Extraction And Quality Control Of Active Flavonoid Components From Portulaca Oleracea L. And Their Inhibition To Aspergillus Flavus

Contamination caused by Aspergillus flavus exists widely in food and feed.Contaminated products lost nutritional value,and they can produce AFT which brought toxic to human and animals by direct and indirect ways.Natural mould-inhibitor from plants not only have good bactericidal and mould-proof function,but also keep the nutritional values of food and feed products.Meanwhile,they will not pollute the environment and it is safe for human and animals,so they have great research value.In this research,Portulaca oleracea L.was selected,an extraction conditions of flavonoids was determined,a HPLC fingerprint of crude extract was built,and bacteriostatic compositions in the crude extract were identified using the method of biological active guidance.The results of the study were as follows:(1)Ultrasonic extraction was used to extract flavonoids from Portulaca oleracea L.Factors including ethanol concentration,solid-liquid ratio,pH value of solvent,ultrasonic time,ultrasonic power,ultrasonic temperature were investigated,and the advantageous extraction conditions were determined as follows: ethanol concentration is 90%,solid-liquid ratio is 1/50,pH value of extraction solvent is 8.5,ultrasonic power is 700 w,ultrasonic time is 40 min,ultrasonic temperature is 60 ?.Under the optimized condition,the extraction amount of flavonoids from Portulaca oleracea L.was up to 3.85mg/g.(2)The fingerprint for crude extract of flavonoids was established using high performance liquid chromatography(HPLC).The author examined the separating effect of detection wavelength,mobile phase modifier,column temperature,flow rate of crude extract of flavonoids of Portulaca oleracea L.,and determined the appropriate conditions of HPLC analysis: wavelength is 325 nm,mobile phase is methanol,modifying agent is acetic acid,the flow rate is 1 mL/min,column temperature is 30 ?.Under this HPLC conditions,the similarity of 10 parallel batches of crude extract of flavonoids was evaluated using Similarity Evaluation System for Chromatographic Fingerprint of TCM software,which were better than 0.97.Meanwhile,its bacteriostatic rates to Aspergillus flavus were 73.47% to 76.47%.Moreover,the validation of methodology experiments showed that the precision,repeatability and stability of the fingerprint were less than 5%.Therefore,the quality control point of crude flavonoids extract of Portulaca oleracea L.is ? 0.97.(3)By using the liquid suspension culture method combined with MTT assay,every class' s extracts of flavonoids of Portulaca oleracea L.to Aspergillus flavus were investigated.Oriented by bacteriostatic effect,the most effective extracts of flavonoids of Portulaca oleracea L.was F 6-5-3.Its minimal inhibitory concentration was 250 ?g/mL.