| By means of monothetic and orthogonal test, the optimum extraction conditions of corn silk bioactive substances(corn silk saponins, corn silk flavonoids, corn silk polysaccharide) were determined in the study. The optimum conditions of corn silk saponins were obtained as follows:80% ethanol as extraction solvent at 70℃for 3h, and the ratio of material to solvent was 1:25, the extraction ration under the optimum conditions was 2.41%. The optimal technics parameters were as following: adding 40% ethanol at 80℃with material/solvent ratio 1:30 for 2h, the extraction efficiency of the flavoniods was 1.67%. The optimal parameters of extracting corn silk polysaccharide by water were as following:material/solvent ratio 1:30, extarcting 3.h at 90℃. The extracting rate reached 4.76%.In this article, determination of corn saponins is analyzed firstly. In the experiment, we optimize the determination systems and conditions. Experimental results revealed that the optimal conditions in the vanillin-perchloriacid method: 0.2mL of freshly prepared 7% vanillin in acetic solution and 0.8mL of perchloric acid was added. Then the mixture was warmed up in a water bath at 70℃for 20 min. After cooling down,5mL ethvle acetate was added in and well shaking, the samples were measured colorimetrically atλ= 540nm. The regressive equation was y=0.0073x+0.0172, R2= 0.9904, the calibration curves was highly significant, linear and stable. The average recovery was 100.3% and RSD=1.11%. The method was accurate, reproducible and could be used to determine the content of saponins from corn silk.Study on acute toxic effects in mice after different doses of the corn silk bioactive substances were given in mice. LD50 was measured by using Horn's method, as a result, LDso>21.50g/kg, this revealed that corn silk bioactive substances are all secure and avirulent. The ability to scavenging DPPH free radicals and the ferric reducing power assay was used to measure the antioxidant capability of the three bioactive substances. The ability of scavenging the DPPH free radicals of corn silk flavonoids was up to 77.18%, while corn silk polysaccharide was 60.24% and corn silk saponins was up to 90.39%. The FRAP value was 271.65 (corn silk flavonoids),691.04 (corn silk polysaccharide) and 462.52 (corn silk saponins). It was first found that corn silk polysaccharide and corn silk saponins both have strong antioxidant ability, what's more, corn silk saponins have stronger scavenging activity to DPPH free radicals and higher level of total antioxidant activity than corn silk polysaccharide and corn silk flavonoids in this study.Meanwhile the bacteriostasis effects and the quality of antimutagenesis were studied in this paper. The results showed that corn silk bioactive substances have strong bacteriostasis effects against Staphylococcus aureus. Its minimal inhibitory concentration to Staphylococcus aureus was 0.8g/mL. The present study clearly demonstrated that corn silk bioactive substances could inhibit mutagenicity of both Fenaminosulf to TA98 and Sodium azide to TA100 directly. The above studies can provide references for application and exploration of corn silk resouces and theoretics gist for exploration of corn silk functional products. |
