Effects Of Nitrate And Flavonoids From Fruits And Vegetables On Vascular Endothelial Function

With the interpretation of the relationship between vascular health and fruit and vegetable intake and the vascular biology study of NO2-/NO3-and flavonoids, the relevance of vascular endothelial function homeostasis to the intake of nitrate rich in vegetables and flavonoids rich in fruits has been highlighted as a key scientific problem to be solved. This study adopted the endothelial function evaluation system, designed and prepared some new animal experimental preparation of nitrate-rich spinach and flavonoid-rich apple. The regulative effect of nitrate-and flavonoid-rich diet in the vascular endothelial function of experimental animal was studied, and the indirect intervention effect of flavonoids in NO3-metabolism in vivo was also investigated. The following contents were investigated in this study:(1) Building a catalytic derivatization method with pentafluorobenzyl (PFB-Br) to simultaneously measure NO3-and NO2-by HPLC-UV. The method is applied to measure the content of NO3-in fresh spinach leaves. The results showed that the spinach leaf is riched in NO3-, almost does not contain NO2-.(2) The composition and content of flavonoid compounds in apple peel and flesh were analyzed by HPLC-UV. Apple peel contains more varieties and higher contents of flavonoid compounds than apple flesh. The content of flavonoids in apple peel is mainly including quercetin-3-O-galactoside、quercetin-3-rhamnoside、rutin and chorogenic acid, while the content of flavonoids in apple pulp is mainly containing chorogenic acid、 quercetin-3-O-galactoside and quercetin-3-rhamnoside.(3) The classical theory holds that the body NO can only be synthesized by endogenous L-Arg (L-arginine) and NOS (nitric oxide synthase). This study demonstrated that the dietary NO3-was another important source of NO synthesis in vivo. The dietary NO3-was reduced to NO2-, which entered into the body fluids and was further restored to NO.(4) Mice were intervened with high fat and high fructose diet to establish cardiovascular endothelial dysfunction model. The protective effect of nitrate and flavonoid from fruits and vegetables in the animal with cardiovascular endothelial dysfunction was researched by the intake of nitrate-rich and flavonoid-rich diet. The TC, TG, HDL-C, LDL-C, GLU, INS, F2t isoprostanes, NO and ET-1level in serum and liver tissue was determined and analyzed, and the index of AI and HOMA-IR. was also calculated. It was founded that the blood vessel damage was mitigated and protected by depressing the level of TC, TG, LDL-C, GLU, INS, F2t isoprostanes, ET-1, the index of AI and HOMA-IR, and improving the HDL-C and NO level when the experiment animals were treated with nitrate-rich and flavonoid-rich diet for a long time.(5) The comparative study of the combination diet of nitrate from spinach and flavonoids from apple revealed that the cardiovascular protective efficacy of simultaneous intake of nitrate-enriched spinach and flavonoid-enriched apple was better than simple intake of nitrate-enriched spinach or flavonoids-enriched apple. And the combination of spinach and apple peel showed a stronger effect than that of spinach and apple flesh. In addition, high-dose of NO3-exhibited a better effect than low-dose and medium-dose of NO3-, and apple peel displayed a superior effect than apple flesh and intact apple in the cardiovascular protection.This study for the first time selected the nitrate-enriched spinach and the flavonoid-enriched apple as the experimental materials, the cardiovascular endothelial dysfunction model developed by high fat and high fructose diet as the evaluation carrier, systematically researched the regulative and protective effect of nitrate-rich and flavonoid-rich diet in the vascular endothelial function of experimental model animal with a trial way close to the diet intake. This study provides a new theoretical basis for accurately elucidating the effect of NO3-and flavonoids in maintaining the vascular function and the underlying molecular nutrition mechanism.