Beta-amyloid-acetylcholine structural interaction: evidence for neuroprotective effects of acetylcholine in neural cells

Alzheimer’s disease (AD) is regarded as a multifactorial disease characterized by a complex pathogenesis including a cholinergic deficit - due to degeneration of cholinergic projections from the basal forebrain - and the extracellular accumulation of amyloid beta (Aβ) peptide. Aβ containing 39 to 42 amino acids is the predominant component of the senile plaques that, together with neurofibrillary tangles, are regarded as the neuropathological hallmarks of AD (Sorrentino et al. 2014). Aβ may assume different conformations changing from random coil or α-helical monomers to β-sheet structures forming toxic oligomers and/or β-sheet mature fibrils. In this framework, we studied the effect of acetylcholine (ACh) on the conformation of Aβ by circular dichroism analysis. Moreover we investigated the ability of ACh to protect neuronal cells from the toxic action of amyloid peptide and to modulate the neuroinflammatory response occurring via the phospholipase A2 (PLA2). Results show that the amount of Aβ(25-35) β-strand raised linearly in absence of ACh, whereas it remained almost constant in presence of ACh. In addition, in a micelle solution mimicking the membrane environment ACh was found effective in increasing and stabilizing the soluble and not toxic helical content of Aβ(25-35) suggesting that ACh is capable to preserve the soluble form of Aβ(25-35), reducing the incipit of Aβ aggregation. In order to assess the neuro-protective ability of ACh against toxic Aβ(25-35) accumulation, we used neural cell (NCC) cultures containing both astrocytes and glial cells prepared from brains embryos from timed pregnant Wistar rats and infused ACh for 48h. By immunostaining, we observed that ACh reduced Aβ(25-35)-induced cell death. Then, we tested the protective effect of ACh on inflammation induced by Aβ administration. NCC were challenged with Aβ(25-35) in the presence and absence of ACh and immunostained for astroglial and neuronal markers: results showed a reduction of the morphological features of astrogliosys in ACh treated cells. PLA2 expression analysis corroborated these data also underlying that ACh can negatively regulate inflammation pathways in glial cells

1,4-Disubstituted-[1,2,3]triazolyl-Containing Analogues of MT-II: Design, Synthesis, Conformational Analysis, and Biological Activity

Side chain-to-side chain cyclizations represent a strategy to select a family of bioactive conformations by reducing the entropy and enhancing the stabilization of functional ligand-induced receptor conformations. This structural manipulation contributes to increased target specificity, enhanced biological potency, improved pharmacokinetic properties, increased functional potency, and lowered metabolic susceptibility. The CuI-catalyzed azide–alkyne 1,3-dipolar Huisgen’s cycloaddition, the prototypic click reaction, presents a promising opportunity to develop a new paradigm for an orthogonal bioorganic and intramolecular side chain-to-side chain cyclization. In fact, the proteolytic stable 1,4- or 4,1-disubstituted [1,2,3]triazolyl moiety is isosteric with the peptide bond and can function as a surrogate of the classical side chain-to-side chain lactam forming bridge. Herein we report the design, synthesis, conformational analysis, and functional biological activity of a series of i-to-i+5 1,4- and 4,1-disubstituted [1,2,3]triazole-bridged cyclopeptides derived from MT-II, the homodetic Asp5 to Lys10 side chain-to-side chain bridged heptapeptide, an extensively studied agonist of melanocortin receptors

A serum nuclear magnetic resonance-based metabolomic signature of antiphospholipid syndrome

Antiphospholipid syndrome (APS) is a rheumatic inflammatory chronic autoimmune disease inducing hypercoagulable state associated with vascular thrombosis and pregnancy loss in women. Cardiac, cerebral and vascular strokes in these patients are responsible for reduction in life expectancy. Timely diagnosis and accurate monitoring of disease are decisive to improve the accuracy of therapy. In the present work, we present a NMR-based metabolomic study of blood sera of APS patients. Our data show that individuals suffering APS have a characteristic metabolomic profile with abnormalities associated to the metabolism of methyl group donors, ketone bodies and amino acids. We have identified for the first time the metabolomic fingerprint characterizing APS disease having potential application to improve APS timely diagnosis and appropriate therapeutic approaches

Binding of the hemopressin peptide to the cannabinoid CB(1) receptor: structural insights

Hemopressin, a bioactive nonapeptide derived from the α1 chain of hemoglobin, was recently shown to possess selective antagonist activity at the cannabinoid CB(1) receptor [Heimann, A. S., et al. (2007) Proc. Natl. Acad. Sci. U.S.A. 104, 20588-20593]. CB(1) receptor antagonists have been extensively studied for their possible therapeutic use in the treatment of obesity, drug abuse, and heroin addiction. In particular, many compounds acting as CB(1) receptor antagonists have been synthesized and subjected to experiments as possible anti-obesity drugs, but their therapeutic application is still complicated by important side effects. Using circular dichroism and nuclear magnetic resonance spectroscopy, this work reports the conformational analysis of hemopressin and its truncated, biologically active fragment hemopressin(1-6). The binding modes of both hemopressin and hemopressin(1-6) are investigated by molecular docking calculations. Our conformational data indicate that regular turn structures in the central portion of hemopressin and hemopressin(1-6) are critical for an effective interaction with the receptor. The results of molecular docking calculations, indicating similarities and differences in comparison to the most accepted CB(1) pharmacophore model, suggest the possibility of new chemical scaffolds for the design of new CB(1) antagonist lead compounds

β-Amyloid-acetylcholine molecular interaction: New role of cholinergic mediators in anti-Alzheimer therapy?

Background: For long time Alzheimer's disease has been attributed to a cholinergic deficit. More recently, it has been considered dependent on the accumulation of the amyloid beta peptide (Aβ), which promotes neuronal loss and impairs neuronal function. Results/methodology: In the present study, using biophysical and biochemical experiments we tested the hypothesis that in addition to its role as a neurotransmitter, acetylcholine may exert its action as an anti-Alzheimer agent through a direct interaction with Aβ. Conclusion: Our data provide evidence that acetylcholine favors the soluble peptide conformation and exerts a neuroprotective effect against the neuroinflammatory and toxic effects of Aβ. The present paper paves the way toward the development of new polyfunctional anti-Alzheimer therapeutics capable of intervening on both the cholinergic transmission and the Aβ aggregation

Binding of the hemopressin peptide to the cannabinoid CB(1) receptor: structural insights.

Hemopressin, a bioactive nonapeptide derived from the α1 chain of hemoglobin, was recently shown to possess selective antagonist activity at the cannabinoid CB(1) receptor [Heimann, A. S., et al. (2007) Proc. Natl. Acad. Sci. U.S.A. 104, 20588-20593]. CB(1) receptor antagonists have been extensively studied for their possible therapeutic use in the treatment of obesity, drug abuse, and heroin addiction. In particular, many compounds acting as CB(1) receptor antagonists have been synthesized and subjected to experiments as possible anti-obesity drugs, but their therapeutic application is still complicated by important side effects. Using circular dichroism and nuclear magnetic resonance spectroscopy, this work reports the conformational analysis of hemopressin and its truncated, biologically active fragment hemopressin(1-6). The binding modes of both hemopressin and hemopressin(1-6) are investigated by molecular docking calculations. Our conformational data indicate that regular turn structures in the central portion of hemopressin and hemopressin(1-6) are critical for an effective interaction with the receptor. The results of molecular docking calculations, indicating similarities and differences in comparison to the most accepted CB(1) pharmacophore model, suggest the possibility of new chemical scaffolds for the design of new CB(1) antagonist lead compounds

Identification of CM223 as a new ligand of farnesyl pyrophosphate synthase with improved antiglioma action

Farnesyl Pirophosphate Synthase (FPPS) is a key enzyme in the mevalonate, isoprenoid biosynthesis pathway. FPPS is nowadays the target of bisphosphonates drugs used in osteoporosis disease, nevertheless it is studied as target for anti-cancer therapeutics. N6-Isopentenyladenosine (i6A) is a modified nucleoside exhibiting anti-tumor effects on human and murine cells. Growing biochemical evidence demonstrate the involvement of FPPS protein in i6A anti-tumor action. We previously demonstrated that i6A interacts with FPPS binding site with K D of ~1mM. This interaction corresponded to a modest inhibition of FPPS enzymatic activity. By STD NMR approaches, here we screened newly synthesized analogs of i6A, designed on the basis of i6A-FPPS interaction data. i6A analogues interact with FPPS exhibiting binding mode very similar to i6A. The binding of i6A analogues highlighted the importance of N6-adenosine substituent in the interaction with FPPS binding site. Ideed, introduction on adenosine scaffold of a benzyl moiety induces a significant improvement of interaction with FPPS target. The altered expression of isoprenoid pathway and in particular of FPPS we found in glioma cells and tissue, allowed them to be targeted by the isoprenoid derivatives. As expected CM223 is more effective than i6A in selectively targeting U87 glioma cells but not normal human astrocytes (NHA). This is achieved by the introduction of intrinisc pathway of apoptosis adn inhibition of proliferation along a portein prenylation blockung ad shown by the increase levels of unprenylated Ras and Rap1A. These open the perspective that a modification of the newly introduced benzyl portion of the i6A molecule, may lead to more active molecules in glioma pharmacological research