| Dental caries is fundamentally a microbial disease, which involves the hard tissue of tooth. The prevention of dental caries have been extensively studied worldwide, however none of the existed preventive ways of dental caries is exclusive. There are many theories and prescribes in ancient Chinese natural medicine dealing with dental caries, which facilitate the study of preventing dental caries by herbal medicine. In our previous study, we find out the water extract of Galla Chinesis has significant anticaries effects in vitro and in biofilm model. But what is the effective anticaries component of Galla Chinesis and how they affect the metabolism and growth of cariogenic bacteria and oral biofilm remains obscure till now. The purples of this study is to investigate the chemical components of Galla Chinesis and their anticaries effect, to trace out and identify the most effective component and to evaluate the anticaries efficacy of the active component in biofilm model.Methods: Based on our previous study, the polyphenol components of Galla Chinesis (GCE) was extracted. Then the GCE was further fractioned using a Sephadex LH-20 column for GCE-A, GCE-B, GCE-C and GCE-D. A series of in vitro anticarious experiments, the inhibition of growth, acid production,glucan generation and initial adherence, have been carried out using the Galla Chinesis extracts. According to the results of these experiments the effective components of Galla Chinesis were found out and their chemical structures are identified using !H-NMR and 13C-NMR. A four-organism bacterial consortium was grown in a biofilm model on hydroxyapatite (HA) discs and bovine enamel blocks in a continuous culture system and exposed to repeated solution pulsing respectively. The negative control group was pulsed with 25mmol/l sucrose solution; positive control group was pulsed with sucrose solution plus 228ppm NaF. While 4.0 mg/ml GCE and 4.0 mg/ml GCE-B solution together with 25mmol/l sucrose was pulsed in the experiment group. During the experiment, the pH responses against the pulses are recorded. After 10 pulses, the biofilm surface structure was observed with the Fluorescence Microscope and the population of the biofilm was enumerated. And the change of enamel structure was also checked under a polarized microscope.Results: GCE and GCE-A, GCE-B, GCE-C and GCE-D were extracted from Galla Chinensis. GCE and GCE-B are proved has the highest anticaries efficacy. Two different compounds are further extracted from GCE-B and they are identified as Gallic Acid and Methyl Gallate. GCE and GCE-B are proved to be effective in vitro anticaries experiments. In the biofilm model, both of GCE and GCE-B can significantly inhibit the adherence of cariogenic bacteria to HA discs compared with the control group of 25 mM sucrose pulsed in, and can facilitate the remove of acid products. They are also found to reduce the extra-cellular polysaccharide production of biofilm. The enamel lesion of GCE pulsed group is also shallower than the negative control.Conclusion: GCE and GCE-B are successfully extracted from Galla Chinensis and two chemical compounds fractioned from GCE-B are identified in the present study. GCE and GCE-B are proved to havesignificant anticaries effect in vitro and in biofilm model, they appear to be a promising source of new agents that may prevent dental caries. The identification of the two compounds from GCE-B will give us some light on the discovery of newly designed anticaries drugs. |
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