Extraction Optimization Of Paramylon And Its Antioxidant Activity In Vitro

Paramylon not only accounts for a large proportion of dry cell weight,but also is the most important energy storage material in Euglena.As a biologically active substance,paramylon has gradually become one of the research hotspots in recent years.Paramylon have many activities,such as antiviral,hypoglycemic,lipid-lowering,anti-tumor and immune-enhancing functions.They have been fully studied in the fields of food,medicine,health care,cosmetics,biofuels,feed,etc.Paramylon have been included in the ranks of new food ingredients.However,there are few articles on the extraction of paramylon and the determination of antioxidant activity in vitro.In order to make better use of paramylon and provide a theoretical basis for its development and utilization in the market,Euglena viridis and E.gracilis were used as experimental materials in this paper to explore the growth cycle of E.gracilis;the conditions for alkaline extraction of paramylon were optimized and the antioxidant activity of paramylon in vitro was determined.The specific results are as follows:(1)The purchased E.gracilis is cultured,and when it is expanded to 1 L,the biomass of E.gracilis is measured,including daily cell density,dry weight,absorbance and the concentration of chlorophyll a,chlorophyll b,total chlorophyll and carotenoid.By recording these data,the growth cycle of E.gracilis was determined to be 9d.(2)The cultured E.viridis and the E.gracilis are lyophilized and harvested,then the paramylon is extracted.Based on the single factor test of the effect of Na OH concentration,extraction time and extraction temperature on the yield of paramylon,the three levels of these three factors were determined and then responded with Design-Expert 8.0.6.1 software.The design of the Box-behnken center was carried out to optimize the extraction process of the alkaline paramylon.The optimum level of extracting paramylon was: extraction time 1.5 h,Na OH concentration 0.7 mol/L,and alkali extraction temperature 40 ?,under this condition,the yield ofparamylon from E.gracilis was 20.57%;the optimum level of extracting E.viridis polysaccharides was also determined: extraction time 3 h,Na OH concentration 0.6 mol/L,extraction temperature 50 ?,under this condition,the actual yield of paramylon was 42.35%,which was 5.42% and 16.22%higher than the traditional method of extracting paramylon.(3)Determination of the antioxidant activity of the extracted paramylon in vitro.The potassium ferricyanide reduction method,DPPH method and salicylic acid colorimetric method were used to determine the reducing power of paramylon and the scavenging ability of DPPH free radicals and hydroxyl radicals(·OH).At the same time,ascorbic acid was used as the positive control.The semi-inhibitory mass concentration(IC50)of DPPH free radicals and ·OH was reduced by 0.3 mg/m L and 0.1 mg/m L,respectively.It was confirmed that paramylon had good antioxidant capacity in vitro.In summary,the growth cycle of E.gracilis is relatively short.The extraction of paramylon by alkaline extraction method actually improves the paramylon yield compared with the traditional method,and the extracted paramylon has better antioxidant activity in vitro,which provides a good theoretical basis for the practical application of paramylon.