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Extraction, Separation And Activity Evaluation Of Flavonoids From Lithocarpus Polystachyus Rehd, And Modification Of Phloridzin Molecule

Posted on:2008-12-13Degree:DoctorType:Dissertation
Country:ChinaCandidate:H Q DongFull Text:PDF
GTID:1101360245987204Subject:Food Science
Abstract/Summary:PDF Full Text Request
Lithocarpus polystachyus Rehd with rich valuable flavonoid and phloridzin, is an abundant plant resource in our country, located mainly as wild plants in the mountain area in southern China, and its rich resource of flavonoid and phloridzin has not been developed. First, this research developed a set of simple and effective technologies for preparative extraction and separation of flavonoid and phloridzin from Lithocarpus polystachyus, which includes: (1) Microwave-assisted extraction of flavonoid from tender leaves of Lithocarpus polystachyus Rehd. The extraction conditions are as the follows, 1.2 % of Ca(OH)2 water solution, solid-liquid ratio of 1:12, pre-boiling for 5 min, 800 W of microwave treating for 25 min. By this technology, 96±2.1 % of extraction rate was reached, and flavonoid and phloridzin contents of the extracted product were 40 % and 29.5 % respectively. (2) Separation and Purification of Flavonoid and phloridzin with macro-porous resin ADS-7. The conditions are as the follows, the ratio (mL/g) of the crud extract solution (flavonoid of 9 mg/mL) and the resin was 5:1, static adsorbing for 2.5h in neutral pH condition, 80 % of ethanol (v/v) as eluant, eluating for 3h at 1BV/h of eluation speed. By this technology the flavonoid and phloridzin contents of the purified product reached 88 % and 80 % respectively. (3) Chromatography with the neutral alumina column and crystallization in the ethanol water solution. The conditions are: Load amount of 20 mg/g, eluating the colum with 65 % ethanol at 1.5 BV/h for 3.3h, the eluation solution was gathered and dried, then the dried sample was dissolved in 60 % ethanol as 80 mg/mL of solution, then the solution was crystallized in a refrigerator at 4℃. By this technology 6.6g of crystal phloridzin with 99.8 % of purity was prepared in one run of purification, and the crystal was confirmed as phloridzin by analysis of ultraviolet absorption spectrum, high performance liquid chromatography (HPLC) and electro spray ionization mass spectrometry (EIS-MS).In the whole process of this technology, only water and ethanol without any other organic solvent and hazard chemicals were used, which guarantee the safety of the extracted and purified products, and minimized threat for the environment pollution.Then, the new functional usages of the flavonoid and phloridzin separated from Lithocarpus polystachyus Rehd were developed, mainly in the preservation of the fresh-cut apple and prevention and cure of diabetes mellitus. (1) The preservation qualities of the fresh-cut apple were significantly enhanced by the treatments of the ADS-7 purified product (ADSF) and the crystal phloridzin, which can completely substitute for the commercial chemical method. ADSF was more suitable than the crystal phloridzin in preserving the fresh-cut apple for its much lower production cost than the crystal phloridzin. During the storage, polyphenoloxidase (PPO) and peroxidase (POD) activities of the fresh-cut apple were significantly inhibited. (2) The mice with alloxan-induced diabetes mellitus were orally administrated with the crude extracts (CA) and the crystal phloridzin(PHL) from Lithocarpus polystachyus Rehd, and their fasting blood level as well as no-fasting level were reduced significantly, and their glucose tolerance curves also were improved. The research results showed that the hypoglycemic mechanisms of CA and PHL in normal and the diabetic mice were different from Acarboe, and the serum malondialdehyde (MDA) level was reduced, activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were promoted, which showed antioxidant abilities in the diabetic mice were enhanced.Finally, the chemical structure of phloridzin was modified according to its chemical and usage characteristics, and the properties of the modified product were evaluated by experiment. The modification was done as the follows, in 0.1 mg phloridzin / 25 mL methyl salicylate, adding Novozym 435? 24.0 g/L, the esterification was conducted under 75℃at 80 rpm of stirring speed for 24h, phloridzin-6"-O-salicylate was efficiently synthesized, and the conversion reached 87.5 %. The experiment results on properties of phloridzin-6"-O-salicylate showed that the ability to scavenge free radical DPPH? of phloridzin-6"-O-salicylate was stronger than phloridzin, and the hypoglycemic effects of phloridzin-6"-O-salicylate also was better than phloridzin.These research results are the strong theory base for the industrialization of developing the special rich resource of Lithocarpus polystachyus Rehd.
Keywords/Search Tags:Lithocarpus polystachyus Rehd, Phloridzin, Preservation, Diabetes, Esterification
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