Synthesis, physical–chemical characterisation and biological evaluation of novel 2-amido-3-hydroxypyridin-4(1H)-ones: Iron chelators with the potential for treating Alzheimer’s disease

Design, synthesis, in silico ADME, DFT, molecular dynamics simulation, anti-tyrosinase, and antioxidant activity of some of the 3-hydroxypyridin-4-one hybrids in combination with acylhydrazone derivatives

Tyrosinase is the rate-limiting enzyme in synthesizing melanin. Melanin is responsible for changing the color of fruits and vegetables and protecting against skin photo-carcinogenesis. Herein, some of the hybrids of 3-hydroxypyridine-4-one and acylhydrazones were designed and synthesized to study the anti-tyrosinase and antioxidant activities. The diphenolase activity of mushroom tyrosinase using L-DOPA assayed the inhibitory effects, and the antioxidant activity was assessed using DPPH free radical. The synthesized derivatives were confirmed using 1H-NMR, 13C-NMR, IR, and Mass spectroscopy. Among analogs, compound 5h bearing furan ring with IC50=8.94 μM was more potent than kojic acid (IC50=16.68 μM). The pharmacokinetic profile of the compounds showed that the tested compounds had suitable oral bioavailability and drug-likeness properties. The molecular docking studies showed that compound 5h was located in the tyrosinase-binding site. Also, the molecular dynamics simulation was performed on compound 5h, proving the obtained molecular docking results. At the B3LYP/6-31 + G** level of theory, the reactivity descriptors for 5 g and 5h were investigated using DFT calculations. Also, IR frequency was calculated to verify DFT results with experimental data. The electrostatic potential energy of the surface and the HOMO and LUMO molecular orbitals were also studied. It agrees with experimental results that the 5h is a soft molecule and ready for chemical reaction with other interacting molecules.Communicated by Ramaswamy H. Sarma.

Hydroxypyrone derivatives in drug discovery: from chelation therapy to rational design of metalloenzyme inhibitors

The versatile structural motif of hydroxypyrone is found in natural products and can be easily converted into hydroxypyridone and hydroxythiopyridone analogues. The favourable toxicity profile and ease of functionalization to access a vast library of compounds make them an ideal structural scaffold for drug design and discovery. This versatile scaffold possesses excellent metal chelating properties that can be exploited for chelation therapy in clinics. Deferiprone [1,2-dimethyl-3-hydroxy-4(1H)-one] was the first orally active chelator to treat iron overload in thalassemia major. Metal complexes of hydroxy-(thio)pyr(id)ones have been investigated as magnetic resonance imaging contrast agents, and anticancer and antidiabetic agents. In recent years, this compound class has demonstrated potential in discovering and developing metalloenzyme inhibitors. This review article summarizes recent literature on hydroxy-(thio)pyr(id)ones as inhibitors for metalloenzymes such as histone deacetylases, tyrosinase and metallo-β-lactamase. Different approaches to the design of hydroxy-(thio)pyr(id)ones and their biological properties against selected metalloenzymes are discussed.

Design and synthesis of novel stilbene-hydroxypyridinone hybrids as tyrosinase inhibitors and their application in the anti-browning of freshly-cut apples

In order to develop the tyrosinase inhibitors with potential application in food industry, a series of stilbene-hydroxypyridinone hybrids were prepared. Among these compounds, 1h was found to possess the most potent tyrosinase inhibitory effect on both monophenolase and diphenolase activities, with IC₅₀ values of 2.72 μM and 15.86 μM, respectively. The inhibitory effect of 1h on monophenolase activity was 4.6 times that of kojic acid. An inhibition kinetic assay indicated that 1h was a mixed-type and reversible inhibitor. The copper-binding and reducing ability assays, molecular docking study, intrinsic and ANS-binding fluorescence assays indicated that copper coordination and reduction is likely to be the causative mechanism for 1h-induced inhibition on tyrosinase. The results of color measurement and browning index determination indicated that treatment with 1h retarded effectively the browning of freshly-cut apples during their storage. Meanwhile, PPO and POD activities in apple slices were found to be effectively inhibited.

Synthesis, physicochemical characterization and neuroprotective evaluation of novel 1-hydroxypyrazin-2(1H)-one iron chelators in an in vitro cell model of Parkinson's disease

Iron dysregulation, dopamine depletion, cellular oxidative stress and α-synuclein protein mis-folding are key neuronal pathological features seen in the progression of Parkinson's disease. Iron chelators endowed with one or more therapeutic modes of action have long been suggested as disease modifying therapies for its treatment. In this study, novel 1-hydroxypyrazin-2(1H)-one iron chelators were synthesized and their physicochemical properties, iron chelation abilities, antioxidant capacities and neuroprotective effects in a cell culture model of Parkinson's disease were evaluated. Physicochemical properties (log β, log D7.4, pL0.5) suggest that these ligands have a poorer ability to penetrate cell membranes and form weaker iron complexes than the closely related 1-hydroxypyridin-2(1H)-ones. Despite this, we show that levels of neuroprotection provided by these ligands against the catecholaminergic neurotoxin 6-hydroxydopamine in vitro were comparable to those seen previously with the 1-hydroxypyridin-2(1H)-ones and the clinically used iron chelator Deferiprone, with two of the ligands restoring cell viability to ≥89% compared to controls. Two of the ligands were endowed with additional phenol moieties in an attempt to derive multifunctional chelators with dual iron chelation/antioxidant activity. However, levels of neuroprotection with these ligands were no greater than ligands lacking this moiety, suggesting the neuroprotective properties of these ligands are due primarily to chelation and passivation of intracellular labile iron, preventing the generation of free radicals and reactive oxygen species that otherwise lead to the neuronal cell death seen in Parkinson's disease.

A systematic review of synthetic tyrosinase inhibitors and their structure-activity relationship

Tyrosinase is a copper-containing oxidation enzyme, which is responsible for the production of melanin. This enzyme is widely distributed in microorganisms, animals and plants, and plays an essential role in undesirable browning of fruits and vegetables, antibiotic resistance, skin pigment formation, sclerotization of cuticle, neurodegeneration, etc. Hence, it has been recognized as a therapeutic target for the development of antibrowning agents, antibacterial agents, skin-whitening agents, insecticides, and other therapeutic agents. With great potential application in food, agricultural, cosmetic and pharmaceutical industries, a large number of synthetic tyrosinase inhibitors have been widely reported in recent years. In this review, we systematically summarized the advances of synthetic tyrosinase inhibitors in the literatures, including their inhibitory activity, cytotoxicity, structure-activity relationship (SAR), inhibition kinetics, and interaction mechanisms with the enzyme. The collected information is expected to provide a rational guidance and effective strategy to develop novel, potent and safe tyrosinase inhibitors for better practical applications in the future.

Iron and Ferroptosis as Therapeutic Targets in Alzheimer's Disease

Alzheimer's disease (AD), one of the most common neurodegenerative diseases worldwide, has a devastating personal, familial, and societal impact. In spite of profound investment and effort, numerous clinical trials targeting amyloid-β, which is thought to have a causative role in the disease, have not yielded any clinically meaningful success to date. Iron is an essential cofactor in many physiological processes in the brain. An extensive body of work links iron dyshomeostasis with multiple aspects of the pathophysiology of AD. In particular, regional iron load appears to be a risk factor for more rapid cognitive decline. Existing iron-chelating agents have been in use for decades for other indications, and there are preliminary data that some of these could be effective in AD. Many novel iron-chelating compounds are under development, some with in vivo data showing potential Alzheimer's disease-modifying properties. This heretofore underexplored therapeutic class has considerable promise and could yield much-needed agents that slow neurodegeneration in AD.

Design, synthesis and biological evaluation of potential anti-AD hybrids with monoamine oxidase B inhibitory and iron-chelating effects

A series of active hybrids combining 3-hydroxypyridin-4(1H)-one and coumarin pharmacophores were designed and synthesized as potential agents for the treatment of Alzheimer's disease (AD). All the compounds exhibited excellent iron-chelating activities (pFe³⁺ = 14.8-19.2) and showed favorable monoamine oxidase B (MAO-B) inhibitory effects compared to the reference drug Pargyline (IC₅₀ = 86.9 nM). Among them, compound 11 g displayed the best MAO-B inhibitory activity with an IC₅₀ value of 99.3 nM. Molecular docking analysis showed that compound 11 g could enter the entrance cavity and substrate cavity of MAO-B. Furthermore, the compound 11 g had an excellent antioxidant effect and was capable of protecting from the amyloid-β_1-42 (Aβ_1-42) induced PC12 cell damage. In silico tools were applied for predicting the blood-brain barrier (BBB) penetration and compound 11 g was proved to overcome the brain exposure challenge. In the mice behavioral study, compound 11 g significantly ameliorated cognitive impairment induced by Scopolamine. More importantly, compound 11 g displayed favorable pharmacokinetic profiles in a rat model. In summary, compound 11 g, with both anti-MAO-B and iron-chelating ability, was proved to be a promising potential anti-AD agent for further optimization.

The essential elements of Alzheimer's disease

Treatments for Alzheimer’s disease (AD) directed against the prominent amyloid plaque neuropathology are yet to be proved effective despite many phase 3 clinical trials. There are several other neurochemical abnormalities that occur in the AD brain that warrant renewed emphasis as potential therapeutic targets for this disease. Among those are the elementomic signatures of iron, copper, zinc, and selenium. Here, we review these essential elements of AD for their broad potential to contribute to Alzheimer’s pathophysiology, and we also highlight more recent attempts to translate these findings into therapeutics. A reinspection of large bodies of discovery in the AD field, such as this, may inspire new thinking about pathogenesis and therapeutic targets.

Hydroxypyridinone-Based Iron Chelators with Broad-Ranging Biological Activities

Iron plays an essential role in all living cells because of its unique chemical properties. It is also the most abundant trace element in mammals. However, when iron is present in excess or inappropriately located, it becomes toxic. Excess iron can become involved in free radical formation, resulting in oxidative stress and cellular damage. Iron chelators are used to treat serious pathological disorders associated with systemic iron overload. Hydroxypyridinones stand out for their outstanding chelation properties, including high selectivity for Fe³⁺ in the biological environment, ease of derivatization, and good biocompatibility. Herein, we overview the potential for multifunctional hydroxypyridinone-based chelators to be used as therapeutic agents against a wide range of diseases associated either with systemic or local elevated iron levels.

Dual-target anti-Alzheimer's disease agents with both iron ion chelating and monoamine oxidase-B inhibitory activity

MAO-B leads to an increase in the levels of hydrogen peroxide and oxidative free radicals, which contribute to the aetiology of the AD. Thus, both iron ion chelators and MAO-B inhibitors can be used to treat AD. Taking the coumarin derivatives and hydroxypyridinones as the lead compounds, a series of dual-target hybrids were designed and synthesised by Click Chemistry. The compounds were biologically evaluated for their iron ion chelating and MAO-B inhibitory activity. Most of the compounds displayed excellent iron ion chelating activity and moderate to good anti-MAO-B activity. Compounds 27b and 27j exhibited the most potent MAO-B inhibitory activity, with IC50 values of 0.68 and 0.86 μM, respectively. In summary, these dual-target compounds have the potential anti-AD activity.

Aroylhydrazones constitute a promising class of 'metal-protein attenuating compounds' for the treatment of Alzheimer's disease: a proof-of-concept based on the study of the interactions between zinc(II) and pyridine-2-carboxaldehyde isonicotinoyl hydrazone

With the increasing life expectancy of the world's population, neurodegenerative diseases, such as Alzheimer's disease (AD), will become a much more relevant public health issue. This fact, coupled with the lack of efficacy of the available treatments, has been driving research directed to the development of new drugs for this pathology. Metal-protein attenuating compounds (MPACs) constitute a promising class of agents with potential application on the treatment of neurodegenerative diseases, such as AD. Currently, most MPACs are based on 8-hydroxyquinoline. Recently, our research group has described the hybrid aroylhydrazone containing the 8-hydroxyquinoline group INHHQ as a promising MPAC. By studying the known structure-related ligand HPCIH, which does not contain the phenol moiety, as a simplified chemical model for INHHQ, we aimed to clarify the real impact of the aroylhydrazone group for the MPAC activity of a compound with potential anti-Alzheimer's activity. The present work describes a detailed solution and solid-state study of the coordination of HPCIH with Zn²⁺ ions, as well as its in vitro binding-ability towards this metal in the presence of the Aβ(1-40) peptide. Similar to INHHQ, HPCIH is able to efficiently compete with Aβ(1-40) for Zn²⁺ ions, performing as expected for an MPAC. The similarity between the behaviors of both ligands is remarkable. Taken together, the data presented herein point to aroylhydrazones, such as the compounds HPCIH and the previously published INHHQ, as encouraging MPACs for the treatment of AD.

β-Lactoglobulin Peptide Fragments Conjugated with Caffeic Acid Displaying Dual Activities for Tyrosinase Inhibition and Antioxidant Effect

The regulation of tyrosinase activity and reactive oxygen species is of great importance for the prevention of dermatological disorders in the fields of medicine and cosmetics. Herein, we report a strategy based on solid-phase peptide chemistry for the synthesis of β-lactoglobulin peptide fragment/caffeic acid (CA) conjugates (CA-Peps) with dual activities of tyrosinase inhibition and antioxidation. The purity of the prepared conjugates, CA-MHIR, CA-HIRL, and CA-HIR, significantly increased to 99%, as acetonide-protected CA was employed in solid-phase coupling reactions on Rink amide resins. The tyrosinase inhibitory activities of all CA-Pep derivatives were higher than the activity of kojic acid, and CA-MHIR exhibited the highest tyrosinase inhibition activity (IC₅₀ = 47.9 μM). Moreover, CA-Pep derivatives displayed significantly enhanced antioxidant activities in the peroxidation of linoleic acid as compared to the pristine peptide fragments. All CA-Pep derivatives showed no cytotoxicity against B16-F1 melanoma cells.

Novel hydroxypyridinone derivatives containing an oxime ether moiety: Synthesis, inhibition on mushroom tyrosinase and application in anti-browning of fresh-cut apples

A range of hydroxypyridinone derivatives were synthesized starting from kojic acid. Among them, 10 and 11 were found to possess the strongest inhibitory effect on monophenolase activity of mushroom tyrosinase, having IC₅₀ values of 2.04 and 1.60μM, respectively. The IC₅₀ values of 10 and 11 for the inhibition of diphenolase activity of mushroom tyrosinase were determined as 13.89 and 7.99μM, respectively. Investigation of the inhibitory mechanism of these two compounds indicated that the inhibition was reversible and of a competitive-uncompetitive mixed type. The K_I and K_IS values of 10 were determined to be 24.84 and 32.54μM, respectively, and the corresponding values for 11 being 18.07 and 21.34μM, respectively. The effect of 11 on the browning process of fresh-cut apples was evaluated by measuring the color change and browning index. The results indicated that 11 had a significant effect on controlling the browning of fresh-cut apple slices.

Engineering of the cytochrome P450 monooxygenase system for benzyl maltol hydroxylation

Maltol derivatives are utilized in a variety of fields due to their metal-chelating abilities, and modification of the 2-methyl side chain is known to effectively expand their functional diversity. In the present study, microbial enzymes were screened for hydroxylating activity towards the 2-methyl group in a maltol derivative, 3-benzyloxy-2-methyl-4-pyrone (BMAL). Novosphingobium sp. SB32149 was found to have the ability to convert BMAL into 3-benzyloxy-2-hydroxymethyl-4-pyrone (BMAL-OH). The enzymes responsible, a cytochrome P450 monooxygenase (P450nov), a ferredoxin (FDXnov), and a ferredoxin reductase (FDRnov), were identified in the SB32149 strain. In the reaction with recombinant Escherichia coli expressing P450nov, FDXnov, and FDRnov, BMAL-OH was successfully produced from BMAL. Moreover, using the directed evolution approach, four amino acid substitutions, L188P/F218L/L237M in P450nov and A10T in FDXnov, were found to enhance BMAL-OH production. Consequently, up to 5.2 g/L BMAL-OH was obtained from 8.0 g/L BMAL by bioconversion using a 250-mL jar fermenter, indicating that this strain may be useful for synthesis of maltol derivatives which could have potential applications in various fields.

Synthesis and biological evaluation of deferiprone-resveratrol hybrids as antioxidants, Aβ1-42 aggregation inhibitors and metal-chelating agents for Alzheimer's disease

A series of deferiprone-resveratrol hybrids have been designed and synthesized as multitarget-directed ligands (MTDLs) through merging the chelating moiety 3-hydroxypyridin-4-one into the structure of resveratrol, a natural antioxidant agent and β-amyloid peptide (Aβ) aggregation inhibitor. The in vitro biological evaluation revealed that most of these newly synthesized compounds exhibited good inhibitory activity against self-induced Aβ_1-42 aggregation, excellent antioxidant activity and potent metal chelating capability. Compounds 3i and 4f were identified as the most promising MTDLs with triple functions, possessing micromolar IC₅₀ values for Aβ_1-42 aggregation inhibition, greater 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS^•+) scavenging activity than Trolox and similar pFe(III) values to that of deferiprone.

Multifunctional diamine AGE/ALE inhibitors with potential therapeutical properties against Alzheimer's disease

An important part of pathogenesis of Alzheimer's disease (AD) is attributed to the contribution of AGE (Advanced Glycation Endproducts) and ALE (Advanced Lipid peroxidation Endproducts). In order to attenuate the progression of AD, we designed a new type of molecules that consist of two trapping parts for reactive carbonyl species (RCS) and reactive oxygen species (ROS), precursors of AGE and ALE, respectively. These molecules also chelate transition metals, the promoters of ROS formation. In this paper, synthesis of the new AGE/ALE inhibitors and evaluation of their physicochemical and biological properties (carbonyl trapping capacity, antioxidant activity, Cu(2+)-chelating capacity, cytotoxicity and protective effect against in vitro MGO-induced apoptosis in the model AD cell-line PC12) are described. It is found that compounds 40b and 51e possess promising therapeutic potentials for treating AD.

Amyloid β25-35 induced ROS-burst through NADPH oxidase is sensitive to iron chelation in microglial Bv2 cells

Iron chelation therapy and inhibition of glial nicotinamide adenine dinucleotide phosphate (NADPH) oxidase can both represent possible routes for Alzheimer's disease modifying therapies. The metal hypothesis is largely focused on direct binding of metals to the N-terminal hydrophilic 1-16 domain peptides of Amyloid beta (Aβ) and how they jointly give rise to reactive oxygen species (ROS) production. The cytotoxic effects of Aβ through ROS and metals are mainly studied in neuronal cells using full-length Aβ1-40/42 peptides. Here we study cellularly-derived ROS during 2-60min in response to non-metal associated mid domain Aβ25-35 in microglial Bv2 cells by fluorescence based spectroscopy. We analyze if Aβ25-35 induce ROS production through NADPH oxidase and if the production is sensitive to iron chelation. NADPH oxidase inhibitor diphenyliodonium (DPI) is used to confirm the production of ROS through NADPH oxidase. We modulate cellular iron homeostasis by applying cell permeable iron chelators desferrioxamine (DFO) and deferiprone (DFP). NADPH oxidase subunit gp91-phox level was analyzed by Western blotting. Our results show that Aβ25-35 induces strong ROS production through NADPH oxidase in Bv2 microglial cells. Intracellular iron depletion resulted in restrained Aβ25-35 induced ROS.

Protection from neurodegeneration in the 6-hydroxydopamine (6-OHDA) model of Parkinson's with novel 1-hydroxypyridin-2-one metal chelators

We report that novel 1-hydroxypyridin-2-ones show comparable neuroprotective results to deferiprone in a cell culture model of Parkinson's disease.

Disruption of zinc and copper interactions with Aβ(1–40) by a non-toxic, isoniazid-derived, hydrazone: a novel biometal homeostasis restoring agent in Alzheimer's disease therapy?

A non-toxic hydrazone with potential anti-Alzheimer activity: this organic ligand disrupts anomalous metal–Aβ(1–40) interactions, and, thus, seems suitable as a metal-protein attenuating compound.

Structural and vibrational study of 8-hydroxyquinoline-2-carboxaldehyde isonicotinoyl hydrazone--a potential metal-protein attenuating compound (MPAC) for the treatment of Alzheimer's disease

A comprehensive structural and vibrational study of the potential metal-protein attenuating compound 8-hydroxyquinoline-2-carboxaldehyde isonicotinoyl hydrazone is reported. X-ray diffraction data, as well as FT-IR and Raman frequencies, were compared with the respective theoretical values obtained from DFT calculations. Theory agrees well with experiment. In this context, an attempt of total assignment concerning the FT-IR and Raman spectra of the title compound was performed, shedding new light on previous partial assignments published elsewhere.

In silico and in vitro studies to elucidate the role of Cu2+ and galanthamine as the limiting step in the amyloid beta (1-42) fibrillation process

The formation of fibrils and oligomers of amyloid beta (Aβ) with 42 amino acid residues (Aβ 1-42 ) is the most important pathophysiological event associated with Alzheimer's disease (AD). The formation of Aβ fibrils and oligomers requires a conformational change from an α-helix to a β-sheet conformation, which is encouraged by the formation of a salt bridge between Asp 23 or Glu 22 and Lys 28. Recently, Cu(2+) and various drugs used for AD treatment, such as galanthamine (Reminyl(®) ), have been reported to inhibit the formation of Aβ fibrils. However, the mechanism of this inhibition remains unclear. Therefore, the aim of this work was to explore how Cu(2+) and galanthamine prevent the formation of Aβ1-42 fibrils using molecular dynamics (MD) simulations (20 ns) and in vitro studies using fluorescence and circular dichroism (CD) spectroscopies. The MD simulations revealed that Aβ1-42 acquires a characteristic U-shape before the α-helix to β-sheet conformational change. The formation of a salt bridge between Asp 23 and Lys 28 was also observed beginning at 5 ns. However, the MD simulations of Aβ 1-42 in the presence of Cu(2+) or galanthamine demonstrated that both ligands prevent the formation of the salt bridge by either binding to Glu 22 and Asp 23 (Cu(2+) ) or to Lys 28 (galanthamine), which prevents Aβ 1-42 from adopting the U-characteristic conformation that allows the amino acids to transition to a β-sheet conformation. The docking results revealed that the conformation obtained by the MD simulation of a monomer from the 1Z0Q structure can form similar interactions to those obtained from the 2BGE structure in the oligomers. The in vitro studies demonstrated that Aβ remains in an unfolded conformation when Cu(2+) and galanthamine are used. Then, ligands that bind Asp 23 or Glu 22 and Lys 28 could therefore be used to prevent β turn formation and, consequently, the formation of Aβ fibrils.

Design and synthesis of hydroxypyridinone-L-phenylalanine conjugates as potential tyrosinase inhibitors

A range of hydroxypyridinone-L-phenylalanine conjugates were synthesized starting from kojic acid. Their tyrosinase activity was determined, and it was found that one of the compounds ((S)-(5-(benzyloxy)-1-octyl-4-oxo-1,4-dihydropyridin-2-yl)methyl 2-amino-3-phenylpropanoate, 5e) showed potent inhibitory effect against mushroom tyrosinase, the IC50 values for monophenolase and diphenolase activities being 12.6 and 4.0 μM, respectively. It was also demonstrated that these conjugates are mixed-type inhibitors, suggesting they could bind to both the free enzyme and the enzyme-substrate complexes. MTT assay indicated that 5e was nontoxic to three cell lines. This compound may find applications in food preservation and cosmetics.

Ferric complexes of 3-hydroxy-4-pyridinones characterized by density functional theory and Raman and UV-vis spectroscopies

Deferiprone and other 3-hydroxy-4-pyridinones are used in metal chelation therapy of iron overload. To investigate the structure and stability of these compounds in the natural aqueous environment, ferric complexes of deferiprone and amino acid maltol conjugates were synthesized and studied by computational and optical spectroscopic methods. The complexation caused characteristic intensity changes, a 300× overall enhancement of the Raman spectrum, and minor changes in UV-vis absorption. The spectra were interpreted on the basis of density functional theory (DFT) calculations. The CAM-B3LYP and ωB97XD functionals with CPCM solvent model were found to be the most suitable for simulations of the UV-vis spectra, whereas B3LYP, B3LYPD, B3PW91, M05-2X, M06, LC-BLYP, ωB97XD, and CAM-B3LYP functionals were all useful for simulation of the Raman scattering. Characteristic Raman band frequencies for 3-hydroxy-4-pyridinones were assigned to molecular vibrations. The computed conformer energies consistently suggest the presence of another isomer of the deferiprone-ferric complex in solution, in addition to that found previously by X-ray crystallography. However, the UV-vis and Raman spectra of the two species are similar and could not be resolved. In comparison to UV-vis, the Raman spectra and their combination with calculations appear more promising for future studies of iron sequestrating drugs and artificial metalloproteins as they are more sensitive to structural details.

Oxidative stress in neurodegenerative diseases: mechanisms and therapeutic perspectives

The incidence and prevalence of neurodegenerative diseases (ND) increase with life expectancy. This paper reviews the role of oxidative stress (OS) in ND and pharmacological attempts to fight against reactive oxygen species (ROS)-induced neurodegeneration. Several mechanisms involved in ROS generation in neurodegeneration have been proposed. Recent articles about molecular pathways involved in ROS generation were reviewed. The progress in the development of neuroprotective therapies has been hampered because it is difficult to define targets for treatment and determine what should be considered as neuroprotective. Therefore, the attention was focused on researches about pharmacological targets that could protect neurons against OS. Since it is necessary to look for genes as the ultimate controllers of all biological processes, this paper also tried to identify gerontogenes involved in OS and neurodegeneration. Since neurons depend on glial cells to survive, recent articles about the functioning of these cells in aging and ND were also reviewed. Finally, clinical trials testing potential neuroprotective agents were critically reviewed. Although several potential drugs have been screened in in vitro and in vivo models of ND, these results were not translated in benefit of patients, and disappointing results were obtained in the majority of clinical trials.