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Our endeavors in the design, synthesis, and biological assessment of five-membered-ring-fused tacrines as potential therapeutic agents for Alzheimer's disease are summarized. Particularly, we have identified racemic 4-(2-methoxyphenyl)-3-methyl-2,4,6,7,8,9-hexahydropyrazolo[4′,3′:5,6]pyrano[2,3-b]quinolin-5-amine, a pyranopyrazolotacrine, as having the best nontoxic profile at the highest concentrations used (300 μM); this allows cell viability, is less hepatotoxic than tacrine, and is a potent noncompetitive AChE inhibitor (IC50 = 1.52 ± 0.49 μM). It is able to completely inhibit the Ee AChE-induced Aβ1–40 aggregation in a statistically significant manner without affecting the Aβ1–40 self-aggregation at 25 μM, and shows strong neuroprotective effects (EC50 = 0.82 ± 0.17 μM). 1 Introduction 2 Furo-, Thieno-, and Pyrrolotacrines 3 Pyrazolo-, Oxazolo-, and Isoxazolotacrines 4 Indolotacrines 5 Pyrano- and Pyridopyrazolotacrines 6 Conclusions and Outlook [ABSTRACT FROM AUTHOR]

Herein I present a review on the synthesis of ipsenol and ipsdienol, two aggregation pheromones of bark beetles, isolated from different species of genus Ips, and serious pests of conifer forests. I have covered the literature for around fifty years, since 1968 to 2020. This account has been divided in different sections and sub‐sections, including a general and brief outlook on their isolation, structure and biological activity, to continue with the reported synthesis of racemic ipsenol and ipsdienol, including my own contribution to topic, and the presentation of reports describing the synthesis of enantiomerically pure ipsenol and ipsdienol. Particular attention has been devoted to identify and highlight racemic or enantiomerically pure "isoprene synthons", and isoprenylation methods employed in the synthesis of ipsenol and ipsdienol, of general interest for related terpene derivatives synthesis. [ABSTRACT FROM AUTHOR]

Herein, we have updated the progress and developments of the Carbanion‐mediated Sulfonate (or Sulfonamide) Intermolecular Coupling, and Intramolecular Cyclization, abbreviated as CSIC reaction (CSICr), in the last seventeen years from the seminal review published in 2003 in this same Journal. CSICr has proven to be a useful and versatile synthetic tool, efficiently providing a number of open‐chain [alkane(sulfonamide)sulfonates] or cylic (sultams and sultones) synthetic intermediates or final products of high value in organic and medicinal chemistry. [ABSTRACT FROM AUTHOR]

Herein we report the synthesis of the new statin derivative MC609 in 80 % overall yield by sequential transformation of simvastatin including dehydration, and Michael addition of N‐benzyl hydroxylamine followed by cyclization. The preparation of nitronestatins MC649 and MC645 is also described from (2S,4R)‐4‐((tert‐butyldimethylsilyl)oxy)‐6‐oxotetrahydro‐2H‐pyran‐2‐carbaldehyde by reaction with N‐benzyl hydroxylamine, and N‐hydroxylamine followed by reduction with sodium cyanoborohydride and coupling with commercially available 2‐chloro‐6‐methylquinoline‐3‐carbaldehyde, in 77 % and 24 % overall yield, respectively. [ABSTRACT FROM AUTHOR]

Notwithstanding the clinical use of tacrine was hampered by severe hepatotoxicity, tacrine still remains a reference scaffold in the search for new efficient drugs for Alzheimer's disease therapy. In this account we summarize the efforts toward the development and characterization of non‐hepatotoxic tacripyrines and related tacrine analogues resulting from the substitution of the benzene ring by a 1,4‐dihydropyridine, a 1,2,3,4‐tetrahydropyrimidine or a pyridone nucleus. These efforts have successfully led to the identification of a number of promising hits endowed with interesting multifunctional profiles. These include the 4′‐metoxytacripyrine (S)‐ITH122, able to target cholinesterases (ChEs), beta‐amyloid (Aβ) and Ca2+ channels, the racemic 3′‐methoxytacripyrimidine EB65F2, the first fully balanced micromolar inhibitor of ChEs and Ca2+ channels, and tacripyrine (−)‐SCR1693 a GSK‐3β (enzyme involved in tau phosphorylation) inhibitor able to also lower Aβ production in N2a cells. [ABSTRACT FROM AUTHOR]

Abstract Tacrine was the first drug approved for the treatment of Alzheimer's disease (AD) in 1993, which was withdrawn in 2013 due to its hepatotoxicity. However, new, non-hepatotoxic tacrine derivatives have been constantly searched for. In this context, since 1997, we have prepared a number of diversely functionalized tacrines by changing the benzene ring present in tacrine to five- or six-membered aromatic ring cores that could present anticholinesterasic activity and additional pharmacological properties. The new compounds were designed as juxtaposed structures between tacrine and the well-known Ca2+ antagonists 1,4-dihydropyridines, with the goal of obtaining multi-target directed ligands for AD. In this account, we present our results on the PyridoTacrine (PyrTac) family of tacrine analogues, resulting from the substitution of the benzene ring by a pyridine. We highlight their pharmacological profile and review similar analogues in the literature. A first set of PyrTac showed inhibitory activity of cholinesterases (ChE) and a blocking profile of voltage-gated Ca2+ channels (VGCC). A second family with improved ChE inhibition lost VGCC blocking activity. However, the lead compound of this family (5f) presented an activating profile of the phosphatase 2A (PP2A) and showed interesting outcomes in experimental in vivo models of AD and stroke. We have identified the PyrTac ethyl 5-amino-2-methyl-6,7,8,9-tetrahydrobenzo[ b ] [1,8]naphthyridine-3-carboxylate (5f), which presents additional pharmacological properties beyond the mere cholinergic improvement. These new properties warrant attention to 5f and its further development as a new potential therapeutic agent for AD therapy. Graphical abstract Image 1 Highlights • Tacrine is a good scaffold to design multitarget drugs for Alzheimer's disease. • Pyridotacrines are derivatives from the replacement of the benzene-fused ring by pyridine. • Pyridotacrines avoid toxic metabolism and allow the design of multitarget compounds. • Among contributions by others, we described several families of Pyridotacrines. • Our compounds presented new biological activities of relevance for Alzheimer's disease. [ABSTRACT FROM AUTHOR]

The synthesis, antioxidant capacity, and anti-inflammatory activity of four novel N-benzyl-2-[4-(aryl)-1H-1,2,3-triazol-1-yl]ethan-1-imine oxides 10a–d are reported herein. The nitrones 10a–d were tested for their antioxidant properties and their ability to inhibit soybean lipoxygenase (LOX). Four diverse antioxidant tests were used for in vitro antioxidant assays, namely, interaction with the stable free radical DPPH (1,1-diphenyl-2-picrylhydrazyl radical) as well as with the water-soluble azo compound AAPH (2,2′-azobis(2-amidinopropane) dihydrochloride), competition with DMSO for hydroxyl radicals, and the scavenging of cationic radical ABTS•+ (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) radical cation). Nitrones 10b, 10c, and 10d, having the 4-fluorophenyl, 2,4-difluorophenyl, and 4-fluoro-3-methylphenyl motif, respectively, exhibited high interaction with DPPH (64.5–81% after 20 min; 79–96% after 60 min), whereas nitrone 10a with unfunctionalized phenyl group showed the lowest inhibitory potency (57% after 20 min, 78% after 60 min). Nitrones 10a and 10d, decorated with phenyl and 4-fluoro-3-methylphenyl motif, respectively, appeared the most potent inhibitors of lipid peroxidation. The results obtained from radical cation ABTS•+ were not significant, since all tested compounds 10a–d showed negligible activity (8–46%), much lower than Trolox (91%). Nitrone 10c, bearing the 2,4-difluorophenyl motif, was found to be the most potent LOX inhibitor (IC50 = 10 μM). [ABSTRACT FROM AUTHOR]

Highlights: [•] We hypothesize protection’s mechanism of melatonin against chemical warfare agents. [•] Oxidative stress is the key element in the pathogenesis of chemical warfare agents. [•] We described chemical mechanisms of the reaction of melatonin with sulfur mustard. [Copyright &y& Elsevier]

In this work, we present a deep theoretical study on the intriguing and unexpected gold-catalyzed cycloisomerization of siloxy enynes to cyclohexadienes. To this end, we have evaluated the electronic and steric properties for three types of alkynyl substituents along the reaction paths and the implications on the evolution through divergent, competitive pathways. For an alkynyl -OR substituent, the results strongly suggest a polarization of the π electrons along the delocalized C2-C1-O system in the key cyclopropyl-carbene intermediate, which is enhanced by the bulkiness of the R group. The results reproduce the experimental observations in excellent agreement and provide interesting and useful clues for predicting the effects of the alkynyl substituent on the nature of the key intermediate and, hence, on the reactivity mode and selectivity. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis, molecular modeling, and pharmacological analysis of new multipotent simple, and readily available 2-aminopyridine-3,5-dicarbonitriles (3–20), and 2-chloropyridine-3,5-dicarbonitriles (21–28), prepared from 2-amino-6-chloropyridine-3,5-dicarbonitrile (1) and 2-amino-6-chloro-4-phenylpyridine-3,5-dicarbonitrile (2) is described. The biological evaluation showed that some of these molecules were modest inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE), in the micromolar range. The 2-amino (3, 4), and 2-chloro derivatives 21–23, 25, 26 were AChE selective inhibitors, whereas 2-amino derivatives 5, 14 proved to be selective for BuChE. Only inhibitor 24 was equipotent for both cholinesterases. Kinetic studies on compound 23 showed that this compound is a mixed-type inhibitor of AChE showing a K i of 6.33μM. No clear SAR can be obtained form these data, but apparently, compounds bearing small groups such as the N,N′-dimethylamino or the pyrrolidino, regardless of the presence of a 2-amino, or 6-chloro substituent in the pyridine ring, preferentially inhibit AChE. Molecular modeling on inhibitors 4, 5, 22, and 23 has been carried out to give a better insight into the binding mode on the catalytic active site (CAS), and peripheral anionic site (PAS) of AChE. The most important differences in the observed binding relay on the modifications of the group at C2, as the amino group forms two hydrogen bonds that direct the binding mode, while in the case of compounds with a chlorine atom, this is not possible. The neuroprotective profile of these molecules has been investigated. In the LDH test, only compounds 26, 3, 22, and 24 showed neuroprotection with values in the range 37.8–31.6% in SH-SY5Y neuroblastoma cells stressed with a mixture of oligomycin-A/rotenone, but in the MTT test only compound 17 (32.9%) showed a similar profile. Consequently, these compounds can be considered as attractive multipotent therapeutic molecules on two key pharmacological receptors playing key roles in the progress of Alzheimer, that is, cholinergic dysfunction and oxidative stress, and neuronal vascular diseases. [Copyright &y& Elsevier]

The synthesis of new 7-azabicyclo[2.2.1]heptane derivatives has been achieved in a four-step synthetic sequence, starting from readily available cyclohex-3-enecarboxylic acid, Curtius reaction, stereoselective bromination leading to major benzyl(cis-3,trans-4-dibromocyclohex-1-yl)carbamates (amides or sulfonamides), followed by NaH-mediated intramolecular cyclization. The synthesis and free radical cyclization of precursors 4-7, as well as the synthesis of a conformationally constrained epibatidine analogue 3 exploiting the reactivity of the 7-azabicyclo[2.2.1]hept-2-yl radical in intramolecular reactions, are described. The N-sulfonyl functional motif is the only one to afford a cyclized product when incorporated in the radical precursor. [ABSTRACT FROM AUTHOR]

Abstract: N-Arylmethyl-7-azabicyclo[2.2.1]heptane (I) derivatives have been synthesized by deprotection of N-protected, N-(arylmethyl)cyclohex-3-enamines, bromination of the resulting secondary cyclohex-3-enamines, followed by base-promoted cyclization (route a), or by bromination of N-protected, N-(arylmethyl)cyclohex-3-enamines followed by deprotection and base-mediated cyclization (route b). In these protocols we have observed that the bromination of the key intermediates (12, 13, and 19) is stereoselective leading to major trans-3-cis-4-dibromides (14, 17, and 20), whose mild base-mediated heterocyclization (on compound 14), or the two-step acid hydrolysis plus base-promoted cyclization (on compounds 17 and 20), gave products 6 and 7 in good yield. A mechanistic investigation using DFT has been carried out to explain the results observed in this work. [Copyright &y& Elsevier]

The mechanisms for the formation of conformationally constrained epibatidine analogues by intramolecular free radical processes have been computationally addressed by means of DFT methods. The mechanism and the critical effect of the 7-nitrogen protecting group on the outcome of these radical-mediated cyclizations are discussed. Theoretical findings account for unexpected experimental results and can assist in the selection of proper precursors for a successful cyclization. [ABSTRACT FROM AUTHOR]

Abstract: The chelation of the Lewis acid Ti(OiPr)4 provides the necessary conformational control to induce π-facial selectivity on the cyanation process. The steric hindrance imposed by the α-substituent restrains the addition for l-amino acid derivatives. [Copyright &y& Elsevier]

The mechanism of the intramolecular Pt(II)-catalyzed Rautenstrauch cyclopropanation and the stereochemical implications have been investigated by computational methods. The reaction takes place through a cyclopropanation step preceding the cleavage of the C-O bond, thus ensuring the transfer of chiral information from the stereogenic propargylic center. Our results agree with experimental findings and account for the origin of the substrate-dependent selectivity on the basis of subtle electronic effects and steric interactions in the cyclopropanation transition-state structure. [ABSTRACT FROM AUTHOR]

The reactivity of the Pt(II)-mediated processes of unsaturated compounds strongly depends on the substrate structure, and the catalytic activation process may follow different reaction paths, such as skeletal rearrangements, cyclizations, and isomerizations. Herein, we analyze and report the striking effect of an ester group as an alkyne substituent on the reactivity of propargylic enynes, which has been shown to inhibit the expected Rautenstrauch process. The computed results agree with experimental evidence and provide a comprehensible rationalization. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis and the biological evaluation (neuroprotection, voltage dependent calcium channel blockade, AChE/BuChE inhibitory activity and propidium binding) of new multipotent tetracyclic tacrine analogues (5–13) are described. Compounds 7, 8 and 11 showed a significant neuroprotective effect on neuroblastoma cells subjected to Ca2+ overload or free radical induced toxicity. These compounds are modest AChE inhibitors [the best inhibitor (11) is 50-fold less potent than tacrine], but proved to be very selective, as for most of them no BuChE inhibition was observed. In addition, the propidium displacement experiments showed that these compounds bind AChE to the peripheral anionic site (PAS) of AChE and, consequently, are potential agents that can prevent the aggregation of β-amyloid. Overall, compound 8 is a modest and selective AChE inhibitor, but an efficient neuroprotective agent against 70mM K+ and 60μM H2O2. Based on these results, some of these molecules can be considered as lead candidates for the further development of anti-Alzheimer drugs. [Copyright &y& Elsevier]

Abstract: The synthesis and biological evaluation of ethyl 5-amino-4-(3-pyridyl)-2-methyl-6,7,8,9-tetrahydro-4H-pyrano[2,3-b]quinoline-3-carboxylates (9–11) is described. We have found that these compounds inhibit AChE with a mild potency, mitigates the [Ca2+]c triggered by high K+, and cause neuroprotection against Ca2+ overloading and free radical-induced neuronal death. [Copyright &y& Elsevier]

Abstract: PtCl2-catalyzed cycloisomerization of polyunsaturated precursors derived from hep-1-en-6-yne skeleton, such as 1, and 3, as well as the O-(bromomethyl)dimethylsilyl (2, 4) derivatives, gave mixtures of skeletal rearrangement products and/or polycyclic molecules incorporating a cyclopropyl ring system. The introduction of additional unsaturated moieties on the precursor, such as O-propenyl derivative (15), may give rise to further cycloisomerization processes. However, some critical features on the precursor seem to control and drive the catalytic process to specific products with a high regio- and stereoselectivity. In this paper, we have carried out a computational DFT study for the PtCl2-cycloisomerization of the polyunsaturated O-propenyl precursor in order to propose a mechanism and identify these key properties. Different cyclopropanation modes have been evaluated and the results have revealed that the most favorable pathway involves a 5-exo carbocyclopropanation mode, in agreement with the experimental observations. Electronic and structural factors have been shown to be responsible for the observed selectivity. [Copyright &y& Elsevier]

The article discusses the synthesis and pharmacology of galantamine. Synthetic approaches of galantamine rely on the biomimetic approach and intramolecular Heck reaction. Galantamine can be regarded as norbelladine through intramolecular oxidative phenol coupling. Intramolecular reaction is use as an alternative to create the spiro quaternary carbon atom of galantamine type of alkaloids. Galantamine serves as allosteric potentiator of neuronal nicotenic receptors for acetylcholine and modulator of neurotransmitter release.

Transformations of enynes upon treatment with electrophilic transition-metal complexes, such as PtCl2, are strongly substrate-dependent processes and may yield a wide variety of cyclic compounds. Despite the high versatility, many of these processes could be closely related from a mechanistic point of view. Theoretical analyses of the plausible reaction mechanisms provide support for a unified mechanistic picture based on the electrophilic activation of the triple bond by the catalyst, which triggers the nucleophilic alkene attack through an endo- or exo-cyclization mode, to form the cyclopropylcarbene species. Then, these common key intermediates may evolve through alternative paths to afford a range of cyclic compounds. The preference for each path and the evolution of these intermediates are governed by the nature of the starting enyne. The effects induced by different structural motifs, such as the role played by a heteroatom directly attached to the triple bond, the tether length, the substitution on the acetylenic position, and the gem-dialkyl substitution on the tether, among others, are discussed. The proposed common mechanistic scheme can rationalize and account for the experimental observations accumulated. [ABSTRACT FROM AUTHOR]

Abstract: The PtCl2-mediated cycloisomerization of unsaturated propargylic carboxylates yields differently functionalized bicyclo[4.1.0]heptane enol esters from moderate to good yield, in a very diastereoselective manner. We have prepared and submitted to PtCl2-catalyzed cycloisomerization a series of differently substituted hept-1-en-6-ynes with different O-acyl (acetyl, trichloroacetyl, 3,4,5-trimethoxybenzoyl, etc.) protecting groups at propargylic positions, investigating also the effect of the geometry at the double bond, as well as the effect of the number of substituents at the alkene moiety. As a result, we have found that the O-acetyl migrating group is the best one in terms of simplicity and chemical yields. In this reaction we have isolated mixtures of compounds formed by minor 1-acetoxy-allenes and major bicyclo[4.1.0]heptane derivatives. Major products are the result of a sequential process involving steps of cycloisomerization plus cyclopropanation, followed by acyl migration. The basic methanolysis (K2CO3, MeOH) of these intermediates gave mixtures of cis and trans-caran-2-ones. This two-step protocol (cycloisomerization plus basic methanolysis) for the syntheses of α,β-unsaturated cyclopropyl ketones constitutes a synthetic alternative to the usual unfriendly, intramolecular cyclopropanation of unsaturated α-diazocarbonyl derivatives. The formation of these bicyclo[4.1.0]heptane derivatives is a simple, but efficient entry into the skeleton of the ‘carane’ family of natural products. [Copyright &y& Elsevier]

Abstract: The Curtius rearrangement of cyclohex-3-ene carboxylic acid using diphenylphosphoryl azide in the presence of triethylamime and ethanol, t-butanol or benzyl alcohol has been described. As a result the synthesis of ethyl, t-butyl or benzyl N-(1-cyclohex-3-enyl)carbamates has been achieved in one pot, in good chemical yield. A series of transformations of benzyl N-(1-cyclohex-3-enyl)carbamate, such as iodination and epoxidation, as well as opening of the corresponding ring epoxide, have been carried out leading to some useful oxygenated cyclohexylamimo building blocks. [Copyright &y& Elsevier]

Examines the sources, biological activities and synthesis of naturally occurring cyclohexane epoxides. Perspective on naturally occurring epoxycyclohexane derivatives isolated from various organisms; Application of iodine hypervalent mediated oxidation of aromatic derivatives; Utilization of enzymatic resolution of racemic mixtures.

The triphenyltin hydride-mediated free radical cyclization of the radical precursors 1, 7 and 12 is described. This is a new stereoselective entry into the 1,7 dioxaspiro[4,4]nonane ring system. [Copyright &y& Elsevier]

Focuses on the synthesis of carbocycles from carbohydrates. Factors affecting the cyclooctane synthesis; Use of ring-closing metathesis strategy to prepare natural calystegine B[sub 2]; Significance on the synthesis of compound 92 from D-glucose.

A series of strategies (the Pauson-Khand reaction and the 1,3-dipolar cycloaddition reaction) have been analyzed in order to develop new and original synthetic protocols for the synthesis of enantiomerically pure medium-sized carbocycles. The intramolecular Pauson-Khand reaction on dideoxy-3,4:5,6-bis-O-(1-methylethylidene)-D/L-glycero-D-gluco-non-1-en-8 -ynitol (4) is a low yielding, but highly stereoselective acyclic enyne precursor 1,2-procedure for the synthesis of bicyclo[5.3.0]decanones of type 5. In the second approach ("the nitrone route"), the intramolecular nitrone cycloaddition of precursors 14 and 19 derived from D-mannose has afforded the corresponding 9-oxa-8-azabicyclo[5.3.0]decanes as a mixture of trans fused isomers, in a critically dependent reaction of a pre-existing isopropylidene group which entropically favors the approach of the reactive species; this is the first documented example of a 1,3-dipolar cycloaddition in 7-alkenyl nitrones. [ABSTRACT FROM AUTHOR]

The intramolecular Pauson–Khand (PK) reaction of 4-bromomethyldimethylsilyloxy-4-ethynyl-6,6-dimethyloct-1-en-7-yne (1), the differently functionalized 4-ethynyl-octa-1,7-dienes (2–6), and 5-ethynyl-5-hydroxy-2,4,4-trimethyl-nona-1,8-diene (7) is reported. The resulting bicyclo[3.3.0]oct-1-en-3-ones (22–29) and (33–35) have been obtained in good yield, with moderate stereoselectivity. Major isomers (22, 24, 26, 28) have the free or protected hydroxyl group cis to H-6a at the fused ring carbon. In dienyne compound 7 the gem-dimethyl functional group, with the same length for both alkenyl chains, dictates the regiochemistry of the PK reaction, affording major bicyclo derivatives 33 and 34 (in a 4.6:1 ratio, the major isomer (33) having the free hydroxyl group cis to the methyl group at C-6a), and compound 35 with the hydroxyl group trans to proton H-6a at ring junction. All new adducts are potential useful building blocks for the total synthesis of angularly fused triquinanes. [Copyright &y& Elsevier]

The formation of the unexpected secondary products (3 and 9) during Dondoni's one-carbon homologation of 6-deoxy-6-iodo-2,3:4,5-bis-O-isopropylidene-D-glucose (1) are described. [ABSTRACT FROM AUTHOR]

Sigma receptors (σRs) represent very attractive biological targets for the development of potential agents for the treatment of several neurological disorders. In the search for new small molecule drugs against neuropathic pain, we identified 2-{[2-(1-benzylpiperidin-4-yl)ethyl]amino}-6-[methyl(prop-2-yn-1-yl)amino]pyridine-3,5-dicarbonitrile (5) as a polyfunctionalized small pyridine with potent dual-target activities against acetylcholinesterase (AChE) (IC50 = 13 nM) and butyrylcholinesterase (BuChE) (IC50 = 3.1 µM), exhibiting high σ1R affinity (Ki(hσ1R) = 1.45 nM) and 290-fold selectivity over the σ2R subtype. These results are in good agreement with those found in the molecular modeling of compound 5. This is possibly due to the preferred combination in this molecule of a linker n = 2 connecting the N-Bn-piperidine motif to the C2 pyridine, without a phenyl group at C4, and a N-Me-substituted propargyl amine in the chain located at C6. [ABSTRACT FROM AUTHOR]

The first synthesis of polyfunctionalized 4-ferrocenyl-4H-pyran and 4-ferrocenyl-1,4-dihydropyridine derivatives, as well as some of their relevant properties, including an electrochemical study and some aspects of their biological profile have been described. [Copyright &y& Elsevier]

Eleven new differently substituted N,7-diphenylpyrimido [4,5-d]pyrimidin-4-amines 4a–k were synthesized from readily available reagents in a simple and inexpensive two-step procedure with yields up to 57%. Neuroprotective analysis against H2O2 and analysis using ORAC assays identified compounds 4g, 4i and 4j as promising antioxidant compounds. These compounds also showed potent inhibition of Aβ1–42 self-aggregation, and suitable physicochemical properties predicted by Datawarior software V6.1.0, this biological activity and physicochemical property being of great interest for pathologies linked to oxidative stress, such as Alzheimer's disease. [ABSTRACT FROM AUTHOR]

Olesoxime, a cholesterol derivative with an oxime group, possesses the ability to cross the blood–brain barrier, and has demonstrated excellent safety and tolerability properties in clinical research. These characteristics indicate it may serve as a centrally active ligand of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), whose disruption of activity with organophosphate compounds (OP) leads to uncontrolled excitation and potentially life-threatening symptoms. To evaluate olesoxime as a binding ligand and reactivator of human AChE and BChE, we conducted in vitro kinetic studies with the active metabolite of insecticide parathion, paraoxon, and the warfare nerve agents sarin, cyclosarin, tabun, and VX. Our results showed that both enzymes possessed a binding affinity for olesoxime in the mid-micromolar range, higher than the antidotes in use (i.e., 2-PAM, HI-6, etc.). While olesoxime showed a weak ability to reactivate AChE, cyclosarin-inhibited BChE was reactivated with an overall reactivation rate constant comparable to that of standard oxime HI-6. Moreover, in combination with the oxime 2-PAM, the reactivation maximum increased by 10–30% for cyclosarin- and sarin-inhibited BChE. Molecular modeling revealed productive interactions between olesoxime and BChE, highlighting olesoxime as a potentially BChE-targeted therapy. Moreover, it might be added to OP poisoning treatment to increase the efficacy of BChE reactivation, and its cholesterol scaffold could provide a basis for the development of novel oxime antidotes. [ABSTRACT FROM AUTHOR]

The article discusses the use of melatonin to prevent the toxicity induced by chemical warfare agents. It mentions several study on the use of melatonin in several important functions such as vasomotor control and adrenal function. According to a study melatonin possesses antiexcitatory actions, regulates immune function and energy metabolism, including anti-inflammatory properties.

Herein we report the synthesis of ten newly substituted 3‐phenyl‐5‐aryl‐3,5‐dihydro‐4H‐benzo[6,7]chromeno[2,3‐d]pyrimidin‐4,6,11‐triones ("benzochromenopyrimidines") in a one‐step reaction, by reacting ethyl 2‐amino‐4‐aryl‐5,10‐dioxo‐5,10‐dihydro‐4H‐benzo[g]chromene‐3‐carboxylates with aniline, and triethyl orthoformate, under acidic catalyst and solvent‐free conditions. These benzochromenopyrimidines were submitted to biological evaluation for in vitro anti‐cancer activity, several derivatives showing higher activity than commonly used chemotherapeutic agents such as oxaliplatin, 5‐fluorouracil, and paclitaxel. In particular, the 5‐(2‐Methoxyphenyl)‐3‐phenyl‐3,5‐dihydro‐4H‐benzo[6,7]chromeno[2,3‐d]pyrimidine‐4,6,11‐trione was identified as the most potent inhibitor among all the new ligands, showing significant cytotoxic activity against all the cancer cell lines tested [human colon cancer cell lines, LoVo and HCT‐116; human lung cancer cells (A549 line)], as evidenced by the significant decrease in IC50 values, while maintaining low cytotoxicity against normal cells. These promising results suggest that this compound deserves further investigation as a potential hit compound for the development of a selective anticancer drug in cancer therapy. [ABSTRACT FROM AUTHOR]

Herein, we report an ultrasonic promoted facile and convenient “one-pot” procedure for the synthesis of new [1,2,4]triazolo[1,5-a]pyridine derivatives3, 4and5, using Amberlite IRA-400, in short reaction times and high yields and its comparison with classical reaction conditions. The structures of new compounds were assigned with the help of analytical1H,13C NMR, and mass spectral studies. [ABSTRACT FROM PUBLISHER]

Herein we report that 4‐aminopyrimidine‐5‐carbonitriles 3 a–i were efficiently synthesized by reacting suitable 2‐(ethoxyalkylene)malononitriles 1 a–c with easily available amidine hydrochlorides 2 a–d, in good yields using a simple synthetic scheme. To predict their pharmacological properties a comprehensive in silico analysis was conducted. Consequently, appropriate compounds 3 a–h were screened for their antiproliferative activity against two colorectal‐cancer‐cell lines and one lung cancer cell line. These analyses revealed that 4‐amino‐6‐methyl‐2‐(p‐tolyl) pyrimidine‐5‐carbonitrile (3 c) and 4‐amino‐2‐(4‐chlorophenyl)‐6‐methyl pyrimidine‐5‐carbonitrile (3 h) exhibited the most potent inhibitory activity against human LoVo and HCT‐116 cancer cells, and that the most potent inhibitory activity against human A549 cells was observed for compound 3 h. [ABSTRACT FROM AUTHOR]

Great effort has been devoted to the synthesis of novel multi-target directed tacrine derivatives in the search of new treatments for Alzheimer's disease (AD). Herein we describe the proof of concept of MBA121, a compound designed as a tacrine–ferulic acid hybrid, and its potential use in the therapy of AD. MBA121 shows good β-amyloid (Aβ) anti-aggregation properties, selective inhibition of human butyrylcholinesterase, good neuroprotection against toxic insults, such as Aβ1–40, Aβ1–42, and H2O2, and promising ADMET properties that support translational developments. A passive avoidance task in mice with experimentally induced amnesia was carried out, MBA121 being able to significantly decrease scopolamine-induced learning deficits. In addition, MBA121 reduced the Aβ plaque burden in the cerebral cortex and hippocampus in APPswe/PS1ΔE9 transgenic male mice. Our in vivo results relate its bioavailability with the therapeutic response, demonstrating that MBA121 is a promising agent to treat the cognitive decline and neurodegeneration underlying AD. [ABSTRACT FROM AUTHOR]

Alzheimer's disease (AD) is a multifactorial neurodegenerative disease that has a heavy social and economic impact on all societies and for which there is still no cure. Multitarget-directed ligands (MTDLs) seem to be a promising therapeutic strategy for finding an effective treatment for this disease. For this purpose, new MTDLs were designed and synthesized in three steps by simple and cost-efficient procedures targeting calcium channel blockade, cholinesterase inhibition, and antioxidant activity. The biological and physicochemical results collected in this study allowed us the identification two sulfonamide-dihydropyridine hybrids showing simultaneous cholinesterase inhibition, calcium channel blockade, antioxidant capacity and Nrf2-ARE activating effect, that deserve to be further investigated for AD therapy. [ABSTRACT FROM AUTHOR]

Cerebral ischemia is a condition affecting an increasing number of people worldwide, and the main cause of disability. Current research focuses on the search for neuroprotective drugs for its treatment, based on the molecular targets involved in the ischemic cascade. Nitrones are potent antioxidant molecules that can reduce oxidative stress. Here we report the neuroprotective properties and the antioxidant power of the six new quinolylnitrones (QNs) 1–6 for their potential application in stroke therapy. QNs 1–4 are 2-chloro-8-hydroxy-substituted QNs bearing N-t-butyl or N-benzyl substituents at the nitrone motif located at C3, whereas QN5 and QN6 are 8-hydroxy QNs bearing N-t-butyl or N-benzyl substituents at the nitrone motif located at C2, respectively. In vitro neuroprotection studies using QNs 1–6 in an oxygen-glucose-deprivation model of cerebral ischemia, in human neuroblastoma cell cultures, indicate that all QNs have promising neuroprotective, anti-necrotic, anti-apoptotic, and anti-oxidant properties against experimental ischemia–reperfusion in neuronal cultures. QN6 stands out as the most balanced nitrone out of all tested QNs, as it strongly prevents decreased neuronal metabolic activity (EC50 = 3.97 ± 0.78 μM), as well as necrotic (EC50 = 3.79 ± 0.83 μM) and apoptotic cell death (EC50 = 3.99 ± 0.21 μM). QN6 showed high capacity to decrease superoxide production (EC50 = 3.94 ± 0.76 μM), similar to its parent molecule α-phenyl-tert-butyl nitrone (PBN) and the well-known anti-oxidant molecule N-acetyl-l-cysteine (NAC). Thus, QN6 demonstrated the highest antioxidant power out of the other tested QNs. Finally, in vivo treatment with QN6 in an experimental permanent stroke model elicited a significant reduction (75.21 ± 5.31%) of the volume size of brain lesion. Overall, QN6 is a potential agent for the therapy of cerebral ischemia that should be further investigated. [ABSTRACT FROM AUTHOR]

Novel multitarget-directed ligands BIGI 4a-d and BIGI 5a-d were designed and synthesized with a simple and cost-efficient procedure via a one-pot three-component Biginelli reaction targeting acetyl-/butyrylcholinesterases inhibition, calcium channel antagonism, and antioxidant ability. Among these multitarget-directed ligands, BIGI 4b, BIGI 4d, and BIGI 5b were identified as promising new hit compounds showing in vitro balanced activities toward the recognized AD targets. In addition, these compounds showed suitable physicochemical properties and a good druglikeness score predicted by Data Warrior software. [ABSTRACT FROM AUTHOR]

Twenty-four novel compounds bearing tetrahydroacridine and N-propargyl moieties have been designed, synthesised, and evaluated in vitro for their anticholinesterase and anti-monoamine oxidase activities. Propargyltacrine 23 (IC50 = 21 nM) was the most potent acetylcholinesterase (AChE) inhibitor, compound 20 (IC50 = 78 nM) showed the best inhibitory human butyrylcholinesterase (hBChE) profile, and ligand 21 afforded equipotent and significant values on both ChEs (human AChE [hAChE]: IC50 = 0.095±0.001 µM; hBChE: IC50 = 0.093±0.003 µM). Regarding MAO inhibition, compounds 7, 15, and 25 demonstrated the highest inhibitory potential towards hMAO-B (IC50 = 163, 40, and 170 nM, respectively). In all, compounds 7, 15, 20, 21, 23, and 25 exhibiting the most balanced pharmacological profile, were submitted to permeability and cell viability tests. As a result, 7-phenoxy-N-(prop-2-yn-1-yl)-1,2,3,4-tetrahydroacridin-9-amine hydrochloride (15) has been identified as a permeable agent that shows a balanced pharmacological profile [IC50 (hAChE) = 1.472 ±0.024 µM; IC50 (hBChE) = 0.659 ±0.077 µM; IC50 (hMAO-B) = 40.39 ± 5.98 nM], and consequently, as a new hit-ligand that deserves further investigation, in particular in vivo analyses, as the preliminary cell viability test results reported here suggest that this is a relatively safe therapeutic agent. [ABSTRACT FROM AUTHOR]

Ten new differently substituted 3-benzyl-5-aryl-3,5-dihydro-4H-benzo[6,7]chromeno[2,3-d]pyrimidin-4,6,11-triones 3 were synthesized by a simple and cost-efficient procedure in a one-pot, three-component reaction from readily available ethyl 2-amino-4-aryl-5,10-dioxo-5,10-dihydro-4H-benzo[g]chromene-3-carboxylates, benzylamine and triethyl orthoformate under solvent- and catalyst-free conditions. All the new compounds were screened for their antiproliferative activity against two colorectal-cancer-cell lines. The results showed that the compounds 3-benzyl-5-phenyl-3,5-dihydro-4H-benzo[6,7]chromeno[2,3-d]pyrimidine-4,6,11-trione (3a) and 3-benzyl-5-(3-hydroxyphenyl)-3,5-dihydro-4H-benzo[6,7]chromeno[2,3-d]pyrimidine-4,6,11-trione (3g) exhibited the most potent balanced inhibitory activity against human LoVo and HCT-116 cancer cells. [ABSTRACT FROM AUTHOR]

Alzheimer's disease (AD) is a complex disorder characterized by impaired neurotransmission in cholinergic and monoaminergic neurons, which, in combination with the accumulation of misfolded proteins and increased oxidative stress, leads to the typical features of the disease at the biomolecular level. Given the limited therapeutic success of approved drugs, it is imperative to explore rationally supported therapeutic approaches to combat this disease. The search for novel scaffolds that bind to different receptors and inhibit AD disease-related enzymes could lead to new therapeutic solutions. Here, we describe N-hydroxy-N-propargylamide hybrids 1–6, which were designed by combining the structures of Contilisant—a multifunctional anti-AD ligand—and ferulic acid, a natural antioxidant with various other biological activities. Among the synthesized compounds, we identified compound 4 as a micromolar inhibitor of hAChE with a potent radical-scavenging capacity comparable to resveratrol and Trolox. In addition, compound 4 chelated copper(II) ions associated with amyloid β pathology, mitochondrial dysfunction, and oxidative stress. The promising in vitro activity combined with favorable drug-like properties and predicted blood-brain barrier permeability make compound 4 a multifunctional ligand that merits further studies at the biochemical and cellular levels. [ABSTRACT FROM AUTHOR]

In our search for new neuroprotective agents for stroke therapy to improve the pharmacological profile of the compound quinolylnitrone QN23, we have prepared and studied sixteen new, related and easily available quinolylnitrones. As a result, we have identified compounds QN4 and QN15 as promising candidates showing high neuroprotection power in a cellular experimental model of ischemia. Even though they were found to be less active than our current lead compound QN23, QN4 and QN15 provide an improved potency and, particularly for QN4, an expanded range of tolerability and improved solubility compared to the parent compound. A computational DFT-based analysis has been carried out to understand the antioxidant power of quinolylnitrones QN23, QN4 and QN15. Altogether, these results show that subtle, simple modifications of the quinolylnitrone scaffold are tolerated, providing high neuroprotective activity and optimization of the pharmacological potency required for an improved design and future drug developments in the field. [ABSTRACT FROM AUTHOR]

[Display omitted] • Polyfunctionalized 4-phenylpyridine-3,5-dicarbonitrile 12 is a multitarget ligand. • Compound 12 behaves as a sigma1 receptor antagonist modulator. • 12 Reverses mechanical allodynia in mice with paclitaxel-induced neuropathic pain. In the search for new small molecules for the therapy of neuropathic pain, we found that 2-{3-[ N -(1-benzylpiperidin-4-yl)propyl]amino}-6-[ N -methyl- N -(prop-2-yn-1-yl)amino]-4-phenylpyridine-3,5-dicarbonitrile (12) induced a robust antiallodynic effect in capsaicin-induced mechanical allodynia, a behavioural model of central sensitization, through σ 1 R antagonism. Furthermore, administration of compound 12 to neuropathic animals, fully reversed mechanical allodynia, increasing its mechanical threshold to levels that were not significantly different from those found in paclitaxel-vehicle treated mice or from basal levels before neuropathy was induced. Ligand 12 is thus a promising hit-compound for the therapy of neuropathic pain. [ABSTRACT FROM AUTHOR]