Protective Effects of Compounds from Cimicifuga dahurica against Amyloid Beta Production in Vitro and Scopolamine-Induced Memory Impairment in Vivo.

Cimicifuga dahurica has traditionally been used as an antipyretic, analgesic, and anti-inflammatory agent and as a treatment for uterine and anal prolapse. This study has investigated the potential beneficial effects of this medicinal plant and its components on Alzheimer's disease (AD) with a focus on amyloid beta (Aß) production and scopolamine-induced memory impairment in mice. An ethanol extract from C. dahurica roots decreased Aß production in APP-CHO cells [Chinese hamster ovarian (CHO) cells stably expressing amyloid precursor protein (APP)], as determined by an enzyme-linked immunosorbent assay and Western blot analysis. Then, the compounds isolated from C. dahurica were tested for their antiamyloidogenic activities. Four compounds (1-4) efficiently interrupted Aß generation by suppressing the level of ß-secretase in APP-CHO cells. Moreover, the in vivo experimental results demonstrated that compound 4 improved the cognitive performances of mice with scopolamine-induced disruption on behavioral tests and the expression of memory-related proteins. Taken together, these results suggest that C. dahurica and its constituents are potential agents for preventing or alleviating the symptoms of AD.

Anti-Amyloidogenic Effects of Asarone Derivatives From Perilla frutescens Leaves against Beta-Amyloid Aggregation and Nitric Oxide Production.

Alzheimer's disease (AD) is a progressive, neurodegenerative brain disorder associated with loss of memory and cognitive function. Beta-amyloid (Aß) aggregates, in particular, are known to be highly neurotoxic and lead to neurodegeneration. Therefore, blockade or reduction of Aß aggregation is a promising therapeutic approach in AD. We have previously reported an inhibitory effect of the methanol extract of Perilla frutescens (L.) Britton (Lamiaceae) and its hexane fraction on Aß aggregation. Here, the hexane fraction of P. frutescens was subjected to diverse column chromatography based on activity-guided isolation methodology. This approach identified five asarone derivatives including 2,3-dimethoxy-5-(1E)-1-propen-1-yl-phenol (1), ß-asarone (2), 3-(2,4,5-trimethoxyphenyl)-(2E)-2-propen-1-ol (3), asaronealdehyde (4), and α-asarone (5). All five asarone derivatives efficiently reduced the aggregation of Aß and disaggregated preformed Aß aggregates in a dose-dependent manner as determined by a Thioflavin T (ThT) fluorescence assay. Furthermore, asarone derivatives protected PC12 cells from Aß aggregate-induced toxicity by reducing the aggregation of Aß, and significantly reduced NO production from LPS-stimulated BV2 microglial cells. Taken together, these results suggest that asarone derivatives derived from P. frutescens are neuroprotective and have the prophylactic and therapeutic potential in AD.

Inhibitory effect of α-amyrin acetate isolated from Fraxinus rhynchophylla on Th17 polarization.

BACKGROUND: T helper 17 (Th17) cells, which are differentiated from CD4+ T cells, drive inflammation, leading to autoimmune diseases such as psoriasis, rheumatoid arthritis, and inflammatory bowel disease. Therefore, inhibiting Th17 polarization could be a therapeutic target for inflammatory diseases. PURPOSE: We investigated the inhibitory effect of Fraxinus rhynchophylla (Oleaceae) on Th17 differentiation and found its active component. STUDY DESIGN: The activity of F. rhynchophylla and its active constituent was verified using CD4+ cells extracted from C57BL/6 mice. METHODS: Micro-environment for Th17 polarization was provided to CD4+ cells and the effect of treatment with samples was measured by enzyme linked immunosorbent assay (ELISA), polymerase chain reaction (PCR), and Western blot. RESULTS: The extract of F. rhynchophylla Hance and its chemical constituent, α-amyrin acetate, which was isolated via bioassay-guided isolation, significantly inhibited Th17 polarization as revealed when interleukin (IL)-17, a characteristic cytokine produced by Th17 cells, was measured. Furthermore, the inhibitory effect of α-amyrin acetate was compared to the amyrin derivatives, α-amyrin and ß-amyrin. All displayed a suppressive effect on Th17 polarization and all reduced the expression of single transducer and activator of transcription 3 (STAT3) and retinoic acid receptor-related orphan receptor γt (RORγt), which are crucial transcription factors regulating Th17 differentiation. α-Amyrin acetate, however, exhibited the most prominent effects, which indicates that the functional group, acetate, might strengthen the inhibitory effect on Th17 differentiation. CONCLUSION: Taken together, these results suggest that the extract of F. rhynchophylla and its active constituent, α-amyrin acetate, could be applied as a potential therapeutic agent for autoimmune disorders such as rheumatoid arthritis.

Phenylpropanoids from cinnamon bark reduced ß-amyloid production by the inhibition of ß-secretase in Chinese hamster ovarian cells stably expressing amyloid precursor protein.

ß-Amyloid (Aß) is a substance of Alzheimer disease (AD), which is generated via the amyloidogenic pathway from amyloid precursor protein (APP) by ß-secretase and γ-secretase. Inhibition of Aß production is a potential therapeutic approach to AD. Thus, we tested the hypothesis that cinnamon bark (Cinnamomi Cortex Spissus), the dried bark of Cinnamomum cassia Blume (Lauraceae), and its constituents are beneficial to AD. The methanol extract of cinnamon bark efficiently reduced Aß40 production in Chinese hamster ovarian (CHO) cells stably expressing APP as determined by enzyme-linked immunosorbent assay. Bioassay-guided isolation of cinnamon bark extract was carried out using open column chromatography and high-performance liquid chromatography, and the following 6 phenylpropanoids were isolated: syringaresinol (1); medioresinol (2); coumarin (3); 2-hydroxycinnamaldehyde (4); cryptamygin A (5); and 3',5,7-trimethoxy epicatechin (6). Among these, 4 µg/mL medioresinol and cryptamygin A reduced Aß40 production by 50% and 60%, respectively, compared with dimethyl sulfoxide-treated control cells. The IC50 values of medioresinol and cryptamygin A for the inhibition of Aß40 production were 10.8 and 8.2 µg/mL, respectively. Furthermore, treatment of APP-CHO cells with either compound decreased the amount of ß-secretase and sAPPß (the proteolytic fragment of APP catalyzed by ß-secretase). These results suggest that the antiamyloidogenic activity of cinnamon bark extract was exerted by medioresinol and cryptamygin A via a reduction in the amount of ß-secretase. The extract of cinnamon bark contains potentially valuable antiamyloidogenic agents for the prevention and treatment of AD.