Study On Separation And Purification Of Luteolin From Peanut Shells And The Antibacterial Effects Of The Extract

Peanut shell contains many nutrients and polyphenols. Luteolin is a kind offlavonoid which has the affects of antibiosis, anti-inflammatory and oxidationresistance.This paper focuses on developing peanut shell extracts as a food preservative andaims to study the relation of luteolin’s extract rate and antibacterial activity in peanutshell extracts. On the basis of antibacterial effects, we aim to optimize the luteolin’sextraction and separation conditions, and to have a deep study of peanut shellextracts’ antibacterial effects. The main experiment results are as follows:a) The content of luteolin in the extracts from peanut shell was examined by HPLC.In the selected chromatographic conditions, there was good liner relationshipbetween the concentrations of luteolin and their peak areas in the ranges of5⁵0μg/mL（r=0.9990）; the average recovery was100.3%（n=6, RSD=1.43%）;b) The absolute content of luteolin in peanut shell extracts is relevant to extractionsolvent and assisted extraction methods. The antibacterial effects of extracts aredifferent under the same concentration. To an extract using the same solvent orsame assisted method, its antibacterial rate increases and antibacterial effectsbecome significant with its concentraction rises. Via correlation analysis, we gotthe conclusion that there is a significant positive correlation betweenStaphylococcus aureus’ antibacterial rate and the content of luteolin in extracts.Therefore, we got a best extraction process by selecting water bath reflux method,single factor and orthogonal experiment. The best extraction process:85℃waterbath reflux,70%ethanol aqueous solution, solid-liquid ratio was1:20, extractedtwo times, each time was1.5h, the extraction of luteolin content reached7.41mg/g.c) Through static adsorption and desorption as well as dynamic adsorption anddesorption, the sorption and desorption properties of D101macroporous resin forluteolin were studied to gain optimum process. The process parameters: theconcentration of luteolin is0.07mg/mL, the loading ethanol volume fraction of20%, sample pH is6, desorption pH is9, eluant is70%ethanol and its volume（mL） is4BV.d) Do experiments on the antibacterial effect difference of peanut shell extracts by filter paper method and plate count method. The results showed that under thesame concentration, there existed significant differences of antibacterial effectsamong different bacteria. For the antibacterial effects, Gram-positive bacteria arethe most significant, next are Gram-negative bacteria, molds and yeasts. Have atest on MIC and MBC of peanut shell extracts on Staphylococcus aureus, Bacillussubtilis and Escherichia coli, and results further showed that there is significantdifference of antibacterial activity among different bacteria. By measuringOD₅₄₀of different periods and the corresponding total number of colonies, wefound that peanut shell extracts have the bacteriostasis action to Staphylococcusaureus.