Screening Of Inhibitor To Advanced Glycation End Products In Banana Flowers And Investigation Of The Inhibition Mechanism

Advanced glycation end products(AGEs) is the stability products from non-enzymatic glycosylation reaction between carbonyl (from reducing sugar) and amino (from proteins, lipids, nucleic acids), including etc. To clarify the inhibitor for AGEs in banana flowers, the active components from the ethanol extraction of banana flowers was screened using bovine serum albumin-fructose model, and then gain the monomeric compound through separating, purifying and characterizing. The activity and inhibition kinetics was evaluated using a-glucosidase and a-amylase model. The inhibition mechanism of the extraction from different glycosylation reaction stage for AGEs was studied. The protein molecular in bovine serum albumin-fructose model was characterized using SDS-PAGE. The steam explosion method for SDF was established and the biological activity of SDF was evaluated. The main content is as follows:1. The extraction, purification, characterization and activity determination of ethanol extraction of banana flowers. This study used modern chromatography with petroleum ether, ethyl acetate, n-butanol to extract the ethanol extraction of banana flowers. Various components were screened using the BSA-fructose non-enzymatic glycosylation model and the results showed that the components from petroleum ether and ethyl acetate had better activity, the inhibition rate to AGEs are7.26%and8.93%. Three compounds was separated by petroleum ether and ethyl acetate phase, according to the physical and chemical properties and spectral data were identified as:Cyclomusalenone(1),(24R)-4a,14a,24-trimethyl-5a-cholesta-8,25(27)-dien-3?-ol (2),?-sitosterin (3), the components of (1) and (2) were separated firstly form banana flowers.2. The activity and inhibition kinetics of AGEs inhibitor in key enzyme system. The a-glucosidase and a-amylase are the key factor of the absorption of glucose in digestive tract, so inhibit the activity of two enzymes can prevent the body's absorption of glucose and then reduce the production of AGEs. The activity of three compounds extracted of banana flower was determined using the a-glucosidase and a-amylase and then the inhibition types of a-glucosidase and a-amylase were determined. With acarbose as the positive control, inhibition rate of the banana flowers extraction to a-glucosidase and a-amylase activity was determine, the results show that under the same concentration, banana flower extractions exhibit different inhibition effect to a-glucosidase and a-amylase. The Cyclomusalenone (1),(24R)-4a,14a,24-trimethyl-5a-cholesta-8,25(27)-dien-3?-ol (2), ?-sitosterin (3) achieved better inhibition effect to a-glucosidase, the IC50of them were11.33?g/mL,43.0?g/mL and283.67?g/mL, and then the inhibition types were reversible inhibition, mixed inhibition and competitive inhibition; to ?-amylase, the IC50of them were52.55?g/mL,43.0?g/mL and532.02?g/mL, and then inhibition types were noncompetitive inhibition, irreversible inhibition and competitive inhibition.3. The inhibition effect of the extraction of banana flowers to AGEs by different non-enzymatic glycosylation reaction model system.The inhibitors of AGEs were added to determine the inhibition rate from different non-enzymatic glycosylation reaction model system. BSA-fructose model was suitable for evaluation of all of non-enzymatic glycosylation reaction, BSA-acetone aldehyde model can be used for the evaluation of middle stage of non-enzymatic glycosylation reaction, arginine-acetone aldehyde model was used for evaluation of main types, the methylglyoxal model was used for evaluation of the activity of AGEs to restrain removal of carbonyl. In the BSA-fructose model, the inhibition rate of ?-sitosterol and cyclomusalenone on AGEs were61.37%and51.75%, respectively; the positive control of AG was63.96%. In BSA-acetone aldehyde model, arginine-acetone aldehyde model, methylglyoxal model, the inhibition rate of sitosterol and cyclomusalenone were60.25%,60.25%;67.17%,46.42%;32.57%and31.45%, respectively.4. SDS-PAGE of protein in BSA-fructose model.The molecular weight of proteins from the24h reaction between the extraction of banana flowers and BSA-fructose system was investigated by SDS-PAGE. The result showed protein molecular weight bands decreases with the increase of sitosterol and cyclomusalenone concentration, but it is still higher than that of BSA blank control, proving the sitosterol and cyclomusalenone may have the effect that prevent protein crosslinking, thus inhibiting the formation of AGEs.5. The physicochemical properties of the soluble dietary fiber from banana flower.There is a large amount of soluble dietary fiber in banana flowers, so steam blasting technology was used to improve the SDF yield and biological activity. The results showed that the steam explosion treatment of banana flower SDF can not only increase yield, adsorption of glucose and oil, the ability to remove DPPH free radicals and enhance the capacity of the reduction of Fe3+, it also has the inhibition of AGEs and ?-glycosidic activity. The SDF structure was characterized using infrared spectroscopy, scanning electron microscopy (sem) and thermogravimetric technology. The structure of SDF has changed during the release of high temperature and high pressure steam explosion, the honeycomb pore structure appeared and SDF thermal stability was increased.