| The platycodon grandiflorum which belongs to campanulaceae, is one kind of perennial herbaceous plants, and is also one of our medicine edible plants. There are many active ingredients in platycodon grandiflorum, such as saponins, polyphenols, polysaccharides, flavonoids, terpenoids, and steroids. It contains ten many kinds of amino acids and magnesium, iron, zinc and other trace elements. Edible parts taste bitter, can be used in the treatment of exogenous cough, sore throat and spit the lung disease. Modern pharmacology study shows that platycodon grandiflorum is good to liver, anti-oxidation, anti-inflammatory, anti-tumor. It also can fall blood sugar, fall hematic fat, and regulate immune.(1) Platycodon grandiflorum was proved to own saponins、sugar and glycosides, polyphenol, flavonoid, steroids and terpenoid, grease and organic acids and other active ingredients. By comparing the ethanol extraction, ultrasonic extraction and ultrasonic extraction assisted by ethanol, choosing ethanol ultrasonic assisted extraction as the characteristics of polyphenol extraction method. Through the single factor tests and response surface optimization method, the condition was optimized to be 62% ethanol by ultrasonic extraction in 32 min, volume and liquid ratio was 21:1, extraction temperature 62℃, the ultrasonic power was 450 w, leaching time was 1.5 h. Under the condition, the maximum yield of polyphenol from platycodon grandiflorum was 1.647 mg/g.(2) The polyphenol crude extract was extracted by petroleum ether and ethyl acetate, and purified by macroporous adsorption resin. After comparing, choosing AB-8 resin as the purification resin. The best purification condition was:the pH value of 5.84, when the sample flow rate of 1.0 mL/min, adsorption time of 1.0 h. Using 60% ethanol as elution agent, using 2 times eluant, the elution flow rate of 0.6 mL/min. Under this condition, the average concentration of 45.402 mg/g which was detected before purification of platycodon grandiflorum polyphenol could increase to 94.013mg/g, the total antioxidant average capacity increased from 60.167 U/mL to 122.047 U/mL.(3) The platycodon grandiflorum polyphenol were proved to have two components by the glucan LH-20 gel separation. Using ultraviolet and infrared spectrum analysis, as a result, platycodon grandiflorum polyphenol have maximum absorption peak at 280nm, each function group caused by vibration characteristic absorption peaks were accord with the structure of the polyphenol. To further verify the characteristics of polyphenol samples, the HPLC determination was used. Finally, it seemed to be hydroxy cinnamic acid and catechin, which were detected to be 6.050μg/mL and 8.226μg/mL, respectively. They accounted for 41.13% and 30.25% of the proportion of the total polyphenols in the platycodon grandiflorum.(4) In the same concentration of platycodon grandiflorum polyphenols and ascorbic acid, the total antioxidant capacity of the two was compared through T-AOC kit. The result show out that ascorbic acid was better. To study the abilities of eliminating free radicals of O2-·, hydroxyl and DPPH was to study the antioxidant capacity of polyphenol in vitro. The results show that the clearance of free radicals is positively correlated to the concentrations of the sample. SC50 is the platycodon grandiflorum polyphenols concentration needed to scaveng 50% free radical. The SC50 of the hydroxyl radicals was the lowest, which was only 0.11 mg/mL. While the SC50 of O2-· and DPPH were 0.19 mg/mL and 0.86 mg/mL respectively. The result above shows that platycodon grandiflorum polyphenols have certain antioxidant capacity. |
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