• Journal of Physiology & Pathology in Korean Medicine
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• v.28 no.3
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• pp.317-321
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• 2014

Amyloid-${\beta}$ protein ($A{\beta}$) is a pathological component of Alzheimer's disease (AD) by participating in the senile plaque formation in the patient's brain. Although the exact mechanism of $A{\beta}$ toxicity is not fully elucidated, it is considered to be closely related to its fibrillation process. For prevention of AD, recent studies have suggested various small molecules which inhibit $A{\beta}$ fibrillation. In this report, ${\beta}$-asarone found in acorus plant has been investigated as an anti-amyloid molecule. ${\beta}$-Asarone was demonstrated to prevent in vitro fibrillation of $A{\beta}$ by inducing the oligomer formation that obviously decreased cytotoxicity. Therefore, ${\beta}$-asarone could be suggested as an inhibitory agent of $A{\beta}$ fibrillation and toxicity, which would help us not only to understand underlying principle of amyloidogenesis mechanism but also to develop a controlling strategy toward AD.

• Journal of Integrative Natural Science
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• v.5 no.2
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• pp.107-119
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• 2012

Polymerization of monomeric amyloid-${\beta}$ peptides ($A{\beta}$) into soluble oligomers and insoluble fibrils is one of the major pathways triggering the pathogenesis of Alzheimer's disease (AD). Using small molecules to prevent the polymerization of $A{\beta}$ peptides can, therefore, be an effective therapeutic strategy for AD. In this study, we investigated the effects of mono- and bi-flavonoids on $A{\beta}42$ toxicity and fibrillogenesis and found that the bi-flavonoid, taiwaniaflavone (TF) effectively and specifically inhibits $A{\beta}$ toxicity and fibrillogenesis. Compared to TF, the mono-flavonoid apigenin (AP) is less effective and less specific. Our data showed that differential effects of the mono- and bi-flavonoids on $A{\beta}$ fibrillogenesis correlate with their varying cytoprotective efficacies. We also found that other bi-flavonoids, namely 2',8"-biapigenin, amentoflavone, and sumaflavone, can also effectively inhibit $A{\beta}$ toxicity and fibrillogenesis, implying that the participation of two mono-flavonoids in a single bi-flavonoid molecule enhanced their activity. Bi-flavonoids, while strongly inhibited $A{\beta}$ fibrillogenesis, accumulated nontoxic $A{\beta}$ oligomeric structures, suggesting that these are off-pathway-oligomers. Moreover, TF abrogated the toxicity of preformed $A{\beta}$ oligomers and fibrils, indicating that TF and other bi-flavonoids may also reduce the toxicity of toxic $A{\beta}$ species. Altogether, our data clearly show that bi-flavonoids, possibly due to the possession of two $A{\beta}$ binders separated by an appropriate size linker, are likely to be promising therapeutics to suppress $A{\beta}$ toxicity.

• 한국약용작물학회:학술대회논문집
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• 2006.04a
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• pp.75-90
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• 2006

Both synthetic and endogenous $A{\beta}$ are degraded by peptidase G. Both $A{\beta}40$ and 42 are cleaved by peptidase G. Peptidase G cleaves $A{\beta}40$ into small fragments ($A{\beta}18$) which lacks aggregation property and are not toxic to neuron. Peptidase G seems to degrade multimeric $A{\beta}$ more efficiently than monomeric $A{\beta}$. Peptidase G protects neurons from toxicity induced by $A{\beta}$ by cleaving it into smaller fragments. Thus, dis-regulation of peptidase G could contribute amyloid deposit found in AD brain.

• Journal of Chitin and Chitosan
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• v.23 no.4
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• pp.220-227
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• 2018

Amyloid plaque is a product of aggregation of ${\beta}$-amyloid peptide ($A{\beta}$) and is an important factor in the pathogenesis of Alzheimer's Disease (AD). $A{\beta}$ is a major component of amyloid plaque and vascular deposits in the AD brain. The enzyme ${\beta}$-secretase is required for the production of $A{\beta}$; thus, prevention of the formation of $A{\beta}$ through the inhibition of ${\beta}$-secretase is a major focus in the study of the treatment of AD. In this study, we investigated ${\beta}$-secretase inhibitory activity of an Arctoscopus japonicus peptide. An Alcalase hydrolysate had the highest ${\beta}$-secretase inhibitory activity. A ${\beta}$-secretase inhibitory activity peptide was separated using ion exchange column chromatography (carboxy-methyl: CM, quaternary methyl ammonium: QMA) and reverse phase high performance liquid chromatography (RP-HPLC) on a C18 column. The $IC_{50}$ value of the purified peptide was $248.2{\pm}1.73{\mu}g/mL$. The ${\beta}$-secretase inhibitory peptide was identified as a six amino acid residue of Gly-Pro-Val-Gly-Ala-Pro (MW: 497.27 Da). In cell viability experiments, the final purified fraction, the carboxy-methyl ion exchange column fraction (CM-F1) showed no significant cytotoxic effect in SH-SY5Y cells at concentrations below $100{\mu}g/mL$ in 24 h. The results of this study suggest that peptides separated from Arctoscopus japonicus may be beneficial as ${\beta}$-secretase inhibitor compounds in functional foods.

• Journal of Integrative Natural Science
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• v.6 no.3
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• pp.143-150
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• 2013

Prevailing role of intracellular amyloid ${\beta}$ ($iA{\beta}$) in Alzheimer's disease (AD) initiation and progression attracts more and more attention in recent years. To address whether $iA{\beta}$ induces early alterations of electrophysiological properties in cultured human primary neurons, we delivered $iA{\beta}$ with adenovirus and measured the electrophysiological properties of infected neurons with whole-cell recordings. Our results show that $iA{\beta}$ induces an increase in neuronal resting membrane potentials, a decrease in $K^+$ currents and a hyperpolarizing shift in voltage-dependent activation of $K^+$ currents. These results suggest the electrophysiological impairments induced by $iA{\beta}$ may be responsible for its neuronal toxicity.

• Biomolecules & Therapeutics
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• v.29 no.3
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• pp.290-294
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• 2021

Extracellular beta amyloid (Aβ) plaques are the neuropathological hallmarks of Alzheimer's disease (AD). Accordingly, reducing Aβ levels is considered a promising strategy for AD prevention. 3'-O-acetyl-24-epi-7,8-didehydrocimigenol-3-O-β-D-xylopryranoside significantly decreased the Aβ production and this effect was accompanied with reduced sAPPβ production known as a soluble ectodomain APP fragment through β-secretases in HeLa cells overexpressing amyloid precursor proteins (APPs). This compound also increased the level of sAPPα, which is a proteolytic fragment of APP by α-secretases. In addition, 3'-O-acetyl-24-epi-7,8-didehydrocimigenol-3-O-β-D-xylopryranoside decreased the protein level of β-secretases, but the protein levels of A disintegrin and metalloproteinase (ADAM) family, especially ADAM10 and ADAM17, are increased. Thus, 3'-O-acetyl-24-epi-7,8-didehydrocimigenol-3-O-β-D-xylopryranoside could be useful in the development of AD treatment in the aspect of amyloid pathology.

• Molecules and Cells
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• v.24 no.1
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• pp.69-75
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• 2007

Alzheimer's disease is a neurodegenerative disorder associated with progressive loss of cognitive function and memory. Amyloid beta peptide ($A{\beta}$) is the major component of senile plaques and is known to exert its cytotoxic effect mainly by producing $H_2O_2$. Vascular endothelial growth factor (VEGF) is elevated in the cerebrospinal fluid (CSF) and brain of AD patients, and $H_2O_2$ is one of the factors that induce VEGF. Therefore, we tested whether $A{\beta}$ might be responsible for the increased VEGF synthesis. We found that $A{\beta}$ induced the production of $H_2O_2$ in vitro. Comparison of the amount of $H_2O_2$ required to induce VEGF synthesis in HN33 cells and the amount of $H_2O_2$ produced by $10{\mu}M\;A{\beta}_{1-42}$ in vitro suggested that a toxic concentration of $A{\beta}$ might induce VEGF synthesis in these cells. However, toxic concentrations of $A{\beta}$ failed to induce VEGF synthesis in several cell systems. They also had no effect on antioxidant enzymes such as glutathione peroxidase, catalase, and peroxiredoxin in HN33 cells. $Cu^{2+}$, $Zn^{2+}$ and $Fe^{3+}$ are known to accumulate in the brains of AD patients and promote aggregation of $A{\beta}$, and $Cu^{2+}$ by itself induces synthesis of VEGF. However, there was no synergistic effect between $Cu^{2+}$ and $A{\beta}_{1-42}$ in the induction of VEGF synthesis and $Zn^{2+}$ and $Fe^{3+}$ also had no effect on the synthesis of VEGF, alone or in combination with $A{\beta}$.

• The Journal of Internal Korean Medicine
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• v.19 no.2
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• pp.381-391
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• 1998

The present study was done to investigate the effects of Bombusae concretio Salicea (BCS) on cultured astrocyte cell system and lipid peroxidation in $A{\beta}25-35$ treatment conditions. Cell killing was significantly enhanced by addition of increasing concentrations of $A{\beta}25-35$. Pretreatment of BCS attenuated in cell killing enhanced by increasing concentrations of $A{\beta}25-35$. MDA level induced by $A{\beta}25-35$ treatment was significantly increased and the level was slightly reduced by pretreatment of BCS. The present study showed that $A{\beta}25-35$ strongly increased MDA level and the level was enhanced by addition of increasing concentrations of In conclusion, it was shown that $A{\beta}25-35$ is not only potent lipid peroxide inducer, but also cause protection of neurodegeneration induced by $A{\beta}25-35$. It can be concluded that the activation of antioxidative enzymes may be related to the inhibition of lipid peroxidative reactions. We cannot fully explain to effects of BCS at present; however, the ability of BCS to reduce cell killing and MDA level induced by $A{\beta}25-35$ suggest that BCS may be a protective agent for free radical generating compounds such as $A{\beta}25-35$.

• BMB Reports
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• v.50 no.12
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• pp.634-639
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• 2017

We aimed to assess the anti-inflammatory and antioxidative properties of KHG26792, a novel azetidine derivative, in amyloid ${\beta}$ ($A{\beta}$)-treated primary microglial cells. KHG26792 attenuated the $A{\beta}-induced$ production of inflammatory mediators such as IL-6, $IL-1{\beta}$, $TNF-{\alpha}$, and nitric oxide. The levels of protein oxidation, lipid peroxidation, ROS, and NADHP oxidase enhanced by $A{\beta}$ were also downregulated by KHG26792 treatment. The effects of KHG26792 against the $A{\beta}-induced$ increases in inflammatory cytokine levels and oxidative stress were achieved by increasing the phosphorylation of $Akt/GSK-3{\beta}$ signaling and by decreasing the $A{\beta}-induced$ translocation of $NF-{\kappa}B$. Our results provide novel insights into the use of KHG26792 as a potential agent against $A{\beta}$ toxicity, including its role in the reduction of inflammation and oxidative stress. Nevertheless, further investigations of cellular signaling are required to clarify the in vivo effects of KHG26792 against $A{\beta}-induced$ toxicity.

• Molecules and Cells
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• v.27 no.6
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• pp.651-656
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• 2009

The formation of ${\beta}$-amyloid peptide ($A{\beta}$) is initiated from cleavage of amyloid precursor protein (APP) by a family of protease, ${\alpha}$-, ${\beta}$-, and ${\gamma}$-secretase. Sub W, a substrate peptide, consists of 10 amino acids, which are adjacent to the ${\beta}$-cleavage site of wild-type APP, and Sub M is Swedish mutant with double mutations on the left side of the ${\beta}$-cleavage site of APP. Sub W is a normal product of the metabolism of APP in the secretary pathway. Sub M is known to increase the efficiency of ${\beta}$-secretase activity, resulting in a more specific binding model compared to Sub W. Three-dimensional structures of Sub W and Sub M were studied by CD and NMR spectroscopy in water solution. On the basis of these structures, interaction models of ${\beta}$-secretase and substrate peptides were determined by molecular dynamics simulation. Four hydrogen bonds and one water-mediated interaction were formed in the docking models. In particular, the hydrogen bonding network of Sub M-BACE formed spread over the broad region of the active site of ${\beta}$-secretase (P5-P3'), and the side chain of P2- Asn formed a hydrogen bond specifically with the side chain of Arg235. These are more favorable to the cleavage of Sub M by ${\beta}$-secretase than Sub W. The two substrate peptides showed different tendency to bind to ${\beta}$-secretase and this information may useful for drug development to treat and prevent Alzheimer's disease.