Study On Preparation Technology And Antioxidant Activity Of Polysaccharides From Dendrocalamus Latiflorus Munro Leaves In Chishui County

There are many studies have shown that bamboo leaves are rich in flavonoids,polysaccharides,terpenes,proteins,and a variety of minerals and trace elements.Among them,bamboo leaf polysaccharides are effective in anti-fatigue,hypoglycemic,anti-oxidation,and anti-tumor properties.Chishui County is rich in bamboo resources,and the development and utilization of bamboo resources has a certain scale.In order to promote the further development of the bamboo industry in Chishui County,this paper mainly studies Dendrocalamus latiflorus Munro,which has abundant production in Chishui County.Taking the leaves of Dendrocalamus latiflorus Munro after degreasing extraction with high concentration ethanol as raw material to explore hot water reflux extraction,ultrasonic-assisted extraction,and microwave-assisted extraction.The optimum extraction conditions were obtained,and the amplification process of hot water reflux extraction was explored.Separation and purification of Polysaccharides from Dendrocalamus latiflorus Munro leaves through water extraction and alcohol precipitation,chemical method,crude cellulose column separation,semi-permeable membrane dialysis and gel chromatography filtration.Using ultraviolet spectrophotometer,infrared spectrometer,gel chromatography and other analytical instruments to preliminary characterized the structural characteristics of the polysaccharides from Dendrocalamus latiflorus Munro leaves.In addition,the antioxidant properties of Polysaccharides were also explored.The main conclusions are as follows:1.Three different test methods were used to extract polysaccharides from defatted Dendrocalamus latiflorus Munro leaves.Both hot water reflux extraction and microwave-assisted extraction selected material-to-liquid ratio,extraction temperature,and extraction time as three factors to optimize three-level response surface.The conditions were optimized based on the extraction yield of bamboo leaf polysaccharides.The optimal extraction process conditions of bamboo leaf polysaccharides were as follows.Hot water reflux extraction method:material-to-liquid ratio 1:25 g/m L,extraction temperature 88°C,extraction time 150min,under these extraction conditions,the extraction yield of polysaccharides was1.12%.Microwave-assisted extraction method:The material-liquid ratio was 1:27g/m L,the extraction time was 42 min,and the extraction temperature was 80°C.Under this technological condition,three parallel tests were carried out.The average extraction yield of polysaccharides was 1.62%.The ultrasonic-assisted extraction method used the material-liquid ratio,ultrasonic temperature,ultrasonic time,and ultrasonic power as four single factors.Based on the single factor test,the Design Expert software was used to optimize the response surface design of four factors and three levels.Combined with the actual operating conditions,the best extraction process was obtained:The liquid ratio was 1:25 g/m L,the extraction temperature was69°C,the extraction time was 39 min,and the ultrasonic power was 300 W.Under these conditions,the extraction yield of polysaccharides was 2.26%.Besides,the scale-up process research was carried out on the basis of a small test of hot water reflux extraction.The results showed that 15 kg of defatted bamboo leaves were used as raw materials,a 400 L multifunctional extraction tank was used,the material-to-liquid ratio was 1:18 kg/L,the extraction temperature was 80°C,and the extraction time was 120 min,and the extraction was performed 3 times.At this time,the extraction yield of polysaccharides was 0.56%.The pilot test had laid a certain scientific basis for the industrialization of the extraction process of polysaccharides from bamboo leaves.2.Using activated carbon method combined with polyamide method for decolorization,Sevage method（n-butanol/chloroform=1:4,V/V）for deproteinization.The structure of the polysaccharides from Dendrocalamus latiflorus Munro was characterized by ultraviolet and infrared spectroscopy.The results showed that the preliminarily purified polysaccharides were basically free of nucleic acid and protein.The infrared spectrum showed that the Dendrocalamus latiflorus Munro leaf polysaccharides might be pyran-type polysaccharides.The characteristic peak at 798cm^-1indicated that the polysaccharides may contain mannose.3.The crude polysaccharides from Dendrocalamus latiflorus Munro leaves were fractionated and refined by cellulose column chromatography to obtain four polysaccharide components.The four polysaccharides components were further separated and purified by Sephadex G-150 dextran gel with H₂O,0.1M,0.3M Na Cl solution elution.The GPC test results showed that they were homogeneous polysaccharides with peak molecular weights of 122357,84566,and 56443,respectively.4.A preliminary study on the in vitro antioxidant activity of Polysaccharides from Dendrocalamus latiflorus Munro had shown that the polysaccharides have strong antioxidant capacity.When the concentration reaches 5.0 mg/m L,the scavenging ability of DLP to DPPH free radicals was basically the same as that of Vc;The scavenging ability of polysaccharides from Dendrocalamus latiflorus Munro leaves to hydroxyl free radicals can reach 65%of that of Vc when the concentration of polysaccharide was 5.0 mg/m L;The scavenging activity of superoxide anion free radicals was low,within the chosen concentration range,the clearance rate was less than 50%.The purified DLP-A1 had good antioxidant activity.When the concentration reaches 1.0 mg/m L,the scavenging ability of DPPH free radical was higher than that of Vc,and the scavenging ability of hydroxyl free radical and superoxide free radical was higher than that of crude polysaccharide.In summary,three methods were used to extract polysaccharides from defatted leaves of Dendrocalamus latiflorus Munro,and a series of methods were used to purify the polysaccharides.The structure of the purified polysaccharides was characterized,and the in vitro antioxidant capacity of Polysaccharides from leaves of Dendrocalamus latiflorus Munro was also studied.The results can provide theoretical basis and data support for the further processing and utilization of Dendrocalamus latiflorus Munro leaf resources,and have important guiding significance for the comprehensive utilization of bamboo raw materials and the further upgrading and development of bamboo industry in Chishui area.