Synthesis Process Optimization Of L-Selenocysteine And Extraction Of Natural Selenium Polysaccharide From Malt

Selenium is one of the 14 essential trace elements known to the human body,among which selenium substituted amino acids and selenium polysaccharides are common selenium additives and have become a hot topic in the field of selenium research in recent years.Selenocysteine is the 21^stkind of amino acid encoded by the gene,which provids the selenoprotein needed by the human body.Selenium polysaccharide has the advantages of low toxicity,small side effects,easy absorption,etc.At the same time,L-SeC and selenium polysaccharide have good pharmacological effects.On the basis of existing methods,this study optimized the synthesis process of L-SeC and the extraction process of natural malt selenium polysaccharides,making the two processes have advantages such as low cost,simple reaction operation,and mild conditions,laying the foundation for their industrial production.Review the existing synthesis routes and preparation methods,optimize the various conditions of the routes and methods through single factor experiments,obtain the optimal synthesis and extraction process,and then conduct repeated experiments to verify its stability.（1）For the synthesis of L-SeC,flammable and explosive sodium borohydride or potassium borohydride are generally used.The source of raw materials is inconvenient,and a large number of toxic gases are generated.Therefore,safer and mild sodium bisulfite formaldehyde and sodium triacetoxy group borohydride are selected to replace them.This method is easy to obtain raw materials,easy to operate,low cost,mild reaction,and easy to scale up production.Then optimize the synthesis process based on single factor experiments.（2）Natural malt selenium polysaccharides were extracted from selenium rich malt using water extraction and alcohol precipitation method.Single factor experiments were conducted to investigate the effects of extraction time,extraction temperature,extraction frequency,and liquid-solid ratio on the yield of polysaccharides.The optimal extraction process was determined,and then elemental selenium and inorganic selenium were used to selenify natural malt selenium polysaccharides.The optimized synthesis process of L-SeC is as follows:reacting sodium bisulfite formaldehyde with selenium powder and sodium hydroxide to generate Na₂Se₂solution,n（sodium bisulfite formaldehyde）:n（selenium powder）:n（Na OH）=28:10:8,reaction temperature 65℃,reaction time 1.5 hours;3-Chloro-L-alanine hydrochloride undergoes hydrolysis reaction with the prepared Na₂Se₂solution to obtain L-SeC₂in a yield of 74.4%.Then L-SeC₂was reacted with sodium tri acetoxy group borohydride to obtain L-SeC,n（sodium tri acetoxy group borohydride）:n（L-SeC₂）=27:10,reaction temperature 40℃,reaction time 30 min,yield 77.1%.（2）The optimal extraction process for natural malt selenium polysaccharides is as follows:extraction time 1.5 hours,extraction temperature 90℃,extraction times 3 times,liquid to material ratio 5:1.The optimal decolorization conditions are:the amount of activated carbon is 0.50 g,the decolorization temperature is 60℃,and the decolorization time is 1 hour.Under this process,the yield of polysaccharides is 86.0%.The selenium content of natural malt selenium polysaccharides was determined to be 96.18μg/g using an atomic fluorescence spectrometer,and then the dried natural malt selenium polysaccharides were selenified using the HNO₃-Na₂Se O₃method.The selenium content of selenified malt polysaccharides was 783.32μg/g.The L-SeC synthesis scheme and natural maltose polysaccharide preparation process obtained in this study are stable,reliable,and easy to separate.The entire process is simple,with good reproducibility,and suitable for the industrial production of L-SeC and natural maltose selenium polysaccharides.