Study On Extraction, Purification And Function Of Flavonoids From Choerospondias Axillaris Peel

In this study, Choerospondias axillaris peel as the research object, the purification method and extraction process conditions, and the antibacterial and antioxidant activities in vitro of flavonoids in Choerospondias axillaris peel had been researched. This study is a relatively systematic and comprehensive one. In this paper the main experimental results were listed respectively as follows.1. The Box-Behnken design combined with response surface methodology was applied to optimize heat reflux extraction methods for total flavonoids from Choerospondias axillaris peel. A series of single-factor experiments were made to investigate the effects of ethanol concentration, solid-to-liquid ratio, extraction time and temperature on flavonoids yield, and based on these, response surface methodology (RSM) was employed to optimize the extraction conditions of flavonoids. The optimal extraction conditions were found to be:ethanol concentration of60%and solid-to-liquid ratio of1:25(g/mL) for extraction duration of1.6h at65℃. Under these conditions, the yield of flavonoids was9.72%.2. The purpose of separating and purifying the flavonoids from Choerospondias axillaris peel was researched and compared with six kinds of macroporous resins including HP2MGL、LSA-10、AB-8、NKA-9、DA-201and D101. The results showed that the HP2MGL macroporous resin was a good sorbent of the flavonoids, its adsorption rate was57.29%and desorption rate was96.72%. The optimum conditions for separation and purification the flavonoids by HP2MGL resin were:adsorption of sample solution with an initial concentration of1.3mg/mL, sample flow rate1mL/min, elution rate1mL/min, desorption using50%(v/v) ethanol, ratio of sample solution volume to resin weight of30:1(mL/g). After treatment with HP2MGL resin in the optimized separation and purification conditions, the purity of Choerospondias axillaris peel flavonoids can reach the height of76.73%, which is about3.73times higher than the previous of16.21%. 3. In this study, six foodborne pathogenic bacteria, such as:Enteroinvasive Escherichia coli, Salmonella typhimurium, Shigella sonnei, Staphylococcus aureus, Listeria monocytogenes, Enterobacter sakazakii, were selected to research the bacteriostasis activity experiments in vitro. The Choerospondias axillaris peel extraction, which was treated with HP2MGL resin inhibiting the bacteria was researched by the inhibition zone diameter, the MIC and MBC had also been test. The results showed that the purified flavonoids extracts had better inhibition effects on gram positive bacteria than gram negative bacteria. The purified flavonoids extracts had the significant inhibition of Listeria monocytogenes, Staphylococcus aureus, for all MIC and MBC were5mg/mL and10mg/mL, respectively. The inhibition of Shigella sonnei is the weakest. The Choerospondias axillaris peel flavonoids extaction was potential natural preservative which could inhibit some foodborne pathogenic bacteria.4. The antioxidant activities of the Choerospondias axillaris peel flavonoids extraction were evaluated in vitro by ferric ion reducing power, scavenging capability of DPPH free radical, total antioxidant capability. The results showed that the Choerospondias axillaris peel flavonoids extraction have significant antioxidant activities.