Studies On Separation Of Neuroprotective Components From Fructus Alpinia Oxyphyllea And Their Activities

Fructus Alpinia Oxyphyllae is the dry fruit of Alpinia Oxyphylla Miq. (Zingiberaceae), an important traditional Chinese herbal medicine with a history of thousands of years. It has been widely used as a tonic, aphrodisiac, anti-salivation, anti-polyuria, and anti-diarrhea according to the Chinese Pharmacopoeia.Through bioassay-guided fractionation way, the ethanol extract of Fructus Alpinia Oxyphyllae was extracted with petroleum ether, chloroform, ethyl acetate, n-butanol according to the different polarity of solvent, the extracts of petroleum-ether phase(ASP) chloroform phase(ASC) ethyl-acetate phase(ASE) n-butanol phase(ASB) and water phase(ASW) were obtained respectively. We studied the antioxidant activities of these five extracts in the cell-free system, finding that ASC ASE ASB and ASW can scavenge DPPH free radicals to the certain extent, while ASE showed the best effect. Based on chemical and spectroscopic data, ASE was successively separated, a phenolic compound was isolated and identified as protocatechuic acid (PCA).PC 12 cells attacked by hydrogen peroxide (H2O2) were designated as the model by which the protective effects of the five extracts and PCA on the cell damages from reactive oxygen species (ROS) were investigated. Lactate dehydrogenase (LDH) assay was used to investigate the effects of PCA on cell membrane structures. The experiment results indicated that ASE and PCA protected PC 12 cells against oxidative toxicity significantly, which may be mediated by stabilizing the cell membrane structures.Aged rats were injected intraperitoneally with PCA at a dose of 5 mg/kg per day for 7 days, behavioral testing was performed in Y-maze. In order to make clear the neuroprotective mechanism of PCA, the activities of endogenous antioxidants and the content of lipid peroxide in brain were assayed. The results proved that PCA improved the cognition of aged rats, reduced the content of lipid peroxide, increased the activity of glutathione peroxidase. All these suggested that PCA was a potential neuroprotective agent and its neuroprotective effects were achieved at least partly by promoting endogenous antioxidant enzymatic activities and inhibiting free radical generation.Aged rats were injected intraperitoneally with PCA at single doses of 5 mg/kg (low dose) or 10 mg/kg (high dose) per day for 7 days. The splenic weights were observed. The activitiesof endogenous antioxidants and the content of lipid peroxide in spleen and liver were assayed. The results proved that PCA significantly elevated the splenic weights, increased the activities of GSH-PX and CAT, decreased MDA level of aged rats. All these suggested that PCA was a potential anti-aging agent and its effects on spleen and liver were achieved at least partly by promoting endogenous antioxidant enzymatic activities and normalizing age-associated alterations.