| Dioscorea opposita is a kind of medical and edible crop. It is reported that dehydroepiandrosterone (DHEA), a hormone derived from Chinese yam, has functions of anti-aging, anti-cancer, anti-obestity and anti-diabetic. Forty-one varieties of Chinese yam from Henan, Fujian, Shangxi, Jiangxi and other places were collected in this study. The results were as follow:1,Optimization of DHEA examination condition and extraction technologyThe optimum conditions of determining DHEA by HPLC were as follow : the wavelength 215 nm, mobile phase(ethanol:water) 75:25, the temperature was 30℃, mobile phase flow rate 0.8 ml/ min."TG-1"was utilized as experimental material to make single factor and orthogonal experiment. The best extraction technology parameters were as follow: using water as fermentation solvent, solid/liquid 1:20, fermented in water bath at 60℃for 48h, adding 2% volume fraction of sulphuric acid, acidolysis at 90℃for 24h, adding 20% NaOH solution to neutralise, drying and grinding to fine powder, petroleum ether soxhlet extraction for 24h, concentrating the extract solution under reduced pressure, settling volume and testing. In this condition, the extraction efficiency of"TG-1"'s DHEA was 5.73mg/100g.2,The study on genetic resources of yam varieties with high DHEA"WK-3"(8.15mg/100g) had the highest DHEA content from root, which was 2.21 times higher than that of"Tiegun No.2"from Henan(control group). In root epidermis, the variety with highest DHEA is"TG-1"(25.63mg/100g), which was 2.03 times higher than"Tiegun No.2"(control group). And"CT yam"had the highest DHEA content from yam bean (scientific name: bubil, reproductive organs of the above ground part, taking 5%-10% of output of root). It was up to 7.57mg/100g, which was 73.23% higher than that of root (4.37mg/100g).3,The anti-tumor experimental study of yam DHEA in vivo.The little mice S180 fleshy tumor model was established, using DHEA standard sample and three varieties of yams with high DHEA, i.e.,"WK-3"(Henan),"CT yam"(Fujian) and"Jiangxi yam"for tumor research. When administered intragastrically with 2.08mg/kg?d, the result showed that the inhibitory rate from"WK-3"DHEA was 34.72% (CTX was49.28%), the highest. Each group could remarkably increase the thymus index and the spleen index of tumor mouse. The"WK-3"increased most. Its thymus index was 3.44mg/g, which was 47.64% higher than control group (2.33mg/g); and its spleen index was 10.58mg/g, which was 28.55% higher than control group (8.23mg/g). All the anti-tumor effects showed does-effect relationship. 4,The anti-oxidant experimental studies of yam DHEA in vivo.Drosophila melanogaster was used as subjects. The effect of"WK-3"(the DHEA concentration was 0.005%, extracting DHEA from 61.35g yam by 100ml culture medium) was the best: the average lifetime of male flies (62.17d) was 14.42% times higher than the control group, and the average maximum longevity of male flies(73.67d) had extended 17.55%; the average lifetime of female flies (65.33d) was 16.46% times higher than the control group, and the average maximum longevity of female flies(76.63d) had extended 20.36%."WK-3"(DHEA concentration:0.005%) could increase the superoxide dismutase(SOD) content and total antioxidation capacity (T-AOC) highest: in male flies, the SOD(4.27U/mg) was 11.58% higher than the control group, the T-AOC(0.56 unit/mg protein) had increased 30.23%; in female flies, the SOD(3.89U/mg) was 15.67% higher than the control group, and the T-AOC(0.51 unit/mg protein) had increased 36.94%."CT yam"(concentration 0.005%) decreased the MDA of male flies most, which was 19.31%."WK-3"(concentration 0.005%) decreased the MDA of female flies most, which was 18.11%.
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