Dissertation > Excellent graduate degree dissertation topics show

Study on Inhibitory Effects of Flavones on N-Nitrosodiethylamine Formation in Vitro

Author: JiangHuiPing
Tutor: ZhengQunXiong
School: Zhejiang Technology and Business University
Course: Of Food Science
Keywords: Flavonoids N-nitrosamines Effect Quercetin Product
CLC: R285
Type: Master's thesis
Year: 2009
Downloads: 146
Quote: 0
Read: Download Dissertation

Abstract

NO ₂ ^{- are possible under acidic conditions in vitro and in vivo with the amine nitrosation reaction generated a strong carcinogenic N-nitrosamines, and induce mechanism cancerous. Therefore, how to clear NO ₂ ^{- or inhibit the formation of N-nitrosamines, thereby reducing the tumor incidence rate has become the field of food safety research, one of the hot spots. Flavonoids as a natural plant secondary metabolites widely distributed in plants, due to its anti-oxidation, anti-tumor, anti-aging and other physical activity, has been developed into a variety of health food. With the deepening of the flavonoids active research, the discovery the flavonoids also has clear NO ₂ ^{- , the efficacy of inhibition of N-nitrosamines generated, research in this area still remains levels of flavonoids crude extract, such as bamboo leaves flavonoids, licorice flavonoids, buckwheat flavonoids. Inhibition of flavonoid monomer N-nitroso diethylamine (N-nitrosodiethylamine, NDEA) synthesis depth exploration for the effective use of flavonoids as exogenous N-nitrosamines synthesis inhibitor laid foundation. The study includes: 1. Establish NO ₂ ^{- and NDEA measurement method. To table no epigallocatechin gallate gallate (EGCE) as a reference, select quercetin, luteolin, chrysin three different structure of monomeric flavonoids study investigated flavonoid structure, the concentration of the antioxidant capacity NDEA generate a relationship between the amount. Select catechol, resorcinol, hydroquinone, pyrogallol object, the effects of the location and the number of phenolic hydroxyl groups of NDEA generated. 3 under the conditions of simulated gastric juice (pH 3.0, 37 ° C), the analysis of flavonoids in representative material quercetin resulting product after NDEA generated. Preparative HPLC (PRE-HPLC) separation and purification of the product; using UV-visible spectrophotometer (UV / VIS), high performance liquid - mass spectrometry (HPLC-MS/MS) and NMR ( 1 ^{H-NMR ) identification of the structure of the product; using a mixture of ^{1 H-NMR characteristics map speculate product content relationship, the use of reversed-phase high performance liquid chromatography - diode array detector (RP-HPLC-DAD) to verify the estimation result. On this basis, the crude extracts of three species of chrysanthemum rice, ginkgo biloba, wormwood yellow remuneration study investigated NO ₂ ^{- clearance rate and The inhibition rate NDEA generated with the crude extract concentration, reaction time, pH, temperature changes. The results are as follows: quercetin, luteolin, chrysin The clear of NO ₂ ^{- ability clearance increase with flavonoid concentration increase, the size of as follows: quercetin gt; Osmanthus grass prime gt; chrysin. The three flavonoids generation of carcinogens NDEA has a double impact - play a catalytic role in low concentrations, high concentrations disincentive. Proportional to the clearance rate and inhibition rate and the antioxidant capacity of flavonoids. Speculate that the effect of the dual role of the flavonoids by comparing the impact generated by the different phenolic hydroxyl structure of phenols to NDEA and flavonoid molar concentration and its phenolic hydroxyl position: the phenolic hydroxyl group on each ring of the flavonoid activity difference between the larger, B ring highest activity of the phenolic hydroxyl group, C ring followed by a phenolic hydroxyl group, ring A phenolic hydroxyl-reactive weakest. Yellow remuneration concentration reaches a certain amount, NO ₂ ^{- completely yellow emoluments on the B-ring the ortho phenolic hydroxyl reaction generated stable o-quinone-type product, which inhibit NDEA generated; flavonoid concentration is too low, the the ortho phenolic hydroxyl group on the flavonoid B ring insufficient and the NO _{2 ^{- complete reaction, the excess NO ₂ ^{- Further reaction with the meta-position on the phenolic hydroxyl groups in the A ring, resulting in a stronger nitrosation reagent thereby promote NDEA generated. In addition, the flavonoids structure related to the strength of the effect of the phenolic hydroxyl number of how many and flavonoids, quercetin, luteolin, the chrysin three hydroxyl number of turn reduce strength in turn weaken its role in the same concentration, the exact role The mechanism has yet to be studied further. 2 derived through analysis: under the conditions of simulated gastric fluid, quercetin inhibit NDEA generated process is oxidized into the compound C ₁ [2 - (3,4-dihy drxybenzoyl) -2,4 flavonoids crude extracts of chrysanthemum rice, ginkgo biloba, wormwood findings of two bold flavonoid content (Ju meters: 7.17 mg / mL, and wormwood: 5.20 mg / mL) with a clear NO ₂ ^{- , inhibit NDEA generate the ability, the clearance rate and inhibition rate and reaction time, flavonoid consumption into a positive, and pH negative correlation. In addition, too low or too high a temperature is not conducive to flavonoids inhibit the generation of NDEA. Ginkgo crude extracts containing free phenolic hydroxyl group of flavonoids content is too low (0.85mg/mL) of three flavonoid crude extract in its NO ₂ ^{- worst clearance rate, and has always been to promote the generation of NDEA. Conclusion: The results show that, when the molar concentration of flavonoids in acidic conditions, reaches a certain amount, flavonoids have the nitrite oxidation reduction reaction competitively inhibits amines with NO ₂ ^{- binding and thus the ability to produce carcinogenic N-nitrosamine formation, inhibition effect of flavonoid antioxidant capacity and concentration was positively correlated; When flavonoid concentration is too low, its N-nitrosamines generation has a role in promoting. This dual role of the flavonoids may be related to the position and free phenolic hydroxyl groups in the flavonoid concentration and its structure, the detailed mechanism remains to be further studied. By analyzing quercetin NDEA generated after the product was drawn, flavonoids inhibit N-nitrosamine formation in the process itself is nitrous oxide to generate the corresponding oxidized product.}}}}}}}}}}}}}}}

Study on Inhibitory Effects of Flavones on N-Nitrosodiethylamine Formation in Vitro

Abstract

Related Dissertations