| Summary: | 博士 === 中國醫藥大學 === 中國藥學暨中藥資源學系博士班 === 101 === This study intended to assess the neuroprotective effect of yam (Dioscorea japonica Thunb. var. pseudojaponica (Hay.) Yamam.) and diosgenin on the senescent mice induced by D-galactose.The study intend to assay the antioxidative capacity and antioxidative component of yam in vitro experiments.The mice in the experiments were administered orally with yam (20, 100 or 500 mg/kg for 4 weeks, from the sixth week) or diosgenin (1, 5, 25 and 125 mg/kg, 4 weeks, from sixth week).The learning and memory abilities of the mice in Morris water maze test and the mechanisms involved in the neuroprotective effect of yam or diosgenin on the mice brain tissue were investigated. The content of diosgenin in the yam was also detected by using HPLC.
This study intended to explore the antioxidative component analysis of yam(total polyphenols,flavonoids,and flavonols assay),the antioxidative capacity of yam(Trolox total antioxidative capacity, FRAP antioxidative capacity determination, DPPH radical scavenging assay).The yam was found to possess antioxidative activity in vitro experiments.Diosgenin did not possess antioxidative activity.Mice treated withyamor diosgenin (5, 25 and 125 mg/kg, p.o.) were found to significantly improved their learning and memory abilities in Morris water maze test compared to those treated with D-gal (200 mg/kg for 10 weeks). In addition, yam or diosgenin (5, 25 and 125 mg/kg, p.o.)were also found to increase the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) and decreased the malondialdehyde (MDA) level on the brain of D-gal treated mice. Finally the amount of diosgenin in the yam is 5.49 mg/ g extract.
To sum up, the results indicated that the antioxidative activities of yam was related to polyphenols. Diosgenin did not possess antioxidative activity.Yam or diosgenin had the potential to be a useful treatment for cognitive impairment in TCMs. Its beneficial effect may be partly mediated via enhancing endogenous antioxidant enzymatic activities.
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