Natural polyphenol: Their pathogenesis-targeting therapeutic potential in Alzheimer's disease.

Alzheimer's disease (AD) is a detrimental neurodegenerative disease affecting the elderly. Clinically, it is characterized by progressive memory decline and subsequent loss of broader cognitive functions. Current drugs provide only symptomatic relief but do not have profound disease-modifying effects. There is an unmet need to identify novel pharmacological agents for AD therapy. Neuropathologically, the characteristic hallmarks of the disease are extracellular senile plaques containing amyloid ß-peptides and intracellular neurofibrillary tangles containing hyperphosphorylated microtubule-associated protein tau. Simultaneously, oxidative stress, neuroinflammation and mitochondrial dysfunction in specific brain regions are early events during the process of AD pathologic changes and are associated with Aß/tau toxicity. Here, we first summarized probable pathogenic mechanisms leading to neurodegeneration and hopefully identify pathways that serve as specific targets to improve therapy for AD. We then reviewed the mechanisms that underlie disease-modifying effects of natural polyphenols, with a focus on nuclear factor erythroid 2-related factor 2 activators for AD treatment. Lastly, we discussed challenges in the preclinical to clinical translation of natural polyphenols. In conclusion, there is evidence that natural polyphenols can be therapeutically useful in AD through their multifaceted mechanism of action. However, more clinical studies are needed to confirm these effects.

Lead toxicity and potential therapeutic effect of plant-derived polyphenols.

BACKGROUND: Due to its unique physical and chemical properties, lead is still used worldwide in several applications, especially in industry. Both environmental and industrial lead exposures remain a public health problem in many developing and rapidly industrializing countries. Plant polyphenols are pleiotropic in their function and have historically made a major contribution to pharmacotherapy. PURPOSE: To summarize available pre-clinical and limited clinical evidence on plant polyphenols as potential antidotes against lead poisoning and discuss toxic mechanisms of lead. METHOD: A comprehensive search of peer-reviewed publications was performed from core collections of electronic databases such as PubMed, Web of Science, Google Scholar, and Science Direct. Articles written in English-language from inception until December 2022 were selected. RESULTS: In this review, we review key toxic mechanisms of lead and its pathological effects on the neurological, reproductive, renal, cardiovascular, hematological, and hepatic systems. We focus on plant polyphenols against lead toxicity and involved mechanisms. Finally, we address scientific gaps and challenges associated with translating these promising preclinical discoveries into effective clinical therapies. CONCLUSION: While preclinical evidence suggests that plant polyphenols exhibit bioprotective effects against lead toxicity, scant and equivocal clinical data highlight a need for clinical trials with those polyphenols.

Nrf2 as a potential target for Parkinson's disease therapy.

Parkinson's disease (PD) is a complex neurodegenerative disorder featuring both motor and nonmotor symptoms associated with a progressive loss of dopaminergic neurons in the substantia nigra pars compacta. Conventionally, PD treatment options have focused on dopamine replacement and provide only symptomatic relief. However, disease-modifying therapies are still unavailable. Mechanistically, genetic and environmental factors can produce oxidative stress which has been implicated as a core contributor to the initiation and progression of PD through the degeneration of dopaminergic neurons. Importantly, nuclear factor erythroid 2-related factor 2 (Nrf2) is essential for maintaining redox homeostasis by binding to the antioxidant response element which exists in the promoter regions of most genes coding for antioxidant enzymes. Furthermore, protein kinase C, mitogen-activated protein kinases, and phosphotidylinositol 3-kinase have been implicated in the regulation of Nrf2 activity during PD. Here, we review the evidence supporting the regulation of Nrf2 through Keap1-dependent and Keap1-independent mechanisms. We also address that targeting Nrf2 may provide a therapeutic option to mitigate oxidative stress-associated PD. Finally, we discuss currently known classes of small molecule activators of Nrf2, including Nrf2-activating compounds in PD.

Paeoniflorin and Plycyrrhetinic Acid Synergistically Alleviate MPP+/MPTP-Induced Oxidative Stress through Nrf2-Dependent Glutathione Biosynthesis Mechanisms.

Recently, combination therapy has proven to be an effective strategy for treating polygenic/multifactorial/complex disorder such as Parkinson's disease (PD). Here, we hypothesized that dual up-regulation of glutamate cysteine ligase (GCL) catalytic subunit (GCLc) and GCL modifier subunit (GCLm) via nuclear factor E2-related factor (Nrf2) contribute to the antioxidant effect of paeoniflorin (PF) synergistically with glycyrrhetinic acid (GA) (henceforth called PF/GA) in the context of MPP+/MPTP neurotoxicity. Expectedly, CompuSyn synergism/antagonism analysis showed that PF/GA exerts synergistic neuroprotection. Moreover, the antioxidant effect of PF was significantly enhanced by the combined administration of GA, although GA alone did not confer the effect. Mechanistically, PF triggered extracellular signal-regulated kinase (ERK1/2) phosphorylation, resulting in Nrf2 nuclear translocation from cytoplasmic pool via de novo synthesis in MPP+-challenged SH-SY5Y cells. Concomitantly, GA activates Akt which in turn induces nuclear accumulation of Nrf2. Especially, PF/GA up-regulated glutamate-cysteine ligase catalytic subunit (Gclc) and glutamate-cysteine ligase modifier subunit (Gclm) are formed via two separate pathways. Furthermore, these results were confirmed through pathway blockade assays using PD98059 (ERK1/2 inhibitor), LY294002 (phosphatidylinositol-3-kinase inhibitor), and shRNA-induced Nrf2 knockdown. Additionally, using a mouse MPTP-induced model of PD, we demonstrated that PF/GA synergistically ameliorates both motor deficits and oxidative stress in the ventral midbrain. In parallel, PF/GA also up-regulated both GCLc and GCLm expression at levels of transcription and translation. Conversely, antiparkinsonism and antioxidant effects of PF/GA were not observed in Nrf2-knockout MPTP-mice. Collectively, these results show that ERK1/2 and Akt activation contribute to the synergistic antioxidant effect of PF/GA. Hence, PF/GA regimen warrants further preclinical and possible clinical study for PD.

[Antioxidant mechanism of gastrodin combined with isorhynchophylline in inhibiting MPP~+-induced apoptosis of PC12 cells].

Gastrodiae Rhizoma-Uncariae Ramulus cum Uncis is the most frequently used herbal pair in the treatment of Parkinson's disease(PD). Gastrodin and isorhynchophylline are important components of Gastrodiae Rhizoma-Uncariae Ramulus cum Uncis herb pair with anti-Parkinson mechanism. This study aimed to investigate the effect of gastrodin combined with isorhynchophylline on 1-methyl-4-phenylpyridinium(MPP~+)-induced apoptosis of PC12 cells and their antioxidant mechanism. The leakage of lactate dehydrogenase(LDH) from cells to media was analyzed by spectrophotometry. Apoptotic cells were labeled with Annexin V-fluorescein isothiocyanate(FITC) and propidium iodide(PI) and analyzed by flow cytometry. The cell cycle was analyzed using propidium iodide(PI) staining. Lipid peroxidation(LPO) level was analyzed by spectrophotometry. The mRNA expression of caspase-3 was examined by Real-time RT-PCR. The protein expressions of heme oxygenase 1(HO-1) and NADPH: quinoneoxidore-ductase 1(NQO-1) were determined by Western blot. Gastrodin combined with isorhynchophylline reduced the percentage of Annexin V-positive cells and cell cycle arrest in MPP~+-induced PC12 cells. Gastrodin combined with isorhynchophylline down-regulated the mRNA expression of caspase-3, up-regulated the protein expressions of HO-1 and NQO-1, and reduced LPO content in MPP~+-induced PC12 cells. PD98059, LY294002 or LiCl could partially reverse these changes pretreated with gastrodin combined with isorhynchophylline, suggesting that gastrodin combined with isorhynchophylline inhibited MPP~+-induced apoptosis of PC12 cells and oxidative stress through ERK1/2 and PI3 K/GSK-3ß signal pathways. Our experiments showed that gastrodin combined with isorhynchophylline could down-re-gulate the mRNA expression of caspase-3 and up-regulate the protein expressions of HO-1 and NQO-1, so as to reduce oxidative stress and inhibit apoptosis.

Puerarin suppresses MPP+/MPTP-induced oxidative stress through an Nrf2-dependent mechanism.

In this study, we hypothesized that anti-parkinsonian effect of puerarin is attributable to its antioxidant properties via Nrf2-dependent glutathione (GSH) biosynthesis mechanism. Experimentally, we found that puerarin attenuated 1-methyl-4-phenylpyridinium (MPP+)-induced oxidative stress through elevating biosynthetic capacity of GSH in PC12 cells. Mechanistically, puerarin suppressed Fyn phosphorylation by GSK-3ß-dependent mechanism in MPP+-challenged PC12 cells. Furthermore, puerarin induced accumulation of Nrf2 in the nucleus via inhibiting its nuclear exclusion. In parallel, puerarin up-regulated antioxidant response element (ARE)-driven catalytic subunits from glutamate cysteine ligase (GCLc) expression at levels of transcription and translation. Most interestingly, pharmacological inhibitor of GSK-3ß or Fyn shRNA blocked puerarin-induced Nrf2 activation in MPP+-challenged PC12 cells. Concomitantly, puerarin ameliorated motor deficits and inhibited oxidative stress in the ventral midbrain in MPTP-intoxicated wild-type (WT) mice, but failed to attenuate MPTP neurotoxicity and up-regulate GCLc gene in Nrf2-knockout (Nrf2-/-) mice, suggesting that anti-parkinsonian effect of puerarin was dependent on Nrf2. Additionally, puerarin regulated Fyn and GSK-3ß phosphorylation in the ventral midbrain in MPTP-intoxicated WT mice. Collectively, the results of the study provide molecular insights into the potential therapeutic action of puerarin in Parkinson's disease, suggesting that puerarin may be a promising candidate for the treatment of Parkinson's disease.

Ferulic Acid Ameliorates MPP+/MPTP-Induced Oxidative Stress via ERK1/2-Dependent Nrf2 Activation: Translational Implications for Parkinson Disease Treatment.

Parkinson's disease (PD) is a neurodegenerative disorder closely associated with oxidative stress. The biochemical and cellular alterations that occur after cell and mouse treatment with the parkinsonism-inducing neurotoxin MPP+/MPTP are remarkably similar to those observed in idiopathic PD. Previously, we showed that ferulic acid (FA) has antioxidant properties and the ability to activate nuclear factor E2-related factor 2 (Nrf2). The present study tested the hypothesis that FA attenuates MPP+/MPTP-induced oxidative stress by regulating crosstalk between sirtuin 2 (SIRT2) and Nrf2 pathways. To test this hypothesis, we performed in vitro and in vivo studies using MPP+/MPTP-challenged SH-SY5Y cells or mice treated with or not with FA. FA marginally inhibited SIRT2 in parallel with α-synuclein at levels of transcription and translation in SH-SY5Y cells challenged with MPP+. Moreover, FA attenuated MPP+-induced oxidative stress, as indicated by reactive oxygen species, lipid hydroperoxides, GSH/GSSG ratio, and NAD+/NADH ratio. Mechanistically, FA strongly upregulated the glutamate cysteine ligase catalytic subunit and heme oxygenase-1 expression at the levels of transcription and translation. Interestingly, FA-mediated extracellular signal-regulated kinases 1 and 2 (ERK1/2) activation contributed to nuclear accumulation of Nrf2 via de novo synthesis, which was validated by the use of dominant negative ERK2. Surprisingly, activation of the ERK1/2 and inhibition of SIRT2 by FA are mediated by independent mechanisms. Furthermore, FA ameliorated motor deficits and oxidative stress in the ventral midbrain in MPTP-treated (25 mg/kg, i.p., daily for 5 days) wild-type mice and α-synuclein knockout mice, but not in Nrf2 knockout mice. Collectively, FA exerts antioxidant effects through ERK1/2-mediated activation of the Nrf2 pathway, and these results may have important translational value for the treatment of PD.

[Effect of maternal exposure to Curcumae Rhizoma during pregnancy on neurodevelopment and apoptosis mechanism in offspring].

Curcumae Rhizoma is a Chinese medicinal herb that is contraindicated during pregnancy. Cold-congelation and blood-stasis are corresponding syndromes to Curcumae Rhizoma. Whether syndrome-based treatment is associated with developmental neurotoxicity of Curcumae Rhizoma remains to be unclear. To verify the theory of traditional Chinese medicine of "syndrome-based treatment during pregnancy", the present study induced the mice blood stasis model by immersing mice in ice water. Pregnant C57 BL/6 wild type(WT) mice and pregnant Nrf2 knock out(KO) mice were randomly divided into control groups and Rhizoma Curcumae exposure groups. The mice were exposed to Rhizoma Curcumae during day 5 to day 18 after pregnancy. The neurodevelopment was examined to evaluate the differences of developmental neurotoxicity between normal and blood-stasis pregnant mice exposed to Rhizoma Curcumae. caspase-3 and caspase-9 activity in brain of the offspring were measured by colorimetric assays. Bcl-2 mRNA and protein expression in brain of the offspring were examined by Real-time RT-PCR and Western blot, respectively. According to the findings, C57 BL/6 mice exposed to Rhizoma Curcumae(10.0 g·kg~(-1)) had a longer positive occurring time of the surface righting reflex test of offspring and higher caspase-3 and caspase-9 activities in brain of offspring, compared with the normal control group, but with no significant change in those of blood-stasis pregnant mice offspring. However, mice exposed to Rhizoma Curcumae(10.0 g·kg~(-1)) showed no change in Bcl-2 gene expression and p38 MAPK phosphorylation in brain of the offspring. Nrf2 gene knockout using CRISPR/Cas9 resulted in a longer positive occurring time of the surface righting reflex test of offspring and higher caspase-3 and caspase-9 activities in brain of offspring. In conclusion, developmental neurotoxicity of the blood-stasis pregnant mice exposed to Rhizoma Curcumae was weaker than that of the normal pregnant mice. Nrf2 activation involved in the phenomenon of Rhizoma Curcumae of "syndrome-based treatment during pregnancy", but the upstream signal pathway mechanism value shall be further investigated.

Emodin suppresses activation of hepatic stellate cells through p38 mitogen-activated protein kinase and Smad signaling pathways in vitro.

The aim of this study was to evaluate the hypothesis that emodin inhibits extracellular matrix (ECM)-related gene expression in activated hepatic stellate cells (HSCs) by blocking canonical or/and noncanonical components of transforming growth factor ß1 (TGFß1) intracellular signaling. Here, we demonstrate that emodin suppressed the gene expression of HSCs activation markers type I collagen, fibronectin, and α-smooth muscle actin, as well as HSCs proliferation. Mechanistically, emodin suppresses TGFß1, TGFß receptor II, TGFß receptor I, and Smad4 gene expression, as well as Smad luciferase activity. Simultaneously, emodin reduced p38 mitogen-activated protein kinase (p38MAPK ) activity but not c-Jun N-terminal kinases and extracellular signal-regulated kinases 1 and 2 phosphorylation in HSC-T6 cells. Interestingly, deprivation of TGFß using a neutralizing antibody abolished emodin-mediated inhibitions of the both Smad transcriptional activity and p38MAPK phosphorylation. Furthermore, emodin-mediated inhibition of HSCs activation could be partially blocked by PD98059 inhibition of p38MAPK or short hairpin RNA-imposed knockdown of Smad4. Conversely, simultaneous inhibition of Smad4 and p38MAPK pathways completely reverses the effects of emodin, suggesting that Smad and p38MAPK locate downstream of TGFß1 and regulate collagen genes expression in HSCs. Collectively, these data suggest that emodin is a promising candidate for the treatment of hepatic fibrosis.

ß-Ecdysterone protects SH-SY5Y cells against ß-amyloid-induced apoptosis via c-Jun N-terminal kinase- and Akt-associated complementary pathways.

Recently, the significantly higher incidence of Alzheimer's disease (AD) in women than in men has been attributed to the loss of neuroprotective estrogen after menopause. Does phytoestrogen have the ability to protect against amyloid-ß (Aß) toxicity? The aim of this study was to evaluate hypothesis that ß-ecdysterone (ß-Ecd) protects SH-SY5Y cells from Aß-induced apoptosis by separate signaling pathways involving protein kinase B (Akt) and c-Jun N-terminal kinase (JNK). Here, we demonstrate that phytoestrogen ß-Ecd inhibits Aß-triggered mitochondrial apoptotic pathway, as indicated by Bcl-2/Bax ratio elevation, cytochrome c (cyt c) release reduction, and caspase-9 inactivation. Interestingly, ß-Ecd upregulates Bcl-2 expression in SH-SY5Y cells under both basal and Aß-challenged conditions, but downregulates Bax expression only in Aß-challenged conditions. Subsequently, Akt-dependent NF-κB activation is required for Bcl-2 upregulation, but not Bax downregulation, in response to ß-Ecd, which was validated by the use of LY294002 and Bay11-7082. Notably, ß-Ecd attenuates the Aß-evoked reactive oxygen species (ROS) production, apoptosis signal-regulating kinase 1 (ASK1) phosphorylation and JNK activation without altering the basal ASK1 phosphorylation and JNK activation. ROS-scavenging by diphenyleneiodonium (DPI) abrogated the ability of ß-Ecd to alter the activation of ASK1. Simultaneously, inhibition of JNK by SP600125 abolished ß-Ecd-induced Bax downregulation in Aß-challenged SH-SY5Y cells, whereas LY294002 failed to do so. Consequently, ß-Ecd possesses neuroprotection by different and complementary pathways, which together promote a Bcl-2/Bax ratio. These data support our hypothesis and suggest that ß-Ecd is a promising candidate for the treatment of AD.

Gastrodin and Isorhynchophylline Synergistically Inhibit MPP+-Induced Oxidative Stress in SH-SY5Y Cells by Targeting ERK1/2 and GSK-3ß Pathways: Involvement of Nrf2 Nuclear Translocation.

The pathogenesis of Parkinson's disease (PD) is multifactorial event. Combination therapies might be more effective in controlling the disease. Thus, the studies reported were designed to test the hypothesis that gastrodin (GAS)-induced de novo synthesis of nuclear factor E2-related factor 2 (Nrf2) and isorhynchophylline (IRN) inhibition of Nrf2 nuclear export contribute to their additive or synergistic neuroprotective effect. Here, we have demonstrated that the combination of GAS and IRN (GAS/IRN) protects SH-SY5Y cells against 1-methyl-4-phenylpyridinium (MPP+) toxicity in a synergistic manner. Concomitantly, GAS/IRN led to a statistically significant reduction of oxidative stress, as assessed by reactive oxygen species (ROS) and lipid hydroperoxides (LPO), and enhancement of both glutathione (GSH) and thioredoxin (Trx) systems compared with treatment with either agent alone in MPP+-challenged SH-SY5Y cells. Interestingly, GAS but not IRN activated extracellular signal-regulated kinases 1 and 2 (ERK1/2), leading to a increase in de novo synthesis of Nrf2 and nuclear import of Nrf2. Simultaneously, IRN but not GAS suppressed both constitutive glycogen synthase kinase (GSK)-3ß and Fyn activation, which inhibited nuclear export of Nrf2. Importantly, simultaneous inhibition of GSK-3ß pathway by IRN and activation of ERK1/2 pathway by GAS synergistically induced accumulation of Nrf2 in the nucleus in SH-SY5Y cells challenged with MPP+. Furthermore, the activation of the ERK1/2 pathway and inhibition of GSK-3ß pathway by GAS/IRN are mediated by independent mechanisms. Collectively, these novel findings suggest an in vitro model of synergism between IRN and GAS in the induction of neuroprotection warrant further investigations in vivo.

Isorhynchophylline Attenuates MPP+-Induced Apoptosis Through Endoplasmic Reticulum Stress- and Mitochondria-Dependent Pathways in PC12 Cells: Involvement of Antioxidant Activity.

Endoplasmic reticulum stress (ERS) and mitochondrial dysfunctions are thought to be involved in the dopaminergic neuronal death in Parkinson's disease (PD). In this study, we found that isorhynchophylline (IRN) significantly attenuated 1-methyl-4-phenylpyridinium (MPP+)-induced apoptotic cell death and oxidative stress in PC12 cells. IRN markedly reduced MPP+-induced-ERS responses, indicative of inositol-requiring enzyme 1 (IRE1) phosphorylation and caspase-12 activation. Furthermore, IRN inhibits MPP+-triggered apoptosis signal-regulating kinase 1 (ASK1)/c-Jun N-terminal Kinase (JNK) signaling-mediated mitochondria-dependent apoptosis pathway. IRN-mediated attenuation of endoplasmic reticulum modulator caspase-12 activation was abolished by diphenyleneiodonium (DPI) or IRE-1α shRNA, but not by SP600125 or pifithrin-α in MPP+-treated PC12 cells. Inhibitions of MPP+-induced both cytochrome c release and caspase-9 activation by IRN were blocked by pre-treatment with DPI or pifithrin-α, but not by IRE-1α shRNA. IRN blocks the generation of reactive oxygen species upstream of both ASK1/JNK pathway and IRE1/caspase-12 pathway. Altogether, our in vitro findings suggest that IRN possesses potent neuroprotective activity and may be a potential candidate for the treatment of PD.

Comparison of the curdione in brain of blood stasis pregnant rats and its offsprings with the normal group rats by UPLC-Q-TOF-MS.

Curdione is a main active component of curcuma rhizomes (Ezhu), which shows an excellent antithrombotic activity. In this study, the concentration of Curdione in pregnant rats and their offspring brain was determined using ultra-performance liquid chromatography-quadrupole time-of-flight/mass spectrometry (UPLC-Q-TOF-MS) method. The water extraction then alcohol precipitation extract from Ezhu was administered through tail intravenous injection. The pharmacokinetic parameters were analyzed to compare the differences between the blood stasis group rats and normal group rats. Using Schisandrol A as an internal standard, samples were extracted using dichloromethane and isopropanol (90:10, v/v). Calibration plot was linear over the range of 0.5-200µg•mL.-1. for Curdione in brain with the lower quantification limit being 0.5µg•mL-1. The recoveries of Curdione and IS from brain were more than 93.31% and 90.90% separately. The RSD for both intra- and inter-day precision were <6.49%, RE were -14.84%~-2.8%. The pharmacokinetic parameters Cmax and AUC among the four kinds of rats had significant difference. The Curdione distributed in rat brain in model group is less than normal group. Ezhu medicine may show the therapeutic effect but not the reproductive toxicity on mother or unborn baby to cure the pregnant women under the adaptive symptoms.

Astragaloside IV attenuates lead acetate-induced inhibition of neurite outgrowth through activation of Akt-dependent Nrf2 pathway in vitro.

Recently, oxidative stress is strongly associated with lead (Pb)-induced neurotoxicity. We reported previously that Astragaloside IV (AS-IV) possesses potent antioxidant properties. Here, we evaluate the hypothesis that AS-IV attenuates lead acetate (PbAc)-mediated inhibition of neurite outgrowth might mainly result from its antioxidant property via serine/threonine protein kinase (Akt)-dependent activation of the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. Interestingly, AS-IV attenuates PbAc-induced inhibition of neurite outgrowth and displayed potential antioxidant properties by inhibiting reactive oxygen species (ROS). Concomitantly, AS-IV enhanced phase II detoxifying enzymes such as heme oxygenase 1 (HO-1), thioredoxin reductase (TrxR), and glutamate cysteine ligase catalytic subunit (GCLc). Conversely, AS-IV had no effect on GCL modulatory subunit (GCLm) and superoxide dismutase (SOD) activity/expression. Furthermore, AS-IV evoked Akt phosphorylation, and subsequent induced phosphorylation of glycogen synthase kinase-3ß (GSK-3ß) at Ser9 (that is, inactivation), which stimulated Nrf2-mediated antioxidant response element (ARE)-containing activation. Importantly, Akt locates upstream of GSK-3ß and regulates phase II detoxifying enzymes gene expression through Nrf2 nuclear accumulation in PC12 cells exposed to PbAc. Noteworthy, these results were further confirmed through signalling pathway inhibitors, dominant negative mutant and short hairpin RNA technology. Collectively, these in vitro findings suggest that AS-IV attenuates PbAc-induced inhibition of neurite outgrowth attributed to its antioxidant properties and may be a promising candidate for the treatment of lead developmental neurotoxicity.

Synergistic protective effect of paeoniflorin and ß-ecdysterone against rotenone-induced neurotoxicity in PC12 cells.

There are several factors, like oxidative stress and neurons loss, involving neurodegenerative diseases such as Parkinson's disease (PD). The combination of antioxidant and anti-apoptotic agent is becoming a promising approach to fight against PD. This study evaluates the hypothesis that paeoniflorin (PF) and ß-ecdysterone (ß-Ecd) synergize to protect PC12 cells against toxicity induced by PD-related neurotoxin rotenone. The combination of PF and ß-Ecd, hereafter referred to as the PF/ß-Ecd, at suboptimal concentrations increased the viability of rotenone-exposed PC12 cells in a synergistic manner. PF and ß-Ecd cooperate to attenuate the rotenone-induced apoptosis by decrease in Bax expression, caspase-9 activity, and caspase-3 activity. PF or PF/ß-Ecd, but not ß-Ecd, inhibited rotenone-triggered protein kinase C-δkinase C-δ (PKCδ) upregulation and nuclear factor κB (NF-κB) activation. ß-Ecd or PF/ß-Ecd, but not PF, enhanced serine/threonine protein kinase (Akt) activation, promoted nuclear factor E2-related factor 2 (Nrf2) nuclear accumulation, suppressed reactive oxygen species (ROS) production. Neuroprotection of PF/ß-Ecd could be completely blocked by PKCδ inhibitor rottlerin plus Akt specific inhibitor LY294002. Dual blockade of the PKCδ/NF-κB pathway by PF and activation of Akt/Nrf2 pathway by ß-Ecd results in a synergistic neuroprotective effect against rotenone-induced neurotoxicity in vitro. These findings provide the rationale for determining the in vivo activity of combined therapy with PF and ß-Ecd against PD.

ß-Ecdysterone Protects SH-SY5Y Cells Against 6-Hydroxydopamine-Induced Apoptosis via Mitochondria-Dependent Mechanism: Involvement of p38(MAPK)-p53 Signaling Pathway.

Parkinson's disease (PD) is a neurological disorder pathologically characterized by loss of dopaminergic neurons in the substantia nigra. No curative therapy is available for PD. We recently found that phytoestrogen ß-ecdysterone (ß-Ecd) is able to reduce MPP(+)-induced apoptosis in PC12 cells. This study investigated the potential of ß-Ecd to protect against SH-SY5Y cell apoptosis induced by the PD-related neurotoxin 6-hydroxydopamine (6-OHDA) and the underlying mechanism for this cytoprotection. In the present study, pretreatment with ß-Ecd significantly reduced 6-OHDA-induced apoptosis of SH-SY5Y cells by a mitochondria-dependent pathway, as indicated by downregulation of Bax and PUMA (p53 upregulated modulator of apoptosis) expression, suppressing ΔΨm loss, inhibiting cytochrome c release, and attenuating caspase-9 activation. Furthermore, we showed that the inhibition of p38 mitogen-activated protein kinase (p38(MAPK))-dependent p53 promoter activity contributed to the protection of SH-SY5Y cells from apoptosis, which was validated by the use of SB203580 or p38ß dominant negative (DN) mutants. Additionally, knock-down apoptosis signal-regulating kinase 1 (ASK1) by specific shRNA and blockade reactive oxygen species (ROS) by pharmacological inhibitor competently prevented ß-Ecd-mediated inhibition of p38(MAPK) and ASK1 phosphorylation, respectively. These data provide the first evidence that ß-Ecd protects SH-SY5Y cells against 6-OHDA-induced apoptosis, possibly through mitochondria protection and p53 modulation via ROS-dependent ASK1-p38(MAPK) pathways. The neuroprotective effects of ß-Ecd make it a promising candidate as a therapeutic agent for PD.

Phytoestrogen ß-Ecdysterone Protects PC12 Cells Against MPP+-Induced Neurotoxicity In Vitro: Involvement of PI3K-Nrf2-Regulated Pathway.

Epidemiological studies have strongly linked postmenopausal estrogens uptake with a reduced risk of developing Parkinson's disease (PD) in women. Estrogen replacement therapy may be beneficial in early PD. The aim of this study is to evaluate the hypothesis that the neuroprotective effects of phytoestrogen ß-ecdysterone (ß-Ecd) might mainly result from its antioxidant capability by the activation of the phosphoinositide-3-kinase (PI3K)-nuclear factor E2-related factor 2 (Nrf2)-regulated signaling pathway. We found that ß-Ecd is able to protect MPP(+)-induced oxidative stress and apoptosis in PC12 cells in a concentration-dependent manner. ß-Ecd increased the Akt kinase activity and the Akt signaling pathways, including glycogen synthase kinase 3-ß inactivation, nuclear translocation of Nrf2, upregulation of HO-1 expression, but without affecting activity of both NF-κB and calpain. Enhancement of antioxidant response element (ARE) promoter-driven luciferase activity by ß-Ecd correlated with the blockade of oxidative stress. Antioxidative effects of ß-Ecd could be blocked by pharmacologic inhibition of the PI3K pathways with LY294002 or Nrf2 pathway with shRNA-mediated knockdown of Nrf2 but not by SP600125 (JNK inhibitor), SB203580 (p38-MAPK inhibitor), or PD98059 (ERK1/2 inhibitor). Together, our results indicate that the inducible effect of ß-Ecd on HO-1 expression might be mediated, at least in part, by activating Akt kinase pathway and subsequent enhancement of Nrf2/ARE signaling pathway. In concert, these data suggest that ß-Ecd may be a potential candidate for further preclinical study aimed at the treatment of PD.

Ferulic acid suppresses activation of hepatic stellate cells through ERK1/2 and Smad signaling pathways in vitro.

Hepatic stellate cells (HSCs) are the primary source of matrix components in hepatic fibrosis. Ferulic acid (FA) has antifibrotic potential in renal and cardiac disease. However, whether FA comprises inhibitive effects of HSCs activation remains to be clarified. This study aims at evaluating the hypothesis that FA inhibits extracellular matrix (ECM)-related gene expression by the interruption of the extracellular signal-regulated kinases 1 and 2 (ERK1/2) or/and Smad signaling pathways in HSC-T6. Our results indicated that FA significantly inhibited both viability and activation of HSC-T6 cells in vitro. In addition, we demonstrated, for the first time, that FA dramatically inhibited the expression of α1(I) collagen (Col-I) and fibronectin at levels of transcription and translation. Moreover, FA treatment inhibited Smad transcriptional activity, as evaluated by transient transfection with a plasmid construction containing SMAD response element and the luciferase reporter gene. Furthermore, FA inhibition of HSCs activation involved in both focal adhesion kinase (FAK)-dependent ERK1/2 and Smad signaling pathways with independent manner. Blocking transforming growth factor-ß by a neutralizing antibody caused a marked reduction in both ERK1/2 and Smad signaling. These results support FA as an effective therapeutic agent for the prevention and treatment of hepatic fibrosis.

Gastrodin prevents motor deficits and oxidative stress in the MPTP mouse model of Parkinson's disease: involvement of ERK1/2-Nrf2 signaling pathway.

AIMS: Current no effective therapy is available to halt the progression of Parkinson's disease (PD). Oxidative stress has been implicated in the etiology of PD. The present study evaluates the hypothesis that prevention of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced motor deficits by gastrodin might mainly result from its antioxidant property via interrupting extracellular signal regulated protein kinases (ERK) 1/2-nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway. MAIN METHODS: Pretreatment of mouse model of PD is established by treating C57BL/6 mice with 4 doses of MPTP (30 mg/kg per day, i.p.), with gastrodin (60 mg/kg per day) administered by daily intraperitoneal injection for 2 weeks. Motor behavior of mice was monitored by open-field test and rotarod test. Real-time polymerase chain reaction and Western blotting were used to analyze the expression of genes. KEY FINDINGS: MPTP-induced motor deficits were partially and significantly forestalled by gastrodin. Gastrodin treatment prevented MPTP-induced oxidative stress, as measured by malondialdehyde in midbrain. Interestingly, MPTP-intoxicated mice treated with gastrodin robustly increased heme oxygenase 1, superoxide dismutase, glutathione levels, and Nrf2 nuclear translocation in striatum of MPTP-intoxicated mice. Furthermore, results herein suggest that the antioxidant pathway activated by gastrodin involves ERK1/2 phosphorylation. SIGNIFICANCE: Gastrodin protects midbrain of MPTP-intoxicated mice against oxidative stress, in part, through interrupting ERK1/2-Nrf2 pathway mechanism, which will give us an insight into the potential of gastrodin in terms of opening up new therapeutic avenues for PD.

Puerarin alleviates cognitive impairment and oxidative stress in APP/PS1 transgenic mice.

Increasing evidence demonstrates that ß-amyloid (Aß) elicits oxidative stress, which contributes to the pathogenesis and disease progression of Alzheimer's disease (AD). Thus, there is interest in developing antioxidant therapies for the prevention/treatment of cognitive decline during AD. We reported previously that puerarin has antioxidative properties in vitro. Therefore, the aim of the present study was to determine whether puerarin improves cognitive function and reduces oxidative stress in amyloid precursor protein/presenilin-1 (APP/PS1) mice, a well established AD mouse model, and explore its potential mechanism. Our results show that oral administration of puerarin significantly ameliorates cognitive impairment in APP/PS1 mice assessed by the Morris water maze (MWM) test. This was accompanied by a significant decrease in the levels of lipid peroxidation (LPO) through, at least in part, induction of nuclear factor erythroid 2-related factor 2 (Nrf2) target gene heme oxygenase 1 (HO-1) in the hippocampus of APP/PS1 transgenic mice at 9 months of age, but without altering brain Aß burden. Furthermore, puerarin significantly activated Akt, reduced activation of glycogen synthase kinase 3ß (GSK-3ß), and induced nuclear translocation of Nrf2 in the hippocampus of APP/PS1 mice but did not alter ERK1/2 phosphorylation. Thus, puerarin may improve cognitive performance in APP/PS1 mice through activation of the Akt/GSK-3ß signaling pathway. These findings suggest that puerarin might be an attractive agent for prevention and treatment of cognitive impairment and dementia.