Comprehensive Extraction Technology And Antioxidant Activity Of Flavonoid And Polysaccharide From Asparagus

Flavonoids and polysaccharides are the main natural bioactive components in Asparagus officinalis. The extraction of bioactive components from asparagus is one important direction of further asparagus processing development. This could not only increase the value of vegetable, but also make full use of the resource waste and decrease environmental pollution. The extraction and purification of flavonoids and polysaccharides from asparagus, and their antioxidant activity and interaction were studied in this paper. The results were as follows:1. The comprehensive extraction technology of flavonoids and polysaccharides from green asparagus was studied. The results showed that the optimal extraction conditions of asparagus flavonoids were ethanol concentration 70%, ratio of material to ethanol of 1:25, temperature 80℃for 2 h (extract twice), the extraction rate of flavonoids was 0.85%. Three times amount of ethanol was added to the flavonoids concentrate and then the mixture was centrifugalized. After the precipitate was vacuum-dried, crude polysaccharides were obtained, the extraction rate of polysaccharides was 1.92%.2. The extracted flavonoids from asparagus were initially purified by macroporous resin. The optimal extracting parameters of sample concentration, eluant concentration and the pH of eluant were investigated. The results demonstrated that:NKA-Ⅱwas better to separate the flavonoids than others. The adsorption capacity and desorption ratio of NKA-Ⅱwere 0.768mg/ml and 77.59%respectively, and the optimal absorption-desorption conditions were sample concentration 0.332mg/ml, ethanol concentration 70%, the pH of eluant 7. The concentration of flavonoids were 60.7%after purification. Protein was removed from the extracted solution by adding 1.0% trichloroacetic acid (TCA). The decolorization of asparagus polysaccharides with active carbon were studied. The optimal decolorization conditions were time 5min and the amount of active carbon 0.1%.3. In vitro, it was shown that the asparagus flavonoids were found to have significant capacity of scavenging free radicals in a concentration of dose-dependent manner. The scavenging effects on superoxide anion free radical by flavonoids with the concentration of 2.5mg/ml were equal to the concentration of 0.05mg/ml ascorbic acid, and on hydroxyl free radical by flavonoids with the concentration of 10mg/ml were equal to the concentration of 2.5mg/ml ascorbic acid. The scavenging effects on superoxide anion free radical and hydroxyl free radical by ascorbic acid were better than asparagus flavonoids.4. The polysaccharides of asparagus on reactive oxidative free radical were studied. In vitro, it was shown that the polysaccharides were found to have significant capacity of scavenging free radicals in a concentration of dose-dependent manner. The scavenging effects on superoxide anion free radical by polysaccharide with the concentration of 10mg/ml were equal to the concentration of 0.02mg/ml, and on hydroxyl free radical by polysaccharide with the concentration of 10mg/ml were equal to the concentration of 2mg/ml ascorbic acid. The scavenging effects on superoxide anion free radical and hydroxyl free radical by ascorbic acid were better than asparagus polysaccharides.5. The interaction between rutin and asparagus polysaccharides was investigated by Ultra-violet and visible spectroscopy, Circular Dichroism spectroscopy and fluorescence spectroscopy. It was shown that the hydrogen bonding interaction was possibly between rutin and asparagus polysaccharide.