Study On Aβ And Bioactive Compounds From Natural Products By Capillary Electrophoresis

Alzheimer’s disease(AD), a neurodegenerative disease, has been seriously affecting human’s congnitive ability and quality of life. So far, it is widely believed that AD may be caused by the deposition of β-amyloid(Aβ). Therefore, Aβ can be considered as a potential drug target for the treatment and pathogenesis of AD. Among the drug therapy, metallothionein(MT), a small molecular weight and high metal content protein, can regulate the metal ion level and change the pathological process of Aβ in the human body. Also of note is that active ingredients of natural products can play an important role in the treatment of AD. It is reported that coffeequinic acid in purple potato can improve the learning and spatial cognitive ability indicating a potential drug for the treatment of AD. Therefore, it is necessary to deeply study the active ingredients in purple potato.Analysis of pesticide residues is an important part of the quality control in the planting process of purple potato. Triazine herbicide is a kind of widely used pesticide in the field. Long-term exposure to the pesticide can increase risk of dementia and other diseases. It has great significance to develop novel techniques for the fast detection of pesticides.Capillary electrophoresis(CE) is one of the most powerful tools to analysis complex sample matrix, possessing the advantages of high efficiency, fast, low sample consumption and so on. CE is used as the major technique in this paper. The interaction between biomolecules was studied by CE. To overcome the shortcoming of low sensitivity of CE, Qu ECh ERS(Quick, Easy, Cheap, Effective, Rugged and Safe) was adopted for sample preparation and purification to increase the signal-to-noise ratio. Dextran@Fe3O4 magnetic nanoparticles were used for selective enrichment of sample to improve the sensitivity. The paper focus on the followings:1. The interaction between Aβ1-16 and MT was investigated by frontal analysis / capillary electrophoresis. The separation was performed within an uncoated fused silica capillary with detection wavelength at 192 nm. The optimal conditions were implemented: 60 mmol/L borax buffer at p H 8.48, injection time of 18 s under the pressure of 50 mbar and separation voltage of 12 k V. 0.1% DMSO was added as electroosmosis marker. The Klotz equation was used to calculate the binding parameters. The number of binding sites is 0.5. The binding constant is 8.9×103 M-1.2. Dextran@Fe3O4 magnetic nanoparticles were prepared by one-step synthesis and used to selectively extract the active ingredients of purple potato. The resultant extracts were analyzed by capillary zone electrophoresis. The electrophoresis was performed within an uncoated fused silica capillary. The separation conditions were carefully considered: The running buffer was 17.5 mmol/L borate buffer containing 20% methanol(V/V) at p H = 9.3, detection wavelength at 192 nm, separation voltage 18 k V with positive polarity and injection time 15 s. The extract factors such as the dosage of the nanoparticles, adsorption time, the eluant, and elution time were optimized. Under the optimal conditions, at least six active ingredients of purple potato were selectively discovered.3. A rapid and highly efficient method was developed to determine triazine herbicides in purple potato combined with Qu ECh ERS and micellar electrokinetic capillary chromatography(MEKC). In the process of Qu ECh ERS, acetonitrile was used as extraction agent, and primary secondary amine(PSA) and graphitized carbon black(GCB) were used as sample purification adsorbent. The optimum separation conditions are running buffer 30 mmol/L Tris-HCl-40 mmol/L SDS-10% methanol(V/V) at p H 7.77, separation voltage of 15 k V, injection time of 7s and DMSO as the electroosmosis marker. The detection limits of three model herbicides, metribuzin, hexazinoe and cyanazine are 60, 60 and 20 ng/m L, respectively. The addition standard recovery was between 82.2% and 110.0%.