Investigation On Flavonoid From Rosa Roxburghii Tratt. And Its Biological Activity

Rosa roxburghii Tratt. is a kind of wild food and medicine resource which plays an important role in the development of local economy in the west of China. In order to realize the further and continuable exploitation of that resource, the bioactive components should be investigated firstly. We used HPLC to determine the flavonoid aglycones in the hydrolyzed sample of fruit of Rosa roxburghii Tratt. The result showed that there are three kinds of flavonoid aglycones in the fruits of Rosa roxburghii Tratt., myricetin, quercetin and kaempferol and the contents of them are 92.89, 13.57 and 16.65mg/100g separately.In order to explore the industrialization potential of the flavonoid from Rosa roxburghii Tratt. (FRR), the optimum extracting and purifying conditions of flavonoids in Rosa roxburghii Tratt., the Orthogonal Design was applied in different conditions of alcohol extraction and column purification. It can be concluded that the flavonoids should be extracted once by 20 : 1 of 50% ethanol for four hours and at 90 ℃, and then be purified on HPD600 column by using such eluting conditions that 10 : l(v : v) of 40% ethanol elutes the column at the speed of 3 ml/min. In addition, one flavonoid compound was separated from the fruits by column chromatography. The structure of that compound was determined as quercetin by UV, ~1H-NMR and EI-MS.Subsequently, the biological activity of FRR was studied. Firstly, the effects of FRR on the normal rats' metabolism of glucose, lipid and antioxidant system were observed. The data indicated that the dose of 100mg/kg FRR can significantly reduce the serum triglyceride, serum and liver MDA, increase the content of serum GSH, and thus improve the antioxidant capability in normal rats. However, FRR has no effect on other serum biochemical indexes.Secondly, the preventive effect of FRR on diabetic mice induced by alloxan was examined. Po. 100mg/kg FRR for four weeks could significantly reduce serum glucose and triglyceride of model mice, increase the level of serum insulin and the activities of SOD and CAT in pancreas and decrease the level of MDA markedly.Furthermore, FRR is able to weaken the damage of 0 cells induced by alloxan, so it can be concluded that FRR has preventive effect on diabetic mice. However, FRR has no direct therapeutical effect on diabetic rats induced by STZ, while it has positive effect on triglyceride and serum SOD and GSH in such rats.It can be observed that FRR is able to reduce serum triglyceride of both normal rats and diabetic ones, which implies that FRR may have positive effect on hypertriglyceridemia. After studying the five kinds of preparative methods of hypertriglyceridemia model, the best method, high-sugared food (normal food plus 40% sugar), was chosen to feed mice for six weeks and do the following experiments.During the preventive study, FRR can reduce serum triglyceride and LDL-C and improve the level of HDL-C, but has no influence on serum cholesterol and liver lipid. At the same time, during the therapy experiment, both lOOmg/kg and 200mg/kg FRR can also significantly decrease serum triglyceride. As a result, FRR has both preventive and therapeutical effects on hypertriglyceridemia.The experimental study on underlying mechanism of FRR on metabolism of sugar and lipid showed that the effect of FRR has no relationship to a-glucosidase, sucrase and insulin secretion. However, FRR can remarkably inhibit the formation of AGEs induced by glyoxal and fructose incubated with BSA. Especially, the inhibitory effect of nonenzymatic glycation induced by glyoxal was more potent and the inhibitory rate can amount to 83.6% when the dose of FRR was lmg/ml.Successively, we did the research on in vitro antioxidant activities of FRR. The chemical luminescence assay and the colorimetric assay was applied to determine the oxygen radicals( O 2, H2O2 , DPPH ' ) scavenging capacity of FRR and the effect of FRR on oxidative damage of erythrocyte induced by H2O2 was investigated. The data showed that FRR could potently scavenge the oxygen radicals, inhibit the erythrocyte oxidative damage, and decrease the content of MD A in rat hepatocyte remarkably. As a result, FRR could be regarded as a potential antioxidant. Associated with the in vivo experiment results that FRR has no effect on liver glycogen, serum lactic acid and gluconeogenesis, it can come into a conclusion that the mechanism of the effect of FRR on sugar and lipid metabolism was its significant antioxidant capability.Since the disorder of lipid metabolism is correlative with cardiovascular diseases and FRR has positive regulatory capacity of lipid metabolism, it can be assumed that it has potential therapy capability on cardiovascular diseases. Therefore, OX-LDL was used to damage in vitro cultured endothelial cells from ox primaryartery and the preventive capability of FRR on that damage was studied. The data showed that FRR can prevent the endothelial cells from damage induced by OX-LDL. But none of NOS, SOD activity and NO secretion are involved in that activity. Therefore, FRR can directly inhibit the apoptosis of endothelial cells induced by OX-LDL.Finally, the acute toxicity experiment was done to evaluate the security of FFRT. The three groups of mice were given (po.) FRR one or several times one day and the dose was 2g/kg, 5g/kg and lOg/kg respectively. The results indicated that there were no dead mice found in each group and the activity of each mouse was observed and considered normal. The tolerance of mice against FRR was equal to or larger than 10 mg/kg, so it can be concluded that FRR can be considered secure.