The total triterpenoid saponins of Xanthoceras sorbifolia improve learning and memory impairments through against oxidative stress and synaptic damage.

BACKGROUND: X. sorbifolia is a widely cultivated ecologicalcrop in the north of China which is used to produce biodiesel fuel. It also possesses special medicinal value and has attracted keen interests of researchers to explore its bioactivity. PURPOSE: To extract the total triterpenoid saponins from the husk of X. sorbifolia (TSX) and investigate its effects on Alzheimer's disease (AD). STUDY DESIGN: TSX was prepared via modern extraction techniques. Its effects on two AD animal models, as well as the preliminary mechanism were investigated comprehensively. METHODS: The behavioral experiments including Y maze test, Morris water maze test and passive avoidance test were performed to observe the learning and memory abilities of the animals. ELISA assays, transmission electron microscope observation and Western blotting were employed in mechanism study. RESULTS: TSX, the main composition of X. sorbifolia, accounted for 88.77% in the plant material. It could significantly increase the spontaneous alternation in Y maze test (F (6, 65)=3.209, P<0.01), prolong the swimming time in the fourth quadrant in probe test of Morris water maze test (F (6, 71)=4.019, P<0.01), and increase the escape latency in passive avoidance test (F (6, 65)=3.684, P<0.01) in AD model animals. The preliminary mechanism research revealed that TSX could significantly increase the contents of hippocampal Ach and ChAT, and enhance activity of ChAT in hippocampus of quinolinic acid injected rats (F (5, 61)=3.915, P 0.01; F (5, 61)=3.623, P<0.01, F (5, 61)=4.344, P<0.01, respectively). It could also increase the activities of T-AOC and T-SOD, and decrease the content of MDA in hippocampus of Aß1-42 injected mice (F (5, 30)=5.193, P<0.01, F (5, 30)=2.865, P<0.05, F (5, 30)=4.735, P<0.01, respectively). Moreover, it significantly increased the expressions of SYP, PSD-95 and GAP-43 in hippocampus (F (4, 27)=3.495, P<0.05; F (4, 27)=2.965, P<0.05; F (4, 27)=4.365, P<0.01, respectively), and improved the synaptic ultra-structure damage in model rats. CONCLUSION: TSX could significantly improve the impairments of learning and memory. The preliminary mechanism might associate with its protection effects against oxidative stress damage, cholinergic system deficiency and synaptic damage. TSX are perfectly suitable for AD patients as medicine or functional food, which would be a new candidate to treat AD.

Xanthoceraside ameliorates mitochondrial dysfunction contributing to the improvement of learning and memory impairment in mice with intracerebroventricular injection of aß1-42.

The effects of xanthoceraside on learning and memory impairment were investigated and the possible mechanism associated with the protection of mitochondria was also preliminarily explored in Alzheimer's disease (AD) mice model induced by intracerebroventricular (i.c.v.) injection of Aß1-42. The results indicated that xanthoceraside (0.08-0.32 mg/kg) significantly improved learning and memory impairment in Morris water maze test and Y-maze test. Xanthoceraside significantly reversed the aberrant decrease of ATP levels and attenuated the abnormal increase of ROS levels both in the cerebral cortex and hippocampus in mice injected with Aß1-42. Moreover, xanthoceraside dose dependently reversed the decrease of COX, PDHC, and KGDHC activity in isolated cerebral cortex mitochondria of the mice compared with Aß1-42 injected model mice. In conclusion, xanthoceraside could improve learning and memory impairment, promote the function of mitochondria, decrease the production of ROS, and inhibit oxidative stress. The improvement effects on mitochondria may be through withstanding the damage of Aß to mitochondrial respiratory chain and the key enzymes in Kreb's cycle. Therefore, the results from present study and previous study indicate that xanthoceraside could be a competitive candidate for the treatment of AD.

Steroidal glycosides from Reineckia carnea herba and their antitussive activity.

Two new steroidal glycosides, 1α,3α-dihydroxy-5ß-pregn-16-en-20-one 3-O-α-L-rhamnopyranoside (1) and 1ß,3ß,27-trihydroxycholest-16-en-22-one 1,3-di-O-α-L-rhamnoside (2), along with seven known steroidal glycosides (3-9), were isolated from Reineckia carnea herba. Their structures were determined by detailed analysis of their 1D- and 2D-NMR and MS spectra. Compound 9 was isolated for the first time from the Reineckia genus. Except for 8, compounds 2, 3, 4, 5, 6, 7, and 9 displayed clear in vitro antitussive activity.

Saponins with neuroprotective effects from the roots of Pulsatilla cernua.

Four new oleanene-type triterpenoid saponins together with six known saponins were isolated from the roots of Pulsatilla cernua and their structures were elucidated on the basis of spectroscopic data, including 2D NMR spectra and chemical evidence. Among these one of the aglycones (gypsogenin) is reported for the first time from this genus. Some of these compounds showed significant neuroprotective effects against the cytotoxicity induced by ß-amyloid(25-35) (Aß(25-35)) on human neuroblastoma SH-SY5Y cells.

Silibinin attenuates cognitive deficits and decreases of dopamine and serotonin induced by repeated methamphetamine treatment.

Cognitive deficits are a core feature of patients with methamphetamine (METH) abuse. It has been reported that repeated METH treatment impairs long-term recognition memory in the novel object recognition test (NORT) in mice. Recent studies indicate that silibinin, a flavonoid derived from the herb milk thistle, has potent neuroprotective effects in cell cultures and several animal models of neurological diseases. However, its effect on the cognitive deficit induced by METH remains unclear. In the present study, we attempt to clarify the effect of silibinin on impairments of recognition memory caused by METH in mice. Mice were co-administered silibinin with METH for 7 days and then cognitive function was assessed by NORT after 7-day withdrawal. Tissue levels of dopamine and serotonin as well as their metabolites in the prefrontal cortex and hippocampus were measured 1 day after NORT. Silibinin dose-dependently ameliorated the impairment of recognition memory caused by METH treatment in mice. Silibinin significantly attenuated the decreases in the dopamine content of the prefrontal cortex and serotonin content of the hippocampus caused by METH treatment. We also found a correlation between the recognition values and dopamine and serotonin contents of the prefrontal cortex and hippocampus. The effect of silibinin on cognitive impairment may be associated with an amelioration of decreases in dopamine and serotonin levels in the prefrontal cortex and hippocampus, respectively. These results suggest that silibinin may be useful as a pharmacological tool to investigate the mechanisms of METH-induced cognitive impairments.

Anti-inflammatory activity of 21(alpha, beta)-methylmelianodiols, novel compounds from Poncirus trifoliata Rafinesque.

The fruits of Poncirus trifoliata (L.) are widely used in Oriental medicine as a remedy for allergic inflammation. As a part of our program to screen medicinal plants for potential anti-inflammatory compounds, 21alpha-methylmelianodiol (21alpha-MMD) and 21beta-methylmelianodiol (21beta-MMD), which are two isomers of 21-methylmelianodiol isolated from the fruits of P. trifoliata for the first time, were found to inhibit nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. 21alpha-MMD and 21beta-MMD attenuated LPS-induced inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2 protein expressions as well as the mRNA levels of iNOS, COX-2, tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta). To investigate the mechanism involved, we examined the effect of 21alpha-MMD and 21beta-MMD on LPS-induced nuclear factor-kappaB (NF-kappaB) activation. Both 21alpha-MMD and 21beta-MMD significantly inhibited LPS-induced NF-kappaB transcriptional activity in RAW 264.7 macrophages. Moreover, the in vivo anti-inflammatory effect of 21alpha-MMD was examined in two mouse models of acute inflammation. In the carrageenan-induced paw edema model, administration of 21alpha-MMD (20 and 100 mg/kg, i.p.) dose-dependently reduced paw swelling. In addition, 21alpha-MMD significantly inhibited the dye leakage in an acetic acid-induced vascular permeability assay. Taken together, our data indicate that 21-methylmelianodiol is an important constituent of the fruit of P. trifoliata, and that the inhibition of iNOS and COX-2 expression by 21alpha-MMD and 21beta-MMD might be one of the mechanisms responsible for their anti-inflammatory effects.

A cell-based model of alpha-synucleinopathy for screening compounds with therapeutic potential of Parkinson's disease.

AIM: To develop a cell-based model by stable transfection of SH-SY5Y with mutant A53T human alpha-synuclein, recapitulating neurotoxicity of alpha -synuclein overexpression. METHODS: The overexpression of mutant alpha -synuclein was analyzed by Western blotting, immunocytochemistry, and RT-PCR. Cell viability was processed when treated with different concentrations of 1-methyl-4-phenylpyridinium (MPP+) and exogenous dopamine (DA) for 24, 48, and 72 h by 3-(4,5- dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Early apoptosis and late apoptosis/necrosis were analyzed by flow cytometry using Annexin V and propidium iodide double staining, respectively. DNA was isolated and applied to agarose gel for electrophoresis; the typical DNA "ladder"represented severe apoptosis. We also used this model to screen 99 compounds with therapeutic potential by MTT assay. RESULTS: One of the stably-transfected clones overexpressed exogenous genes on both the protein level and the transcriptive level. Significant differences in cytotoxicity were found between the pcDNA3.1(+) group and the pcDNA3.1(+)-hm alpha-synuclein group in the presence of the same concentration of MPP+ and DA within the same incubation time. The level of either early apoptosis or late apoptosis/necrosis was remarkably increased in transfected cells compared with the control after treatment with 100 micromol/L MPP+ for 24 h. In addition, the presence of the typical DNA "ladder" was observed in the pcDNA3.1(+)-hm alpha-synuclein group when treated with 200 micromol/L MPP+ for 48 h. After the screening experiment, 12 of the 99 compounds were found to decrease DA-induced cytotoxicity on cell viability. CONCLUSION: We established a cell-based model which is useful for studying the function of alpha-synuclein and screening compounds with therapeutic potential. In addition, it was identified that cells overexpressing A53T mutant alpha-synuclein were significantly vulnerable against MPP+ or dopamine exposures.

The protective effects of phenolic constituents from Gastrodia elata on the cytotoxicity induced by KCl and glutamate.

Seven phenolic compounds (1-7) were isolated from the tubers of Gastrodia elata. Their structures were elucidated on the basis of MS and NMR spectral data. p-Ethoxymethyl phenyl-O-beta-D-glucoside (1) was proved to be a new compound, with N-(p-hydroxybenzyl)-adenosine (7) isolated from this plant for the first time. In this study, the protective effects of the six constituents (1-6) on PC12 cells against the cytotoxicity induced by KCl and glutamate were also investigated. The viability of the PC12 cells was significantly enhanced by pretreatment with the six phenolic constituents.