| Halophila ovalis. is a marine perennial flowering plant, belonging to Halophila Thou., Hydrocharitacea, Helobiae, Monocotyledoneae, Liliopsidal. Halophila ovalis. is an important part of seaweed bed. Recently, investigations have not been conducted on the flavonoid from the seagrass Halophila ovalis in China. The research of Halophila ovalis. were mostly concentrated on its taxonomy, morphology and physiology.The flavonoids are widely existed in plant kingdom. Studies have shown that they also possess a number of physical-chemical functions such as anti-aging activity, antioxidant activity, antitumor activity, antibacteria, cancer-depressed and etc. Generally, the research of flavonoids is limited to terrestrial higher plants, but higher plants in the ocean have not been fully exploited.Halophila ovalis., a kind of higher plant in the ocean, is studied in the extraction technology, purification technology, determining the construction and antioxidant activity of flavonoids in this paper. The main findings are as follows:At first, the detection of the basic ingredients of Halophila ovalis. were carried out.The seagrass is found to be a healthy food resource, which is rich of carbohydrate(17.18%),protein (11.66%) and lack of fat (1.16%). There are 7 kinds of essential amino acids among the 15 kinds of amino acids which were detected. The essential amino acids account for about 34.70% in all kinds of amino acids. Valine has the highest amount among the essential amino acids while methionine has the lowest amount. Among the nonessential amino acid, the amount of glutamic acid is the highest while histidine the lowest. Also, Halophila ovalis. is rich of delicious amino acid.Secondly, the extraction of flavonoids tests are conducted from Halophila ovalis., Single factor experiments and orthogonal tests were performed to optimize the extraction technology with traditional ethanol technology, ultrasonic assisted technology and cellulose-assisted technology. The best total flavonoids yield of above three kinds of extraction technologies is the cellulose-assisted extraction technology, with yield of 2.10%.Thirdly, the ethyl acetate soluble portion and butanolic soluble portion were prepared by the solvant extraction method. Five kinds of macroporous resin were examined by static test. The results showed that the adsorption property and desorption property of AB-8 are the best. The optimum conditions are as follows:the pH value of sample is 3, sample concentration is 1.20mg/mL, eluant is 75% ethanol, the adsorption and desorption temperature are both 25℃. Under those optimum conditions, the content of flavonoids increases from 28.34±0.55 to 48.28%±1.26%. The purity of the purified flavonoids can be increased by 1.7 times. Two kinds of Halophila ovalis. flavonoids purified are determined by LC and MS. They are apigenin-7-O-β-glucopyranoside and Chrysoeriol-7-O-β-glucopyranoside.Finally, antioxidative activity of flavonoids from Halophila ovalis. were investigated by examining the reducing power and the scavenging effects on hydroxyl radicals(·OH) and superoxide anion(O2-), DPPH radicals and nitro so-group. The results showed that the reducing power of the two flavonoids monomers were slightly lower than Vitamin C, indicating that they had strong reducing power. However, the two flavonoids monomers showed better scavenging effects on hydroxyl radicals (·OH) than Vitamin C and other flavonoid extracts from Halophila ovalis.. Flavonoids from Halophila ovalis. can scavenge radicals and nitroso-group, indicating its potential as a natural antioxidant. |
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