RESUMO
Circadian rhythm is involved in the development and diseases of many tissues. However, as an essential environmental regulating factor, its effect on amelogenesis has not been fully elucidated. The present study aims to investigate the correlation between circadian rhythm and ameloblast differentiation and to explore the mechanism by which circadian genes regulate ameloblast differentiation. Circadian disruption models were constructed in mice for in vivo experiments. An ameloblast-lineage cell (ALC) line was used for in vitro studies. As essential molecules of the circadian system, Bmal1 and Per2 exhibited circadian expression in ALCs. Circadian disruption mice showed reduced amelogenin (AMELX) expression and enamel matrix secretion and downregulated expression of BMAL1, PER2, PPARγ, phosphorylated AKT1 and β-catenin, cytokeratin-14 and F-actin in ameloblasts. According to previous findings and our study, BMAL1 positively regulated PER2. Therefore, the present study focused on PER2-mediated ameloblast differentiation and enamel formation. Per2 knockdown decreased the expression of AMELX, PPARγ, phosphorylated AKT1 and β-catenin, promoted nuclear β-catenin accumulation, inhibited mineralization and altered the subcellular localization of E-cadherin in ALCs. Overexpression of PPARγ partially reversed the above results in Per2-knockdown ALCs. Furthermore, in in vivo experiments, the length of incisor eruption was significantly decreased in the circadian disturbance group compared to that in the control group, which was rescued by using a PPARγ agonist in circadian disturbance mice. In conclusion, through regulation of the PPARγ/AKT1/β-catenin signalling axis, PER2 played roles in amelogenin expression, cell junctions and arrangement, enamel matrix secretion and mineralization during ameloblast differentiation, which exert effects on enamel formation.
RESUMO
Box-Behnken design-response surface methodology was used to optimize the transformation from chlorogenic acid to neochlorogenic acid.Based on single factor experiments,the experiment design were developed by box-benhnhen central composite design with causal factors of the reaction temperature,time and PH to neochlorogenic acid.The optimum transformation conditions were as follow:reaction temperature at 107℃,reaction time of 60 min,the PH of 4.72.Under the optimum extraction technology conditions,the productivity of neochlorogenic acid was 64.20％.Neochlorogenic acid was isolated and purified.The determination and characterization of neochlorogenic acid was detected by HPLC,1H-NMR,13C-NMR and ESI-MS.The results showed that the content of neochlorogenic acid reached to 98.78％ and the yield of 87.37％.
RESUMO
This study was aimed to establish a separation method for neochlorogenic acid reference substances from Lonicera japonica. Refined neochlorogenic acid inL. japonica water extract was separated and concentrated by HPD200A macroporous resin, which was isolated and purified by medium-low-pressure preparative chromatography and determined by HPLC. The structure was identified by various spectroscopic data including ESI-MS,1H-NMR and13C-NMR. The results showed that the optimal purification technology conditions were as follows: washed with 5BV of water, collected elution, concentration, drying; neochlorogenic acid crude products were eluted with acetonitrile-0.5% formic acid solution (10:90) with the flow rate of 20 mL·min-1; and the detection wavelength was 326 nm. The contents of the prepared neochlorogenic acid reached to 98.86% and the yield was 89.1%. It was concluded that the method was effective for the preparation of neochlorogenic acid with high purity. It can be used to prepare the reference substances for quantitative analysis and content determination of Chinese materia medica.