Extraction And Purification Of Mulberry Leaf Flavonoids And Its Hypouricemic Activity

Leaves from Morus alba L.is a kind of traditional Chinese medicine. Mulberry leaf flavonoids are the mainly active ingredient in mulberry leaves. The technique of extraction and separation of active ingredient has been investigated in this paper. Thenceforth, the hypouricemic activity of the mulberry leaves flavonoids was explored.Mulberry leaf flavonoids were analysed with high performance liquid chromatography. Rrutin, myricetin, quercetin, kaempferol are the main ingredients in it. Factors of temperature, extraction time, ethanol concentration,volume of solvent and extraction frequency were evaluated for their effects on extraction process by orthogonal designed experiments. The results showed that the optimum conditions were 80℃,2 times,1.5 hours,70% ethanol-herb ratio of volume to mass was 20:1 respectively.In order to get purer mulberry leaf flavonoids, macroporous resin was adopted. The adsorption ability of macroporous resin was evaluated by yield and purity of the flavonoids. The kind of HPD826 was the best of the five macroporous resin. The optimum process conditions were 3 BV 60% ethanol as eluting solvent, adding sample rate in about 2 BV/h, eluting rate in about 1 BV/h. The yield of Mulberry leaf flavonoids by this process was 1.95%,and the purity was 55.41%.Pharmacology study showed that mulberry leaf flavonoids could adjust the activity of a-glucosidase, lower blood glucose, antitumor, etc. Results indicated that MLF inhibit rat liver XO activity on dose dependent. Normal mice were administered orally with MLF at doses of 50,100,150 mg./kg*d-1.The results showed that mulberry leaf flavonoids had no significant effect on uric acid levels and liver XO activity in normal mice.Experimental animal model of hyperuricemia was induced by uricase inhibitor potassium oxonate. Potassium oxonate-induced hyperuricemic mice were administered orally with MLF at doses of 50,100,150 mg/kg*d-1, while distilled water and allopurinol at 50 mg/kg*d-1 were given to the hyperuricemic control group and positive control group. The results showed that oral administration of 200 mg/kg*d-1 MLF to hyperuricemic mice exhibited significant reduction in the blood uric acid levels 16.67% and in XO activity 6.05%. The oral administration of 50 mg./kg*d-1 MLF also caused remarkable reduction in the blood uric acid levels, but without remarkable reduction in XO activity.Long-term hyperuicemia caused kidney damage and gout, renal damage cause uric acid excretion obstacles. We studied the hypouricemic effect of MLF by using model of adenine-reduced hyperuricemia in rats. In this test, Adenine-induced hyperuricemic mice were administered orally with MLF at doses of 50,100,150 mg/kg*d-1, while distilled water and allopurinol at 50 mg/kg*d-1 were given to the hyperuricemic control group and positive control group. The results showed that oral administration of 100 mg/kg*d-1 MLF to hyperuricemic mice exhibited significant reduction in the blood uric acid levels at different time periods:17.83% at 7th d, 21.17% at 14th d, and oral administration of 200 mg/kg*d-1 MLF caused remarkable reduction in the blood uric acid levels at different time periods:21.09% at 7th d, 27.15% at 14th d. Oral administration of 200 mg/kg*d-1 MLF also caused remarkable reduction in the blood triglyceride levels 41.95% and in the blood free fatty acid levels 42.05% at 21th d. Transmission electron microscopy (TEM) observation results showed that MLF protected kidney cells of rats which treated by adenine.All the results mentioned above showed that MLF could decrease the levels of blood uric acid. It also protect kidney cell and prevent it from further damage, improve the metabolism of triglyceride and adjust body weight in hyperuricemic mice. It was concluded that MLF had good activity on adenine-reduced hyperuricemic rats, but its molecular mechanism need further study.