobial effect of the Nelumbo nucifera leaf extract. There have been no studies related to dental caries inducing bacteria up to now.This study reviewed the inhibitory effect of glucose transferase (GTase) activation and acid production to confirm the anticariogenic activity of Nelumbo nucifera leaf extract.This study used 100 g Nelumbo nucifera leaves cultivated in Yeongcheon-si, Gyeongbuk, after adding 70% methanol tenfold. The leaves were then concentrated (Gotary vacuum evaporator; N-Nseries, EYELA Co., Japan) and were placed under an aspirator (A-3S, EYELA Co., Japan) and a freeze dryer (Ilshin Lab Co., Korea). The anticariogenic effect of Nelumbo nucifera leaves extract was investigated using the growth inhibitory effect, as well as GTase activation.Among the nine kinds of oral-disease-causing bacteria, the Nelumbo nucifera leaf extract most effectively inhibited the growth of Streptococcus anginosus (S. anginosus), but it was difficult to inhibit the growth of Streptococcus oralis (S. oralis). For the anticariogenic effect of Nelumbo nucifera leaf extract, GTase activation was inhibited by at least 50% in all the nine types of bacteria, including Streptococcus mutans (S. mutans). It was shown that Nelumbo nucifera leaf extract had the strongest GTase activation inhibitory effect (85%) in S. anginosus. In addition, Nelumbo nucifera leaf extract showed an acid production inhibitory effect in the nine types of strains by maintaining almost pH 6.2 even after being cultured for 24 hours in the Nelumbo-nucifera-leaf-extract-added culture, while the control culture without Nelumbo nucifera leaf extract showed only about pH 5.0 after 4 hours.In conclusion, Nelumbo nucifera leaf extract showed the strongest GTase activation inhibitory effect in S. anginosus. Based on this, it was confirmed that Nelumbo nucifera leaf extract showed anticariogenic activity against oral cavity disease microorganisms.
