In silico Study of Acetylcholinesterase and Beta-secretase Inhibitors: Potential Multitarget Anti-Alzheimer's Agents.

BACKGROUND: Alzheimer's disease is a progressive neurodegenerative process with multifactorial characteristics. This disease follows the natural aging process, affecting mainly people over 65 years. Pharmacotherapeutic treatment currently combats symptoms related to cognitive function. Several targets have begun to attract the interest of the scientific community to develop new drug candidates which have better pharmacokinetic and lower toxicity parameters. OBJECTIVE: The present study aims to design new candidates for acetylcholinesterase/ß-secretase (AChE/BACE1) multitarget inhibitor drugs. METHODS: 17 natural products were selected from the literature with anticholinesterase activity and 1 synthetic molecule with inhibitory activity for BACE1. Subsequently, the molecular docking study was performed, followed by the derivation of the pharmacophoric pattern and prediction of pharmacokinetic and toxicological properties. Finally, the hybrid prototype was designed. RESULTS: All selected molecules showed interactions with their respective target enzymes. Derivation of the pharmacophoric pattern from molecules that interacted with the AChE enzyme resulted in 3 pharmacophoric regions: an aromatic ring, an electron-acceptor region and a hydrophobic region. The molecules showed good pharmacokinetic and toxicological results, showing no warnings of mutagenicity and/or carcinogenicity. After the hybridization process, three hybrid molecules were obtained, which showed inhibitory activity for both targets. CONCLUSION: It is concluded that research in the field of medicinal chemistry is advancing towards the discovery of new drug candidates that bring a better quality of life to patients with AD.

Design of Multitarget Natural Products Analogs with Potential Anti-Alzheimer's Activity.

BACKGROUND: Alzheimer's disease (AD) is a neurodegenerative condition and the most common type of dementia among the elderly. The enzymes acetylcholinesterase (AChE) and nitric oxide synthase (NOS) have a pivotal role in the pathophysiology of this disease. OBJECTIVE: This study aimed to select medicinal plant-derived molecules with reported inhibition of AChE and design optimized molecules that could inhibit not only AChE, but also NOS, potentially increasing its efficacy against AD. METHODS: 24 compounds were selected from the literature based on their known AChE inhibitory activity. Then, we performed molecular orbital calculations, maps of electrostatic potential, molecular docking study, identification of the pharmacophoric pattern, evaluation of pharmacokinetic and toxicological properties of these molecules. Next, ten analogs were generated for each molecule to optimize their effect where the best molecules of natural products had failed. RESULTS: The most relevant correlation was between HOMO and GAP in the correlation matrix of the molecules' descriptors. The pharmacophoric group's derivation found the following pharmacophoric features: two hydrogen bond acceptors and one aromatic ring. The studied molecules interacted with the active site of AChE through hydrophobic and hydrogen bonds and with NOS through hydrogen interactions only but in a meaningful manner. In the pharmacokinetic and toxicological prediction, the compounds showed satisfactory results. CONCLUSION: The design of natural products analogs demonstrated good affinities with the pharmacological targets AChE and NOS, with satisfactory pharmacokinetics and toxicology profiles. Thus, the results could identify promising molecules for treating Alzheimer's disease.

Potential colchicine binding site inhibitors unraveled by virtual screening, molecular dynamics and MM/PBSA.

Microtubules have been widely studied in recent decades as an important pharmacological target for the treatment of cancer especially due to its key role in the mitosis process. Among the constituents of the microtubules, αß-tubulin dimers stand out in view of their four distinct interaction sites, including the so-called colchicine binding site (CBS) - a promising target for the development of new tubulin modulators. When compared to other tubulin sites, targeting the CBS is advantageous because this site is able to host ligands with lower molecular volume and lipophilicity, thus reducing the chances of entailing the phenomenon of multiple drug resistance (MDR) - one of the main reasons of failure in chemotherapy. However, colchicine, the first ligand ever discovered with affinity towards the CBS, despite modulating the action of microtubules, has shown toxicity in clinical studies. Therefore, in order to expand the known chemical space of scaffolds capable of interacting with CBS and to design non-toxic colchicine binding site inhibitors, we conducted a robust virtual screening pipeline. This has been rigorously validated and consisted of ligand- and structure-based methodologies, which allowed us to select four promising CBS inhibitors called tubLCQF1-4. These four compounds were also evaluated with long trajectories molecular dynamics simulations and respective results were used for the theoretical determination of the free energy released in the formation of the complexes, using the Molecular Mechanics Poisson-Boltzmann Surface Area (MM/PBSA) methodology.

Molecular Docking, Physicochemical Properties, Pharmacokinetics and Toxicity of Flavonoids Present in Euterpe oleracea Martius.

BACKGROUND: Euterpe oleracea Martius, popularly known as açaí, is a fruit rich in α- tocopherols, fibers, lipids, mineral ions, and polyphenols. It is believed that the high content of polyphenols, especially flavonoids, provides several health-promoting effects to the açaí fruit, including anti-inflammatory, immunomodulatory, antinociceptive and antioxidant properties. Most of the flavonoids are antioxidant molecules of plant origin that act as a trap for free radicals, reacting and neutralizing them, thus offering perspectives in preventing oxidative damage. OBJECTIVE: In this study, we aim to perform an in silico evaluation of flavonoids present in the pulp and the oil of Euterpe oleracea Martius, evaluating their potential to serve as antioxidant agents. METHODS: Firstly, we selected 16 flavonoids present in Euterpe oleracea Martius pulp and oil, and then their physicochemical properties were analyzed concerning the Lipinski's Rule of Five. Moreover, we evaluated their pharmacokinetic properties using the QikProp module of the Schrödinger software as well as their toxicity profile, using the DEREK software. Docking simulations, using the GOLD 4.1 software, as well as pharmacophoric hypotheses calculation of molecules were also performed. RESULTS: Flavonoids present in the açaí pulp including catechin, epicatechin, luteolin, chrisoeriol, taxifolin, apigenin, dihydrokaempferol, isovitexin, and vitexin presented good oral bioavailability. Regarding the pharmacokinetic properties, the compounds catechin, epicatechin, isovitexin, luteolin, chrisoeriol, taxifolin, and isorhamnetin rutinoside presented the best results, besides high human oral absorption. Regarding the prediction of toxicological properties, compounds isorhamnetin rutinoside and rutin presented mutagenicity for hydroxynaphthalene or derivate, and regarding the docking simulations, all the compounds investigated in this study presented key interactions with the corresponding targets. CONCLUSION: The flavonoids catechin, chrysoeriol, and taxifolin presented the best results according to the evaluation conducted in this study. These computational results can be used as a theoretical basis for future studies concerning the development of drug candidates, as well as to enlighten biological tests in vitro and in vivo, which can contribute to the treatment of neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, and Huntington's disease.

Identification of novel αß-tubulin modulators with antiproliferative activity directed to cancer therapy using ligand and structure-based virtual screening.

Among several strategies related to cancer therapy targeting the modulation of αß-tubulin has shown encouraging findings, more specifically when this is achieved by inhibitors located at the colchicine binding site. In this work, we aim to fish new αß-tubulin modulators through a diverse and rational VS study, and thus, exhibiting the development of two VS pipelines. This allowed us to identify two compounds 5 and 9 that showed IC50 values of 19.69 and 21.97 µM, respectively, towards possible modulation of αß-tubulin, such as assessed by in vitro assays in C6 glioma and HEPG2 cell lines. We also evaluated possible mechanisms of action of obtained hits towards the colchicine binding site of αß-tubulin by using docking approaches. In addition, assessment of the stability of the active (5 and 9) and inactive compounds (3 and 13) within the colchicine binding site was carried out by molecular dynamics (MD) simulations, highlighting the solvent effect and revealing the compound 5 as the most stable in the complex. At last, deep analysis of these results provided some valuable insights on the importance of using mixed ligand- and structure-based strategies in VS campaigns, in order to achieve higher chemical diversity and biological effect as well.

Antioxidant Effect of Flavonoids Present in Euterpe oleracea Martius and Neurodegenerative Diseases: A Literature Review.

INTRODUCTION: Neurodegenerative diseases (NDDs) are progressive, directly affecting the central nervous system (CNS), the most common and recurrent are Alzheimer's disease (AD) and Parkinson's disease (PD). One factor frequently mentioned in the etiology of NDDs is the generation of free radicals and oxidative stress, producing cellular damages. Studies have shown that the consumption of foods rich in polyphenols, especially those of the flavonoid class, has been related to the low risk in the development of several diseases. Due to the antioxidant properties present in the food, a fruit that has been gaining prominence among these foods is the Euterpe oleracea Mart. (açaí), because it presents in its composition significant amounts of a subclass of the flavonoids, the anthocyanins. METHODS: In the case review, the authors receive a basic background on the most common NDDs, oxidative stress and antioxidants. In addition, revisiting the various studies related to NDDs, including flavonoids and consumption of açaí. RESULTS: Detailed analysis of the recently reported case studies reveal that dietary consumption of flavonoid-rich foods, such as açaí fruits, suggests the efficacy to attenuate neurodegeneration and prevent or reverse the age-dependent deterioration of cognitive function. CONCLUSION: This systematic review points out that flavonoids presenting in açaí have the potential for the treatment of diseases such as PD and AD and are candidates for drugs in future clinical research. However, there is a need for in vitro and in vivo studies with polyphenol that prove and ratify the therapeutic potential of this fruit for several NDDs.

Alzheimer's Disease: A Review from the Pathophysiology to Diagnosis, New Perspectives for Pharmacological Treatment.

Dementia is characterized by the impairment of cognition and behavior of people over 65 years. Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder in the world, as approximately 47 million people are affected by this disease and the tendency is that this number will increase to 62% by 2030. Two microscopic features assist in the characterization of the disease, the amyloid plaques and neurofibrillary agglomerates. All these factors are responsible for the slow and gradual deterioration of memory that affect language, personality or cognitive control. For the AD diagnosis, neuropsychological tests are performed in different spheres of cognitive functions but since not all cognitive functions may be affected, cerebrospinal fluid biomarkers are used along with these tests. To date, cholinesterase inhibitors are used as treatment, they are the only drugs that have shown significant improvements in the cognitive functions of AD patients. Despite the proven effectiveness of cholinesterase inhibitors, an AD carrier, even while being treated, is continually subjected to progressive degeneration of the neuronal tissue. For this reason, other biochemical pathways associated with the pathophysiology of AD have been explored as alternatives to the treatment of this condition such as inhibition of ß-secretase and glycogen synthase kinase-3ß. The present study aims to conduct a review of the epidemiology, pathophysiology, symptoms, diagnosis and treatment of Alzheimer's disease, emphasizing the research and development of new therapeutic approaches.

Discovery of novel dual acetylcholinesterase inhibitors with antifibrillogenic activity related to Alzheimer's disease.

AIM: Alzheimer's disease is a progressive and neurodegenerative disorder of the CNS, affecting elderly people. The current pharmacological approach is based on the improvement of cholinergic neurotransmission by inhibiting acetylcholinesterase (AChE) with AChE inhibitors. The disease is also characterized by the accelerated accumulation of ß-amyloid plaques around neurons. Furthermore, in vitro studies revealed that AChE can induce ß-amyloid peptide (Aß) aggregation. METHODOLOGY: Computer-aided molecular design by virtual screening was here employed to discover novel potential AChE inhibitors, with antifibrillogenic properties, in other words, inhibiting Aß aggregation. RESULTS: Compounds 1, 4 and 6 showed interesting AChE inhibition. In addition, they particularly inhibit Aß aggregation in vitro, indicating to be promising novel anti-Alzheimer agents.

Virtual Screening and Statistical Analysis in the Design of New Caffeine Analogues Molecules with Potential Epithelial Anticancer Activity.

About 132 thousand cases of melanoma (more severe type of skin cancer) were registered in 2014 according to the World Health Organization. This type of cancer significantly affects the quality of life of individuals. Caffeine has shown potential inhibitory effect against epithelial cancer. In this study, it was proposed to obtain new caffeine-based molecules with potential epithelial anticancer activity. For this, a training set of 21 molecules was used for pharmacophore perception procedures. Multiple linear regression analyses were used to propose mono-, bi-, tri-, and tetra-parametric models applied in the prediction of the activity. The generated pharmacophore was used to select 350 molecules available at the ZINCpharmer server, followed by reduction to 24 molecules, after selection using the Tanimoto index, yielding 10 molecules after final selection by predicted activity values > 1.5229. These ten molecules had better pharmacokinetic properties than the other ones used as reference and within the clinically significant limits. Only two molecules show minor hits of toxicity and were submitted to molecular docking procedures, showing BFE (binding free energy) values lower than the reference values. Statistical analyses indicated strong negative correlations between BFE and pharmacophoric properties (high influence on BFE lowering) and practically null correlation between BFE and BBB. The two most promising molecules can be indicated as candidates for further in vitro and in vivo analyzes.

Structure- and ligand-based drug design of novel p38-alpha MAPK inhibitors in the fight against the Alzheimer's disease.

Alzheimer's disease (AD) is characterized microscopically by the presence of amyloid plaques, which are accumulations of beta-amyloid protein inter-neurons, and neurofibrillary tangles formed predominantly by highly phosphorylated forms of the microtubule-associated protein, tau, which form tangled masses that consume neuronal cell body, possibly leading to neuronal dysfunction and ultimately death. p38α mitogen-activated protein kinase (MAPK) has been implicated in both events associated with AD, tau phosphorylation and inflammation. p38α MAPK pathway is activated by a dual phosphorylation at Thr180 and Tyr182 residues. Drug design of p38α MAPK inhibitors is mainly focused on small molecules that compete for Adenosine triphosphate in the catalytic site. Here, we used different approaches of structure- and ligand-based drug design and medicinal chemistry strategies based on a selected p38α MAPK structure deposited in the Protein Data Bank in complex with inhibitor, as well as others reported in literature. As a result of the virtual screening experiments performed here, as well as molecular dynamics, molecular interaction fields studies, shape and electrostatic similarities, activity and toxicity predictions, and pharmacokinetic and physicochemical properties, we have selected 13 compounds that meet the criteria of low or no toxicity potential, good pharmacotherapeutic profile, predicted activities, and calculated values ​​comparable with those obtained for the reference compounds, while maintaining the main interactions observed for the most potent inhibitors.

Novel aryl ß-aminocarbonyl derivatives as inhibitors of Trypanosoma cruzi trypanothione reductase: binding mode revised by docking and GRIND2-based 3D-QSAR procedures.

Trypanothione reductase has long been investigated as a promising target for chemotherapeutic intervention in Chagas disease, since it is an enzyme of a unique metabolic pathway that is exclusively present in the pathogen but not in the human host, which has the analog Glutathione reductase. In spite of the present data-set includes a small number of compounds, a combined use of flexible docking, pharmacophore perception, ligand binding site prediction, and Grid-Independent Descriptors GRIND2-based 3D-Quantitative Structure-Activity Relationships (QSAR) procedures allowed us to rationalize the different biological activities of a series of 11 aryl ß-aminocarbonyl derivatives, which are inhibitors of Trypanosoma cruzi trypanothione reductase (TcTR). Three QSAR models were built and validated using different alignments, which are based on docking with the TcTR crystal structure, pharmacophore, and molecular interaction fields. The high statistical significance of the models thus obtained assures the robustness of this second generation of GRIND descriptors here used, which were able to detect the most important residues of such enzyme for binding the aryl ß-aminocarbonyl derivatives, besides to rationalize distances among them. Finally, a revised binding mode has been proposed for our inhibitors and independently supported by the different methodologies here used, allowing further optimization of the lead compounds with such combined structure- and ligand-based approaches in the fight against the Chagas disease.

Cubebin and derivatives as inhibitors of mitochondrial complex I. Proposed interaction with subunit B8.

The effects on mitochondrial respiration and complex I NADH oxidase activity of cubebin and derivatives were evaluated. The compounds inhibited the state 3 glutamate/malate-supported respiration of hamster liver mitochondria with IC(50) values ranging from 12.16 to 83.96 microM. NADH oxidase reaction was evaluated in submitochondrial particles. The compounds also inhibited this activity, showing the same order of potency observed for effects on state 3 respiration, as well as a tendency towards a non-competitive type of inhibition (K(I) values ranging from 0.62 to 16.1 microM). A potential binding mode of these compounds with complex I subunit B8, assessed by docking calculations, is proposed.

A molecular modeling and QSAR study of suppressors of the growth of Trypanosoma cruzi epimastigotes.

In this work, we have used molecular modeling and QSAR tools to study 18 dithiocarbamate suppressors of the growth of Trypanosoma cruzi epimastigotes, which have been reported in the literature as superoxide dismutase (SOD) inhibitors. The principal component analysis (PCA) showed that the descriptors superficial area, heat of formation, logarithm of the partition coefficient, charge of the nitrogen atom from the dithiocarbamate group and Charges of the two carbon atoms adjacent to that nitrogen are responsible for the classification between the higher and lower trypanomicid activity. Using multiple linear regression (MLR) and docking methods it was possible to identify the probable bioactive isomers that suppress of the growth of T. cruzi epimastigotes. Our best partial least square (PLS) model obtained with these six descriptors yields a good correlation between experimental and predicted biological activities and compares two different SODs as possible target for interaction with the dithiocarbamates.