| Schizophyllan is a neutral extracellular polysaccharide secreted by Schizophyllum commune,with anti-tumor,immunomodulatory,anti-inflammatory,antibacterial activity,moisture retention and other biological activities.It leads to a lower bioavailability and a restriction on the application of schizophyllan because of its high molecular weight,high viscosity,poor solubility in water.The research on the carboxymethyl modification of schizophyllan and antioxidant activity and moisturizing activity of modified polysaccharide were studied,which provided the theoretical basis and reference for the application of schizophyllan in cosmetics.The molecular weight classification of the schizophyllan from deep fermentation was studied by ultrafiltration membrane with different molecular weight cut-offs.The effects of ultrafiltration pressure,temperature and time on the membrane flux were studied.The results showed that under the conditions of the membrane pressure of 1 bar,the temperature of 25 ? and the time of 60 min,the higher membrane flux was obtained.The content of polysaccharide with above 500 ku of molecular weight accounted for 43%,between 500 and 200 ku for 24.6%,between 200 and 100 ku for 6.85%,and below 100 ku for 3.54%.In the isopropanol medium,with sodium hydroxide and chloroacetic acid,the carboxymethyl modification of schizophyllan was studied.The modification process was optimized by using the response surface method,to research the effect of the reaction conditions on the degree of substitution(DS)of the carboxymethyl.The results showed that under the conditions of the ratio of chloroacetic acid to schizophyllan 2.38:1,the reaction temperature 61.6 ?,the reaction time 2.8 hours,the maximum degree of substitution 0.54 was obtained.The result of solubility experiment showed that water solubility of modified schizophyllan increased greatly.DPPH method and ORAC method were used to investigate the antioxidant activity of carboxymethyl schizophyllan(CM-SPG)with different molecular weight and degree of substitution.The results showed that the antioxidant activity of CM-SPG was negatively correlated with the molecular weight,and was positively correlated with the degree of substitution of carboxymethyl.When the molecular weight of the CM-SPG with DS of 0.52 were above 500 ku,between 500 and 200 ku,between 200 and 100 ku,the EC50 value of DPPH radical scavenging of carboxymethyl schizophyllan were 9.02 mg/m L,5.89 mg/m L and 3.53 mg/m L respectively,and the ORAC value of carboxymethyl schizophyllan were(1804.6±143.6)?mol Trolox /100 g,(3087.6±210.8)?mol Trolox /100 g and(4275.4±245.6)?mol Trolox /100 g,respectively.The moisture absorption and moisture retention activity of carboxymethyl schizophyllan in vitro by weighing method was investigated,and the results showed that under the conditions of the relative humidity 43% and 81%,the moisture absorption of CM-SPG was obviously higher than that of the SPG,better than that of the glycerol(Gl)and hyaluronic acid(HA);in the dry silica gel environment,the moisture retention of CM-SPG was weaker than that of SPG,superior to that of HA;in relative humidity 43%,the moisture retention of CM-SPG was superior to all but glycerol.The surface instrument method was used to evaluate the moisturizing activity of carboxymethyl schizophyllan by using the skin hydration degree tester,the skin moisture evaporation tester and the skin elasticity tester.The results showed that the moisture retention of CM-SPG increased first and then decreased with the DS of carboxymethyl,and it had a better moisturizing property when the DS was 0.45.Compared with the traditional moisturizing agent glycerol and hyaluronic acid,CM-SPG was better than HA in the skin hydration,but less than glycerol,and CM-SPG was better than HA and Gl in skin barrier.The moisture retention of the essence and lotion of CM-SPG was better than that of HA.Schizophyllan is a kind of potential moisturizing agent with significant moisturizing effect. |
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