Protective effect of a triazine-derivative (AA3E2) on beta-amyloid-induced damages in SK-N-MC cells

Beneficial Effects of a Combination of Curcuma longa L. and Citrus junos Against Beta-Amyloid Peptide-Induced Neurodegeneration in Mice

Both Curcuma longa (CL) and Citrus junos Tanaka (CJ) have been used to treat various diseases due to their anti-inflammatory and antioxidative stress activities. In this study, we investigated the ameliorative effect of the combination of CL extract and CJ extract (CCC) against beta-amyloid (Aβ) peptide-induced neurological damage. CCC prevented neurocytotoxicity in vitro. In addition, it was confirmed that abnormal alternation behavior and memory impairment caused by Aβ peptide were reversed by treatment with CCC. Furthermore, CCC treatment led to recovery of the cholinergic system and reactive oxygen species (ROS) oxidative damage defense system. CCC induced expressions of cyclic-adenosine monophosphate response element-binding protein (CREB)-responsive element-binding protein and brain-derived neurotrophic factor were confirmed as was the significantly improved processing in the hippocampus of the mouse Aβ peptides. Accordingly, these results suggest that CCC can prevent and/or reverse neurocytotoxicity and cognitive deficits in a mouse model of Alzheimer's disease.

Ameliorative Effects of Dendropanax morbifera on Cognitive Impairment Via Enhancing Cholinergic Functions and Brain-Derived Neurotrophic Factor Expression in β-Amyloid-Induced Mice

Alzheimer's disease accounts for the majority of dementia and shows hallmarks such as sequential cognitive dysfunction and abnormal behavior. Dendropanax morbifera (DM) has traditionally been used to treat a variety of diseases in East Asia. The aim of this study was to assess the therapeutic effects of DM on brain neuron damage and on cognitive deficit in neuronal cell induced by Aβ_1-42 in mice. Treatment with DM reduced the levels of intracellular reactive oxygen species and protected against the death of neuronal cells induced by Aβ_1-42 peptide. In addition, it was also found that pretreatment with DM decreased cognitive damage induced by Aβ peptide via enhancing the cholinergic system and antioxidant defense system in mice. Furthermore, the study verified that the change in the expression of both cyclic-adenosine monophosphate response element binding protein and of brain-derived neurotrophic factor in the hippocampus in Aβ peptide-treated mice was significantly ameliorated after treatment with DM. Accordingly, these results suggest that pretreatment with DM defends against oxidative stress and cognitive impairment caused by Aβ peptide.

A novel inhibitor of amyloid β (Aβ) peptide aggregation: from high throughput screening to efficacy in an animal model of Alzheimer disease

Compelling evidence indicates that aggregation of the amyloid β (Aβ) peptide is a major underlying molecular culprit in Alzheimer disease. Specifically, soluble oligomers of the 42-residue peptide (Aβ42) lead to a series of events that cause cellular dysfunction and neuronal death. Therefore, inhibiting Aβ42 aggregation may be an effective strategy for the prevention and/or treatment of disease. We describe the implementation of a high throughput screen for inhibitors of Aβ42 aggregation on a collection of 65,000 small molecules. Among several novel inhibitors isolated by the screen, compound D737 was most effective in inhibiting Aβ42 aggregation and reducing Aβ42-induced toxicity in cell culture. The protective activity of D737 was most significant in reducing the toxicity of high molecular weight oligomers of Aβ42. The ability of D737 to prevent Aβ42 aggregation protects against cellular dysfunction and reduces the production/accumulation of reactive oxygen species. Most importantly, treatment with D737 increases the life span and locomotive ability of flies in a Drosophila melanogaster model of Alzheimer disease.

Protective effects of 1,3-diaryl-2-propen-1-one derivatives against H₂O₂ -induced damage in SK-N-MC cells

Alzheimer's disease (AD) is an age-related neurodegenerative disorder of the central nervous system resulting in memory loss and dementia. Some of the associated pathogenic changes are amyloid peptide aggregation, excitotoxicity, oxidative stress and inflammation. Oxidative stress plays an indispensable role in the pathophysiology of AD. Therefore, antioxidant therapies appear to be promising approaches in dealing with AD patients. In that line, we evaluated the free radical scavenging capabilities of 13 different chalcones (1,3-diphenyl-2-propen-1-one) derivatives against the free-radical damaging effects of hydrogen peroxide (H₂O₂) on the SK-N-MC neuroblastoma cell line. Pretreatment of the cells for 3 h with 20 µ m of each of these derivatives (compounds 8-20) followed by exposure to 300 µ m H₂O₂ for 24 h indicated that all compounds, except compound 20, were capable of restoring the viabilities of cells relative to the control (H₂O₂ -treated) cells. The destructive effect of H₂O₂ on the adhesive behavior of the cells was almost totally restored by each of the derivatives. In addition, each of the derivatives except compounds 20 and 14 significantly reduced the extent of lipofuscin formation among the cells time-dependently. Despite these activities, some of the derivatives, such as compounds 12 and 19, did not reduce the H₂O₂ -induced intracellular ROS (reactive oxygen species) levels, meaning that these two derivatives act through a different mechanism other than free-radical scavenging activity. On the other hand, for those derivatives acting as anti-oxidants, structure-activity evaluation clearly revealed that the hydroxyl group of vanillin ring is required for their free-radical scavenging activities.

Anti-amyloidogenic effect of AA3E2 attenuates beta-amyloid induced toxicity in SK-N-MC cells

Beta-amyloid peptide (Abeta) is believed to play a recognized role in pathogenesis of Alzheimer's disease (AD). Self-association of Abeta peptide into amyloid fibrils causes neurotoxicity. Compounds capable of interfering with Abeta-Abeta interaction through binding to nucleation sites can inhibit Abeta amyloidogenesis and Abeta-induced cytotoxicity. AA3E2 is a triazine-derivative whose anti-amyloidogenic ability has previously been established. In the present study, we evaluated the protective effect of AA3E3 against Abeta(1-42)-induced toxicity in SK-N-MC cell line. The cell exposure to the co-incubated Abeta(1-42) with AA3E2 decreased the cell viability loss dose-dependently, compared to cells exposed to Abeta(1-42) fibrils. Co-incubation with AA3E2 also attenuated the ROS production, activation of caspase-3 and the extent of apoptotic cell death induced by Abeta(1-42) fibril. Moreover, the 3D structure of the molecular associates between Abeta(1-42) and AA3E2 were theoretically determined by docking studies. Our docking data indicated that AA3E2 inhibits the formation of Abeta fibril likely via binding to the nucleation site within the hydrophobic region of Abeta (KLVFF). These observations provide the background for future design of more elegant beta-breaking agents for dissolution of Abeta fibrillar aggregates.