Extraction And Purification Of Flavonoids From Bamboo Leaves And Its Antimicrobial Activity

Bamboo is a grass(Poaceae) Bambusoideae(Bambuaoideae) perennial evergreen plant.In recent years,studies have shown that bamboo leaf extract has significant anti-free radical,antioxidant, antibacterial,anti-fatigue,anti-tumor,regulate blood lipids,cardiovascular and cerebrovascular protection,as well as pesticides and other biological functions and pharmacological activity.Flavonoids was extracted from bamboo leaves with ethanol,the extraction process was optimized;Then products were separated and purified with many methods.The main results were as follows:(1) On the base of the single factor experiments of ultrasonic-assisted extraction technique of flavonoids from bamboo leaves,the method of response surface analysis(RSA) with three factors and three levels was adopted and the factors influencing the technological parameters were determined by means of regression analysis.The results showed that the optimum conditions were:70%of the ethanol concentration,500 W of the ultrasonic power,the ratio of material to solvent of 1:20,30 min of extraction time,under such condition the extraction rate of flavonoids from bamboo leaves was 1.94%.(2) Seven kinds of macro porous resins were selected to compare their performances in absorbing and desorbing flavonoids in Bamboo leaves.The optimal absorbent material for flavonoids in Bamboo leaves was decided.Experimental results show that AB-8 resin possesses higher absorption and desorption capacity.The optimum parameters for separation were as follows:the range of the sample pH was 5;flow rate 1 mL/min,the optimal solution for the adsorption was 50%ethanol with3BV at the flow rate of1mL/min.The purity of flavonoids was 28.94%.(3) At the same time,chromatographic conditions were further optimized as well.We separated four flavonols successfully thus making determination of flavonols in test by HPLC possible.(4) Flavonoids from bamboo leaves(≥1.5 mg/mL) shows strong antimicrobial activities on Staphylococcus aureus,Escherichia coli,Bacillus subtilis. (5) Research on the antimicrobial properties of the raw extract.①It indicated that the pH of food matrix have great influence on antimicrobial properties,the antimicrobial activities enhanced with the increase of food acidity,so it can be used as preservative in slightly acid food;②From the result we can know that temperature have little effect on antimicrobial activities,treated 10 minutes below 100℃the antimicrobial activities were not affected,while treated 10 minutes under 120℃,although the antimicrobial properties were affected,it was relative less,so the extract can be a high temperature resistance natural preservative.