Synthesis of new α-Aryl-α-tetralones and α-Fluoro-α-aryl-α-tetralones, preliminary antiproliferative evaluation on drug resistant cell lines and in silico prediction of ADMETox properties.

α-aryl-α-tetralones and α-fluoro-α-aryl-α-tetralones derivatives were synthesized by palladium catalyzed α-arylation reaction of α-tetralones and α-fluoro-α-tetralones, with bromoarenes in moderate to good yields. These compounds were evaluated for their in vitro anti-proliferative effects against human breast cancer and leukemia cell lines with diverse profiles of drug resistance. The most promising compounds, 3b, 3c, 8a and 8c, were effective on both neoplastic models. 3b and 8a induced higher toxicity on multidrug resistant cells and were able to avoid efflux by ABCB1 and ABCC1 transporters. Theoretical calculations of the physicochemical descriptors to predict ADMETox properties were favorable concerning Lipinski's rule of five, results that reflected on the low effects on non-tumor cells. Therefore, these compounds showed great potential for development of pharmaceutical agents against therapy refractory cancers.

Theoretical studies and NMR assay of coumarins and neoflavanones derivatives as potential inhibitors of acetylcholinesterase.

Currently Alzheimer's disease (AD) is a devastating neurological disorder that mainly affects the elderly. The treatment of AD has as main objective to increase the levels of ACh in the synaptic cleft by inhibiting the cholinesterase enzymes, which are responsible for the degradation of ACh. Twenty one synthesized coumarins and neoflavanones (4-arylcoumarins) and theoretical studies were used to select the most promising ligands for in vitro experimental studies by Nuclear Magnetic Resonance. The eight compounds selected for the experimental study only 12b (effectiveness 68.54 ±â€¯3.22%) was promising AChE inhibitor. This compound (12b) presents substituents at positions 4, 5, 6, 7 and 8 in a coumarin nucleus, being the most significant characteristic in comparison to the other studied compounds. These results can be used for the design and synthesis of other possible derivatives with inhibitory potential of AChE.

Phenylhydrazides as inhibitors of Leishmania amazonensis arginase and antileishmanial activity.

Searching for new substances with antileishmanial activity, we synthesized and evaluated a series of α,α-difluorohydrazide and α,α-difluoramides against Leishmania amazonensis arginase (LaArg). Four α,α-difluorohydrazide derivatives showed activity against LaArg with Ki in the range of 1.3-26 µM. The study of the kinetics of LaArg inhibition showed that these substances might act via different inhibitory mechanisms or even by a combination of these. The compounds were tested against L. amazonensis promastigotes and the best result was obtained to the compound 4 (EC50 of 12.7 ±â€¯0.3 µM). In addition, in order to obtain further insight into the binding mode of such compounds, molecular docking studies were performed to obtain additional validation of experimental results. Considering these results, it is possible to conclude that α,α-difluorohydrazide derivatives are a promising scaffold in the development of new substances against the etiological agent of leishmaniasis by targeting LaArg.

11a-N-tosyl-5-carbapterocarpans: Synthesis, antineoplastic evaluation and in silico prediction of ADMETox properties.

11a-N-tosyl-5-carbapterocarpans (5a-c and 6a-c), 9-N-tosyl-4,4a,9,9a-tetrahydro-3H-carbazole (7), 11a-N-tosyl-5-carbapterocarpen (8) analogues of LQB-223 (4a), were synthesized through palladium catalyzed azaarylation of substituted dihydronaphtalenes (14a-c) and cyclohexadiene (15), respectively, with N-tosyl-o-iodoaniline (11). In order to understand the role of the N-tosyl moiety for the pharmacological activity, the azacarbapterocarpen (9) was also synthesized by Fischer indol reaction. The structural requirements at the A and D-rings for the antineoplastic activity toward human leukemias and breast cancer cells were evaluated as well. Substitutions on the A-ring of 4a and analogues alter the effect on different breast cancer subtypes. On the other hand, A-ring is not essential for antileukemic activity since compound 7, which does not contain the A-ring, showed efficacy with high selectivity indices for drug-resistant leukemias. On the other hand, substitutions on the D-ring of 4a for fluorine or iodine did not improve the antileukemic activity. In silico studies concerning Lipinskís rule of five, ADMET properties and drug scores of those compounds were performed, indicating good physicochemical properties for all compounds, in special for compound 7.

Anti-inflammatory properties of pterocarpanquinone LQB-118 in mice.

Pterocarpanquinone (+/-)-LQB-118 presents antineoplastic and antiparasitic properties and also shows great inhibitory effect on TNF-α release in vitro. Here, its anti-inflammatory activity was evaluated in a lipopolysaccharide (LPS)-induced lung inflammation model in C57BL/6 mice. LPS inhalation induced a marked neutrophil infiltration to the lungs which was reduced by intraperitoneal treatment with (+/-)-LQB-118 in a similar manner to that of dexamethasone and even better than that of acetylsalicylic acid. Moreover, (+/-)-LQB-118 administration resulted in decrease of NF-κB activation and KC level in lungs, with a pronounced inhibitory effect on TNF-α release, measured in bronchoalveolar lavage fluid. Trying to understand the anti-inflammatory mechanism by which (+/-)-LQB-118 acts, we performed a molecular modeling analysis, including docking to estrogen receptors α and ß. Results suggested that (+/-)-LQB-118 may bind to both receptors, with a similar orientation to 17-ß-estradiol. Together, these results showed that (+/-)-LQB-118 exhibits an anti-inflammatory effect, most likely by inhibiting TNF-α release and NF-κB activation, which may be related to the estrogen receptor binding.

Molecular modeling studies of Yersinia pestis dihydrofolate reductase.

Considering the risk represented by plague today as a potential biological warfare agent, we propose cytosolic Yersinia pestis dihydrofolate reductase (YpDHFR) as a new target to the design of selective plague chemotherapy. This enzyme has a low homology with the human enzyme and its crystallographic structure has been recently deposited in the Protein Data Bank (PDB). Comparisons of the docking energies and molecular dynamic behaviors of five known DHFR inhibitors inside a 3D model of YpDHFR (adapted from the crystallographic structure) and human DHFR (HssDHFR), revealed new potential interactions and suggested insights into the design of more potent HssDHFR inhibitors as well as selective inhibitors for YpDHFR.

Docking studies on the binding of quinoline derivatives and hematin to Plasmodium falciparum lactate dehydrogenase.

The literature has reported that ferriprotoporphyrin IX (hematin) intoxicates the malarial parasite through competition with NADH for the active site of the enzyme lactate dehydrogenase (LDH). In order to avoid this, the parasite polymerizes hematin to hemozoin. The quinoline derivatives are believed to form complexes with dimeric hematin, avoiding the formation of hemozoin and still inhibiting LDH. In order to investigate this hypothesis we calculated the docking energies of NADH and some quinoline derivatives (in the free forms and in complex with dimeric hematin) in the active site of the Plasmodium falciparum LDH (PfLDH). Ours results showed better docking score values to the complexes when compared to the free compounds, pointing them as more efficient inhibitors of Pf_LDH. Further we performed Molecular Dynamics (MD) simulations studies on the best docking conformation of the complex chloroquine-dimeric hematin with PfLDH. Our in silico results corroborate experimental data suggesting a possible action route for the quinoline derivatives in the inhibition of PfLDH.

Development of new acetylcholinesterase reactivators: molecular modeling versus in vitro data.

In this work a theoretical methodology for evaluation of the association and kinetic reactivation constants of oximes using the Molegro and Spartan softwares was proposed and validated facing in vitro data previously reported in the literature. Results showed a very good agreement between the theoretical binding free energies of the reactivators and experimental data, suggesting that the proposed methodology could work well in the prediction of kinetic and thermodynamics parameters for oximes that might be helpful for the design and selection of new and more effective oximes.

Development of new acetylcholinesterase reactivators: molecular modeling versus in vitro data.

In this work a theoretical methodology for evaluation of the association and kinetic reactivation constants of oximes using the Molegro and Spartan softwares was proposed and validated facing in vitro data previously reported in the literature. Results showed a very good agreement between the theoretical binding free energies of the reactivators and experimental data, suggesting that the proposed methodology could work well in the prediction of kinetic and thermodynamics parameters for oximes that might be helpful for the design and selection of new and more effective oximes.

Crude ethanol extract from babassu (Orbignya speciosa): cytotoxicity on tumoral and non-tumoral cell lines.

Plant-derived substances have been considered as important sources of drugs, including antineoplasic agents. Babassu mesocarp is popularly used in Brazil as a food additive, and in popular medicine against several conditions, such as inflammations, menstrual pains and leukaemia. From babassu Orbignya speciosa (Mart.) Barb. Rodr. [Arecaceae (Palmae)] epicarp/mesocarp, an ethanol extract was prepared and named OSEME, which was tested on the viability,morphology and metabolism of several cell lines, such as the leukaemic cell lines, HL-60, K562 and the latter multidrug resistant counterpart K562-Lucena 1, the human breast cancer cell line MCF-7, the mouse fibroblast cell line 3T3-L1 and fresh human lymphocytes. OSEME promoted a dose-dependent decrease on the viability of all cells. This effect was much more pronounced on the tumoral cell lines than on non-tumoral cells, a phenomenon revealed by the dose of OSEME which promotes half of maximal effect (ID50). The decrease on viability was followed by shrinkage of cells, alteration on their morphology, and a markedly nuclear condensation. Curiously, stimulation of 6-phosphofructokinase activity (6.6-times) was observed on HL-60 cells, treated with OSEME, when compared to control treated with ethanol (vehicle). These results support evidences to suggest OSEME as a promising source of novel antineoplasic agents.

Crude ethanol extract from babassu (Orbignya speciosa): cytotoxicity on tumoral and non-tumoral cell lines

Plant-derived substances have been considered as important sources of drugs, including antineoplasic agents. Babassu mesocarp is popularly used in Brazil as a food additive, and in popular medicine against several conditions, such as inflammations, menstrual pains and leukaemia. From babassu Orbignya speciosa (Mart.) Barb. Rodr. [Arecaceae (Palmae)] epicarp/mesocarp, an ethanol extract was prepared and named OSEME, which was tested on the viability,morphology and metabolism of several cell lines, such as the leukaemic cell lines, HL-60, K562 and the latter multidrug resistant counterpart K562-Lucena 1, the human breast cancer cell line MCF-7, the mouse fibroblast cell line 3T3-L1 and fresh human lymphocytes. OSEME promoted a dose-dependent decrease on the viability of all cells. This effect was much more pronounced on the tumoral cell lines than on non-tumoral cells, a phenomenon revealed by the dose of OSEME which promotes half of maximal effect (ID50). The decrease on viability was followed by shrinkage of cells, alteration on their morphology, and a markedly nuclear condensation. Curiously, stimulation of 6-phosphofructokinase activity (6.6-times) was observed on HL-60 cells, treated with OSEME, when compared to control treated with ethanol (vehicle). These results support evidences to suggest OSEME as a promising source of novel antineoplasic agents.

Substâncias derivadas de plantas têm sido usadas como importante fonte de agentes antineoplásicos. O mesocarpo do babaçu é popularmente usado no Brasil como suplemento alimentar e na medicina popular para o tratamento de várias afecções, tais como: inflamações, cólicas menstruais e leucemia. A partir do epicarpo/mesocarpo do babaçu Orbignya speciosa (Mart.) Barb. Rodr. [Arecaceae (Palmae)] foi preparado um extrato etanólico, denominado OSEME, o qual foi incubado com as seguintes linhagens humanas leucêmicas: HL-60, K562 e a sua derivada resistente a múltiplas drogas, K562-Lucena 1; além destas, foram testadas a linhagem humana de câncer de mama, MCF-7; a linhagem de fibroblastos de camundongo, 3T3-L1 e linfócitos humanos de sangue periférico. OSEME promoveu diminuição da viabilidade em todas as linhagens celulares testadas de maneira dose-dependente. Este efeito foi mais pronunciado sobre as linhagens celulares tumorais quando comparado às não tumorais, o que foi revelado pela dose de OSEME capaz de promover metade do efeito máximo (ID50). A diminuição da viabilidade foi acompanhada por danos sobre a morfologia celular com pronunciada condensação citoplasmática e nuclear. Curiosamente, quando a linhagem HL-60 foi tratada com OSEME, foi detectado um aumento de 6,6 vezes da atividade da enzima 6-fosfofrutoquinase, quando comparado ao grupo controle (células tratadas com o veículo etanol). Esses resultados sugerem que OSEME pode ser uma promissora fonte de novos agentes antineoplásicos.