Study On The Chemical Constituents Of The Seeds From Lycium Barbarum L.

Lycium barbarum L. as a deciduous shrub belonging to the Lycium genus and an expensive Chinese medicine, has many activities such as anti-aging, protecting the nervous system, anti-fatigue, improving endurance, promoting metabolism, decreasing blood glucose, anti-oxidation, anti-tumor and immune regulation. The chemical composition of L. barbarum includes polysaccharides, pigments, alkaloids, sterols, flavonoids, fatty acids, volatile oils and other ingredients.The seeds of L. barbarum from its fruit can be obtained after be squeezed juice. After the oil is extracted from the seeds, the residue is normally used feed or fertilizer. Up to now, there are few published papers reported the active components especially secondary metabolites from the seeds of L. barbarum except for a few reports on seed oil content, oil composition as well as some researches on polysaccharide and enzyme activity.In this study, the seeds and seed residue of L. barbarum were used as the materials for the researches on four aspects:(1) The polysaccharide of the seeds and seed residue of L. barbarum was extracted and determined with Phenol-sulfuric acid method and the total phenolic content and the total flavonoid content were analyzed by UV-colorimetric method;(2) The antioxidant activity of the polysaccharides from L. barbarum seed was tested with scavenging activity of DPPH radical, hydroxyl radicals and superoxide anion radical, and the total reducing power;(3) The extract conditions for optimize isolation of the compounds from the seeds by comparing the HPLC chromatogram were studied with different extraction methods, different solvents and different material(the seeds and the residue);(4) The compounds of the methylene chloride extract and the aqueous extract were isolated by combining different column chromatography like silica gels, ODS and Sephadex LH-20. The purity of the isolated compounds was analyzed by TLC and HPLC methods and the structure of compounds was identified by NMR spectroscopy.The main results are showed as follows:1. The polysaccharide content of L. barbarum seed is higher than the seed residue with 28.4 mg/g and 13.2 mg/g respectively. The total phenols and total flavonoids content of L. barbarum seeds were 26.7 mg/g and 5.8 mg/g respectively.2. The polysaccharides from L. barbarum seed have a concentration-dependent effect on scavenging three free radicals, while the concentration increased, the clearance rate also increased. Scavenging effect on DPPH radical is better than that on hydroxyl radicals and superoxide anion radical at the same concentration. At the concentration of 0.6 mg/m L, the scavenging rates on DPPH radical, hydroxyl radicals and superoxide anion radical were 84.2%, 61% and 40% respectively. The total reducing ability of L. barbarum seed polysaccharides was also correlated with its concentration positively.3. The optimize solvent for better isolation result from the seed and seed residue of L. barbarum was 95% ethanol. There was no obvious difference between thermal reflux extraction method and ultrasonic extraction method. From HPLC chromatography of four different solvents extracts and the remaining aqueous phase, which were obtained seriously from the crude ethanol extracts, the better isolation results were observed in the petroleum ether extract, methylene chloride extract and the remaining aqueous phase. In the two used materials, the seed residue extract was found with more isolated peaks than the seed extract.4. Eleven compounds were isolated from the dichloromethane extract and the extracted remaining aqueous, and the structure of eight known compounds was identified as ?-sitosterol(compound 1), palmitic acid(Compound 3), hawthorn acid(compound 4), scopoletin(compound 6), stigmasterol(compound 8), daucosterol(compound 9), scopolamine glycoside(compound 10) and ferulic aldehyde(compound 11) respectively.In summary, this study showed that L. barbarum seed and seed residue contains polysaccharides, phenols, flavonoids and other antioxidant active ingredients. The isolated compounds include sterols, phenolic acids, coumarone glycosides and other ingredients. The chemical composition of the seeds of L. barbarum is similar with the constituents of the fruit.