Secondary Metabolites with Antioxidant Activities for the Putative Treatment of Amyotrophic Lateral Sclerosis (ALS): "Experimental Evidences".

Amyotrophic lateral sclerosis (ALS) is a fatal motor neuron disorder that is characterized by progressive loss of the upper and lower motor neurons at the spinal or bulbar level. Oxidative stress (OS) associated with mitochondrial dysfunction and the deterioration of the electron transport chain are factors that contribute to neurodegeneration and perform a potential role in the pathogenesis of ALS. Natural antioxidant molecules have been proposed as an alternative form of treatment for the prevention of age-related neurological diseases, in which ALS is included. Researches support that regulations in cellular reduction/oxidation (redox) processes are being increasingly implicated in this disease, and antioxidant drugs are aimed at a promising pathway to treatment. Among the strategies used for obtaining new drugs, we can highlight the isolation of secondary metabolite compounds from natural sources that, along with semisynthetic derivatives, correspond to approximately 40% of the drugs found on the market. Among these compounds, we emphasize oxygenated and nitrogenous compounds, such as flavonoids, coumarins, and alkaloids, in addition to the fatty acids, that already stand out in the literature for their antioxidant properties, consisting in a part of the diets of millions of people worldwide. Therefore, this review is aimed at presenting and summarizing the main articles published within the last years, which represent the therapeutic potential of antioxidant compounds of natural origin for the treatment of ALS.

Synthesis and Evaluation of 2-Aminothiophene Derivatives as Staphylococcus aureus Efflux Pump Inhibitors.

2-aminothiophene derivatives (2AT) in which the thiophene ring is fused with a cycloalkyl or a N-acylated piperidine ring by positions 5 and 6 and carrying a 3-carbethoxy group were synthesized and their bacterial growth and enzyme inhibitory effects against efflux proteins of Staphylococcus aureus leading to resistance to fluoroquinolones and erythromycin (ERY) were investigated. Compounds that most effectively decreases the minimum inhibitory concentrations (MICs) of ciprofloxacin (CIP) were assayed for their dose and time effects on the accumulation and efflux of ethidium bromide (EtBr) in the SA-1 strain. None of the compounds displayed antibacterial activity however, three derivatives carrying 2-amino, 2-aminoacetyl and 2-aminotrifluoroacetyl group enhanced the activity of CIP and ERY by 8- and 16-fold, respectively, and were able to restore the sensitivity of resistant strains, acting as typical efflux pump inhibitors (EPIs). The 2-aminoacetyl and 2-aminotrifluoroacetyl derivatives and two other piperidinyl 2-aminotrifluoroacetyl derivatives increased EtBr accumulation in a dose- and time-dependent manner, and one of them was also able to inhibit the EtBr efflux. Taken together, these results represent an important advance in the development of new EPIs, and demonstrate that 2AT represent a good scaffold for developing new antibiotic adjuvants.

1-Hy-droxy-3,4-dimeth-oxy-10-methyl-acridin-9-one.

There are two independent mol-ecules in the asymmetric unit of the title compound, C16H15NO4, which was isolated from fruits of Zanthoxylum leprieurii. The atoms of the three rings of each mol-ecule are close to coplanar with the largest deviations from the least-squares planes being 0.084 (3) Šand 0.069 (2) Å. Each molecule features an intramolecular O-H⋯·O hydrogen bond. In the crystal, C-H⋯·O hydrogen-bonding inter-actions link the mol-ecules into a three-dimensional network.

An electrochemical biosensor based on Hairpin-DNA modified gold electrode for detection of DNA damage by a hybrid cancer drug intercalation.

An efficient and new electrochemical biosensor for detection of DNA damage, induced by the interaction of the hybrid anti-cancer compound (7ESTAC01) with DNA, was studied by differential pulse voltammetry (DPV). The biosensor consists of a Stem-Loop DNA (SL-DNA) probe covalently attached to the gold electrode (GE) surface that hybridizes to a complementary DNA strand (cDNA) to form a double-stranded DNA (dsDNA). The interaction and DNA damage induced by 7ESTAC01 was electrochemically studied based on the oxidation signals of the electroactive nucleic acids on the surface of the GE by DPV. As a result, the SL-DNA/GE and dsDNA/GE were tested with the reduced 7ESTAC01, showing the voltammetric signal of guanine and adenine, increase in the presence of 7ESTAC01. Under optimum conditions, the dsDNA/GE biosensor exhibited excellent DPV response in the presence of 7ESTAC01. The bonding interaction between 7ESTAC01 and calf thymus DNA (ctDNA) was confirmed by UV-Vis absorption spectroscopy, dynamic simulations (performed to investigate the DNA structure under physiological conditions), and molecular docking. Theoretical results showed the presence of hydrogen bonding and intercalation in the minor groove of DNA, involving hydrophobic interactions.

Chemical analysis of Brasilimeria Stach, 1949 (Hexapoda, Collembola, Neanuridae) hemolymphatic secretion, and description of a new species.

Though Collembola is a widespread hexapod its use of chemical compounds for defense has been reported for only a few European species. Chemical composition analyses of the hemolymphatic secretion of Neotropical Collembola using Gas Chromatography with Mass Spectrometry (GC-MS) has been performed for the first time. The GC-MS analysis revealed 32 constituents, such as aliphatic and aromatic hydrocarbons, esters, alcohols, a phenol, an aldehyde and a ketone. Benzyl benzoate, the main component (at 46.98%), is a compound with known acaricide and insecticide properties. This is the first report on chemical constituents produced by Neotropical Pseudachorutinae, genus Brasilimeria, and will permit future secretion comparisons for Collembola. The taxonomic description of the species producing the secretion analyzed is provided; Brasilimeria assu sp. nov. (Collembola, Neanuridae, Pseudachorutinae) is the third known species of the genus; an updated diagnosis of the genus, an identification key, and further remarks on the species Brasilimeria Stach, 1949 are provided.

Correlation between DNA/HSA-interactions and antimalarial activity of acridine derivatives: Proposing a possible mechanism of action.

Acridines are considered an important class of compounds due to their wide variety of biological activities. In this work, we synthesized four acridine derivatives (1-4) and evaluated their biological activity against the Plasmodium falciparum W2 line, as well as studied the interaction with ctDNA and HSA using spectroscopic techniques and molecular docking. The acridine derivative 2 (IC50 = 0.90 ±â€¯0.08 µM) was more effective against P. falciparum than primaquine (IC50 = 1.70 ±â€¯0.10 µM) and similar to amsacrine (IC50 = 0.80 ±â€¯0.10 µM). In the fluorescence and UV-vis assays, it was verified that the acridine derivatives interact with ctDNA and HSA leading to a non-fluorescent supramolecular complex formation. The non-covalent binding constants ranged from 2.09 to 7.76 × 103 M-1, indicating moderate interaction with ctDNA. Through experiments with KI, fluorescence contact energy transfer and competition assays were possible to characterize the main non-covalent binding mode of the acridines evaluated with ctDNA as intercalation. The binding constants obtained showed a high linear correlation with the IC50 values against the antimalarial activity, suggesting that DNA may be the main biological target of these molecules. Finally, HSA interaction studies were performed and all evaluated compounds bind to the site II of the protein. The less active compounds (1 and 3) presented the highest affinity to HSA, indicating that the interaction with carrier protein can affect the (bio)availability of these compounds to the biological target.

Docking of Natural Products against Neurodegenerative Diseases: General Concepts.

BACKGROUND: Since antiquity, humanity has used medicinal plant preparations to cure its ills, and, as research has progressed, new technologies have enabled more investigations on natural compounds which originate from plants, fungi, and marine species. The health benefits that these natural products provide have become a motive for treatment studies of various diseases. OBJECTIVE: Among them, the neurodegenerative diseases like Alzheimer's and Parkinson's, a major age-related neurodegenerative disorder. Studies with natural products for neurodegenerative diseases (particularly through molecular docking) search for, and then focus on those ligands which offer effective inhibition of the enzymes monoamine oxidase and acetylcholinesterase. METHOD: This review introduces the main concepts involved in docking studies with natural products: and also in our group, which has conducted a docking study of natural products isolated from Tetrapterys mucronata for inhibition of acetylcholinesterase. RESULTS: We observed that compounds 4 and 5 formed more interactions than the theoretical ligand, but that ligands with greater activity also interacted with residues HIS 381 and GLN 527. CONCLUSION: We have reported on our docking study performed with AChE and alkaloids isolated from the plant Tetrapterys mucronata. Our docking results corroborate the experiments conducted, and emphasize the positive contribution that these theoretical studies involving natural products bring to the fight against neurodegenerative diseases.

A new coumarin derivative, 4-acetatecoumarin, with antifungal activity and association study against Aspergillus spp.

Fungal infections have become a concern for health professionals, and the emergence of resistant strains has been reported for all known classes of antifungal drugs. Among the fungi causing disease, we highlight those that belong to the genus Aspergillus. For these reasons, the search for new antifungals is important. This study examines the effects of a coumarin derivative, 4-acetatecoumarin (Cou-UMB16) both alone and together with antifungal drugs, and its mode of action against Aspergillus spp. Cou-UMB16 was tested to evaluate its effects on mycelia growth, and germination of Aspergillus spp. fungal conidia. We investigated its possible action on cell walls, on the cell membrane, and also the capacity of this coumarin derivative to enhance the activity of antifungal drugs. Our results suggest that Cou-UMB16 inhibits Aspergillus spp. virulence factors (mycelia growth and germination of conidia) and affects the structure of the fungal cell wall. When applying Cou-UMB16 in combination with azoles, both synergistic and additive effects were observed. This study concludes that Cou-UMB16 inhibits mycelial growth and spore germination, and that the activity is due to its action on the fungal cell wall, and that Cou-UMB16 could act as an antifungal modifier.

Dynamic Simulation, Docking and DFT Studies Applied to a Set of Anti-Acetylcholinesterase Inhibitors in the enzyme ß-Secretase (BACE-1): An Important Therapeutic Target in Alzheimer`s disease.

BACKGROUND: Alzheimer`s disease (AD) affects mainly elderly people over 60 years of age. Currently, there are more than 35 million people with this disease worldwide. The enzyme ß-secretase is involved in the processing of the amyloid precursor protein and plays a key role in the physiopathology of AD. The action of some acetylcholinesterase inhibitors (AChEI) as ß-secretase inhibitors has been reported. OBJECTIVE: The aim of this study was to highlight the modes of the binding of acetylcholinesterase ligands onto the active site of the ß-secretase enzyme. METHODS: Molecular dynamics and docking were used in order to identify pivotal interactions that favor the inhibitory activity and provide a rational basis for planning novel ß-secretase inhibitors. Additionally, density functional theory (DFT) was used to provide accurate energy values for the complexes. A mechanistic study of the amide hydrolysis was also performed at the M06/6-31G(d) basis set. RESULTS: Of the 100 AChE inhibitors, 10 were able to interact with Asp32 and/or Asp228 residues from the enzyme BACE-1, suggesting that these could act as multi-target compounds. These inhibitors were selected for DFT studies in order to provide more accurate energy values. Interestingly, the range of energy values (-27.01 to -8.64 kJ mol-1) obtained was in agreement with the anti-AChE activity. The results obtained in the mechanistic study of compound 93 using DFT are in agreement with theoretical studies described in the literature. CONCLUSION: The results reported in this study will advance our understanding of the influence of the distinct chemical structures of inhibitors at the active site and aid the development of new virtual screening protocols to design novel AChE multi-target inhibitors.

Docking Studies for Multi-Target Drugs.

The most basic principle of drug action is found in the lock and key model, where the highest possible affinity for a target that also avoids side effects is desired. For many years this was understood as being "one drug, for one target, for one disease", however researchers began to observe that certain diseases are best treated with multi-target drugs. In recent years, studies have sought out polypharmacological compounds acting on multiple targets against complex (multifactorial) diseases, such as cancer, neurodegenerative disease, and certain infections. One of the computational tools used in research for multifunctional drugs is Molecular Docking. Through this methodology of Computer-Aided Drug Design, we observe complexes formed between ligands and interesting targets (often many), for a particular disease. This review reports on docking studies as used in investigations of new multi-target compounds; it also shows the various ways that such studies are used in the search for multifunctional compounds.

Artificial Neural Network Methods Applied to Drug Discovery for Neglected Diseases.

Among the chemometric tools used in rational drug design, we find artificial neural network methods (ANNs), a statistical learning algorithm similar to the human brain, to be quite powerful. Some ANN applications use biological and molecular data of the training series that are inserted to ensure the machine learning, and to generate robust and predictive models. In drug discovery, researchers use this methodology, looking to find new chemotherapeutic agents for various diseases. The neglected diseases are a group of tropical parasitic diseases that primarily affect poor countries in Africa, Asia, and South America. Current drugs against these diseases cause side effects, are ineffective during the chronic stages of the disease, and are often not available to the needy population, have relative high toxicity, and face developing resistance. Faced with so many problems, new chemotherapeutic agents to treat these infections are much needed. The present review reports on neural network research, which studies new ligands against Chagas' disease, sleeping sickness, malaria, tuberculosis, and leishmaniasis; a few of the neglected diseases.

Evaluation of Antifungal Activity and Mode of Action of New Coumarin Derivative, 7-Hydroxy-6-nitro-2H-1-benzopyran-2-one, against Aspergillus spp.

Aspergillus spp. produce a wide variety of diseases. For the treatment of such infections, the azoles and Amphotericin B are used in various formulations. The treatment of fungal diseases is often ineffective, because of increases in azole resistance and their several associated adverse effects. To overcome these problems, natural products and their derivatives are interesting alternatives. The aim of this study was to examine the effects of coumarin derivative, 7-hydroxy-6-nitro-2H-1-benzopyran-2-one (Cou-NO2), both alone and with antifungal drugs. Its mode of action against Aspergillus spp. Cou-NO2 was tested to evaluate its effects on mycelia growth and germination of fungal conidia of Aspergillus spp. We also investigated possible Cou-NO2 action on cell walls (0.8 M sorbitol) and on Cou-NO2 to ergosterol binding in the cell membrane. The study shows that Cou-NO2 is capable of inhibiting both the mycelia growth and germination of conidia for the species tested, and that its action affects the structure of the fungal cell wall. At subinhibitory concentration, Cou-NO2 enhanced the in vitro effects of azoles. Moreover, in combination with azoles (voriconazole and itraconazole) Cou-NO2 displays an additive effect. Thus, our study supports the use of coumarin derivative 7-hydroxy-6-nitro-2H-1-benzopyran-2-one as an antifungal agent against Aspergillus species.

Evidence for the involvement of descending pain-inhibitory mechanisms in the attenuation of cancer pain by carvacrol aided through a docking study.

AIMS: The present study evaluated the carvacrol (CARV) effect on hyperalgesia and nociception induced by sarcoma 180 (S180) in mice. MAIN METHODS: Carvacrol treatment (12.5-50mg/kgs.c.) once daily for 15days was started 24h after injection of the sarcoma cells in the hind paw (s.c.). Mice were evaluated for mechanical sensitivity (von Frey), spontaneous and palpation-induced nociception, limb use and tumor growth on alternate days. CARV effects on the central nervous system were evaluated through immunofluorescence for Fos protein. Molecular docking studies also were performed to evaluate intermolecular interactions of the carvacrol and muscimol, as ligands of interleukin-10 and GABAA receptors. KEY FINDINGS: CARV was able to significantly reduce mechanical hyperalgesia and spontaneous and palpation-induced nociception, improve use paw, decrease the number of positively marked neurons in lumbar spinal cord and activate periaqueductal gray, nucleus raphe magnus and locus coeruleus. CARV also caused significant decreased tumor growth. Docking studies showed favorable interaction overlay of the CARV with IL-10 and GABAA. SIGNIFICANCE: Together, these results demonstrated that CARV may be an interesting option for the development of new analgesic drugs for the management of cancer pain.

Dimethyl 2-[(acridin-9-yl)methyl-idene]malonate.

In the title compound, C(19)H(15)NO(4), the acridine system is essentially planar (r.m.s. deviation = 0.015 Å). The crystal packing exhibits π-π inter-actions between pairs of centrosymmetric mol-ecules, one of them between the central heterocyclic rings and others between the outer benzene rings of the acridine systems, with centroid-centroid distances of 3.692 (1) and 3.754 (1) Å, respectively. These pairs are further linked by additional π-π inter-actions along the a-axis direction through one of the two outer benzene ring of neighboring mol-ecules, with a centroid-centroid distance of 3.642 (2) Å.

Ethyl 2-(3-phenyl-thio-ureido)-5,6-di-hydro-4H-cyclo-penta-[b]thio-phene-3-carboxyl-ate.

In the title compound, C(17)H(18)N(2)O(2)S(2), the angle between the mean plane defined by the atoms of the 5,6-dihydro-4H-cyclo-penta-[b]thio-phene moiety (r.m.s. deviation = 0.19 Å) and the phenyl ring is 72.8°(2). The mol-ecular conformation is stabilized by an intra-molecular N-H⋯O inter-action, which generates an S(6) ring motif. In the crystal, pairs of N-H⋯S hydrogen bonds link the mol-ecules to form inversion dimers with an R(2) (2)(8) ring motif.

Synthesis of 1,2,3-triazole derivatives and in vitro antifungal evaluation on Candida strains.

1,2,3-Triazoles have been extensively studied as compounds possessing important biological activities. In this work, we describe the synthesis of ten 2-(1-aryl-1H-1,2,3-triazol-4-yl)propan-2-ols via copper catalyzed azide alkyne cycloaddition (CuAAc or click chemistry). Next the in vitro antifungal activity of these ten compounds was evaluated using the microdilution broth method against 42 isolates of four different Candida species. Among all tested compounds, the halogen substituted triazole 2-[1-(4-chlorophenyl)-1H-(1,2,3)triazol-4-yl]propan-2-ol, revealed the best antifungal profile, showing that further modifications could be done in the structure to obtain a better drug candidate in the future.

Comparative computational studies of 3,4-dihydro-2,6-diaryl-4-oxo-pyrimidine-5-carbonitrile derivatives as potential antinociceptive agents.

In this study, the antinociceptive properties of 3,4-dihydro-2,6-diaryl-4-oxo-pyrimidine-5-carbonitrile derivatives 5a-i at doses of 25 and 50 mg/kg were evaluated in mice, using the abdominal constriction test. Molecular modeling studies were also performed using density functional theory calculations. These data provided information about the electrostatic and ionization potentials and were used to compare the antinociceptive activity of the title compounds. The most active compounds were 3,4-dihydro-2-(4-chlorophenyl)-6-(4-methoxyphenyl)-4-oxo-pyrimidine-5-carbonitrile (5b) and 3,4-dihydro-2,6-diphenyl-4-oxo-pyrimidine-5-carbonitrile (5i), which inhibited the number of abdominal constrictions, at 50 mg/kg dose, in 88.6% and 88% of the sample, respectively. A preliminary SAR study demonstrated that halogen replacement in the phenyl rings of the compounds under study reduces the antinociceptive activity. DFT calculations showed that there is a high correlation between the ionization potentials and the analgesic properties of the compounds. It was found that compounds with a positive ionization potential (compounds 5b and 5i) were found to be the best analgesic drugs in this series.