| The research on the pathology of cardiovascular diseases has attracted much more attention in recent years. Heme, one of the main forms of iron existentence in living body, has been reported to catalyze protein oxidation and protein nitration. Flavonoids are a group of natural antioxidants and there were many researches concerning their antioxidative effect and pharmacology. In this thesis, nitration of LDL and cardic protein has been studied, and the antioxidant effects of some flavonoids have also been discussed. The main results in this work are as follows:(1) The effects of hemin-nitrite-H2O2 on LDL oxidation and nitration were studied in vitro. The results showed that hemin-nitrite-H2O2 system could effectively induce LDL protein nitration, lipid peroxidation, and protein oxidation. Baicalein, baicalin and quercetin, could dose dependently inhibit hemin-nitrite-H2O2 system induced protein nitration and lipid peroxidation. However, these flavonoids showed different effects on hemin-nitrite-H2O2 system inducing protein oxidation. Quercetin showed strongest inhibitory effect on nitration and lipid peroxidation. As to protein nitration, bacailin showed strongest inhibiting effect.(2) The optimal system of heart nitration in vitro was eatablised, and the effects of different flavonoids on cardic protein nitration were compared. Breviscapinum,baicalein,quercetin,baicalin showed good effect at inhibiting cardic protein nitration, while puerarin and apigenin's effects were comparatively weak.(3) Male rats are divided into two groups, and were given three consecutive intraperitoneal injections of alloxan(100 mg·kg-1) to induce type 1 diabetic model. Then they were killed and their different organs were collected in different course of diseases, iNOS and nitro-tyrosine level in different organs such as hearts were determined. Under present condition, degree of protein nitration in muscle has no significant difference between two groups.
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