Amentoflavone Promotes Cellular Uptake and Degradation of Amyloid-Beta in Neuronal Cells.

Deposition of fibrillar forms of amyloid ß-protein (Aß) is commonly found in patients with Alzheimer's disease (AD) associated with cognitive decline. Impaired clearance of Aß species is thought to be a major cause of late-onset sporadic AD. Aß secreted into the extracellular milieu can be cleared from the brain through multiple pathways, including cellular uptake in neuronal and non-neuronal cells. Recent studies have showed that the naturally-occurring polyphenol amentoflavone (AMF) exerts anti-amyloidogenic effects. However, its effects on metabolism and cellular clearance of Aß remain to be tested. In the present study, we demonstrated that AMF significantly increased the cellular uptake of both Aß1-40 and Aß1-42, but not inverted Aß42-1 in mouse neuronal N2a cells. Though AMF promoted internalization of cytotoxic Aß1-42, it significantly reduced cell death in our assay condition. Our data further revealed that the internalized Aß is translocated to lysosomes and undergoes enzymatic degradation. The saturable kinetic of Aß uptake and our pharmacologic experiments showed the involvement of receptor-mediated endocytosis, in part, through the class A scavenger receptors as a possible mechanism of action of AMF. Taken together, our findings indicate that AMF can lower the levels of extracellular Aß by increasing their cellular uptake and clearance, suggesting the therapeutic potential of AMF for the treatment of AD.

Biflavonoid-Induced Disruption of Hydrogen Bonds Leads to Amyloid-ß Disaggregation.

Deposition of amyloid ß (Aß) fibrils in the brain is a key pathologic hallmark of Alzheimer's disease. A class of polyphenolic biflavonoids is known to have anti-amyloidogenic effects by inhibiting aggregation of Aß and promoting disaggregation of Aß fibrils. In the present study, we further sought to investigate the structural basis of the Aß disaggregating activity of biflavonoids and their interactions at the atomic level. A thioflavin T (ThT) fluorescence assay revealed that amentoflavone-type biflavonoids promote disaggregation of Aß fibrils with varying potency due to specific structural differences. The computational analysis herein provides the first atomistic details for the mechanism of Aß disaggregation by biflavonoids. Molecular docking analysis showed that biflavonoids preferentially bind to the aromatic-rich, partially ordered N-termini of Aß fibril via the π-π interactions. Moreover, docking scores correlate well with the ThT EC50 values. Molecular dynamic simulations revealed that biflavonoids decrease the content of ß-sheet in Aß fibril in a structure-dependent manner. Hydrogen bond analysis further supported that the substitution of hydroxyl groups capable of hydrogen bond formation at two positions on the biflavonoid scaffold leads to significantly disaggregation of Aß fibrils. Taken together, our data indicate that biflavonoids promote disaggregation of Aß fibrils due to their ability to disrupt the fibril structure, suggesting biflavonoids as a lead class of compounds to develop a therapeutic agent for Alzheimer's disease.

Contribution of reactive oxygen species to cerebral amyloid angiopathy, vasomotor dysfunction, and microhemorrhage in aged Tg2576 mice.

Cerebral amyloid angiopathy (CAA) is characterized by deposition of amyloid ß peptide (Aß) within walls of cerebral arteries and is an important cause of intracerebral hemorrhage, ischemic stroke, and cognitive dysfunction in elderly patients with and without Alzheimer's Disease (AD). NADPH oxidase-derived oxidative stress plays a key role in soluble Aß-induced vessel dysfunction, but the mechanisms by which insoluble Aß in the form of CAA causes cerebrovascular (CV) dysfunction are not clear. Here, we demonstrate evidence that reactive oxygen species (ROS) and, in particular, NADPH oxidase-derived ROS are a key mediator of CAA-induced CV deficits. First, the NADPH oxidase inhibitor, apocynin, and the nonspecific ROS scavenger, tempol, are shown to reduce oxidative stress and improve CV reactivity in aged Tg2576 mice. Second, the observed improvement in CV function is attributed both to a reduction in CAA formation and a decrease in CAA-induced vasomotor impairment. Third, anti-ROS therapy attenuates CAA-related microhemorrhage. A potential mechanism by which ROS contribute to CAA pathogenesis is also identified because apocynin substantially reduces expression levels of ApoE-a factor known to promote CAA formation. In total, these data indicate that ROS are a key contributor to CAA formation, CAA-induced vessel dysfunction, and CAA-related microhemorrhage. Thus, ROS and, in particular, NADPH oxidase-derived ROS are a promising therapeutic target for patients with CAA and AD.

Evaluation of 64Cu-Based Radiopharmaceuticals that Target Aß Peptide Aggregates as Diagnostic Tools for Alzheimer's Disease.

Positron emission tomography (PET) imaging agents that detect amyloid plaques containing amyloid beta (Aß) peptide aggregates in the brain of Alzheimer's disease (AD) patients have been successfully developed and recently approved by the FDA for clinical use. However, the short half-lives of the currently used radionuclides 11C (20.4 min) and 18F (109.8 min) may limit the widespread use of these imaging agents. Therefore, we have begun to evaluate novel AD diagnostic agents that can be radiolabeled with 64Cu, a radionuclide with a half-life of 12.7 h, ideal for PET imaging. Described herein are a series of bifunctional chelators (BFCs), L1-L5, that were designed to tightly bind 64Cu and shown to interact with Aß aggregates both in vitro and in transgenic AD mouse brain sections. Importantly, biodistribution studies show that these compounds exhibit promising brain uptake and rapid clearance in wild-type mice, and initial microPET imaging studies of transgenic AD mice suggest that these compounds could serve as lead compounds for the development of improved diagnostic agents for AD.

Passive immunotherapy targeting amyloid-ß reduces cerebral amyloid angiopathy and improves vascular reactivity.

Prominent cerebral amyloid angiopathy is often observed in the brains of elderly individuals and is almost universally found in patients with Alzheimer's disease. Cerebral amyloid angiopathy is characterized by accumulation of the shorter amyloid-ß isoform(s) (predominantly amyloid-ß40) in the walls of leptomeningeal and cortical arterioles and is likely a contributory factor to vascular dysfunction leading to stroke and dementia in the elderly. We used transgenic mice with prominent cerebral amyloid angiopathy to investigate the ability of ponezumab, an anti-amyloid-ß40 selective antibody, to attenuate amyloid-ß accrual in cerebral vessels and to acutely restore vascular reactivity. Chronic administration of ponezumab to transgenic mice led to a significant reduction in amyloid and amyloid-ß accumulation both in leptomeningeal and brain vessels when measured by intravital multiphoton imaging and immunohistochemistry. By enriching for cerebral vascular elements, we also measured a significant reduction in the levels of soluble amyloid-ß biochemically. We hypothesized that the reduction in vascular amyloid-ß40 after ponezumab administration may reflect the ability of ponezumab to mobilize an interstitial fluid pool of amyloid-ß40 in brain. Acutely, ponezumab triggered a significant and transient increase in interstitial fluid amyloid-ß40 levels in old plaque-bearing transgenic mice but not in young animals. We also measured a beneficial effect on vascular reactivity following acute administration of ponezumab, even in vessels where there was a severe cerebral amyloid angiopathy burden. Taken together, the beneficial effects ponezumab administration has on reducing the rate of cerebral amyloid angiopathy deposition and restoring cerebral vascular health favours a mechanism that involves rapid removal and/or neutralization of amyloid-ß species that may otherwise be detrimental to normal vessel function.

Cerebral amyloid angiopathy increases susceptibility to infarction after focal cerebral ischemia in Tg2576 mice.

BACKGROUND AND PURPOSE: We and others have shown that soluble amyloid ß-peptide (Aß) and cerebral amyloid angiopathy (CAA) cause significant cerebrovascular dysfunction in mutant amyloid precursor protein (APP) mice, and that these deficits are greater in aged APP mice having CAA compared with young APP mice lacking CAA. Amyloid ß-peptide in young APP mice also increases infarction after focal cerebral ischemia, but the impact of CAA on ischemic brain injury is unknown. METHODS: To determine this, we assessed cerebrovascular reactivity, cerebral blood flow (CBF), and extent of infarction and neurological deficits after transient middle cerebral artery occlusion in aged APP mice having extensive CAA versus young APP mice lacking CAA (and aged-matched littermate controls). RESULTS: We found that aged APP mice have more severe cerebrovascular dysfunction that is CAA dependent, have greater CBF compromise during and immediately after middle cerebral artery occlusion, and develop larger infarctions after middle cerebral artery occlusion. CONCLUSIONS: These data indicate CAA induces a more severe form of cerebrovascular dysfunction than amyloid ß-peptide alone, leading to intra- and postischemic CBF deficits that ultimately exacerbate cerebral infarction. Our results shed mechanistic light on human studies identifying CAA as an independent risk factor for ischemic brain injury.

Crystal structure of bis-(4-allyl-2-meth-oxy-phen-yl) terephthalate.

The asymmetric unit of the title compound, C28H26O6, contains one half-mol-ecule, with the complete molecule generated by a crystallographic inversion center. The central terephthalate and meth-oxy-benzene rings are approximately perpendicular, making a dihedral angle of 80.31 (5)°. No specific directional contacts are noted in the crystal packing. The terminal vinyl group is disordered over two orientations with an occupancy ratio of 0.796 (4):0.204 (4).

2-(2,5-Dimeth-oxy-phen-yl)-N-[2-(4-hy-droxy-phen-yl)eth-yl]acetamide.

In the title compound, C(18)H(21)NO(4), the dihedral angles between the acetamide group and the meth-oxy- and hy-droxy-substitured benzene rings are 80.81 (5) and 8.19 (12)°, respectively. The benzene rings are twisted with respect to each other, making a dihedral angle of 72.89 (5)°. In the crystal, N-H⋯O and O-H⋯O hydrogen bonds link the mol-ecules into a three-dimensional network.

1-(3-Hy-droxy-phen-yl)-3-(3-meth-oxy-phenyl)thio-urea.

In the title compound, C(14)H(14)N(2)O(2)S, the dihedral angles between the thio-urea group and the methoxyphenyl and hydroxyphenyl rings are 61.91 (4) and 76.90 (4)°, respectively. The benzene rings are twisted with respect to each other, making a dihedral angle of 71.03 (4)°. The H atoms of the thio-urea NH groups are positioned anti to each other. In the crystal, inter-molecular N-H⋯S, N-H⋯O and O-H⋯S hydrogen bonds link the mol-ecules into a three-dimensional network.

Endothelial nitric oxide synthase mediates endogenous protection against subarachnoid hemorrhage-induced cerebral vasospasm.

BACKGROUND AND PURPOSE: Vasospasm-induced delayed cerebral ischemia remains a major source of morbidity in patients with aneurysmal subarachnoid hemorrhage (SAH). We hypothesized that activating innate neurovascular protective mechanisms by preconditioning (PC) may represent a novel therapeutic approach against SAH-induced vasospasm and neurological deficits and, secondarily, that the neurovascular protection it provides is mediated by endothelial nitric oxide synthase (eNOS). METHODS: Wild-type mice were subjected to hypoxic PC or normoxia followed 24 hours later by SAH. Neurological function was analyzed daily; vasospasm was assessed on post-surgery Day 2. Nitric oxide availability, eNOS expression, and eNOS activity were also assessed. In a separate experiment, wild-type and eNOS-null mice were subjected to hypoxic PC or normoxia followed by SAH and assessed for vasospasm and neurological deficits. RESULTS: PC nearly completely prevented SAH-induced vasospasm and neurological deficits. It also prevented SAH-induced reduction in nitric oxide availability and increased eNOS activity in mice with and without SAH. PC-induced protection against vasospasm and neurological deficits was lost in wild-type mice treated with the nitric oxide synthase inhibitor N(G)-nitro-l-arginine methyl ester and in eNOS-null mice. CONCLUSIONS: Endogenous protective mechanisms against vasospasm exist, are powerful, and can be induced by PC. eNOS-derived nitric oxide is a critical mediator of PC-induced neurovascular protection. These data provide strong "proof-of-principle" evidence that PC represents a promising new strategy to reduce vasospasm and delayed cerebral ischemia after SAH.

Effect of dietary supplementation of gallic acid and linoleic acid mixture or their synthetic salt on egg quality.

The effect of a dietary supplementation of gallic acid and linoleic acid mixture (MGL) and their synthetic salt, sodium 2,3-dihydroxy-5-(((9E,12E)-octadeca-9,12-dienyloxy)carbonyl)phenolate (NGL), on egg quality was investigated. A total of 120 laying hens were allotted into five groups over 4weeks of the experimental period. Birds were fed the following diets: (1) control [commercial diet (CD)], (2) 0.05% MGL (w/w, GA:LA=1:1, equal molar ratio), (3) 0.1% MGL, (4) 0.05% NGL, (5) 0.1% NGL. The performance of the hen, the anti-oxidative potential of egg albumen and yolk, and the fatty acid composition and cholesterol content of egg yolk were measured. The TBARS value of egg yolk from hens fed 0.1% MGL and 0.05% NGL was lower than that fed control diet after storage for 14days. The ABTS(+) reducing activity of egg albumen was significantly improved by MGL and NGL, but only NGL had an effect on yolk (p<0.05). The dietary supplementation of 0.05% or 0.1% MGL, and 0.05% NGL raised the PUFAs composition in egg yolk. The cholesterol content of egg yolk from hens fed control diet was higher than those fed 0.1% MGL, 0.05% or 0.1% NGL (p<0.05). In conclusion, a diet consisting of MGL and NGL can improve the antioxidative potential of egg and the fatty acid quality of egg yolk while lowering the cholesterol level.

1-[3-(Hy-droxy-meth-yl)phen-yl]-3-phenyl-urea.

In the title compound, C(14)H(14)N(2)O(2), the dihedral angle between the benzene rings is 23.6 (1)°. The H atoms of the urea NH groups are positioned syn to each other. In the crystal, inter-molecular N-H⋯O and O-H⋯O hydrogen bonds link the mol-ecules into a three-dimensional network.

N-(4-Hy-droxy-phen-yl)-3,4,5-trimeth-oxy-benzamide.

In the title amide compound, C(16)H(17)NO(5), the dihedral angle between the benzene rings is 71.59 (4)°. In the crystal, inter-molecular N-H⋯O and O-H⋯O hydrogen bonds link the mol-ecules into a two-dimensional array parallel to the ab plane.

Sirtuin 1 Mediates Protection Against Delayed Cerebral Ischemia in Subarachnoid Hemorrhage in Response to Hypoxic Postconditioning.

Background Many therapies designed to prevent delayed cerebral ischemia (DCI) and improve neurological outcome in aneurysmal subarachnoid hemorrhage (SAH) have failed, likely because of targeting only one element of what has proven to be a multifactorial disease. We previously demonstrated that initiating hypoxic conditioning before SAH (hypoxic preconditioning) provides powerful protection against DCI. Here, we expanded upon these findings to determine whether hypoxic conditioning delivered at clinically relevant time points after SAH (hypoxic postconditioning) provides similarly robust DCI protection. Methods and Results In this study, we found that hypoxic postconditioning (8% O2 for 2 hours) initiated 3 hours after SAH provides strong protection against cerebral vasospasm, microvessel thrombi, and neurological deficits. By pharmacologic and genetic inhibition of SIRT1 (sirtuin 1) using EX527 and global Sirt1-/- mice, respectively, we demonstrated that this multifaceted DCI protection is SIRT1 mediated. Moreover, genetic overexpression of SIRT1 using Sirt1-Tg mice, mimicked the DCI protection afforded by hypoxic postconditioning. Finally, we found that post-SAH administration of resveratrol attenuated cerebral vasospasm, microvessel thrombi, and neurological deficits, and did so in a SIRT1-dependent fashion. Conclusions The present study indicates that hypoxic postconditioning provides powerful DCI protection when initiated at clinically relevant time points, and that pharmacologic augmentation of SIRT1 activity after SAH can mimic this beneficial effect. We conclude that conditioning-based therapies administered after SAH hold translational promise for patients with SAH and warrant further investigation.

N-(3,4-Difluoro-phen-yl)-3,4,5-trimethoxy-benzamide.

In the title amide, C(16)H(15)F(2)NO(4), the dihedral angle between the benzene rings is 2.33 (15)°. Mol-ecules are linked in the crystal structure by N-H⋯O hydrogen bonding involving N-H and C=O groups of the amide function, leading to a supra-molecular chain along [100].

1-(2-Hy-droxy-eth-yl)-3-(3-meth-oxy-phen-yl)thio-urea.

In the title compound, C(10)H(14)N(2)O(3)S, the 3-meth-oxy-phenyl unit is almost planar, with an r.m.s. deviation of 0.013 Å. The dihedral angle between the benzene ring and the plane of the thio-urea unit is 62.57 (4)°. In the crystal, N-H⋯O and O-H⋯S hydrogen bonds link the mol-ecules into a three-dimensional network.

1-(2,5-Dimeth-oxy-phen-yl)-3-(2-hy-droxy-eth-yl)urea.

In the title compound, C(11)H(16)N(2)O(4), the 2,5-dimeth-oxy-phenyl moiety is almost planar, with an r.m.s. deviation of 0.026 Å. The dihedral angle between the benzene ring and the plane of the urea moiety is 13.86 (5)°. The mol-ecular structure is stabilized by a short intra-molecular N-H⋯O hydrogen bond. In the crystal, inter-molecular N-H⋯O and O-H⋯O hydrogen bonds link the mol-ecules into a three-dimensional network.

N-(3,4-Difluoro-phen-yl)-N'-(2,5-di-methoxy-phen-yl)urea.

In the title compound, C(15)H(14)F(2)N(2)O(3), the dihedral angle between the benzene rings is 64.5 (1)°. One F atom is disordered over two meta positions, with occupancy factors of 0.72 and 0.28. In the crystal, mol-ecules are linked by N-H⋯O hydrogen bonds involving two N-H and one C=O groups of the urea central fragment, leading to a supra-molecular chain along [011].

N-(2,5-Dimeth-oxy-phen-yl)-N'-[4-(2-hy-droxy-eth-yl)phen-yl]urea.

In the title compound, C(17)H(20)N(2)O(4), the 2,5-dimeth-oxy-phenyl unit is essentially planar, with an r.m.s. deviation of 0.015 Å. The dihedral angle between the benzene rings is 43.66 (4)°. The mol-ecular structure is stabilized by a short intra-molecular N-H⋯O hydrogen bond. In the crystal, inter-molecular N-H⋯O and O-H⋯O hydrogen bonds link the mol-ecules into a three-dimensional network.

N-(2,5-Dimeth-oxy-phen-yl)-N'-(4-hy-droxy-pheneth-yl)urea.

In the title compound, C(17)H(20)N(2)O(4), the 2,5-dimeth-oxy-phenyl unit is almost planar, with an r.m.s. deviation of 0.015 Å. The dihedral angle between the 2,5-dimeth-oxy-phenyl ring and the urea plane is 20.95 (8)°. The H atoms of the urea NH groups are positioned syn to each other. The mol-ecular structure is stabilized by a short intra-molecular N-H⋯O hydrogen bond. In the crystal, inter-molecular N-H⋯O and O-H⋯O hydrogen bonds link the mol-ecules into a three-dimensional network.