Fruitless Wolfberry-Sprout Extract Rescued Cognitive Deficits and Attenuated Neuropathology in Alzheimer's Disease Transgenic Mice.

BACKGROUND: Alzheimer's disease (AD) is a neurodegenerative disease featured by memory loss, neuroinflammation and oxidative stress. Overproduction or insufficient clearance of Aß leads to its pathological aggregation and deposition, which is considered the predominant neuropathological hallmark of AD. Therefore, reducing Aß levels and inhibiting Aß-induced neurotoxicity are feasible therapeutic strategies for AD treatment. Wolfberry has been traditionally used as a natural antioxidant and anti-aging product. However, whether wolfberry species has therapeutic potential on AD remains unknown. METHOD: The effects of fruitless wolfberry-sprout extract (FWE) on Aß fibrillation and fibril disaggregation was measured by thioflavin T fluorescence and transmission electron microscope imaging; Aß oligomer level was determined by dot-blot; Cell viability and apoptosis was assessed by MTT and TUNEL assay. The levels of Aß40/42, oxidative stress biomarkers and inflammatory cytokines were detected by corresponding kits. 8-month-old male APP/PS1 mice and their age-matched WT littermates were treated with FWE or vehicle by oral administration (gavage) once a day for 4 weeks. Then the cognitive performance was determined using object recognition test and Y-maze test. The Aß burden and gliosis was evaluated by immunostaining and immunoblotting, respectively. RESULTS: FWE significantly inhibited Aß fibrillation and disaggregated the formed Aß fibrils, lowered Aß oligomer level and Aß-induced neuro-cytotoxicity, and attenuated oxidative stress in vitro. Oral administration of FWE remarkably improved cognitive function, reduced Aß burden, decreased gliosis and inflammatory cytokines release, and ameliorated oxidative stress in the brains of APP/PS1 mice. CONCLUSION: These findings indicate that FWE is a promising natural agent for AD treatment.

Alpha-tocopherol quinine ameliorates spatial memory deficits by reducing beta-amyloid oligomers, neuroinflammation and oxidative stress in transgenic mice with Alzheimer's disease.

The pathologies of Alzheimer's disease (AD) is associated with soluble beta-amyloid (Aß) oligomers, neuroinflammation and oxidative stress. Decreasing the levels of Aß oligomer, glial activation and oxidative stress are potential therapeutic approaches for AD treatment. We previously found alpha-tocopherol quinine (α-TQ) inhibited Aß aggregation and cytotoxicity, decreased the release of inflammatory cytokines and reactive oxygen species (ROS) in vitro. However, whether α-TQ ameliorates memory deficits and other neuropathologies in mice or patients with AD remains unknown. In this study, we reported that orally administered α-TQ ameliorated memory impairment in APPswe/PS1dE9 transgenic mice, decreased oxidative stress and the levels of Aß oligomer in the brains of mice, prevented the production of inducible nitric oxide synthase and inflammatory mediators, such as interleukin-6 and interleukin-1ß, and inhibited microglial activation by inhibiting NF-κB signaling pathway. These findings suggest that α-TQ has potential therapeutic value for AD treatment.

A peptide binding to the ß-site of APP improves spatial memory and attenuates Aß burden in Alzheimer's disease transgenic mice.

Amyloid precursor protein cleaving enzyme 1 (BACE1), an aspartyl protease, initiates processing of the amyloid precursor protein (APP) into ß-amyloid (Aß); the peptide likely contributes to development of Alzheimer's disease (AD). BACE1 is an attractive therapeutic target for AD treatment, but it exhibits other physiological activities and has many other substrates besides APP. Thus, inhibition of BACE1 function may cause adverse side effects. Here, we present a peptide, S1, isolated from a peptide library that selectively inhibits BACE1 hydrolytic activity by binding to the ß-proteolytic site on APP and Aß N-terminal. The S1 peptide significantly reduced Aß levels in vitro and in vivo and inhibited Aß cytotoxicity in SH-SY5Y cells. When applied to APPswe/PS1dE9 double transgenic mice by intracerebroventricular injection, S1 significantly improved the spatial memory as determined by the Morris Water Maze, and also attenuated their Aß burden. These results indicate that the dual-functional peptide S1 may have therapeutic potential for AD by both reducing Aß generation and inhibiting Aß cytotoxicity.

Rutin inhibits ß-amyloid aggregation and cytotoxicity, attenuates oxidative stress, and decreases the production of nitric oxide and proinflammatory cytokines.

Alzheimer's disease (AD) is a complex, multi-factorial neurodegenerative disease. The aggregation of soluble ß-amyloid (Aß) into fibrillar deposits is a pathological hallmark of AD. The Aß aggregate-induced neurotoxicity, inflammatory reactions, oxidative stress, and nitric oxide (NO) generation are strongly linked to the etiology of AD. Here, we show that the common dietary flavonoid, rutin, can dose-dependently inhibit Aß42 fibrillization and attenuate Aß42-induced cytotoxicity in SH-SY5Y neuroblastoma cells. Moreover, rutin decreases the formation of reactive oxygen species (ROS), NO, glutathione disulfide (GSSG), and malondialdehyde (MDA), reduces inducible nitric oxide synthase (iNOS) activity, attenuates mitochondrial damage, increases the glutathione (GSH)/GSSG ratio, enhances the activities of super oxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), and modulates the production of proinflammatory cytokines by decreasing TNF-α and IL-1ß generation in microglia. Taken together, the actions of rutin on multiple pathogenic factors deserves further investigation for the prevention and treatment of AD.

Conformation-dependent scFv antibodies specifically recognize the oligomers assembled from various amyloids and show colocalization of amyloid fibrils with oligomers in patients with amyloidoses.

Increasing evidence indicates that amyloid aggregates, including oligomers, protofibrils or fibrils, are pivotal toxins in the pathogenesis of many amyloidoses such as Alzheimer's disease (AD), Parkinson's disease, Huntington's disease, prion-related diseases, type 2 diabetes and hereditary renal amyloidosis. Various oligomers assembled from different amyloid proteins share common structures and epitopes. Here we present data indicating that two oligomer-specific single chain variable fragment (scFv) antibodies isolated from a naïve human scFv library could conformation-dependently recognize oligomers assembled from α-synuclein, amylin, insulin, Aß1-40, prion peptide 106-126 and lysozyme, and fibrils from lysozyme. Further investigation showed that both scFvs inhibited the fibrillization of α-synuclein, amylin, insulin, Aß1-40 and prion peptide 106-126, and disaggregated their preformed fibrils. However, they both promoted the aggregation of lysozyme. Nevertheless, the two scFv antibodies could attenuate the cytotoxicity of all amyloids tested. Moreover, the scFvs recognized the amyloid oligomers in all types of plaques, Lewy bodies and amylin deposits in the brain tissues of AD and PD patients and the pancreas of type 2 diabetes patients respectively, and showed that most amyloid fibril deposits were colocalized with oligomers in the tissues. Such conformation-dependent scFv antibodies may have potential application in the investigation of aggregate structures, the mechanisms of aggregation and cytotoxicity of various amyloids, and in the development of diagnostic and therapeutic reagents for many amyloidoses.

α-Tocopherol quinone inhibits ß-amyloid aggregation and cytotoxicity, disaggregates preformed fibrils and decreases the production of reactive oxygen species, NO and inflammatory cytokines.

Alzheimer's disease (AD) is a complex, multifactorial neurodegenerative disease. The aggregation of beta-amyloid (Aß) into extracellular fibrillar deposition is a pathological hallmark of AD. The Aß aggregate-induced neurotoxicity, inflammatory reactions and oxidative stress are linked strongly to the etiology of AD. The currently available hitting-one-target drugs are insufficient for the treatment of AD. Therefore, finding multipotent agents able to modulate multiple targets simultaneously is attracting more attention. Previous studies indicated that vitamin E or its constituent such as α-tocopherol (α-T) was able to attenuate the effects of several pathogenetic factors in AD. However, ineffective or detrimental results were obtained from a number of clinical trials of vitamin E. Here, we showed that naturally synthesized RRR-α-tocopherol quinone (α-TQ), a main derivative of α-T, could inhibit Aß42 fibril formation dose-dependently. Further investigations indicated that α-TQ could attenuate Aß42-induced neurotoxicity toward SH-SY5Y neuroblastoma cells, disaggregate preformed fibrils and interfere with natural intracellular Aß oligomer formation. Moreover, α-TQ could decrease the formation of reactive oxygen species (ROS) and NO, and modulate the production of cytokines by decreasing TNF-α and IL-1ß and increasing IL-4 formation in microglia. Taken together, α-TQ targeting multiple pathogenetic factors deserves further investigation for prevention and treatment of AD.

Diverse ecdysterones show different effects on amyloid-ß42 aggregation but all uniformly inhibit amyloid-ß42-induced cytotoxicity.

Amyloid-ß (Aß) plays a pivotal role in Alzheimer's disease (AD) pathogenesis and in toxic mechanisms such as oxidative stress, mitochondrial dysfunction, calcium turbulence, and apoptosis induction. Therefore, interfering with Aß aggregation has long been one of the most promising strategies for AD treatment. Ecdysterones (ECRs) are steroidal hormones in insects and terrestrial plants that have high structural diversity and multiple beneficial pharmacological activities. Here, we studied the effects of six ECRs on Aß aggregation and cytotoxicity. Two ECRs with an acetoxyl group at the 2 or 3 position and saturated chains as side groups showed apparent promotion of Aß42 fibrilization, resulting in less Aß42 oligomers in the samples. Another three with unsaturated side chains clearly inhibited Aß aggregation and disaggregated preformed fibrils, but increased the Aß42 oligomer levels. Nevertheless, our MTT results showed that all ECRs tested inhibited Aß42-induced cytotoxicity. This protective activity may be partly attributable to ECR-mediated amelioration of A&beta42-induced release of reactive oxygen species. Taken together, our findings suggest that ECRs, a series of natural compounds in many plants and insects, have therapeutic potential in AD and that the deduced structure-activity relationships may be beneficial in drug design for the treatment of AD and other amyloidoses.

Ellagic acid promotes Abeta42 fibrillization and inhibits Abeta42-induced neurotoxicity.

Smaller, soluble oligomers of beta-amyloid (Abeta) play a critical role in the pathogenesis of Alzheimer's disease (AD). Selective inhibition of Abeta oligomer formation provides an optimum target for AD therapy. Some polyphenols have potent anti-amyloidogenic activities and protect against Abeta neurotoxicity. Here, we tested the effects of ellagic acid (EA), a polyphenolic compound, on Abeta42 aggregation and neurotoxicity in vitro. EA promoted Abeta fibril formation and significant oligomer loss, contrary to previous results that polyphenols inhibited Abeta aggregation. The results of transmission electron microscopy (TEM) and Western blot displayed more fibrils in Abeta42 samples co-incubated with EA in earlier phases of aggregation. Consistent with the hypothesis that plaque formation may represent a protective mechanism in which the body sequesters toxic Abeta aggregates to render them harmless, our MTT results showed that EA could significantly reduce Abeta42-induced neurotoxicity toward SH-SY5Y cells. Taken together, our results suggest that EA, an active ingredient in many fruits and nuts, may have therapeutic potential in AD.

Resveratrol inhibits beta-amyloid oligomeric cytotoxicity but does not prevent oligomer formation.

Beta-amyloid (Abeta) aggregation has been strongly associated with the neurodegenerative pathology and a cascade of harmful event rated to Alzheimer's disease (AD). Inhibition of Abeta assembly, destabilization of preformed Abeta aggregates and attenuation of the cytotoxicity of Abeta oligomers and fibrils could be valuable therapeutics of patients with AD. Recent studies suggested that moderate consumption of red wine and intake of dietary polyphenols, such as resveratrol, may benefit AD phenotypes in animal models and reduce the relative risk for AD clinical dementia. To understand the mechanism of this neuroprotection, we studied the effects of resveratrol, an active ingredient of polyphenols in wine and many plants, on the polymerization of Abeta42 monomer, the destabilization of Abeta42 fibril and the cell toxicity of Abeta42 in vitro using fluorescence spectroscopic analysis with thioflavin T (ThT), transmission electron microscope (TEM), circular dichroism (CD) and MTT assay. The results showed that resveratrol could dose-dependently inhibit Abeta42 fibril formation and cytotoxicity but could not prevent Abeta42 oligomerization. The studies by Western-blot, dot-blot and ELISA confirmed that the addition of resveratrol resulted in numerous Abeta42 oligomer formation. In conjunction with the concept that Abeta oligomers are linked to Abeta toxicity, we speculate that aside from potential antioxidant activities, resveratrol may directly bind to Abeta42, interfere in Abeta42 aggregation, change the Abeta42 oligomer conformation and attenuate Abeta42 oligomeric cytotoxicity.

Conformation-dependent single-chain variable fragment antibodies specifically recognize beta-amyloid oligomers.

Increasing evidence indicates that beta-amyloid (Abeta) oligomers rather than monomers or fibrils are the major toxic agents that specifically inhibit synaptic plasticity and long-term potentiation (LTP) in Alzheimer's disease (AD). Neutralization of Abeta oligomeric toxicity was found to reverse memory deficits. Here, we report four single-chain variable fragment (scFv) antibodies isolated from the naive human scFv library by phage display that specifically recognized Abeta oligomers but not monomers and fibrils. These conformation-dependent scFv antibodies inhibit both Abeta fibrillation and cytotoxicity and bind to the same type of eptitope displayed on the Abeta oligomers. Such scFv antibodies specifically targeting toxic Abeta oligomers may have potential therapeutic and diagnostic applications for AD.