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Glaucoma is a widespread neurodegenerative disease for which increased intraocular pressure (IOP) is a primary modifiable risk factor. Recently, we have observed that compounds with oxindole scaffolds are involved in the regulation of intraocular pressure and therefore have potential antiglaucomic activity. In this article, we present an efficient method for obtaining novel 2-oxindole derivatives via microwave-assisted (MW) decarboxylative condensation of substituted isatins with malonic and cyanoacetic acids. Various 3-hydroxy-2-oxindoles were synthesized using MW activation for 5–10 min with high yields (up to 98%). The influence of novel compounds applied in instillations on IOP was studied in vivo on normotensive rabbits. The lead compound was found to reduce the IOP by 5.6 Torr (ΔIOP for the widely used antiglaucomatousic drug timolol 3.5 Torr and for melatonin 2.7 Torr).

The development of multi-target-directed ligands (MTDLs) would provide effective therapy of neurodegenerative diseases (ND) with complex and nonclear pathogenesis. A promising method to create such potential drugs is combining neuroactive pharmacophoric groups acting on different biotargets involved in the pathogenesis of ND. We developed a synthetic algorithm for the conjugation of indole derivatives and methylene blue (MB), which are pharmacophoric ligands that act on the key stages of pathogenesis. We synthesized hybrid structures and performed a comprehensive screening for a specific set of biotargets participating in the pathogenesis of ND (i.e., cholinesterases, NMDA receptor, mitochondria, and microtubules assembly). The results of the screening study enabled us to find two lead compounds (4h and 4i) which effectively inhibited cholinesterases and bound to the AChE PAS, possessed antioxidant activity, and stimulated the assembly of microtubules. One of them (4i) exhibited activity as a ligand for the ifenprodil-specific site of the NMDA receptor. In addition, this lead compound was able to bypass the inhibition of complex I and prevent calcium-induced mitochondrial depolarization, suggesting a neuroprotective property that was confirmed using a cellular calcium overload model of neurodegeneration. Thus, these new MB-cycloalkaneindole conjugates constitute a promising class of compounds for the development of multitarget neuroprotective drugs which simultaneously act on several targets, thereby providing cognitive stimulating, neuroprotective, and disease-modifying effects.

A new series of homobivalent Dimebon analogs, bis-γ-carbolines with alkylene, phenylenedialkylene, and triazole-containing spacers, was synthesized. Doubling the γ-carboline pharmacophore increased inhibitory potency against acetylcholinesterase (AChE) compared with Dimebon, while keeping Dimebon’s anti-butyrylcholinesterase activity; therefore, leading to inversion of selectivity. Molecular docking revealed the reasons for the increased anti-AChE activity and ability to block AChE-induced aggregation of β-amyloid for bis-γ-carbolines, which became double-site inhibitors of AChE. Conjugates with ditriazole-containing spacers were the most active antioxidants in both the ABTS-test and prevention of lipid peroxidation in brain homogenates without inhibiting the mitochondrial permeability transition (MPT). Conjugates with alkylene (4a–d), phenylenedialkylene (4e), and monotriazole (8) spacers were less active as antioxidants but prevented induction of the MPT and increased the calcium retention capacity of mitochondria. Lead compound 4e showed neuroprotective potential in a cellular calcium overload model of neurodegeneration. Computational studies showed that all the bis-γ-carbolines were expected to have high values for intestinal absorption and very good blood-brain barrier permeability along with good drug-likeness. Overall, the results showed that new homobivalent Dimebon analogs exhibit an expanded spectrum of biological activity and improved pharmacological properties, making them promising candidates for further research and optimization as multitarget agents for Alzheimer’s disease treatment.

γ-Carboline derivatives were synthesized by the addition of fluorinated vinylpyridines to 2,6-dimethyl-2,3,4,5-tetrahydro-γ-carboline. The effect of repeated intraperitoneal injections of the synthesized derivatives on the progression of motor and cognitive dysfunctions was studied in comparison with Dimebon in 5xFAD transgenic mice as a model of neurodegenerative diseases induced by cerebral amyloidosis.

Ester of the tubulin ligand, 2-methoxyestradiol, with two molecules of DNA alkylating agent chlorambucil was proposed as a “triple” mutual prodrug for blocking rapid metabolism of the initial steroid. The target conjugate was synthesized via the Steglich esterification. The biotesting results demonstrate a very low cytotoxicity to cancer and conditionally normal cells (EC50 ~100 μmol L−1), a weak inhibition of the cell growth (A549: 20%/48 h), no stimulation of apoptosis, and no influence on the microtubule morphology of human lung carcinoma A549 cells and the ability to increase the rate of microtubule assembling. The sharp distinction of these properties from those for the initial 2-methoxyestradiol and chlorambucil molecules indicates that the synthesized prodrug is stable in vitro and demonstrates an expediency of its further testing in vivo.

A series of novel antimitotic agents was designed using the replacement of heterocyclic cores in two tubulin-targeting lead molecules with the acylated 4-aminoisoxazole moiety. Target compounds were synthesized via heterocyclization of β-aryl-substituted vinylketones by tert-butyl nitrite in the presence of water as a key step. 4-Methyl-N-[5-methyl-3-(3,4,5-trimethoxyphenyl)isoxazol-4-yl]benzamide (1aa) was found to stimulate partial depolymerization of microtubules of human lung carcinoma A549 cells at a high concentration of 100 µM and to totally inhibit cell growth (IC

A series of bifunctional Ru(III) complexes with lonidamine-modified ligands (lonidamine is a selective inhibitor of aerobic glycolysis in cancer cells) was described. Redox properties of Ru(III) complexes were characterized by cyclic voltammetry. An easy reduction suggested a perspective for these agents as their whole mechanism of action seems to be based on activation by metal atom reduction. New compounds demonstrated a more pronounced antiproliferative potency than the parental drug; individual new agents were more cytotoxic than cisplatin. Stability studies showed an increase in the stability of complexes along with the linker length. A similar trend was noted for antiproliferative activity, cellular uptake, apoptosis induction, and thioredoxin reductase inhibition. Finally, at concentrations that did not alter water solubility, the selected new complex evoked no acute toxicity in Balb/c mice.

A series of novel organotin(IV) complexes on the base of 2-(N-3′,5′-di-tert-butyl-4′-hydroxyphenyl)-iminomethylphenol (L) of formulae Me2SnBr2(L)2 (1), Bu2SnCl2(L)2(2), Ph2SnCl2(L) (3), Ph2SnCl2(L)2 (4) Ph3SnBr(L)2 (5) were synthesized and characterized by 1H, 13C, 119Sn NMR, IR, ESI-MS and elemental analysis. The crystal structures of initial L and complex 2 were determined by XRD method. It was found that L crystallizes in the orthorhombic syngony. The distorted octahedron geometry around Sn center is observed in the structure of complex 2. Intra- and inter-molecular hydrogen bonds were found in both structures. The antioxidant activity of new complexes as reducing agents, radical scavengers and lipoxygenase inhibitors was estimated spectrophotometrically in CUPRAC and DPPH tests (compounds 1 and 5 were found to be the most active in both methods), and in the process of enzymatic oxidation in vitro of linoleic acid under the action of lipoxygenase LOX 1-B (EC50 > 33.3 μM for complex 2). Furthermore, compounds 1–5 have been investigated for their antiproliferative activity in vitro towards HCT-116, MCF-7 and A-549 and non-malignant WI-38 human cell lines. Complexes 2 and 5 demonstrated the highest activity. The plausible mechanisms of the antiproliferative activity of compounds, including the influence on the polymerization of Tb+MAP, are discussed. Some of the synthesized compounds have also actively induced apoptosis and blocked proliferation in the cell cycle G2/M phase.

We studied the inhibitory activity of methylene blue (MB) γ-carbolines (gC) conjugates (MB-gCs) against human erythrocyte acetylcholinesterase (AChE), equine serum butyrylcholinesterase (BChE), and a structurally related enzyme, porcine liver carboxylesterase (CaE). In addition, we determined the ability of MB-gCs to bind to the peripheral anionic site (PAS) of Electrophorus electricus AChE (EeAChE) and competitively displace propidium iodide from this site. Moreover, we examined the ability of MB-gCs to scavenge free radicals as well as their influence on mitochondrial potential and iron-induced lipid peroxidation. We found that MB-gCs effectively inhibited AChE and BChE with IC50 values in the range 1.73–10.5 μM and exhibited low potencies against CaE (9.8–26% inhibition at 20 μM). Kinetic studies showed that MB-gCs were mixed-type reversible inhibitors of both cholinesterases. Molecular docking results showed that the MB-gCs could bind both to the catalytic active site and to the PAS of human AChE and BChE. Accordingly, MB-gCs effectively displaced propidium from the peripheral anionic site of EeAChE. In addition, MB-gCs were extremely active in both radical scavenging tests. Quantum mechanical DFT calculations suggested that free radical scavenging was likely mediated by the sulfur atom in the MB fragment. Furthermore, the MB-gCs, in like manner to MB, can restore mitochondrial membrane potential after depolarization with rotenone. Moreover, MB-gCs possess strong antioxidant properties, preventing iron-induced lipid peroxidation in mitochondria. Overall, the results indicate that MB-gCs are promising candidates for further optimization as multitarget therapeutic agents for neurodegenerative diseases.

The mitochondria-targeting drugs can be conventionally divided into the following groups: those compensating for the energy deficit involved in neurodegeneration, including stimulants of mitochondrial bioenergetics and activators of mitochondrial biogenesis; and neuroprotectors, that are compounds increasing the resistance of mitochondria to opening of mitochondrial permeability transition (MPT) pores. Although compensating for the energy deficit and inhibition of MPT are obvious targets for drugs used in the very early stages of Alzheimer-like pathology, but their use as the monotherapy for patients with severe symptoms is unlikely to be sufficiently effective. It would be optimal to combine targets that would provide the cognitive-stimulating, the neuroprotective effects and the ability to affect specific disease-forming mechanisms. In the design of such drugs, assessment of their potential mitochondrial-targeted effects is of particular importance. The possibility of targeted drug design for simultaneous action on mitochondrial and neurotransmitter's receptors targets is, in particularly, based on the known interplay of various cellular pathways and the presence of common structural components. Of particular interest is directed search for multitarget drugs that would act simultaneously on mitochondrial calcium-dependent functions, the targets (receptors, enzymes, etc.) facilitating neurotransmission, and the molecular targets related to the action of so-called disease-modifying factors, in particular, the formation and overcoming of the toxicity of β-amyloid or hyperphosphorylated tau protein. The examples of such approaches realized on the level of preclinical and clinical trials are presented below.

The synthesized new binary conjugates of tetrahydro-γ-carbolines, which contained ditriazole spacers of different length, exhibited considerable anticholinesterase and antioxidant activity as well as the potential ability to block the acetylcholinesterase-induced aggregation of β-amyloid in contrast to the original prototype Dimebon. This makes the compounds promising candidates for further investigation as drugs for the treatment of Alzheimer's disease. Special attention should be given to the conjugate containing the hexamethylene intertriazole spacer, which can be considered as a leader in this series of compounds.

New diphenylsulfimide derivatives containing substituents with the 2,6-di-tert-butylphenol moiety at the nitrogen atom were synthesized. Their molecular structures were established by X-ray diffraction. Antioxidant activity was experimentally evaluated by spectrophotometry based on hydrogen transfer to the stable radicals, namely, 2,2-diphenyl-1-picrylhydrazyl and the 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS·+), and using in vitro lipid peroxidation in rat brain and liver homogenates. The presence of phenol and diphenylsulfimide moieties in one molecule leads to a significant enhancement of antioxidant activity. The new compounds exhibit moderate inhibitory activity against enzymes involved in carbohydrate and lipid metabolism. The evaluation of antiglycation activity showed that the new sulfimides taken at a concentration of 100 μmol L–1 have activity comparable with that of aminoguanidine.

A synthetic approach to the vinylation and allylation of tetrahydro-γ-carbolines with alkane dimethyl sulfonates in the presence of sodium hydride was developed. The effect of the synthesized 5-vinyl- and 5-allyl-2,3,4,5-tetrahydro-1H-pyrido[4,3-b]indoles on acetylcholinesterase, butyrylcholinesterase, and carboxylesterase activity, mitochondrial functions, and tubulin polymerization was investigated, and their antioxidant activity was evaluated.

The paper considers the influence of the structure of aminoadamantane–carbazole conjugates linked by five different spacers on their ability to inhibit acetylcholinesterase, butyrylcholinesterase (BChE), and carboxylesterase, the radical scavenging and mitoprotective activity, and tubulin polymerization. The nature of the spacer was found to be determinant for the appearance of anti-BChE and radical-scavenging activity. Aminoadamantane–carbazole conjugates linked by flexible spacers proved to be most effective in these assays. The influence of the conjugates on mitochondrial functions and tubulin polymerization largely depends on the structure of the carbazole moiety. A series of lead compounds promising for further study was identified as potential drugs for the treatment of neurodegenerative diseases, in particular, Alzheimer’s disease.

Phosphorylation of τ-protein, a component of microtubules in brain neurons, is a key pathomorphological sign of Alzheimer’s disease. The development of this intracellular defect can be promoted by Al3+, Fe3+, and Zn2+ ions. The concentrations of these ions in the brain are considerably elevated in Alzheimer’s disease. We performed a comparative study of phosphorylation of microtubular proteins of rat brain in the presence of Al3+, Fe3+, and Zn2+ ions in concentrations of 10-500 μM and microtubular proteins of brain of patients with Alzheimer’s disease. The most likely candidate for the role of a factor that promotes hyperphosphorylation of τ-protein is Al3+ in concentrations of 250 and 500 μM.

Background: Anti-tumor effect of hydroxamic acid derivatives is largely connected with its properties as efficient inhibitors of histone deacetylases, and other metalloenzymes involved in carcinogenesis. Objective: The work was aimed to (i) determine the anti-tumor and chemosensitizing activity of the novel racemic spirocyclic hydroxamic acids using experimental drug sensitive leukemia P388 of mice, and (ii) determine the structure-activity relationships as metal chelating and HDAC inhibitory agents. Method: Outbreed male rat of 200-220 g weights were used in biochemical experiments. In vivo experiments were performed using the BDF1 hybrid male mice of 22-24 g weight. Lipid peroxidation, Fe (II) -chelating activity, HDAC fluorescent activity, anti-tumor and anti-metastatic activity, acute toxicity techniques were used in this study. Results: Chemosensitizing properties of water soluble cyclic hydroxamic acids (CHA) are evaluated using in vitro activities and in vivo methods and found significant results. These compounds possess iron (II) chelating properties, and slightly inhibit lipid peroxidation. CHA prepared from triacetonamine (1a-e) are more effective Fe (II) ions cheaters, as compared to CHA prepared from 1- methylpiperidone (2a-e). The histone deacetylase (HDAC) inhibitory activity, lipophilicity and acute toxicity were influenced by the length amino acids (size) (Glycine < Alanine < Valine < Leucine < Phenylalanine). All compounds bearing spiro-N-methylpiperidine ring (2a-e) are non-toxic up to 1250 mg/kg dose, while compounds bearing spiro-tetramethylpiperidine ring (1a-e) exhibit moderate toxicity which increases with increasing lipophility, but not excite at 400 mg/kg. Conclusion: It was shown that the use of combination of non-toxic doses of cisplatin (cPt) or cyclophosphamide with CHA in most cases result in the appearance of a considerable anti-tumor effect of cytostatics. The highest chemosensitizing activity with respect to leukemia Р388 is demonstrated by the CHA derivatives of Valine 1c or 2c.

A new series of conjugates of aminoadamantane and γ-carboline, which are basic scaffolds of the known neuroactive agents, memantine and dimebon (Latrepirdine) was synthesized and characterized. Conjugates act simultaneously on several biological structures and processes involved in the pathogenesis of Alzheimer’s disease and some other neurodegenerative disorders. In particular, these compounds inhibit enzymes of the cholinesterase family, exhibiting higher inhibitory activity against butyrylcholinesterase (BChE), but having almost no effect on the activity of carboxylesterase (anti-target). The compounds serve as NMDA-subtype glutamate receptor ligands, show mitoprotective properties by preventing opening of the mitochondrial permeability transition (MPT) pore, and act as microtubule stabilizers, stimulating the polymerization of tubulin and microtubule-associated proteins. Structure–activity relationships were studied, with particular attention to the effect of the spacer on biological activity. The synthesized conjugates showed new properties compared to their prototypes (memantine and dimebon), including the ability to bind to the ifenprodil-binding site of the NMDA receptor and to occupy the peripheral anionic site of acetylcholinesterase (AChE), which indicates that these compounds can act as blockers of AChE-induced β-amyloid aggregation. These new attributes of the conjugates represent improvements to the pharmacological profiles of the separate components by conferring the potential to act as neuroprotectants and cognition enhancers with a multifunctional mode of action.

Synthetic approaches to the design of new multitarget agents for the treatment of neurodegenerative diseases are surveyed. These approaches are based on the conjugation of the pharmacophoric indole, phenothiazine, and aminoadamantane moieties via 1-oxopropylene and 2-hydroxypropylene spacers using reactions of acrylate- and epoxide-containing pharmacophores with tetrahydro-γ-carbolines, cycloalkaneindoles, carbazoles, and aminoadamantanes. The review considers data on biological activity of the compounds assessed within a complex screening system. This system includes neurotransmitter targets associated with cognitive compensation, such as cholinesterases and glutamate receptors, mitochondria, the influence on which can provide neuroprotective effects, and microtubules, the stabilization of which leads to the improvement of axonal transport. The ability of the compounds to act as free-radical scavengers was evaluated. Types of polypharmacophoric compounds promising for further development are proposed.

The novel metal complexes of general formula MCl2·L (M = Cu, Fe, Co, Mn, Zn) based on the di-(2-picolyl)amine ligand L with the redox-active ferrocenyl fragment were synthesized and characterized by elemental analysis, IR, 1H, 13C NMR, UV–vis spectroscopy and MALDI-TOF mass spectrometry. The molecular structure of [ZnCl2L] was established by X-ray crystallography. The redox properties of complexes were studied using cyclic voltammetry (CV) method and feasible schemes of electrochemical transformations were proposed. The antioxidant activity of compounds was tested by various methods. The lipoxygenase (LOX) inhibition activity of the studied compounds was evaluated. The in vitro biological experiments were performed using rat brain homogenates. The results demonstrate that ditopic compounds containing ferrocene and redox active dipicolylamine fragments act as polyfunctional antioxidants. These results let us to conclude that combining in one molecule several redox-active metal centers is a promising way of metallodrug design in modern medicinal chemistry.

Alzheimer’s disease has a complex multifactorial nature; therefore, a promising approach for the development of efficient therapeutic agents is the concept of multitarget drugs, which affect several biological targets involved in the pathogenesis of the disease. We developed a synthetic algorithm for conjugating several pharmacophoric ligands acting on the key stages of pathogenesis of several neurodegenerative diseases and synthesized hybrid structures combining the γ-carboline fragment of Dimebon with carbazole and tetrahydrocarbazole moieties. Using the complex primary screening system the structures have been revealed that combine the high inhibitory activity and selectivity towards butyrylcholinesterase with the radical-scavenging activity and the ability to potentiate tubulin polymerization to microtubules with a normal structure and/or prevent mitochondrial permeability transition. The lead compound was identified for future optimization and development of new multi-target drugs against neurodegenerative diseases combining the cognitive-stimulating and neuroprotective potentials.

Novel gold(I) complexes, PPh3AuSR (1) and [(Ph3PAu)2SR]2(BF4)2 (2), with a protective antioxidant group R (R = 3,5-di-tert-butyl-4-hydroxyphenyl) were synthesized and characterized by 1H, 13C, 31P NMR, IR and elemental analyses. The crystal structures of compounds 1 and 2 were determined by X-ray diffraction. Compound 2 has a cluster structure with four Au–Au bonds in the crystal. The tetragold(I) dication is composed of four PPh3Au units with bridging sulfur atoms, where the Au4 moiety has a distorted tetrahedral geometry. The biological impact of gold complexes 1 and 2, and their precursors (RSH and AuPPh3Cl), on lipid peroxidation, mitochondrial functions, the tubulin polymerization, activity of glutathione reductase and cell viability were investigated. A comparative study of the structure–activity relationship was performed. We found that RSH and Au complexes 1 and 2 as opposed to AuPPh3Cl, prevented Fe3+ and tBHP-induced lipid peroxidation in isolated mitochondria. The number of 2,6-di-tert-butylphenol fragments influences the inhibitory effect. AuPPh3Cl induced swelling and depolarization of mitochondria, whereas RSH and the gold complexes 1 and 2, containing 2,6-di-tert-butylphenol groups, showed little to null effect. The thiol ligand RSH and AuPPh3Cl as well as gold complexes 1 and 2 have no impact on tubulin polymerization. The gold complexes were found to inhibit glutathione reductase. The compounds were tested for cytotoxicity against a primary culture of rat cerebellar granule cells. A high toxicity was determined for AuPPh3Cl, while introduction of antioxidant phenol groups decreased the cytotoxicity of the Au complexes. These results open up scope for the design of novel low toxic, gold based pharmacological agents.

Comparison of the cognition-stimulating effects of Dimebon in a wide dose range revealed a non-monotonic and nontrivial wave-like dose-dependence of its activity. Positive results were obtained at low (0.02-0.05 mg/kg) or high (5-10 mg/kg) doses of Dimebon, while intermediate doses were ineffective. This type of the dose dependence of the pharmacological effect can indicate that the substance has several targets. This fact should be taken into consideration when selecting the doses and concentrations of the substance and its analogues for further studies, and for planning treatment schemes and administration doses in clinical studies.

Unknown conjugates of carbazoles and tetrahydrocarbazoles were obtained by the alkylation of carbazoles and tetrahydrocarbazoles with 3,6-substituted 9-oxiranylmethylcarbazoles. The influence of synthesized 1-(9Н-carbazol-9-yl)-3-(1,2,3,4-tetrahydro-5Н-pyrido[4,3-b]-indol-5-yl)propan-2-ones on functional characteristics of brain mitochondria has been studied. The potential neuroprotective activity of a several representatives of conjugates has been demonstrated using glutamate toxicity model.

Earlier unknown conjugates of carbazoles and γ-carbolines were obtained by the reaction of 3,6-substituted 9-oxiranylmethylcarbazoles and 2,8-substituted 2,3,4,5-tetrahydro-1H-pyrido-[4,3]indoles. The effects of synthesized 1-(9H-carbazol-9-yl)-3-(1,2,3,4-tetrahydro-5H-pyrido-[4,3-b]indol-5-yl)propan-2-ones and their hydrochlorides on neuronal NMDA receptors, polymerization of tubulin to form microtubules, and functional characteristics of rat liver mitochondria were studied.

Two series of organotin(IV) carboxylates based on phenolic antioxidants RCOOH and R(CH2)2COOH (R = 3,5-di-tert-butyl-4-hydroxyphenyl) and natural bile (cholanic) acids of formulae (RCOO)2SnMe2 (1); (RCOO)2SnBu2 (2); (R(CH2)2COO)2SnMe2 (3); (R(CH2)2COO)2SnBu2 (4); (cholate)SnPh3 (5); (deoxycholate)SnPh3 (6); (lithocholate)SnPh3 (7); (cholate)SnMe3 (8); (deoxycholate)SnMe3 (9), and (lithocholate)SnMe3 (10) were synthesized and characterized by 1H, 13C NMR, IR and elemental analysis to study their antioxidant and cytotoxic potential. Compounds 1 and 2 were found by X-ray diffraction analysis to be monomers in the solid state; moreover, the carboxyl groups are coordinated bidentately through O atoms. The distorted octahedron geometry around the Sn center in the monocrystals of 1, 2 was revealed. The antioxidant activity of compounds as radical scavengers and reducing agents was evaluated in spectrophotometrical tests with stable radical DPPH, reduction of Cu2+ (CUPRAC method) and interaction with superoxide anion radical. Cytotoxicity in vitro of compounds has been estimated on human cancer (colon cancer HCT-116, lung carcinoma A549, breast cancer MCF-7, neuroblastoma SH-SY5Y) cell lines and normal fibroblasts cells. The IC50 values varied in 0.002–100 μM range for compounds 1–4 depend on the alkyl substituents at Sn center and carboxylate ligand structure. The influence on Fe3+-induced lipid peroxidation, mitochondrial potential and mitochondrial permeability and tubulin assembly have been studied for the compounds 1 and 2. It was shown that the complexes 1 and 2 slightly depolarize the mitochondria but don’t influence the calcium-induced mitochondrial permeability transition. Organotin complexes with cholic and deoxycholic acids as ligands were revealed to induce apoptosis in A549 cells. The percentage of apoptotic cells were 27.9 and 27.1% for triphenyltin complexes with cholic and deoxycholic derivatives, respectively.

Compounds that act on mitochondrial functions are considered as promising drugs for the treatment of neurodegenerative diseases and age-related dementias. As a basis for the creation of such potential drugs, bioisosteric cinnamic acid analogs and polymethoxybenzene derivatives were selected. Derivatives of cinnamic acid have a wide range of biological activities, which can be important for drugs aimed at the treatment of neurodegenerative diseases, in particular Alzheimer′s disease. In this work, the neuroprotective activity of bioisosteric cinnamic acid analogs and polymethoxybenzene derivatives was studied. Among the compounds studied, lead substances 3, 4, and 7 have been identified. These compounds show no intrinsic toxicity and have a neuroprotective effect on the cellular model of neurodegeneration associated with calcium stress. The mechanism of their cytoprotective activity is probably due to the influence on mitochondrial functions, because these compounds effectively suppress the calcium-induced process of mitochondrial permeability jump. In addition, one of the substances investigated (7) has antioxidant properties, showing the ability to inhibit lipid peroxidation (LPO) of rat brain homogenate, which may be an additional mechanism of neuroprotective effect. The data obtained make it possible to recommend the investigated substances as a basis for the creation of effective neuroprotective drugs capable of influencing early stages of the development of neurodegenerative diseases., Соединения, направленно действующие на митохондриальные функции, рассматриваются как перспективные лекарственные препараты для лечения нейродегенеративных заболеваний и возрастных деменций. В качестве основы для создания таких потенциальных лекарственных средств были выбраны биоизостерные аналоги коричной кислоты и производные полиметоксибензолов. Производные коричной кислоты имеют широкий спектр биологических активностей, который может иметь значение для лекарственных препаратов, направленных на лечение нейродегенеративных заболеваний, в частности болезни Альцгеймера. В данной работе исследована нейропротекторная активность биоизостерных аналогов коричной кислоты и производных полиметоксибензолов. Среди исследованных соединений выявлены вещества-лидеры 3, 4 и 7. Эти соединения не проявляют собственной токсичности и оказывают нейропротекторный эффект на клеточной модели нейродегенерации, связанной с кальциевым стрессом. Механизм их цитопротекторной активности, возможно, обусловлен влиянием на функции митохондрий, поскольку эти соединения эффективно подавляют кальций-индуцированный процесс скачка митохондриальной проницаемости. Кроме того, одно из исследованных веществ (7) обладает антиоксидантными свойствами, проявляя способность к ингибированию перекисного окисления липидов (ПОЛ) гомогената мозга крыс, что может быть дополнительным механизмом нейропротекторного эффекта. Полученные данные позволяют рекомендовать исследованные вещества в качестве основы для создания эффективных нейропротекторных препаратов, способных повлиять на ранние стадии развития нейродегенеративных заболеваний.

The article provides an overview of our own results of comparative study of influence of ions of iron, zinc and aluminium on the structure of microtubules from tubulin and microtubules associated proteins of rat brain with data on the structure of microtubules from tubulin and microtubules associated proteins from the brain of patients with Alzheimer′s disease (AD). A significant decrease in the amount of soluble tubulin was found in the postmortem brain of AD patients in comparison with the control group in the hippocampus, frontal cortex and substantia nigra, but not in the inferior olive. In vitro polymerization of tubulin and microtubules associated proteins from the brain of AD patients and electron micrographs of microtubules were obtained. The assembly of microtubules from brains of AD patients is disrupted, resulting in defective structures. On the other hand, the study of the influence of Al3+, Fe3+, Zn2+ on the microtubules from rat brains tubulin and microtubules associated proteins assembly and structure has shown that all studied metals are able to reduce the amount of microtubules and induce the assembly of anomal structures. According to the degree of the destructive effect on the microtubules and, accordingly, the possible significance in the pathogenesis of Alzheimer disease, metal ions can be arranged in the following sequence Al3+ > Zn2+ > Fe3+. Moreover, phosphorylation of tubulin and microtubules associated proteins in the presence of aluminum ions to the greatest extent reflects the phosphorylation of these proteins at AD. Comparison of data on the structure of microtubules after their assembly from brains of AD patients tubulin and microtubules associated proteins from brains of AD patients, and from the brain of rats, but in the presence of metal ions, confirm the conclusion about the possible role of the metals in the AD etiopathogenesis., Обобщены собственные результаты сравнительного исследования эффектов ионов железа, цинка и алюминия на структуру микротрубочек в процессе их сборки из тубулина и микротубуллоассоциированных белков мозга крысы с данными по изменению структуры микротрубочек в процессе их сборки из тубулина и белков, ассоциированных с микротрубочками (МАР от англ. microtubules associated proteins), мозга больных болезнью Альцгеймера (БА). В мозге больных БА выявлено значительное снижение количества растворимого тубулина, по сравнению с контрольной группой, в гиппокампе, лобной коре и чёрной субстанции, но не в нижней оливе. Отработаны условия, позволившие впервые провести in vitro полимеризацию тубулина и MAP мозга больных БА и получить электронные микрофотографии образовавшихся структур. Показано, что при БА нарушен процесс сборки микротрубочек, в результате чего образуются дефектные структуры. С другой стороны, исследование влияния ионов Al3+, Fe3+, Zn2+ на сборку и структуру микротрубочек из тубулина и MAP мозга крысы показало, что любой из исследованных нами металлов способен снижать количество микротрубочек и вызывать образование аномальных структур. По степени деформирующего воздействия на микротубулярную систему клеток мозга и, соответственно, возможной значимости в патогенезе БА, ионы металлов можно расположить в следующей последовательности Al3+ > Zn2+ > Fe3+. Более того, спектр фосфорилирования тубулина и MAP в присутствии ионов алюминия в наибольшей степени отражает фосфорилирование этих белков при болезни Альцгеймера. Сопоставление данных о нарушениях структуры микротрубочек, наблюдаемых при их сборке из препаратов тубулина и MAP из мозга больных БА, и из мозга крыс, но в присутствии ионов металлов, подтверждают вывод о возможной роли металлов в этиопатогенезе болезни Альцгеймера.

Neuronal excitotoxicity which is induced by exposure to excessive extracellular glutamate is shown to be involved in neuronal cell death in acute brain injury and a number of neurological diseases. High concentration of glutamate induces calcium deregulation which results in mitochondrial calcium overload and mitochondrial depolarization that triggers the mechanism of cell death. Inhibition of mitochondrial calcium uptake could be potentially neuroprotective but complete inhibition of mitochondrial calcium uniporter could result in the loss of some physiological processes linked to Ca2+ in mitochondria. Here, we found that a novel compound, TG-2112x, can inhibit only the lower concentrations mitochondrial calcium uptake (induced by 100 nM-5 μM) but not the uptake induced by higher concentrations of calcium (10 μM and higher). This effect was not associated with changes in mitochondrial membrane potential and cellular respiration. However, a pre-treatment of neurons with TG-2112x protected the neurons against calcium overload upon application of toxic concentrations of glutamate. Thus, sequestration of mitochondrial calcium uptake protected the neurons against glutamate-induced mitochondrial depolarization and cell death. In our hands, TG-2112x was also protective against ionomycin-induced cell death. Hence, low rate mitochondrial calcium uptake plays an underestimated role in mitochondrial function, and its inhibition could protect neurons against calcium overload and cell death in glutamate excitotoxicity.

Antioxidant activity of a pharmaceutical substance hypocard was compared with activity of nitromalic acid and well-known agents nicorandil and Mexidol. The ability of these substances to inhibit spontaneous and oxidant-induced LPO process in rat brain homogenate was analyzed. The mechanisms of these effects were studied. The antioxidant properties of hypocard manifested in the inhibition of Fe(II)-induced LPO were significantly more pronounced in comparison with Mexidol and nicorandil.

Oxidative stress and mitochondrial disturbances are the common and important causative factors of aging, and play an important role in the late onset of sporadic neurodegenerative diseases, including Alzheimer disease (AD). Furthermore, emerging evidence from in vitro and in vivo disease models suggests that oxidative stress and increased vulnerability to induction of mitochondrial permeability transition leads to the pathogenesis of the neurological disorders. Towards the goals of developing effective neuroprotectors, this article describes the synthesis and neuroprotective studies of various derivatives of the naturally occurring alkaloid securinine, based on which a lead compound, allomargaritarine (a diastereomer of margaritarine), was identified as an effective therapeutic for neuroprotection. Allomargaritarine exhibits high antioxidant activity, and has significant mitoprotective effect on cellular models of neurodegeneration.

The unique physicochemical properties of silver nanoparticles explain their extensive application in consumer goods, food, and medicinal products. However, the biological effects of nanosilver after peroral exposure of mammals are still debatable. This study describes the biodistribution and biological action of 12nm non-coated silver nanoparticles intragastrically administered to male rats after acute (single exposure) and sub-acute (multiple exposures over 30 days) toxicity experiments. The daily doses were 2000 and 250mg/kg of body weight for single and multiple administrations, respectively. Silver tissue detection was conducted by elemental analysis with the help of atomic absorption spectroscopy. An estimation of the state of exposed animals was made and the dynamics of hematological and biochemical parameters of rats was studied. It was demonstrated that single and multiple administrations resulted in silver accumulation in the liver, kidneys, spleen, stomach, and small intestine. After both one- and repeated-dose exposures, the highest Ag contents were detected in the liver (0.87±0.37μg/g of organ) and kidneys (0.24±0.02μg/g of organ). The concentrations of silver detected in tissues were far smaller than the administered doses (

Dimebon (latrepirdine) is an anti-histaminergic agent which belongs to a fast-growing group of "old" medicines suggested to be of therapeutic utility for pathological conditions different from their original design ("repositioning"). Here, we overview the most recent studies on Dimebon directed to pathological processes in the brain-involving in vivo models of proteinopathies. In the latter, neurodegenerative effects are attributed to a group of aggregate-prone proteins such as γ-synuclein, hyperphosphorylated tau, and fused in sarcoma (FUS), which are engaged in numerous neurological diseases. We also focus on in vitro models comprised of cultured SH-SY5Y neuroblastoma cells expressing mutant forms of transactive response DNA binding protein 43 kDa (TDP-43) and showing a reduced number of TDP-43 inclusion-containing cells upon Dimebon treatment along with activation of autophagy markers. Finally, we discuss Dimebon's action in improving cellular energy balance, stabilizing mitochondrial function by increasing the threshold for nonselective mitochondrial pore opening, as well as increasing the calcium retention capacity of mitochondria and reducing lipid peroxidation. Our results, together with data from other laboratories, warrant re-evaluation of the therapeutic potential of Dimebon and its newly designed analogs as promising disease-modifying agents to treat neurodegenerative disorders. Further, emerging data favor a possible anti-aging effect and application of Dimebon for the treatment of depression, anxiety, and ischemia. The most pronounced effect of Dimebon is observed when treatment starts early in disease onset. This is a major factor which needs to be taken into account when planning future clinical trials.

A series of cytotoxic organotin compounds with Sn–S bonds of formulae Me2Sn(SR)2 (1); Et2Sn(SR)2 (2); (n-Bu)2Sn(SR)2 (3); Ph2Sn(SR)2 (4); R2Sn(SR)2 (5); Me3SnSR (6) Ph3SnSR (7) (R = 3,5-di-tert-butyl-4-hydroxyphenyl), synthesized recently, have been used to study the possible mechanisms of their cytotoxicity. With this aim we have investigated the influence of organotin compounds 1–7 as well as their precursor R2SnCl2 (8) on tubulin assembly in microtubules. Compounds 1, 6–8 reveal the statistically significant inhibition of tubulin polymerization without notable disturbances of microtubules structure. Docking simulations revealed the possibility of organotin compounds to bind in the paclitaxel or vinblastine sites on the tubulin surface, but the mechanism of action of the compounds could not be explained based solely on these data. The influence on mitochondrial potential and induction of mitochondrial permeability transition also have been studied. Organotin compound 7 depolarises the mitochondria and induces the mitochondrial permeability transition. These properties may be the main reason of its cytotoxicity. Since the organotins possess the protective 2,6-di-tert-butylphenol groups the antioxidant potential of these compounds as inhibitors of mitochondrial lipid peroxidation was studied. All compounds under investigation effectively inhibit the Fe3+-induced mitochondrial lipid peroxidation. The comparative study of structure-activity relationship in the lipid peroxidation inhibition was performed. The influence of the organic groups nature, the number of hindered phenol fragments in organotins on their toxic effect is discussed. The introduction of hindered phenol groups decreases the cytotoxicity of compounds. This result opens up the possibility of designing novel anticancer drugs that might possess lower undesirable toxicity against normal cells.

Since 1983, Dimebon (Dimebolin) is used clinically in Russia as an antihistamine drug. Recent interest in Dimebolin is associated with its therapeutic effect in patients with Alzheimer’s disease. Animal studies have shown that Dimebon activity is realized via multiple mechanisms. Our experiments performed on the fibroblast cell culture L929 and C57Bl mice have been shown that Dimebon may block cytotoxic signals induced by the proinflammatory cytokines, tumor necrosis factor α (TNFα). Dimebon (10 μg/mL) protected mouse fibroblast cells L929 against toxic action of TNFα. Pretreatment of mice with Dimebon prevented development of changes in molecular species of sphingomyelins and galactosylceramides induced by a single dose administration of TNAα. Dimebon itself did not induce changes in sphingolipids of the investigated brain structures.

Background: A considerable amount of data suggests the age-related impairments of mitochondrial functions in the development of sporadic forms of neurodegenerative pathologies. Mitochondria and the phenomenon of mitochondrial permeability transition (MPT), which marks the point of no return in cell death cascades, have special value in this regard. It is important that the vulnerability to MPT-inducing factors is increased with aging. Simultaneously the a decrease in the calcium retention capacity of mitochondria are developed, which leads to the disturbance of the functional activity of neurons. Methods: The systematic own investigations and web content related to importance of MPT as the target for the search of neuroprotective and cognitive enhancing drugs, especially with multitargeted action, are reviewed. Results: Here, we have highlighted some experimental data that determines the importance of mitochondria for the search of neuroprotective drugs, and drugs with multitargeted action. We have also discussed a number of new compounds with similar properties. Being MPT inhibitors/modulators, virtually all the compounds described in this review have the ability to exhibit a neuroprotective effect, interact with some other targets, providing coupled beneficial therapeutic effects such as cognitive stimulation, anti-seizure, and antidepressant actions. Conclusion: Inhibitors of mitochondrial permeability transition, which increases calcium retention capacity of mitochondria, are considered as promising neuroprotective drugs able not only to halt the neurodegenerative cascade, but also to increase the functional activity of neurons.

Thiamine is essential for normal brain function and its deficiency causes metabolic impairment, specific lesions, oxidative damage and reduced adult hippocampal neurogenesis (AHN). Thiamine precursors with increased bioavailability, especially benfotiamine, exert neuroprotective effects not only for thiamine deficiency (TD), but also in mouse models of neurodegeneration. As it is known that AHN is impaired by stress in rodents, we exposed C57BL6/J mice to predator stress for 5 consecutive nights and studied the proliferation (number of Ki67-positive cells) and survival (number of BrdU-positive cells) of newborn immature neurons in the subgranular zone of the dentate gyrus. In stressed mice, the number of Ki67- and BrdU-positive cells was reduced compared to non stressed animals. This reduction was prevented when the mice were treated (200 mg/kg/day in drinking water for 20 days) with thiamine or benfotiamine, that were recently found to prevent stress-induced behavioral changes and glycogen synthase kinase-3 beta (GSK-3 beta) upregulation in the CNS. Moreover, we show that thiamine and benfotiamine counteract stress-induced bodyweight loss and suppress stress-induced anxiety-like behavior. Both treatments induced a modest increase in the brain content of free thiamine while the level of thiamine di-phosphate (ThDP) remained unchanged, suggesting that the beneficial effects observed are not linked to the role of this coenzyme in energy metabolism. Predator stress increased hippocampal protein carbonylation, an indicator of oxidative stress. This effect was antagonized by both thiamine and benfotiamine. Moreover, using cultured mouse neuroblastoma cells, we show that in particular benfotiamine protects against paraquat-induced oxidative stress. We therefore hypothesize that thiamine compounds may act by boosting anti-oxidant cellular defenses, by a mechanism that still remains to be unveiled. Our study demonstrates, for the first time, that thiamine and benfotiamine prevent stress-induced inhibition of hippocampal neurogenesis and accompanying physiological changes. The present data suggest that thiamine precursors with high bioavailability might be useful as a complementary therapy in several neuropsychiatric disorders. (C) 2017 Elsevier Inc. All rights reserved.

A new group of compounds, promising for the design of original multitarget therapeutic agents for treating neurodegenerative diseases, based on conjugates of aminoadamantane and carbazole derivatives was synthesized and investigated. Compounds of these series were found to interact with a group of targets that play an important role in the development of this type of diseases. First of all, these compounds selectively inhibit butyrylcholinesterase, block NMDA receptors containing NR2B subunits while maintaining the properties of MK-801 binding site blockers, exert microtubules stabilizing properties, and possess the ability to protect nerve cells from death at the calcium overload conditions. The leading compound C-2h has been shown the most promising effects on all analyzed parameters. Thus, these compounds can be regarded as promising candidates for the design of multi-target disease-modifying drugs for treatment of AD and/or similar neuropathologies.

Dimebon (Dimebolin) is an antihistamine drug which has been used in Russia since 1983. Recently Dimebolin has attracted renewed interest after being shown to have positive effects on persons suffering from Alzheimer's disease. Animal studies have shown that dimebon acts through multiple mechanisms, both blocking the action of neurotoxic beta-amyloid peptides and inhibiting L-type calcium channels, modulating the action of AMPA and NMDA glutamate receptors. Our experiments with cell culture L929 and mice have shown that dimebon may exert its neuroprotective effect by blocking cytotoxic signals induced by proinflammatory cytokines such as TNF-a which are believed to play a central role in Alzheimer's disease. Dimebon (10 mg/ml) protected mouse fibroblasts L929 against the toxic action of TNF-a. Our study included 65 male mice. TNF-a (10 mg per mouse), dimebon (0,2 mg/kg) and their combination were injected intraperitonealy. Changes in the level of molecular species of sphingomyelin and galactosyl ceramide in hippocampus, cerebellum and cerebral cortex within 30 min, 2 h, 4 h, and 24 h after injection were detected by chromato-mass-spectrometry. Maximal changes in sphingomyelin and galactosyl ceramides contents of different molecular species after single TNF-a administration were found in the hippocampus, and were less expressed in the cerebral cortex and cerebellum after 24 h. Dimebon itself did not induce changes in the sphingolipid spectrum in brain sections, but protected them against disorders induced by TNF-a in the brain. Modern strategies in the search of new therapeutic approaches are based on the multitarget properties of new drugs. According to our results TNF-a may serve as a new target for dimebon.Dimebon, nachinaia s 1983 g., ispol'zuetsia v Rossii v kachestve antigistaminnogo sredstva. Povtornoe vozniknovenie interesa k dimebonu obuslovleno obnaruzheniem ego lechebnogo éffekta pri bolezni Al'tsgeĭmera. Issledovaniia, provedennye na zhivotnykh, pokazali, chto aktivnost' dimebona opredeliaetsia mnozhestvom mekhanizmov. Na kletochnoĭ linii L929 fibroblastov myshi i myshakh S57Bl nami pokazano, chto dimebon sposoben blokirovat' toksicheskie signaly, indutsirovannye provospalitel'nym tsitokinom – faktorom nekroza opukholeĭ-al'fa (FNO-a). V doze 10 mkg/ml dimebon zashchishchaet kletki L929 ot toksicheskogo deĭstviia FNO-a. Predvaritel'noe vvedenie dimebona mysham preduprezhdalo izmeneniia molekuliarnykh vidov sfingomielinov (SM) i galaktoziltseramidov, vyzvannye odnokratnoĭ in"ektsieĭ FNO-a. Pri étom sam dimebon ne vyzyval izmeneniĭ v sfingolipidakh issledovannykh struktur mozga.

Background: Oxidative stress and amyloid deposition are tightly interconnected pathological features of Alzheimer disease. In this respect, both amyloid production and aggregation may be stimulated by oxidative stress and also the increase of pathogenic β-amyloid and its aggregated form lead to oxidative stress progression. Therefore, the search for potential drugs with both antioxidant and antiaggregation properties are of great interest. Methods: In this study, we described the stereospecific synthesis of alkaloid securinine aminoderivatives. Results: We showed that the newly synthesized compounds possess antioxidant and metal-chelating properties. Indeed, we report that one compound has inhibitory effects towards μ-amyloid aggregation. Conclusion: Based on these results, aminoderivatives of securinine scaffold are promising compounds for development of new drugs for the treatment of neurodegenerative diseases.

Dimebon (or Latrepirdine) was initially used as an anti-histamergic drug but later new therapeutic properties were rediscovered, adding to a growing body of “old” agents with prominent neuroprotective effects. In the present manuscript, we are focusing on our latest study on Dimebon with regard to brain’s pathological processes using in vivo proteinopathy models. In the study, neurodegenerative pathology has been attributed to a group of aggregate-prone proteins: hyperphosphorylated tau, fused in sarcoma and γ-synuclein , which are involved in a number of neurological disorders. We have also presented our in vitro model based on overexpression of an aberrant mutant form of transactive response DNA binding 43 kDa protein in cultured SH-SY5Y neuroblastoma cells. Dimebon treatment followed by the activation of autophagy markers resulted in reduced number of inclusion containing cells. The most significant effects of Dimebon appeared to be on the improving cellular energy balance, mitochondria stability by increasing the threshold for nonselective mitochondrial pore opening as well as on increased calcium retention capacity while reducing lipid peroxidation. The therapeutic potential of Dimebon and newly designed analogs show disease modifying properties and could be used to treat neurodegenerative disorders. In addition, new data hint on a possible anti-aging effect and potential application of Dimebon for treatment of anxiety, ischemia and depression. Overall, our findings suggest that the most pronounced effect of Dimebon was observed when treatment was started at the early stages of disease onset and this factor needs to be taken into account while planning future clinical trials.