Two new polyacetylenic compounds from Atractylodes chinensis (DC.) Koidz.

Two new polyacetylenic compounds, (6E,12Z)-tetradecadiene-8,10-diyne-1,3-diol (1) and (6Z,12Z)-tetradecadiene-8,10-diyne-1,3-diol (2), were isolated from Atractylodes chinensis (DC.) Koidz. Their structures were established by analysis of spectroscopic data.     

A novel synthetic compound PHID (8-Phenyl-6a, 7, 8, 9, 9a, 10-hexahydro-6H-isoindolo [5, 6-g] quinoxaline-7, 9-dione) protects SH-SY5Y cells against MPP(+)-induced cytotoxicity through inhibition of reactive oxygen species generation and JNK signaling

1-Methyl-4-phenylpyridinium ion (MPP⁺), a neurotoxin selective to dopaminergic neurons and an inhibitor of mitochondrial complex I, has been widely used as an etiologic model of Parkinson's disease. In this study, we investigated the protective effects of a novel synthetic compound, 8-Phenyl-6a,7,8,9,9a,10-hexahydro-6H-isoindolo[5,6-g]quinoxaline-7,9-dione (PHID), on MPP⁺-induced cytotoxicity in SH-SY5Y cells. MPP⁺ induced apoptosis characterized by generation of reactive oxygen species, caspase-3 activation, poly ADP ribose polymerase proteolysis and increase in Bax/Bcl-2 ratio were blocked by PHID in a dose-dependent fashion. Furthermore, MPP⁺-mediated activation of stress-activated protein kinase/c-Jun N-terminal kinase (JNK) was also inhibited by PHID in a dose-dependent manner. The results indicate that PHID protects against MPP⁺-induced apoptosis by blocking reactive oxygen species stimulation and JNK signaling pathways in SH-SY5Y cells, implicating the novel compound in the prevention of progressive neurodegenerative diseases such as Parkinson's disease.     

Protective effect of Chrysanthemum indicum Linne against 1-methyl-4-phenylpridinium ion and lipopolysaccharide-induced cytotoxicity in cellular model of Parkinson’s disease

Chrysanthemum indicum Linn. (CI) has been used in Oriental medicine for several centuries. In the present study, the effect of CI extract was evaluated against 1-methyl-4-phenylpridinium ion (MPP⁺)-induced damage in SH-SY5Y cells and lipopolysaccharide (LPS)-stimulated BV-2 microglial cells. Cell viability, oxidative damage, reactive oxygen species, expression of Bcl-2/Bax, and poly (ADP-ribose) polymerase (PARP) proteolysis were evaluated using SH-SY5Y cells. Production of iNOS, prostaglandin E₂, and pro-inflammatory cytokines like tumor necrosis factor (TNF)-α, interleukin (IL)-1β, interleukin (IL)-6, expression of cyclooxygenase type-2 (COX-2) and type-1 (COX-1) were examined in activated BV-2 microglia. At 1, 10 and 100 μg, CI inhibited cell loss, decreased the reactive oxygen species production, regulated the Bax/Bcl-2 ratio and inhibited PARP proteolysis in MPP⁺-induced SH-SY5Y cells. Furthermore, CI suppressed the production of prostaglandin E_2, expression of cyclooxygenase type-2 (COX-2), blocked IκB-α degradation and activation of NF-κB p65 in BV-2 cells in a dose-dependent manner. The molecular mechanisms involved by CI might involve its inhibitory actions both on neuronal apoptosis and neuroinflammatory NF-κB/IκB-α signaling pathway. The present investigation scientifically supports the long history and safe usage of CI as an important functional food with potential benefits in ameliorating deleterious conditions seen in PD.     

Comparison of cytotoxicity of a quaternary pyridinium metabolite of haloperidol (HP+) with neurotoxinN-methyl-4-phenylpyridinium (MMP+) towards cultured dopaminergic neuroblastoma cells

Haloperidol has recently been found to be metabolized to its pyridinium ion (HP⁺). This conversion of haloperidol to HP⁺ appears to be similar to the activation of the dopaminergic neurotoxinN-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) toN-methyl-4-phenyl pyridinium ion (MPP⁺). MPP⁺ is responsible for the damage of striatal dopaminergic neurons induced by MPTP in humans and animals. It seemed sensible to investigate whether or not HP⁺ might be toxic towards dopaminergic neurons and perhaps associated with some of the residual motofunction side effects of haloperidol. We therefore investigated the neurotoxicity of HP⁺ toward cultured human dopamine neuroblastoma cells (SH-SY5Y) and compared it with that of MPP⁺. HP⁺ reduced the viability as measured by MTT and [³H]thymidine incorporation methods in SH-SY5Y cells. Cell membrane integrity is reduced by the treatment of HP⁺ as measured by intracellular LDH levels. The toxicity was concentration and time dependent. Interestingly, HP⁺ appeared to be more toxic than MPP⁺ towards the SH-SY5Y cells in early phase in cultures. The toxicity of MPP⁺ appear to be progressive and subsequently become more than HP⁺ with prolonged cultivation. In contrary to MPP⁺, the toxic effect of HP⁺ towards a dopamine transporter transfected SK-N-MC cell line is not different from its wild type. This indicates that dopamine uptake system is probably not involved in the cytotoxicity caused by HP⁺.     

Neuroprotective Effect of Astersaponin I against Parkinson’s Disease through Autophagy Induction

An active compound, triterpene saponin, astersaponin I (AKNS-2) was isolated from Aster koraiensis Nakai (AKNS) and the autophagy activation and neuroprotective effect was investigated on in vitro and in vivo Parkinson’s disease (PD) models. The autophagy-regulating effect of AKNS-2 was monitored by analyzing the expression of autophagy-related protein markers in SH-SY5Y cells using Western blot and fluorescent protein quenching assays. The neuroprotection of AKNS-2 was tested by using a 1-methyl-4-phenyl-2,3-dihydropyridium ion (MPP⁺)-induced in vitro PD model in SH-SY5Y cells and an MPTP-induced in vivo PD model in mice. The compound-treated SH-SY5Y cells not only showed enhanced microtubule-associated protein 1A/1B-light chain 3-II (LC3-II) and decreased sequestosome 1 (p62) expression but also showed increased phosphorylated extracellular signal–regulated kinases (p-Erk), phosphorylated AMP-activated protein kinase (p-AMPK) and phosphorylated unc-51-like kinase (p-ULK) and decreased phosphorylated mammalian target of rapamycin (p-mTOR) expression. AKNS-2-activated autophagy could be inhibited by the Erk inhibitor U0126 and by AMPK siRNA. In the MPP⁺-induced in vitro PD model, AKNS-2 reversed the reduced cell viability and tyrosine hydroxylase (TH) levels and reduced the induced α-synuclein level. In an MPTP-induced in vivo PD model, AKNS-2 improved mice behavioral performance, and it restored dopamine synthesis and TH and α-synuclein expression in mouse brain tissues. Consistently, AKNS-2 also modulated the expressions of autophagy related markers in mouse brain tissue. Thus, AKNS-2 upregulates autophagy by activating the Erk/mTOR and AMPK/mTOR pathways. AKNS-2 exerts its neuroprotective effect through autophagy activation and may serve as a potential candidate for PD therapy.     

Mimengosides J and K: two new neuroprotective triterpenoids from the fruits of Buddleja lindleyana

Two new 11-methoxyl substituted triterpenoids, named as mimengosides J (1) and K (2), along with seven known compounds, were isolated from the fruits of Buddleja lindleyana. Their structures were elucidated on the basis of spectroscopic analysis. In addition, the new ones were evaluated for protective effects against damage of SH-SY5Y cells induced by 1-methyl-4-phenylpyridinium ion (MPP⁺) and the results indicated that those may be one of the candidate compositions of Buddleja lindleyana for the treatment of neurodegenerative disease.

     

Two new compounds from a marine-derived Streptomyces sp.

Two new long-chain unsaturated compounds, (2E, 6E)-10-methoxy-3,7-dimethyl-10-oxodeca-2,6-dienoic acid (1) and (2E, 6E)-3,7,11-trimethyldodeca-2,6-dienedioic acid (2), together with seven known compounds were isolated from a marine-derived Streptomyces sp. Their structures were determined by spectroscopic methods, including 2D NMR techniques. Compounds 1 and 2 were investigated for their antibacterial activities.     

Membrane permeability-guided identification of neuroprotective components from Polygonum cuspidatun

Context: Polygonum cuspidatum Sieb et Zucc. (Polygonaceae) possesses various pharmacological activities and has been widely using as one of the most popular and valuable Chinese herbal medicines in clinics. Its usage has increasingly attracted much of our attention and urges investigation on its bioactive components.

Objective: To establish a rapid and valid approach for screening potential neuroprotective components from P. cuspidatum.

Materials and methods: Potential neuroprotective components from P. cuspidatum were screened utilizing liposome equilibrium dialysis followed by high-performance liquid chromatography (HPLC) analysis. Their neuroprotective effects on modulation of protein expression of α7 nAChR, α3 nAChR and synaptophysin (SPY) on SH-SY5Y human neuroblastoma cell line (SH-SY5Y) were evaluated by means of Western blotting.

Results: Two potential compounds, polydatin (C1) and emodin-8-O-β-d-glucoside (C2), were detected and identified in our study. The biological tests showed that both compounds C1 and C2, respectively, at concentrations of 0.1 and 0.25?mg/mL significantly increased protein expression of α7 and α3 nicotinic acetylcholine receptors (nAChRs) in SH-SY5Y cells. Moreover, C1 and C2 at 0.1?mg/mL significantly reversed the Aβ_1-42-induced decrease of α7 and α3 nAChRs protein expression in SH-SY5Y cells. In addition, C2 at 0.1?mg/mL significantly increased protein expression of SPY in SH-SY5Y cells and Aβ_1-42-induced SH-SY5Y cells whereas C1 did not provide any positive effects.

Discussion and conclusion: In conclusion, our approach utilizing liposome equilibrium dialysis combined with HPLC analysis and cell-based assays is a prompt and useful method for screening neuroprotective agents.     

Antioxidant and α-amylase inhibitory activities of extract and isolates from Zygogynum pancheri subsp. arrhantum

One new sesquiterpenoid (5R^*,8R^*,9R^*,10R^*)-cinnamolide (8), and seven known compounds, 5-hydroxy-7-methoxyflavonone (1), 8-hydroxy-3-(4′-hydroxyphenyl)-6,7-(2″,2″-dimethylchromene)-tetralone (2), 8-hydroxy-3-(3′,4′-dihydroxyphenyl)-6,7-(2″,2″-dimethylchromene)-tetralone (3), 1β-E-O-p-methoxycinnamoyl-bemadienolide (4), 1β-O-(E-cinnamoyl)-6α-hydroxy-9-epi-polygodial (5), 1β-O-(E-cinnamoyl)-6α-hydroxypolygodial (6), and 1β-O-E-cinnamoylpolygodial (7) were isolated from the ethyl acetate extract of barks of Zygogynum pancheri subsp. arrhantum (Winteraceae). The structures of these molecules were assigned predominantly based on spectral data. The structure of compound 8 was confirmed by X-ray crystallographic analysis. Compounds 2 and 3 exhibited significant antioxidant activity, whereas compounds 1 and 4–7 showed significant α-amylase inhibitory activity.     

Metabolites from endophytic fungus S20 of Cephalotaxus hainanensis

Three new C-methylated acetogenins, (2E,6Z)-9,10-dihydroxy-4-hydroxymethyl-2,6-decadiene (1), (2E,6Z)-8,9,10-trihydroxy-4-hydroxymethyl-2,6-decadiene (2), and (2E,6Z)-9-hydroxy-4-hydroxymethyl-2,6-nonadiene (3), together with two known compounds, p-hydroxybenzyl alcohol (4) and indolyl-3-carboxylic acid (5), were isolated from endophytic fungus S20 of Cephalotaxus hainanensis Li. Their structures were determined based on HR-ESI-MS and spectroscopic techniques (IR, UV, 1D, and 2D NMR). Compound 5 showed inhibitory effects on Staphylococcus aureus and methicillin-resistant S. aureus by the filter paper disc agar diffusion method.     

MiR-29c protects against inflammation and apoptosis in Parkinson's disease model in vivo and in vitro by targeting SP1

MicroRNAs (miRNAs) have been shown to have complicated implications in the pathogenesis of Parkinson's disease (PD). However, the role of miR-29c and the underlying mechanism in the development of PD remain not well understood. In this work, the MPTP-treated mice or MPP⁺-intoxicated SH-SY5Y cells were established as an in vivo or in vitro PD model. Then the specific agomir of miR-29c was employed to examine its biological function on PD progress. We found that miR-29c was down-expressed but SP1 was high-expressed in substantia nigra pars compacta (SNpc) of MPTP-induced PD mice. Overexpression of miR-29c attenuated dopaminergic neuron loss and α-synuclein accumulation in SNpc of PD mice. Furthermore, the increments of pro-inflammatory cytokines (TNF-α, IL-1β and IL-6) and TUNEL-positive apoptotic cells in MPTP-treated mice were ameliorated by miR-29c. Similarly, in SH-SY5Y cell models of PD, we also found that miR-29c inhibited inflammatory cytokine production, reduced apoptotic rate and suppressed pro-apoptotic regulator activity. In addition, the increased expression of SP1 in PD models was found to be inhibited by miR-29c. Luciferase reporter assay confirmed that SP1 was complementary with miR-29c. Knockdown of SP1 with siRNA restored α-synuclein accumulation, inflammation and apoptosis in MPP⁺-induced SH-SY5Y cells. Collectively, this current work presents that miR-29c may directly target SP1 to protect against the neuroinflammatory and apoptotic responses in PD, providing a potential biomarker for PD diagnosis and treatment.     

MPP<Superscript>+</Superscript>-induced toxicity in the presence of dopamine is mediated by COX-2 through oxidative stress

Accumulating evidence suggests that endogenous dopamine may act as a neurotoxin and thereby participate in the pathophysiology of Parkinson’s disease (PD). Cyclooxygenase-2 (COX-2) has been implicated in the pathogenesis of PD due to its ability to generate reactive oxygen species (ROS). Inhibition of COX-2 leads to neuroprotection by preventing the formation of dopamine-quinone. In this study, we examined whether dopamine mediates 1-methyl-4-phenylpyridinium (MPP⁺)-induced toxicity in primary ventral mesencephalic (VM) neurons, an in vitro model of PD, and if so, whether the protective effects of COX-2 inhibitors on dopamine mediated MPP⁺-induced VM neurotoxicity and VM dopaminergic cell apoptosis result from the reduction of ROS. Reserpine, a dopamine-depleting agent, significantly reduced VM neurotoxicity induced by MPP⁺, whereas dopamine had an additive effect on MPP⁺-induced VM neurotoxicity and VM dopaminergic cell apoptosis. However, inhibition of COX-2 by a selective COX-2 inhibitor (DFU) or ibuprofen significantly attenuated MPP⁺-induced VM cell toxicity and VM dopaminergic cell apoptosis, which was accompanied by a decrease in ROS production in VM dopaminergic neurons. These results suggest that dopamine itself mediates MPP⁺-induced VM neurotoxicity and VM dopaminergic cell apoptosis in the presence of COX-2.     

TGF-β1 Neuroprotection via Inhibition of Microglial Activation in a Rat Model of Parkinson’s Disease

Transforming growth factor (TGF)-β1 is a pleiotropic cytokine with immunosuppressive and anti-inflammatory properties. Recently we have shown that TGF-β1 pretreatment in vitro protects against 1-methyl-4-phenylpyridinium (MPP⁺)-induced dopaminergic neuronal loss that characterizes in Parkinson’s disease (PD). Herein, we aimed to demonstrate that TGF-β1 administration in vivo after MPP⁺ toxicity has neuroprotection that is achieved by a mediation of microglia. A rat model of PD was prepared by injecting MPP⁺ unilaterally in the striatum. At 14 days after MPP⁺ injection, TGF-β1 was administrated in the right lateral cerebral ventricle. Primary ventral mesencephalic (VM) neurons and cerebral cortical microglia were treated by MPP⁺, respectively, and TGF-β1 was applied to neuronal or microglial cultures at 1 h after MPP⁺ treatment. As expected, MPP⁺ resulted in decrease in TGF-β1 production in the substantia nigra and in primary VM neurons and microglia. TGF-β1 intracerebroventricular administration alleviated MPP⁺-induced PD-like changes in pathology, motor coordination and behavior. Meanwhile, TGF-β1 ameliorated MPP⁺-induced microglial activation and inflammatory cytokine production in vivo. Interestingly, TGF-β1 treatment was not able to ameliorate MPP⁺-induced dopaminergic neuronal loss and caspase-3/9 activation in mono-neuron cultures, but TGF-β1 alleviated MPP⁺-induced microglial activation and inflammatory cytokine production in microglia-enriched cultures. This effect of TGF-β1 inhibiting microglial inflammatory response was blocked by Smad3 inhibitor SIS3. Importantly, neuronal exposure to supernatants of primary microglia that had been treated with TGF-β1 reduced dopaminergic neuronal loss and caspase-3/9 activation induced by MPP⁺-treated microglial supernatants. These findings establish that TGF-β1 exerts neuroprotective property in PD by inhibiting microglial inflammatory response via Smad3 signaling.     

Protection of prenylated flavonoids from mori cortex radicis (Moraceae) against nitric oxide-induced cell death in neuroblastoma SH-SY5Y cells

Seven prenylated flavanoids, licoflavone C (1), cyclomulberrin (2), neocyclomorusin (3), sanggenon I (4), morusin (5), kuwanon U (6) and kuwanon E (7), and three 2-arylbenzofurans, moracin P (8), moracin O (9), and mulberrofuran Q (10) were isolated from the MeOH extract of Mori Cortex Radicis. Among these, compounds 2–7 enhanced cell viability in a dose-dependent manner against sodium nitroprusside-induced cell death in neuroblastoma SH-SY5Y cells, which was measured by MTT reduction assay (EC₅₀ values of 4.4, 5.6, 8.0, 6.4, 8.7, and 11.9 μg/mL, respectively). Among 10 compounds, C-3 prenylated flavones (2, 3, and 5) and prenylated flavanones (4, 6, and 7) showed cell protection. However, compound 1 which lacks the prenyl group at C-3 and three 2-arylbenzofurans (8–10) did not show protective effect. The order of cell protection was as follow: C-3 prenylated flavones (2, 3, and 5) > prenylated flavanones (4, 6, and 7) > 2-arylbenzofurans (8–10) and flavone (1). From this result, we show that some prenylated flavones and flavanones might protect neuronal cells against nitrosative stress-mediated cell death. Even though further evaluations are necessary in vitro and in vivo study, we carefully suggest that some prenylated flavonoids from Mori Cortex Radicis might protect neuronal cells from neurodegenerative diseases.     

<Emphasis Type="Italic">In vitro</Emphasis> Na<Superscript>+</Superscript>/K<Superscript>+</Superscript>-ATPase inhibitory activity and antimicrobial activity of sesquiterpenes isolated from <Emphasis Type="Italic">Thujopsis dolabrata</Emphasis>

A series of sesquiterpenes and hinokitiol-related compounds (1–15) was isolated from the essential oil of Thujopsis dolabrata Sieb. et Zucc. var. hondai Makino, and their structures were determined by combined spectroscopic analyses. The inhibitory effects of these compounds on microbial cell growth and Na⁺/K⁺-ATPase were evaluated in vitro. It was found that (−)-elema-1,3,11(13)-trien-12-ol (5), α,β,γ-costol (8), and chamigrenol (11) inhibit the activities of Na⁺/K⁺-ATPase, with IC₅₀ values of 11.2 ± 0.11, 12.2 ± 0.09, and 15.9 ± 0.54 μg/mL, respectively. Thujopsene (1), cedrol (9), γ-cuparenol (10), and chamigrenol (11) showed potent antibacterial activity, with MIC values in the range of 25–50 μg/mL, and β-thujaplicin (12) exhibited a broad spectrum of antibacterial and antifungal activity. These results indicate that these isolated compounds are promising candidates for the development of potent Na⁺/K⁺ ATPase inhibitors and antimicrobial agents.     

A new thiophene and two new monoterpenoids from Xanthium sibiricum

Three new compounds (1–3), together with six known compounds (4–9), were isolated from the fruits of Xanthium sibiricum. The structures and the absolute configurations of sibiricumthionol (1), (+)-(5Z)-6-methyl-2-ethenyl-5-hepten-1,2,7-triol [(+)-2], ( ? )-(5Z)-6-methyl-2-ethenyl-5-hepten-1,2,7-triol [( ? )-2], (2E,4E,1′S, 2′R, 4′S, 6′R)-dihydrophaseic acid (3), (+)-xanthienopyran [(+)-4] and ( ? )-xanthienopyran [( ? )-4] were established by extensive spectroscopic analyses, X-ray crystallographic analysis, ECCD analysis and ECD calculations. Caffeic acid (7) and caffeic acid ethyl ester (8) weekly inhibited α-glucosidase enzymatic activity by 44.5% and 40.2%, respectively, at 40 μM. Protocatechuic acid (9) selectively exhibited cytotoxicity against HepG2 cell lines, with an IC₅₀ value of 2.92 μM.     

Chemical constituents of the Annona glabra fruit and their cytotoxic activity

Abstract

Context: Traditional Chinese medicines have attracted increasing interest as potential sources of novel drugs with a wide range of biological and pharmacological activities. Annona glabra Linn (Annonaceae) is used in traditional medicine as an anticancer drug. Phytochemical investigation of this plant led to the isolation of acetogenins, ent-kauranes, peptides, and alkaloids. In addition, compounds exhibited anticancer, anti-HIV-reserve, and antimalaria.

Objective: Isolation, structure determination, and cytotoxic activity evaluation of compounds from the methanol extract from A. glabra fruits.

Materials and methods: Using chromatographic methods to isolate compounds from the A. glabra methanol extract. The cytotoxic activity of compounds was evaluated by a 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay. In addition, compounds which showed significant cytotoxic activity were chosen for further study apoptosis characteristics.

Results: One new, (2E,4E,1′R,3′S,5′R,6′S)-dihydrophaseic acid 1,3′-di-O-β-d-glucopyranoside, and eight known compounds, (2E,4E,1′R,3′S,5′R,6′S)-dihydrophaseic acid 3′-O-β-d-glucopyranoside (2), icariside D₂ (3), icariside D₂ 6′-O-β-d-xylopyranoside (4), 3,4-dimethoxyphenyl O-β-d-glucopyranoside (5), 3,4-dihydroxybenzoic acid (6), blumenol A (7), cucumegastigmane I (8), and icariside B₁ (9), were isolated from the fruits of A. glabra. Icariside D₂ (3) was found to show significant cytotoxic activity on the HL-60 cell line with the IC₅₀ value of 9.0?±?1.0?µM and did not show cytotoxic activity on the Hel-299 normal cell line. The further test indicated that compound 3 induced apoptosis via alteration of expression of apoptosis-related proteins and decreased phosphorylation of AKT in HL-60 cells.

Discussion and conclusion: The results suggested that the constituents from A. glabra may contain effective compounds which can be used as anticancer agents.     

Similar potency of catechin and its enantiomers in alleviating 1-methyl-4-phenylpyridinium ion cytotoxicity in SH-SY5Y cells

Objectives Previously, the flavonoid (±)‐catechin was shown to exert potent neuroprotective action in the mouse 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine‐induced Parkinson's disease model. The purpose of this study was to investigate whether the different enantiomers of catechin ((+)‐catechin, (?)‐catechin and (±)‐catechin, a 50 : 50 mixture of (+)‐catechin and (?)‐catechin) could protect SH‐SY5Y cells against 1‐methyl‐4‐phenylpyridinium ion (MPP⁺) toxicity by decreasing the generation of oxygen free radicals. The inhibitive effect of (±)‐catechin on JNK/c‐Jun activation was investigated. Methods The effects of (+)‐catechin, (?)‐catechin or (±)‐catechin in protecting against MPP⁺ toxicity were evaluated and compared in SH‐SY5Y cells by testing the release of lactate dehydrogenase. The generation of reactive oxygen species (ROS) was measured by immunochemistry and the phosphorylation level of JNK/c‐Jun was determined by Western blotting. Key findings In SH‐SY5Y cells, (+)‐catechin, (?)‐catechin or (±)‐catechin reduced apoptosis induced by MPP⁺ and decreased ROS generation caused by MPP⁺. Different enantiomers of catechin showed protective effects at similar potency. Moreover (±)‐catechin decreased JNK/c‐Jun phosphorylation which was increased by MPP⁺. Conclusions Catechin and its two enantiomers could protect SH‐SY5Y cells against MPP⁺ cytotoxicity at a similar potency. Antioxidative stress and inhibition of the JNK/c‐Jun signalling pathway might have been involved in the neuroprotective mechanisms of catechin against MPP⁺ cytotoxicity in SH‐SY5Y cells.     

Constituents of the roots of <Emphasis Type="Italic">Ligularia dentata</Emphasis> Hara

Nine known compounds, butyrospermol (1), lupeol (2), stigmast-4-en-3-one (3), stigmast-4-ene-3,6-dione (4), (+)-methyl abscisate (5), methyl indole-3-carboxylate (6), vanillin (7), methyl (E)-caffeate (8), and methyl (E)-ferulate (9), and two new compounds, methyl (E)-feruloylglycolate (10), and methyl-7,8-dihydro-(S)-7-methoxyferulate (11), have been isolated from the roots of Ligularia dentata Hara (Compositae). The structures were elucidated on the basis of spectral data.