Investigating the Potential Anti-Alzheimer's Disease Mechanism of Marine Polyphenols: Insights from Network Pharmacology and Molecular Docking.

Marine polyphenols, including eckol(EK), dieckol(DK), and 8,8'-bieckol(BK), have attracted attention as bioactive ingredients for preventing Alzheimer's disease (AD). Since AD is a multifactorial disorder, the present study aims to provide an unbiased elucidation of unexplored targets of AD mechanisms and a systematic prediction of effective preventive combinations of marine polyphenols. Based on the omics data between each compound and AD, a protein-protein interaction (PPI) network was constructed to predict potential hub genes. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed to provide further biological insights. In the PPI network of the top 10 hub genes, AKT1, SRC, EGFR, and ESR1 were common targets of EK and BK, whereas PTGS2 was a common target of DK and BK. GO and KEGG pathway analysis revealed that the overlapped genes between each compound and AD were mainly enriched in EGFR tyrosine kinase inhibitor resistance, the MAPK pathway, and the Rap1 and Ras pathways. Finally, docking validation showed stable binding between marine polyphenols and their top hub gene via the lowest binding energy and multiple interactions. The results expanded potential mechanisms and novel targets for AD, and also provided a system-level insight into the molecular targets of marine polyphenols against AD.

The Role of Fucoxanthin as a Potent Nrf2 Activator via Akt/GSK-3ß/Fyn Axis against Amyloid-ß Peptide-Induced Oxidative Damage.

Increasing evidence is suggesting that amyloid-ß peptide (Aß), a characteristic of Alzheimer's disease (AD), induces oxidative stress and mitochondrial dysfunction, leading to neuronal death. This study aimed to demonstrate the antioxidant and anti-apoptotic effects of fucoxanthin, a major marine carotenoid found in brown algae, against neuronal injury caused by Aß. Non-toxic dose range of fucoxanthin (0.1-5 µM) were selected for the neuroprotective study against Aß25-35. The PC12 cells were pretreated with different concentrations of fucoxanthin for 1 h before being exposed to 10 µM Aß25-35 for another 24 h. The present results showed that fucoxanthin inhibited Aß25-35-induced cell death by recovering cell cycle arrest and decreasing intracellular reactive oxygen species (ROS) level. The compound enhanced mitochondrial recovery and regulated apoptosis related proteins including B-cell lymphoma 2 (Bcl-2) and Bcl-2-associated X protein (Bax) from Aß25-35-induced oxidative stress. Concomitantly, fucoxanthin increased the expression of nuclear factor E2-related factor 2 (Nrf2) and its downstream phase II detoxifying enzymes including NADPH: quinone oxidoreductase-1 (NQO-1), glutamate cysteine ligase modifier subunit (GCLm), and thioredoxin reductase 1 (TrxR1), whereas it decreased the expression of cytoplasmic Kelch-like ECH-associated protein 1 (Keap1). Moreover, pretreatment of fucoxanthin reduced Fyn phosphorylation via protein kinase B (Akt)-mediated inhibition of glycogen synthase kinase-3ß (GSK-3ß), which increased the nuclear localization of Nrf2, suggesting that the compound enhanced Nrf2 expression by the activation of upstream kinase as well as the dissociation of the Nrf2-Keap1 complex. Further validation with a specific phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 demonstrated that the fucoxanthin-mediated Nrf2 antioxidant defense system was directly associated with the Akt/GSK-3ß/Fyn signaling pathway. In silico simulation revealed that the oxygen groups of fucoxanthin participated in potent interactions with target markers in the Nrf2 signaling pathway, which may affect the biological activity of target markers. Taken together, the present results demonstrated that the preventive role of fucoxanthin on Aß-stimulated oxidative injury and apoptosis via Akt/GSK-3ß/Fyn signaling pathway. This study would provide a useful approach for potential intervention for AD prevention.

Discovery of Pinostrobin as a Melanogenic Agent in cAMP/PKA and p38 MAPK Signaling Pathway.

Melanogenesis is the process of melanin synthesis to protect the skin against ultraviolet radiation and other external stresses. The loss of skin pigmentation is closely related to depigmented skin disorders. The melanogenic effects of pinostrobin, an active flavanone found in honey, were evaluated. B16F10 cells were used for melanin content, tyrosinase activity, and the expression of melanogenesis-related markers. Moreover, computational simulations were performed to predict docking and pharmacokinetics. Pinostrobin increased melanin levels and tyrosinase activity by stimulating the expression of melanogenic regulatory factors including tyrosinase, tyrosinase-related protein (TRP) 1 and microphthalmia transcription factor (MITF). Specifically, the phosphorylation of cAMP response element binding (CREB) involved in the MITF activation was augmented by pinostrobin. Moreover, the compound upregulated the ß-catenin by cAMP/PKA-mediated GSK-3ß inactivation. Co-treatment with a PKA inhibitor, inhibited melanin production, tyrosinase activity, and expression of MITF, p-CREB, p-GSK-3ß and p-ß-catenin, demonstrating that pinostrobin-stimulated melanogenesis was closely related to cAMP/PKA signaling pathway. Furthermore, the combination of pinostrobin and a specific p38 inhibitor, showed that MITF upregulation by pinostrobin was partly associated with the p38 signaling pathway. Docking simulation exhibited that the oxygen group at C-4 and the hydroxyl group at C-5 of pinostrobin may play an essential role in melanogenesis. In silico analysis revealed that pinostrobin had the optimal pharmacokinetic profiles including gastrointestinal absorption, skin permeability, and inhibition of cytochrome (CYP) enzymes. From the present results, it might be suggested that pinostrobin could be useful as a potent and safe melanogenic agent in the depigmentation disorder, vitiligo.

Eugenitol ameliorates memory impairments in 5XFAD mice by reducing Aß plaques and neuroinflammation.

Alzheimer's disease (AD) is caused by various pathological mechanisms; therefore, it is necessary to develop drugs that simultaneously act on multiple targets. In this study, we investigated the effects of eugenitol, which has anti-amyloid ß (Aß) and anti-neuroinflammatory effects, in an AD mouse model. We found that eugenitol potently inhibited Aß plaque and oligomer formation. Moreover, eugenitol dissociated the preformed Aß plaques and reduced Aß-induced nero2a cell death. An in silico docking simulation study showed that eugenitol may interact with Aß1-42 monomers and fibrils. Eugenitol showed radical scavenging effects and potently reduced the release of proinflammatory cytokines from lipopolysaccharide-treated BV2 cells. Systemic administration of eugenitol blocked Aß aggregate-induced memory impairment in the Morris water maze test in a dose-dependent manner. In 5XFAD mice, prolonged administration of eugenitol ameliorated memory and hippocampal long-term potentiation impairment. Moreover, eugenitol significantly reduced Aß deposits and neuroinflammation in the hippocampus of 5XFAD mice. These results suggest that eugenitol, which has anti-Aß aggregation, Aß fibril dissociation, and anti-inflammatory effects, potently modulates AD-like pathologies in 5XFAD mice, and could be a promising candidate for AD therapy.

Decursin prevents melanogenesis by suppressing MITF expression through the regulation of PKA/CREB, MAPKs, and PI3K/Akt/GSK-3ß cascades.

Abnormal melanin synthesis upon UV exposure causes excessive oxidative stress, which leads to skin hyperpigmentation disorders such as freckles, melisma, and age spots. The present study investigated the anti-melanogenic effects of decursin and the underlying mechanism using multiple approaches. Decursin exhibited no cytotoxicity and significantly reduced intracellular tyrosinase activity and melanin content in B16F10 melanoma cells. Decursin also inhibited the expression of melanogenic enzymes such as tyrosinase and tyrosinase-related protein (TRP)- 1, but not TRP-2. Mechanistically, decursin suppressed melanin synthesis through cAMP-dependent protein kinase (PKA)/cAMP response element-binding protein (CREB)-dependent downregulation of microphthalmia-associated transcription factor (MITF), a master transcription factor in melanogenesis. Further, decursin exerted anti-melanogenic effects by downregulating the p38 signaling pathway and upregulating extracellular signal-regulated kinase (ERK) and phosphatidylinositol 3 kinase (PI3K)/protein kinase B (Akt)/glycogen synthesis kinase-3ß (GSK-3ß) cascades. in silico analysis showed that decursin formed specific interactions with residues of upstream regulators of MITF and exhibited optimal pharmacokinetic profiles, including permeability and skin sensitization. Finally, the anti-melanogenic effects of decursin were confirmed ex vivo in 3D human skin models, suggesting its applicability as a protective agent against hyperpigmentation.

Protective effect of sargahydroquinoic acid against Aß25-35-evoked damage via PI3K/Akt mediated Nrf2 antioxidant defense system.

Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by memory loss and cognitive impairment. ß-Amyloid (Aß) is widely accepted as the main neurotoxin that triggers mitochondrial-associated oxidative stress, leading to neuronal death in AD. Following our preliminary research on the neuroprotective effects of the brown alga Sargassum serratifolium, its major compounds, including sargaquinoic acid, sargahydroquinoic acid (SHQA), and sargachromenol, were investigated to elucidate the antioxidant and anti-apoptotic properties of Aß25-35-stimulated PC12 cells. SHQA exhibited the most potent effect on Aß-induced mitochondrial-associated oxidative stress and apoptosis. In addition, the compound enhanced the expression and translocation of nuclear factor-E2-related factor 2 (Nrf2), while reducing the expression of cytoplasmic Kelch-like ECH-associated protein 1 (Keap1). Furthermore, the compound upregulated the expression of Nrf2-regulated antioxidant enzymes, including HO-1, NQO1, GCLc, GCLm, and TrxR1. Co-treatment with SHQA and LY294002, a specific PI3K inhibitor, inhibited nuclear Nrf2 expression and Akt phosphorylation, demonstrating that SHQA-mediated Nrf2 activation was directly associated with the PI3K/Akt signaling pathway. Mechanistic studies indicate that activation of the PI3K/Akt/Nrf2 pathway is the molecular basis for the neuroprotective effects of SHQA. In silico docking simulation revealed that SHQA established specific interactions with the key amino acid residues of PI3K, Akt, and Nrf2-Keap1 via hydrogen bonding and van der Waals interactions, which may affect the biological capacities of target markers. Overall, this is the first report of this novel mechanism of SHQA as a Nrf2 activator against Aß-mediated oxidative damage, suggesting that the compound might be a potential agent for the prevention of AD.

Phytochemical and Over-The-Counter Drug Interactions: Involvement of Phase I and II Drug-Metabolizing Enzymes and Phase III Transporters.

Consumption of plant-derived natural products and over-the-counter (OTC) drugs is increasing on a global scale, and studies of phytochemical-OTC drug interactions are becoming more significant. The intake of dietary plants and herbs rich in phytochemicals may affect drug-metabolizing enzymes (DMEs) and transporters. These effects may lead to alterations in pharmacokinetics and pharmacodynamics of OTC drugs when concomitantly administered. Some phytochemical-drug interactions benefit patients through enhanced efficacy, but many interactions cause adverse effects. This review discusses possible mechanisms of phytochemical-OTC drug interactions mediated by phase I and II DMEs and phase III transporters. In addition, current information is summarized for interactions between phytochemicals derived from fruits, vegetables, and herbs and OTC drugs, and counseling is provided on appropriate and safe use of OTC drugs.

Dieckol Ameliorates Aß Production via PI3K/Akt/GSK-3ß Regulated APP Processing in SweAPP N2a Cell.

The proteolytic processing of amyloid precursor protein (APP) by ß-secretase (BACE1) and γ-secretase releases amyloid-ß peptide (Aß), which deposits in amyloid plaques and contributes to the initial causative events of Alzheimer's disease (AD). In the present study, the regulatory mechanism of APP processing of three phlorotannins was elucidated in Swedish mutant APP overexpressed N2a (SweAPP N2a) cells. Among the tested compounds, dieckol exhibited the highest inhibitory effect on both intra- and extracellular Aß accumulation. In addition, dieckol regulated the APP processing enzymes, such as α-secretase (ADAM10), ß-secretase, and γ-secretase, presenilin-1 (PS1), and their proteolytic products, sAPPα and sAPPß, implying that the compound acts on both the amyloidogenic and non-amyloidogenic pathways. In addition, dieckol increased the phosphorylation of protein kinase B (Akt) at Ser473 and GSK-3ß at Ser9, suggesting dieckol induced the activation of Akt, which phosphorylated GSK-3ß. The specific phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 triggered GSK-3ß activation and Aß expression. In addition, co-treatment with LY294002 noticeably blocked the effect of dieckol on Aß production, demonstrating that dieckol promoted the PI3K/Akt signaling pathway, which in turn inactivated GSK-3ß, resulting in the reduction in Aß levels.

Discovery of Natural Inhibitors of Cholinesterases from Hydrangea: In Vitro and In Silico Approaches.

Alzheimer's disease (AD) is a neurodegenerative disease conceptualized as a clinical-biological neurodegenerative construct where amyloid-beta pathophysiology is supposed to play a role. The loss of cognitive functions is mostly characterized by the rapid hydrolysis of acetylcholine by cholinesterases including acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Moreover, both enzymes are responsible for non-catalytic actions such as interacting with amyloid ß peptide (Aß) which further leads to promote senile plaque formation. In searching for a natural cholinesterase inhibitor, the present study focused on two isocoumarines from hydrangea, thunberginol C (TC) and hydrangenol 8-O-glucoside pentaacetate (HGP). Hydrangea-derived compounds were demonstrated to act as dual inhibitors of both AChE and BChE. Furthermore, the compounds exerted selective and non-competitive mode of inhibition via hydrophobic interaction with peripheral anionic site (PAS) of the enzymes. Overall results demonstrated that these natural hydrangea-derived compounds acted as selective dual inhibitors of AChE and BChE, which provides the possibility of potential source of new type of anti-cholinesterases with non-competitive binding property with PAS.

Akt and calcium-permeable AMPA receptor are involved in the effect of pinoresinol on amyloid ß-induced synaptic plasticity and memory deficits.

Alzheimer's disease (AD) is one of the most prevalent neurodegenerative disorders characterized by memory deficits. Although no drug has given promising results, synaptic dysfunction-modulating agents might be considered potential candidates for alleviating this disorder. Pinoresinol, a lignan found in Forsythia suspensa, is a memory-enhancing agent with excitatory synaptic activation. In the present study, we tested whether pinoresinol reduces learning and memory and excitatory synaptic deficits in an amyloid ß (Aß)-induced AD-like mouse model. Pinoresinol enhanced hippocampal long-term potentiation (LTP) through calcium-permeable AMPA receptor, which was mediated by Akt activation. Moreover, pinoresinol ameliorated LTP deficits in amyloid ß (Aß)-treated hippocampal slices via Akt signaling. Oral administration of pinoresinol ameliorated Aß-induced memory deficits without sensory dysfunction. Moreover, AD-like pathology, including neuroinflammation and synaptic deficit, were ameliorated by pinoresinol administration. Collectively, pinoresinol may be a good candidate for AD therapy by modulating synaptic functions.

REDD1 Is Involved in Amyloid ß-Induced Synaptic Dysfunction and Memory Impairment.

Alzheimer's disease (AD) is a neurodegenerative disease characterized by neurological dysfunction, including memory impairment, attributed to the accumulation of amyloid ß (Aß) in the brain. Although several studies reported possible mechanisms involved in Aß pathology, much remains unknown. Previous findings suggested that a protein regulated in development and DNA damage response 1 (REDD1), a stress-coping regulator, is an Aß-responsive gene involved in Aß cytotoxicity. However, we still do not know how Aß increases the level of REDD1 and whether REDD1 mediates Aß-induced synaptic dysfunction. To elucidate this, we examined the effect of Aß on REDD1-expression using acute hippocampal slices from mice, and the effect of REDD1 short hairpin RNA (shRNA) on Aß-induced synaptic dysfunction. Lastly, we observed the effect of REDD1 shRNA on memory deficit in an AD-like mouse model. Through the experiments, we found that Aß-incubated acute hippocampal slices showed increased REDD1 levels. Moreover, Aß injection into the lateral ventricle increased REDD1 levels in the hippocampus. Anisomycin, but not actinomycin D, blocked Aß-induced increase in REDD1 levels in the acute hippocampal slices, suggesting that Aß may increase REDD1 translation rather than transcription. Aß activated Fyn/ERK/S6 cascade, and inhibitors for Fyn/ERK/S6 or mGluR5 blocked Aß-induced REDD1 upregulation. REDD1 inducer, a transcriptional activator, and Aß blocked synaptic plasticity in the acute hippocampal slices. REDD1 inducer inhibited mTOR/Akt signaling. REDD1 shRNA blocked Aß-induced synaptic deficits. REDD1 shRNA also blocked Aß-induced memory deficits in passive-avoidance and object-recognition tests. Collectively, these results demonstrate that REDD1 participates in Aß pathology and could be a target for AD therapy.

Neuroprotective Effects of Baicalein, Wogonin, and Oroxylin A on Amyloid Beta-Induced Toxicity via NF-κB/MAPK Pathway Modulation.

Amyloid beta (Aß) peptide, one of the most important pathogenic traits of Alzheimer's disease (AD), invokes a cascade of oxidative damage and eventually leads to neuronal death. In the present study, baicalein, wogonin, and oroxylin A, main active flavones in Scutellaria baicalensis, were evaluated for their neuroprotective effects against Aß25-35-stimulated damage. All tested compounds decreased Aß25-35-induced ROS generation and cell cycle arrest. In particular, baicalein exhibited the strongest antioxidant activity. In addition, these compounds suppressed apoptosis by attenuating mitochondrial dysfunction such as loss of membrane potential, Ca2+ accumulation and Bax/Bcl-2 ratio. Furthermore, all tested flavones inhibited the expression of iNOS and COX-2, which resulted in suppressing inflammatory cytokines including TNF-α, NO, and PGE2. Noticeably, all compounds exhibited the anti-inflammatory effects through downregulating NF-κB/MAPK pathway. Especially, oroxylin A was effective against both p65 and IκBα, while wogonin and baicalein were suppressed phospho-p65 and phospho-IκBα, respectively. Taken together, baicalein, wogonin, and oroxylin A can effectively relieve Aß25-35-stimulated neuronal apoptosis and inflammation in PC12 cells via downregulating NF-κB/MAPK signaling pathway.

Discovery of Sulforaphane as a Potent BACE1 Inhibitor Based on Kinetics and Computational Studies.

BACE1 is the rate-limiting enzyme involved in the production and deposition of ß-amyloid (Aß). Since neurotoxic Aß plays a critical role in Alzheimer's disease (AD) pathogenesis, BACE1 has emerged as a key target for preventing AD. In the present study, the potential of sulforaphane, an isothiocyanate found in cruciferous vegetables, as a BACE1 inhibitor has been investigated. Sulforaphane exhibited six times more potent activity against BACE1 compared to well-known positive controls including resveratrol and quercetin. Sulforaphane presented selective and non-competitive BACE1 inhibitory activity with low off-target inhibition of BACE2 and other aspartic and serine proteases. In addition, sulforaphane presented negative binding energy, suggesting that the compound had a high affinity for BACE1. It interacted with locations other than the active binding sites of BACE1 through van der Waals forces. Overall, sulforaphane appeared to be a promising candidate with potent and selective BACE1 inhibitory properties that play an important role in AD prevention.

Geraniin Protects PC12 Cells Against Aß25-35-Mediated Neuronal Damage: Involvement of NF-κB and MAPK Signaling Pathways.

ß-amyloid peptide (Aß) has been considered a critical factor that is associated with the development of oxidative stress and neuroinflammation in the pathogenesis of Alzheimer's disease. This study was performed to evaluate the effect of geraniin on Aß25-35-caused oxidative damage and neuroinflammatory response, and its underlying mechanism. Geraniin protected pheochromocytoma12 (PC12) cells from Aß25-35-mediated cell death by reducing oxidative stress and restoring cell cycle dysregulation. Moreover, geraniin markedly attenuated Aß-triggered DNA injury that was partially associated with decreases in caspase-3 activity. Moreover, the compound significantly downregulated the release of neuroinflammatory factors. Upregulation of nuclear factor-κB activity was suppressed by geraniin, which was due to suppression of JNK, ERK1/2, and the p38 mitogen-activated protein kinase (MAPK) pathway. This was the first study to support further understanding of geraniin as a promising agent against neurotoxicity in the reduction of oxidative stress and neuroinflammation.

Biological and Computational Studies for Dual Cholinesterases Inhibitory Effect of Zerumbone.

Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) mediate the degradation of acetylcholine (ACh), a primary neurotransmitter in the brain. Cholinergic deficiency occurs during the progression of Alzheimer's disease (AD), resulting in widespread cognitive dysfunction and decline. We evaluated the potential effect of a natural cholinesterase inhibitor, zerumbone, using in vitro target enzyme assays, as well as in silico docking and ADMET (absorption, distribution, metabolism, excretion, and toxicity) simulation. Zerumbone showed a predominant cholinesterase inhibitory property with IC50 values of 2.74 ± 0.48 µM and 4.12 ± 0.42 µM for AChE and BChE, respectively; however, the modes of inhibition were different. Computational docking simulation indicated that Van der Waals interactions between zerumbone and both the cholinesterases were the main forces responsible for its inhibitory effects. Furthermore, zerumbone showed the best physicochemical properties for both bioavailability and blood-brain barrier (BBB) permeability. Together, in the present study, zerumbone was clearly identified as a unique dual AChE and BChE inhibitor with high permeability across the BBB, suggesting a strong potential for its physiological benefits and/or pharmacological efficacy in the prevention of AD.

ß-Amyrin Ameliorates Alzheimer's Disease-Like Aberrant Synaptic Plasticity in the Mouse Hippocampus.

Alzheimer's disease (AD) is a progressive and most frequently diagnosed neurodegenerative disorder. However, there is still no drug preventing the progress of this disorder. ß-Amyrin, an ingredient of the surface wax of tomato fruit and dandelion coffee, is previously reported to ameliorate memory impairment induced by cholinergic dysfunction. Therefore, we tested whether ß-amyrin can prevent AD-like pathology. ß-Amyrin blocked amyloid ß (Aß)-induced long-term potentiation (LTP) impairment in the hippocampal slices. Moreover, ß-amyrin improved Aß-induced suppression of phosphatidylinositol-3-kinase (PI3K)/Akt signaling. LY294002, a PI3K inhibitor, blocked the effect of ß-amyrin on Aß-induced LTP impairment. In in vivo experiments, we observed that ß-amyrin ameliorated object recognition memory deficit in Aß-injected AD mice model. Moreover, neurogenesis impairments induced by Aß was improved by ß-amyrin treatment. Taken together, ß-amyrin might be a good candidate of treatment or supplement for AD patients.

Baicalein as a Potential Inhibitor against BACE1 and AChE: Mechanistic Comprehension through In Vitro and Computational Approaches.

One of the major neurodegenerative features of Alzheimer's disease (AD) is the presence of neurotoxic amyloid plaques composed of amyloid beta peptide (Aß). ß-Secretase (BACE1) and acetylcholinesterase (AChE), which promote Aß fibril formation, have become attractive therapeutic targets for AD. P-glycoprotein (P-gp), the major efflux pump of the blood-brain barrier (BBB), plays a critical role in limiting therapeutic molecules. In pursuit of discovering a natural anti-AD candidate, the bioactivity, physicochemical, drug-likeness, and molecular docking properties of baicalein, a major compound from Scutellaria baicalensis, was investigated. Baicalein exhibited strong BACE1 and AChE inhibitory properties (IC50 23.71 ± 1.91 µM and 45.95 ± 3.44 µM, respectively) and reacted in non-competitive and competitive manners with substrates, respectively. in Silico docking analysis was in full agreement with the in vitro results, demonstrating that the compound exhibited powerful binding interaction with target enzymes. Particularly, three continuous hydroxyl groups on the A ring demonstrated strong H-bond binding properties. It is also noteworthy that baicalein complied with all requirements of Lipinski's rule of five by its optimal physicochemical properties for both oral bioavailability and blood-brain barrier permeability. Overall, the present study strongly demonstrated the possibility of baicalein having in vivo pharmacological efficacy for specific targets in the prevention and/or treatment of AD.

Discovery of Nobiletin from Citrus Peel as a Potent Inhibitor of ß-Amyloid Peptide Toxicity.

Increasing evidence has demonstrated that amyloid-ß peptide (Aß), the hallmark of Alzheimer's disease (AD), evokes oxidative and inflammatory cascades, which ultimately lead to the death of neurons. The purpose of the present study is to demonstrate the effect of nobiletin, a representative compound of citrus peel, in preventive and therapeutic approaches against neuronal damage by exposure to Aß25-35. Nobiletin significantly ameliorated Aß25-35-mediated cell death by restoring abnormal changes in intracellular oxidative stress, cell cycle, nuclear morphology, and activity of apoptotic caspase. Regarding anti-inflammatory responses, nobiletin significantly suppressed interleukin-1ß, tumor necrosis factor-α, nitric oxide (NO), and prostaglandin E2 production in response to Aß stimulation. Moreover, nobiletin inhibited Aß-stimulated inducible NO synthase and cyclooxygenase-2 expression, which was attributed to the blockade of nuclear factor-κB p65 and phosphorylation of its inhibitor, IκB-α. Interestingly, nobiletin decreased expression of c-Jun N-terminal kinase and p38 without affecting extracellular signal-regulated kinase 1/2 activation. Taken together, the novel data implicate nobiletin as a potential candidate for the prevention of AD through the inhibition of oxidative stress, apoptosis, and inflammation.

Rubrofusarin inhibits Aß aggregation and ameliorates memory loss in an Aß-induced Alzheimer's disease-like mouse model.

The misfolding and aggregation of amyloid ß (Aß) peptide is a common histopathologic characteristic in patients with Alzheimer's disease, so is considered to play an critical role. In the present study, we examined the effect of rubrofusarin, an ingredient of Cassiae semen, on Aß aggregation and memory loss in an AD mouse model. Rubrofusarin inhibited Aß aggregation in a concentration-dependent manner. Moreover, rubrofusarin dis-aggregated preformed Aß fibrils in a concentration-dependent manner. Although aggregated Aß induced memory loss, Aß pre-incubated with rubrofusarin failed to induce memory loss. Moreover, rubrofusarin administration ameliorated Aß aggregates-induced memory loss. Finally, rubrofusarin reduced glial fibrillary acidic protein or Iba-1-positive area, markers of neuroinflammation, in the hippocampus of Aß-treated mice. These results suggest that rubrofusarin can decrease Aß fibril formation and ameliorate memory loss in the AD mouse model.

The fruit of Crataegus pinnatifida ameliorates memory deficits in ß-amyloid protein-induced Alzheimer's disease mouse model.

ETHNOPHARMACOLOGICAL RELEVANCE: The fruit of Crataegus pinnatifida is a traditional medicine widely used as digestive drug in East Asia. Although Chinese herbal medicine used it for mental health, scientific evidence does not exist, yet. AIMS OF STUDY: The aim of this study is to show that the ethanol extract of the fruit of Crataegus pinnatifida (CPE) has neuroprotective effect on Alzheimer' disease model mice. MATERIALS AND METHODS: Intracerebroventricular injection of Aß was used to induce Alzheimer's disease-like pathology. Passive avoidance and Y-maze tasks were used to examine the effect of CPE on memory impairments by Aß. Immunohistochemistry was used to examine the effect of CPE on glial activation. ThT assay was used to observe the effect of CPE on Aß aggregation. MTT and LDH release assays were utilized to examine effects of CPE on Aß-induced cytotoxicity. RESULTS: CPE prevented memory deficit in Aß-induced memory impairment model. Moreover, CPE prevented glial activation in the hippocampus of Aß-injected model. In in vitro test, CPE inhibited Aß fibril formation in a concentration-dependent manner. CPE also caused disaggregation of Aß fibrils. Along with this, CPE blocked neuronal cell death induced by Aß. CONCLUSIONS: Collectively, these experimental findings demonstrated that CPE could be a candidate for development of AD therapy.