Electron Microscopic Investigation Of Morphologic Effect Of Chelerythrine On Streptococcus Mutans

ObjectiveCaries is the most commom oral disease among hunman beings, and streptococcus mutans (S. mutans)is one of the principal etiological agent of dental caries.Natural products have been the focus of much recent research as potential agents in the prevention of dental caries. Chelerythrine (CHE) is a major extract that comes from a Chinese traditional medicine Chelidonium majus L, which have inhibitory effect on S.mutans. However, the morphology effect mechanism of CHE on S. mutans remains to be elucidated. The purpose of this study was to investigate the effect of CHE on morphology of S.mutans, and to further evaluate its potential antibacterial mechanism.MethodsS. mutans ATCC25175 has been chosen as the experimental bacteria.1.The scanning electron microscopic study was divided into three groups:Chelerythrine solution treatment group (experimental group), blank control group and basic control group. S. mutans was cultured at 37℃in anaerobic environment (80%N2,20%CO2) for 24 hours, biofilms of S. mutans were formed on 1.0cm x 1.0cm x0.02cm standard glass microscope slides in 15ml tubes, and slides were observed by scanning electron microscope (SEM).2. The transmission electron microscopic study was divided into two groups:Chelerythrine solution treatment group and control group. The bacteria were cultured at 37℃in anaerobic environment (80%N2,20%CO2) for 24 hours, and the bacteria structure changes were observed by using transmission electron microscope (TEM).ResultsChelerythrine at the concentration of 1.56mg/ml has significant inhibitory effect on the adherence of S. mutans. The SEM study indicated that there were fewer cells in chains, fewer cell layers in the experimental group than those in the control group. The cells in cleavage formed into irregular morphous, most bacteria appeared as capsule-shaped cells. No clear cross wall of daughter cells was found after division, and typical long bacteria chains were lost. It was revealed by TEM study that Chelerythrine could inhibit the growth of S. mutans by preventing cell division and causing the defective structure of the capsule, cell wall and cell membrane.ConlusionsThe results suggest that Chelerythrine is able to change the super-microscopic structure of S. mutans, and may inhibit the adhesion and growth of S. mutans partly by this mechanism.