| In the last 20 years, evaluation and selection natural resources with high antioxidant activities has been becoming new trend in biology, medicine, food science and technology.As one kind of special local fruit in China, Chinese bayberry has become the favorite of domestic and overseas consumers extremely because of its high nutritive value, delicious tast and virious bioactive ingredients, such as quercitrin, myricetin and other flavonoids. Many diseases duing to alcohol have increased with the rapid alcohol consumption all over the world. Free radical is a main factor resulting in liver damage, and how to prevent liver damage is still a world-wide problem presently. Thus, it’s greatly important and meaningful to select medicine with liver-protective activity. This thesis performed a series of studies on structure, content and antioxidant activities of flavonoids from different varieties of bayberry and studied the mechanism of protecting liver from damage induced by alcohol by means of establishing subacute liver damage model of mice of bayberry flavonoid extract. The results were as followes:LC-MS analysis was applied to three flavonoid crude extracts from’Biqi’,’Shuijing 1’and’Fenhong’bayberry. The results demonstrated that the main flavonoids were myricetin, kaempferol-glucoside (or kaempferol-galactose), myricetin-rhamnoside, myricetin-glucoside (or myricetin-galactose), quercimelin-rhamnoside. In addition, both HPLC and colorimetric analysis indicated that the content of myricitrin, the sum of myricitrin and myricetin, the total flavonoids were higher in the extract of’Biqi’ bayberry than the others.Crude extracts from’Biqi’bayberry had the best effect on scavenging free radicals and inhibition from lipid peroxidation among five varieties of bayberry in different systems. The antioxidant activities of both crude flavonoid extracts and control group were studied by means of chemiluminescence methods, too. The results showed rutin was the highest in all samples examined and’Biqi’bayberry was the best in these five varieties. The antioxidant activities and the content of flavnoids showed a dose-response relationship between flavonoids content and antioxidant activities.Intragastric administration with alcohol was applied to prepare a subacute liver injury model of mice and the flavonoid crude extracts from’Biqi’bayberry with the highest antioxidant activity, was applied as an intervention substance, and the Sunflower Brand liver-protective tablet as a positive control. By means of test-kit detection and histopathology examination, the effect of subacute liver injury of mice induced by alcohol and intervention of flavonoid crude extracts from bayberry on the antioxidant systems and the lipid levels of liver tissue section, serum, liver homogenate tissue, mitochondrium and microsome in mice were studied.1) Result of liver tissue section examination:As normal group, the hepatic lobule structure was clear, hepatic cord was orderly and the liver cells had no obvious pathologieal change. As model group, the normal tissue structure of liver disappeared, the louble margin became unclear, the hepatie cord became disordered, and liver cells exhibited middle or heavy edema. While as treatment group, the lobule structure was clear, the hepatic cord was orderly. The liver cells only suffered from light injury or edema or plasminic loose.2) Effect on serum of mice:Compared with model group, after treated with flavonoid crude extracts from bayberry (in dosages of 100 mg/kg.bw/d,200 mg/kg.bw/d), the activities of AKP and AST in the mice of subacute liver injury, induced by alcohol, decreased significantly (P<0.01), ALT also decreased (P<0.05), the activity of AKP treated with low dosage (50mg/kg.bw/d) decreased significantly (P<0.05), whereas it was not statistically significant in activities of AST, ALT. The content of TG, TC and L-DLC decreased in low, middle, high-dose group. Meanwhile the content of H-DLC increased. With the concentration of flavonoid crude extracts from bayberry increasing, liver-protective effect presented an augmenting tendency.3) Effect on liver homogenate of mice:After treated with flavonoid crude extracts from bayberry in middle and high dosages, the activities of ADH, GSH-Px, GST, GSH, SOD and CAT in the liver homogenate enhanced significantly compared with model group (P<0.01). Meanwhile, the content of MDA, NO and NOS in high-dose group decreased significantly (P<0.01), whereas it was not statistically significant in the low-dose group.4) Effect on hepatic mitochondria of mice:Compared with normal group, the levels of T-SOD, GST, CAT, GSH-Px of hepatic mitochondria in model group enhanced significantly (P<0.01), the activity of antioxidase, such as T-SOD, GST, CAT, GSH-Px improved obviously after intake of high-dose of flavonoid crude extracts and Sunflower Brand liver-protective tablet, and it was extremely significant in statistics (P<0.01). Meanwhile, with the dosage of low, middle, high flavonoid crude extracts increasing, the liver-protective effect presented an augmenting tendency.5) Effect on hepatic microsome of mice:The level of GSH of hepatic microsome in model group decreased rapidly compared with normal group (P<0.01), whereas, the level of MDA rapidly enhanced (P<0.01), and the levels of GST, POD and GSH decreased. Compared with model group, the levels of of MDA, GSH, GST and POD in high-dose group were 4.81±0.52 nmol/mgprot (P<0.01),5.53±0.42 mg/gprot (P<0.01),63.18±7.48 U/mgprot (P<0.01),2.90±0.2.2 U/mgprot (P<0.01) after the intervention of flavonoid crude extracts; The levels of MDA, GSH and GST in middle-dose group presented significant statistically different (P<0.01), and the level of POD enhanced significantly (P<0.05); the levels of MDA, GSH and GST in low-dose group enhanced significantly (P<0.05), whereas the activity of POD was not statistically significant. |
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