Study On Extraction,Purification,Identifieation And Properties Of Anthocyanins From Purple Elephant Grass

Purple elephant grass,also known as the red elephant grass(Pennisetum purporeum Schumab cv.Red),native to Africa,is a high-yielding perennial forage grass,widely cultivated in tropical and subtropical regions,have been widely grown in China.Its leaves and stems were bright purple,and rich in anthocyanins,has a high value.In this paper,with the elephant grass as raw material,A series of experiments were carried out,including the extraction and purification process.stability.antioxidantion in vitro?antimicrobial activity.preliminary structure identification of purple elephant grass anthocyanins,and the purple elephant grass anthocyanins content was measured by pH differential method when the purple elephant grass in different heights.The main achievements are as follows:1.Extraction process of purple elephant grass anthocyaninsTo optimize the extraction technology of total anthocyanins from purple elephant grass by response surface methodology(RSM),the achievements showed that the optimal conditions for the extraction purple elephant grass anthocyanins are the ethanol concentration was 50%,extraction temperature was 35 ?,extraction time was 60 min,solid-liquid ratio was 1:20.2.Purification and preliminary structure identification of purple elephant grass anthocyanins?The X-5resin was the best one for the purification of purple elephant grass by comparing the results of adsorption and desorption rate.The anthocyanins purification conditions:elution solvent 60%ethanol solution,pH=3,with a flow rate of 2mL/min.the anthocyanins recovery was 89.9%.The structure identification results of the purple elephant grass anthocyanins:cyanidin-3-O-glucoside,26.08%of the total anthocyanins in purple elephant grass,and Malvidin,98%of the total anthocyanins in purple elephant grass,also contains two other Malvidins,but the specific structure is unknown.3.Stability and antibacterial activity of the purple elephant grass anthocyanins.the anthocyanins in purple elephant grass is easier soluble in water?methanol?ethanol?acetic acid,apartially soluble in acetone,but insoluble in ethyl acetate,carbon tetrachloride.anthocyanins in pH 2?3?4?5 was more stable,in neutral and alkaline conditions was unstable,and the color change was obvious,if adjusted pH value to 1 in a short time,the anthocyanins will restore the original color;heat and light can accelerate the rate of degradation of purple elephant grass anthocyanins;Mn2+?Mg2+?Ca2+?Na+?Mg2+?K+?Zn2+had no influence on the stability of purple elephant grass anthocyanins,Fe3+,Cu2+,Fe2+ impact the Stability of anthocyanins,,no absorption maximum in the 500-530 nm range;oxidant H2O2 influenced severely the stability of the purple elephant grass anthocyanidins,the greater the concentration of hydrogen peroxide,the faster the rate of degradation of the purple elephant grass anthocyanins.The research achievement shows that Bacillus subtilis?Staphylococcus aureu and Escherichia coli all could be inhibited by Purple elephant grass anthocyanins,the minimal inhibitory concentration were 1.725 mg/mL,1.725 mg/mL,0.863 mg/mL.4.The antioxidant of purple elephant grass anthocyaninsPurple elephant grass anthocyanins have scavenging effect on superoxide anion.hydroxyl radical?DPPH,and with the concentration increasing of anthocyanins the scavenging increase.The linear relationship between the concentration of anthocyanins in purple elephant grass with antioxidant capacity was:y = 0.429x + 1.173,R2 = 0.9947.5.The anthocyanins content in different height purple elephant grassThe anthocyanins contents in the 1.5 m?2.0 m?2.5 m?3.0 m?3.5 m height purple elephant grass were:1.061 mg/g?2.252 mg/g?2.632 mg/g?2.633 mg/g?2.669 mg/g.