Extraction, Purification And Activity Study Of Bitter Polyphenols

Based on Sonchus oleraceus L of shaanxi yulin as raw material, the study mainly involved the following aspects:extraction process was optimized with response surface method, separation and purification was conducted with macroporous resin, the chemical composition of the extract was analyzed with HPLC and the antioxidant activity and antibacterial activity & mechanism was explored in the study. The study had very important practical significance for development of natural antibacterial and antioxidant agent, the utilization & exploitation of the resources of this plant and acceleratio n development of the mountain area economy.The conclusions of this research are as follows:1. The optimum technological conditions for Sonchus oleraceus L polyphenols with ethanol extraction by single factor and response surface method were:extraction temperature 77?, ethanol concentration56%? ratio of material to liquid 1:35g/mL? extraction time 45min. And the results of verification test showed the content of polyphenol compounds was 14.72% under the optimal extraction condition.2. Antioxidant activity of crude product from Sonchus oleraceus L polyphenols was investigated by 3 kinds of antioxidant systems in vitro. And the results showed that Sonchus oleraceus L polyphenol had have strong capacity for scavenging free radicals, reducing capacity as well as inhibition oxidation in the system of beta-carotene and linoleic acid. Within the certain concentration, the ability for 3 above -mentioned antioxidant system of extract of Sonchus oleraceus L showed obvious dose effect relationship.3. The static adsorption/desorption test showed that NKA-9 macroporous resin with larger adsorption capacity and adsorption/desorption rate was suitable for purification of extract from Sonchus oleraceus L among six macroporous resins(AB-8, D101, S-8,D110,X-5 and NKA-9). The dynamic adsorption/desorption characteristics of NKA-9 macroporous resin indicated that the optimum conditions of purification were: the mass concentration of sample was 0.5mg/mL; the adsorption velocity was 3 BV/h; eluting agent concentration was 50%; the pH value of sample was 5.0;elution velocity was 1mL/min. The polyphenols in extract could be basically complete washed off using 450mL volumn of eluent. After enrichment and purification by NKA-9 macroporous resin, the purity of polyphenols was up to 72.38%, and the refined time was 4.92.4. The chromatographic conditions for high performance liquid chromatograp hy(HPLC) were as follows:chromatographic column of Diamonsil-C18(2) colu mn(4.6mmx250mm); mobile phase A:methanol-0.5% phosphate(50:50); velocity of 1.0mL/min; detection wavelength of 360nm; column temperature of room temperature. Chromatographic analysis results indicated that flavonoids extracts contained rutin 0.557mg/g, quercetin 0.405mg/g, apigenin 0.507mg/g, luteolin 0.091mg/g, kaempferol 0.323mg/g.5. The antibacterial activity and antimicrobial mechanism of Sonchus oleraceus L polyphenol were studied by staphylococcus aureus, escherichia coli, shigella dysenteriae, bacillus subtilis, bacillus cereus and salmonella typhimurium. The results showed that the above 6 kinds of microorganisms were sensitve in some extent to the polyphenol and shi gella dysenteriae was the most sensitve whereas bacillus cereus was the least sensitve. Sonchus oleraceus L polyphenols exhibited the damaging effect on the surface of the microbial cell structure and morphology to varying degrees. Sonchus oleraceus L polyphenols can inhibit the growth of the microorganisms in logarithmic phase and have good bacteriostatic effect. The polyphenols increased conductivity of the bacteria suspension; caused intracellular substances leaked out, and thus inhibited the growth of microorganisms.