Magdalena Rennó - Academia.edu (original) (raw)

Papers by Magdalena Rennó

Mini-Reviews in Medicinal Chemistry

: Alzheimer’s disease [AD] is a neurodegenerative, progressive, and fatal disorder characterized ... more : Alzheimer’s disease [AD] is a neurodegenerative, progressive, and fatal disorder characterized by marked atrophy of the cerebral cortex and loss of basal forebrain cholinergic neurons. The main pathological features of AD are related to neuronal degeneration and include extracellular deposition of amyloid beta plaques [Aβ plaques], intracellular formation of neurofibrillary tangles [NFTs], and neuroinflammation. So far, drugs used to treat AD have symptomatic and palliative pharmacological effects, disappearing with continued use due to neuron degeneration and death. Therefore, there are still problems with an effective drug for treating AD. Few approaches evaluate the action of natural products other than alkaloids on the molecular targets of β-amyloid protein [Aβ protein] and/or tau protein, which are important targets for developing neuroprotective drugs that will effectively contribute to finding a prophylactic drug for AD. This review gathers and categorizes classes of natural products, excluding alkaloids, which in silico analysis [molecular docking] and in vitro and/or in vivo assays can inhibit the BACE1 and GSK-3β enzymes involved in AD.

Bioorganic Chemistry, 2021

α-aryl-α-tetralones and α-fluoro-α-aryl-α-tetralones derivatives were synthesized by palladium ca... more 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.

Revista Brasileira de Farmacognosia, 2021

Piper rivinoides Kunth, known in Brazil as “aperta-ruao,” is a medicinal glabrous shrub (3 to 6 m... more Piper rivinoides Kunth, known in Brazil as “aperta-ruao,” is a medicinal glabrous shrub (3 to 6 m high) that belongs to the Piperaceae family. Some bioactive benzofuran neolignans were isolated from this species, and it is important to know about how these compounds interact with cytochrome P450 enzymes. For this purpose, we tested the ethanolic extract from leaves of P. rivinoides and its partitions in hexane and dichloromethane and in three isolated neolignans (eupamotenoid-5, eupamotenoid-6, and conocarpan) in the activity of the CYP1A isoforms. Little is known about the interaction of neolignans with cytochrome P450 enzymes. Activities of 7-ethoxyresorufin-O-deethylase (EROD) and 7-methoxyresorufin O-demethylase (MROD), markers for CYP1A1 and CYP1A2, respectively, were assayed. The CYP1A (EROD) activity half-maximal inhibitory concentrations (IC50) were determined for plant material and pure compounds. IC50 for quercetin and α-naphthoflavone were also determined for comparative ...

Computational Biology and Chemistry, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Bioorganic & Medicinal Chemistry, 2019

Searching for new substances with antileishmanial activity, we synthesized and evaluated a series... more 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 K i 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 (EC 50 of 12.7 ± 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.

Bioorganic chemistry, Jan 17, 2018

11a-N-tosyl-5-carbapterocarpans (5a-c and 6a-c), 9-N-tosyl-4,4a,9,9a-tetrahydro-3H-carbazole (7),... more 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...

Bioorganic & Medicinal Chemistry, 2016

Pterocarpanquinone (+/-)-LQB-118 presents antineoplastic and antiparasitic properties and also sh... more 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 β. Results suggested that (+/-)-LQB-118 may bind to both receptors, with a similar orientation to 17-β-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.

Chemico-Biological Interactions, 2016

The first report in literature of the isolation of coumarinwas in the 1820. After this report, ot... more The first report in literature of the isolation of coumarinwas in the 1820. After this report, other papers were published demonstrating the isolation and synthesis of coumarin and analogues. These compounds have been studying along the years for several different pathologies. One of these pathologies was Alzheimer's disease (AD),being the main cause of dementia in the contemporary world. There are two hypotheses to explain the pathogenesis mechanism and disease symptoms, then having the "amyloid hypothesis" and the "cholinergic hypothesis". Some drugs for AD are based on the theory of "cholinergic hypothesis", which objective is to increase the concentration of ACh in the synaptic cleft by the inhibition of cholinesterases. Over the last twenty years, many studies with coumarins compounds were reported as cholinesterasesinhibitors. The aim of the present review is to discuss the studies and development of new compounds for AD treatment.

RSC Advances, 2015

Here we describe the synthesis and biological effect against Toxoplasma gondii of two new zinc co... more Here we describe the synthesis and biological effect against Toxoplasma gondii of two new zinc complexes containing sulfadiazine: [(SDZ)Zn(μ-BPA)2Zn(SDZ)] 1 and [Zn(SDZ)(HSDZ)(Cl)(OH2)] 2, where SDZ is the anion sulfadiazine.

Journal of Enzyme Inhibition and Medicinal Chemistry, 2015

Parasitology International, 2015

Toxoplasmosis is a widely disseminated disease caused by Toxoplasma gondii, an intracellular prot... more Toxoplasmosis is a widely disseminated disease caused by Toxoplasma gondii, an intracellular protozoan parasite. Standard treatment causes many side effects, such as depletion of bone marrow cells, skin rashes and gastrointestinal implications. Therefore, it is necessary to find chemotherapeutic alternatives for the treatment of this disease. It was shown that a naphthoquinone derivative compound is active against T. gondii, RH strain, with an IC50 around 2.5μM. Here, three different naphthoquinone derivative compounds with activity against leukemia cells and breast carcinoma cell were tested against T. gondii (RH strain) infected LLC-MK2 cell line. All the compounds were able to inhibit parasite growth in vitro, but one of them showed an IC50 activity below 1μM after 48h of treatment. The compounds showed low toxicity to the host cell. In addition, these compounds were able to induce tachyzoite-bradyzoite conversion confirmed by morphological changes, Dolichus biflorus lectin cyst wall labeling and characterization of amylopectin granules in the parasites by electron microscopy analysis using the Thierry technique. Furthermore, the compounds induced alterations on the ultrastructure of the parasite. Taken together, our results point to the naphthoquinone derivative (LQB 151) as a potential compound for the development of new drugs for the treatment of toxoplasmosis.

Revista Virtual de Química, 2012

The Indian clove (Syzygium aromaticum, Myrtaceae) is a well appreciated spice since the ancient t... more The Indian clove (Syzygium aromaticum, Myrtaceae) is a well appreciated spice since the ancient times not only by its flavor and culinary qualities, but also because of its therapeutic uses. Several popular and traditional applications have been reported in literature as well as numerous scientific studies on its activities. In this work we present a synopsis and discussion on S. aromaticum to provide the readers some useful information on the historical aspects, the chemical composition and its large variety of potential applications for the treatment of a number of illnesses.

Chemoinformatics: Directions Toward Combating Neglected Diseases, 2012

Pharmacological Research, 2005

In this work, 22 alcoholic extracts, obtained from 14 species of plants belonging to four familie... more In this work, 22 alcoholic extracts, obtained from 14 species of plants belonging to four families, used for different food and medicinal purposes in Brazil, were evaluated for their capacity to inhibit the reduction of the free radical, 1,1-diphenyl-2-picrylhydrazyl (DPPH), and to protect Saccharomyces cerevisiae cells, an eukaryotic cell model, against the lethal oxidative stress caused by tert-butylhydroperoxide (TBH). Five extracts, two from Lamiaceae family (ethanol and butanol extracts from aerial parts of Hyptis fasciculata) and three from Palmae family (Copernicia cerifera leaves and mesocarp of fruits and the endocarp/mesocarp of fruits from Orbignya speciosa) were able to increase the tolerance of S. cerevisiae to TBH and showed to be active as DPPH radical scavengers, thus indicating that these plant extracts could be considered as potential sources of antioxidants. With the exception of ethanol extract of H. fasciculata, the remainder four extracts exhibited a DPPH radical scavenging activity higher than that obtained from Ginkgo biloba, a reference plant with well documented antioxidant activity. Interestingly, the ethanol extract of G. biloba were not effective for yeast cell protection, reinforcing the antioxidant potential of these extracts.

Journal of the Brazilian Chemical Society, 2008

Neste trabalho é proposto o primeiro modelo por homologia para a nucleosídeo hidrolase de Leishma... more Neste trabalho é proposto o primeiro modelo por homologia para a nucleosídeo hidrolase de Leishmania donovani construído a partir das estruturas das nucleosídeo hidrolases de Crithidia fasciculata e de Leishmania major. Usando as informações de interação entre o inibidor p-aminofeniliminoribitol e a nucleosídeo hidrolase de Crithidia fasciculata foram planejados dois novos potenciais inibidores, os quais apresentam novas interações com alguns resíduos da bolsa hidrofóbica do sítio ativo do modelo. Simulações por dinâmica molecular dos protótipos ancorados nos sítios ativos do modelo e das enzimas usadas como moldes, mostraram que, diferente do p-aminofeniliminoribitol, eles permaneceram ancorados nos sítios ativos das três enzimas ao longo de toda a dinâmica, interagindo fortemente com os aminoácidos da bolsa hidrofóbica. In this work we propose the first homology model for nucleoside hydrolase from Leishmania donovani, built based on the crystallographic structures of Crithidia fasciculata and Leishmania major nucleoside hydrolases. We used the interaction information from the crystallographic model of the enzyme of C. fasciculata in complex with the inhibitor p-aminophenyliminoribitol, to design two new potential inhibitors, which present new interactions with some residues of the hydrophobic pocket of the model active site. Molecular dynamics simulations of the prototypes inside the active sites of the model and the template enzymes showed that, differently from p-aminophenyliminoribitol, they remained tightly bound inside the active sites, interacting strongly with the amino acids from the hydrophobic pocket.

Journal of Biomolecular Structure and Dynamics, 2011

The literature has reported that ferriprotoporphyrin IX (hematin) intoxicates the malarial parasi... more 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.

Journal of Biomolecular Structure and Dynamics, 2011

Considering the risk represented by plague today as a potential biological warfare agent, we prop... more 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.

Journal of Applied Biomedicine, 2011

In order to contribute to a better understanding of the mechanism of action of oximes, we evaluat... more In order to contribute to a better understanding of the mechanism of action of oximes, we evaluated the affinities of 10 new oximes, derived from pyridine-imidazol bicycled systems, for human acetylcholinesterase (HssAChE) complexed with tabun, by estimating their docking energy values and comparing of the values obtained to known oximes using the software Molegro Virtual Docker (MVD) ®. We evaluated the influence of the position of the oxime group as substituent in the structures and, also, the influence of the oxime group syn-anti isomery on the docking score values for all the molecules studied. Results suggest that: the affinities of the 10 new oximes for the tabun inhibited HssAChE active site are better than pralidoxime's and similar to trimedoxime's; the meta-pralidoxime could have more affinity for the HssAChE active site and the oximes' anti isomers could present slightly better affinities for the HssAChE active site than the syn isomers.

European Journal of Medicinal Chemistry, 2012

This study presents new inhibitors of the nucleoside hydrolase from Leishmania donovani (LdNH) wi... more This study presents new inhibitors of the nucleoside hydrolase from Leishmania donovani (LdNH) with in vitro leishmanicidal activity. Biological screening of 214 Brazilian plant extracts was performed to select plants with enzyme inhibitory activity. Two plants were selected for their results, and for their lack of prior phytochemical description: Leandra amplexicaulis DC. (Melastomataceae) and Urvillea rufescens Cambess (Sapindaceae). Three flavonoids were isolated by bioguided fractionation of the hydroethanolic extracts: kaempferol 3-O-a-L-rhamnopyranoside (1) and kaempferol 3-O-b-D-xylopyranosyl-(1/2)-a-Lrhamnopyranoside (2) from L. amplexicaulis, as well as tricetin-4 0-O-methyl flavone (3) from U. rufescens. These flavonoids showed inhibitory activities (IC 50) of 197.4 mM (1), 74.7 mM (2) and 1.1 mM (3) on the LdNH. Their binding mode was proposed based on molecular docking with LdNH and by NMR Saturation Transfer Difference studies. Kinetic studies demonstrate that the most potent inhibitor (3) acts by uncompetitive inhibition. This study reports for the first time the inhibition of LdNH by naturally sourced flavonoids.

Mini-Reviews in Medicinal Chemistry

: Alzheimer’s disease [AD] is a neurodegenerative, progressive, and fatal disorder characterized ... more : Alzheimer’s disease [AD] is a neurodegenerative, progressive, and fatal disorder characterized by marked atrophy of the cerebral cortex and loss of basal forebrain cholinergic neurons. The main pathological features of AD are related to neuronal degeneration and include extracellular deposition of amyloid beta plaques [Aβ plaques], intracellular formation of neurofibrillary tangles [NFTs], and neuroinflammation. So far, drugs used to treat AD have symptomatic and palliative pharmacological effects, disappearing with continued use due to neuron degeneration and death. Therefore, there are still problems with an effective drug for treating AD. Few approaches evaluate the action of natural products other than alkaloids on the molecular targets of β-amyloid protein [Aβ protein] and/or tau protein, which are important targets for developing neuroprotective drugs that will effectively contribute to finding a prophylactic drug for AD. This review gathers and categorizes classes of natural products, excluding alkaloids, which in silico analysis [molecular docking] and in vitro and/or in vivo assays can inhibit the BACE1 and GSK-3β enzymes involved in AD.

Bioorganic Chemistry, 2021

α-aryl-α-tetralones and α-fluoro-α-aryl-α-tetralones derivatives were synthesized by palladium ca... more 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.

Revista Brasileira de Farmacognosia, 2021

Piper rivinoides Kunth, known in Brazil as “aperta-ruao,” is a medicinal glabrous shrub (3 to 6 m... more Piper rivinoides Kunth, known in Brazil as “aperta-ruao,” is a medicinal glabrous shrub (3 to 6 m high) that belongs to the Piperaceae family. Some bioactive benzofuran neolignans were isolated from this species, and it is important to know about how these compounds interact with cytochrome P450 enzymes. For this purpose, we tested the ethanolic extract from leaves of P. rivinoides and its partitions in hexane and dichloromethane and in three isolated neolignans (eupamotenoid-5, eupamotenoid-6, and conocarpan) in the activity of the CYP1A isoforms. Little is known about the interaction of neolignans with cytochrome P450 enzymes. Activities of 7-ethoxyresorufin-O-deethylase (EROD) and 7-methoxyresorufin O-demethylase (MROD), markers for CYP1A1 and CYP1A2, respectively, were assayed. The CYP1A (EROD) activity half-maximal inhibitory concentrations (IC50) were determined for plant material and pure compounds. IC50 for quercetin and α-naphthoflavone were also determined for comparative ...

Computational Biology and Chemistry, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Bioorganic & Medicinal Chemistry, 2019

Searching for new substances with antileishmanial activity, we synthesized and evaluated a series... more 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 K i 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 (EC 50 of 12.7 ± 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.

Bioorganic chemistry, Jan 17, 2018

11a-N-tosyl-5-carbapterocarpans (5a-c and 6a-c), 9-N-tosyl-4,4a,9,9a-tetrahydro-3H-carbazole (7),... more 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...

Bioorganic & Medicinal Chemistry, 2016

Pterocarpanquinone (+/-)-LQB-118 presents antineoplastic and antiparasitic properties and also sh... more 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 β. Results suggested that (+/-)-LQB-118 may bind to both receptors, with a similar orientation to 17-β-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.

Chemico-Biological Interactions, 2016

The first report in literature of the isolation of coumarinwas in the 1820. After this report, ot... more The first report in literature of the isolation of coumarinwas in the 1820. After this report, other papers were published demonstrating the isolation and synthesis of coumarin and analogues. These compounds have been studying along the years for several different pathologies. One of these pathologies was Alzheimer's disease (AD),being the main cause of dementia in the contemporary world. There are two hypotheses to explain the pathogenesis mechanism and disease symptoms, then having the "amyloid hypothesis" and the "cholinergic hypothesis". Some drugs for AD are based on the theory of "cholinergic hypothesis", which objective is to increase the concentration of ACh in the synaptic cleft by the inhibition of cholinesterases. Over the last twenty years, many studies with coumarins compounds were reported as cholinesterasesinhibitors. The aim of the present review is to discuss the studies and development of new compounds for AD treatment.

RSC Advances, 2015

Here we describe the synthesis and biological effect against Toxoplasma gondii of two new zinc co... more Here we describe the synthesis and biological effect against Toxoplasma gondii of two new zinc complexes containing sulfadiazine: [(SDZ)Zn(μ-BPA)2Zn(SDZ)] 1 and [Zn(SDZ)(HSDZ)(Cl)(OH2)] 2, where SDZ is the anion sulfadiazine.

Journal of Enzyme Inhibition and Medicinal Chemistry, 2015

Parasitology International, 2015

Toxoplasmosis is a widely disseminated disease caused by Toxoplasma gondii, an intracellular prot... more Toxoplasmosis is a widely disseminated disease caused by Toxoplasma gondii, an intracellular protozoan parasite. Standard treatment causes many side effects, such as depletion of bone marrow cells, skin rashes and gastrointestinal implications. Therefore, it is necessary to find chemotherapeutic alternatives for the treatment of this disease. It was shown that a naphthoquinone derivative compound is active against T. gondii, RH strain, with an IC50 around 2.5μM. Here, three different naphthoquinone derivative compounds with activity against leukemia cells and breast carcinoma cell were tested against T. gondii (RH strain) infected LLC-MK2 cell line. All the compounds were able to inhibit parasite growth in vitro, but one of them showed an IC50 activity below 1μM after 48h of treatment. The compounds showed low toxicity to the host cell. In addition, these compounds were able to induce tachyzoite-bradyzoite conversion confirmed by morphological changes, Dolichus biflorus lectin cyst wall labeling and characterization of amylopectin granules in the parasites by electron microscopy analysis using the Thierry technique. Furthermore, the compounds induced alterations on the ultrastructure of the parasite. Taken together, our results point to the naphthoquinone derivative (LQB 151) as a potential compound for the development of new drugs for the treatment of toxoplasmosis.

Revista Virtual de Química, 2012

The Indian clove (Syzygium aromaticum, Myrtaceae) is a well appreciated spice since the ancient t... more The Indian clove (Syzygium aromaticum, Myrtaceae) is a well appreciated spice since the ancient times not only by its flavor and culinary qualities, but also because of its therapeutic uses. Several popular and traditional applications have been reported in literature as well as numerous scientific studies on its activities. In this work we present a synopsis and discussion on S. aromaticum to provide the readers some useful information on the historical aspects, the chemical composition and its large variety of potential applications for the treatment of a number of illnesses.

Chemoinformatics: Directions Toward Combating Neglected Diseases, 2012

Pharmacological Research, 2005

In this work, 22 alcoholic extracts, obtained from 14 species of plants belonging to four familie... more In this work, 22 alcoholic extracts, obtained from 14 species of plants belonging to four families, used for different food and medicinal purposes in Brazil, were evaluated for their capacity to inhibit the reduction of the free radical, 1,1-diphenyl-2-picrylhydrazyl (DPPH), and to protect Saccharomyces cerevisiae cells, an eukaryotic cell model, against the lethal oxidative stress caused by tert-butylhydroperoxide (TBH). Five extracts, two from Lamiaceae family (ethanol and butanol extracts from aerial parts of Hyptis fasciculata) and three from Palmae family (Copernicia cerifera leaves and mesocarp of fruits and the endocarp/mesocarp of fruits from Orbignya speciosa) were able to increase the tolerance of S. cerevisiae to TBH and showed to be active as DPPH radical scavengers, thus indicating that these plant extracts could be considered as potential sources of antioxidants. With the exception of ethanol extract of H. fasciculata, the remainder four extracts exhibited a DPPH radical scavenging activity higher than that obtained from Ginkgo biloba, a reference plant with well documented antioxidant activity. Interestingly, the ethanol extract of G. biloba were not effective for yeast cell protection, reinforcing the antioxidant potential of these extracts.

Journal of the Brazilian Chemical Society, 2008

Neste trabalho é proposto o primeiro modelo por homologia para a nucleosídeo hidrolase de Leishma... more Neste trabalho é proposto o primeiro modelo por homologia para a nucleosídeo hidrolase de Leishmania donovani construído a partir das estruturas das nucleosídeo hidrolases de Crithidia fasciculata e de Leishmania major. Usando as informações de interação entre o inibidor p-aminofeniliminoribitol e a nucleosídeo hidrolase de Crithidia fasciculata foram planejados dois novos potenciais inibidores, os quais apresentam novas interações com alguns resíduos da bolsa hidrofóbica do sítio ativo do modelo. Simulações por dinâmica molecular dos protótipos ancorados nos sítios ativos do modelo e das enzimas usadas como moldes, mostraram que, diferente do p-aminofeniliminoribitol, eles permaneceram ancorados nos sítios ativos das três enzimas ao longo de toda a dinâmica, interagindo fortemente com os aminoácidos da bolsa hidrofóbica. In this work we propose the first homology model for nucleoside hydrolase from Leishmania donovani, built based on the crystallographic structures of Crithidia fasciculata and Leishmania major nucleoside hydrolases. We used the interaction information from the crystallographic model of the enzyme of C. fasciculata in complex with the inhibitor p-aminophenyliminoribitol, to design two new potential inhibitors, which present new interactions with some residues of the hydrophobic pocket of the model active site. Molecular dynamics simulations of the prototypes inside the active sites of the model and the template enzymes showed that, differently from p-aminophenyliminoribitol, they remained tightly bound inside the active sites, interacting strongly with the amino acids from the hydrophobic pocket.

Journal of Biomolecular Structure and Dynamics, 2011

The literature has reported that ferriprotoporphyrin IX (hematin) intoxicates the malarial parasi... more 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.

Journal of Biomolecular Structure and Dynamics, 2011

Considering the risk represented by plague today as a potential biological warfare agent, we prop... more 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.

Journal of Applied Biomedicine, 2011

In order to contribute to a better understanding of the mechanism of action of oximes, we evaluat... more In order to contribute to a better understanding of the mechanism of action of oximes, we evaluated the affinities of 10 new oximes, derived from pyridine-imidazol bicycled systems, for human acetylcholinesterase (HssAChE) complexed with tabun, by estimating their docking energy values and comparing of the values obtained to known oximes using the software Molegro Virtual Docker (MVD) ®. We evaluated the influence of the position of the oxime group as substituent in the structures and, also, the influence of the oxime group syn-anti isomery on the docking score values for all the molecules studied. Results suggest that: the affinities of the 10 new oximes for the tabun inhibited HssAChE active site are better than pralidoxime's and similar to trimedoxime's; the meta-pralidoxime could have more affinity for the HssAChE active site and the oximes' anti isomers could present slightly better affinities for the HssAChE active site than the syn isomers.

European Journal of Medicinal Chemistry, 2012

This study presents new inhibitors of the nucleoside hydrolase from Leishmania donovani (LdNH) wi... more This study presents new inhibitors of the nucleoside hydrolase from Leishmania donovani (LdNH) with in vitro leishmanicidal activity. Biological screening of 214 Brazilian plant extracts was performed to select plants with enzyme inhibitory activity. Two plants were selected for their results, and for their lack of prior phytochemical description: Leandra amplexicaulis DC. (Melastomataceae) and Urvillea rufescens Cambess (Sapindaceae). Three flavonoids were isolated by bioguided fractionation of the hydroethanolic extracts: kaempferol 3-O-a-L-rhamnopyranoside (1) and kaempferol 3-O-b-D-xylopyranosyl-(1/2)-a-Lrhamnopyranoside (2) from L. amplexicaulis, as well as tricetin-4 0-O-methyl flavone (3) from U. rufescens. These flavonoids showed inhibitory activities (IC 50) of 197.4 mM (1), 74.7 mM (2) and 1.1 mM (3) on the LdNH. Their binding mode was proposed based on molecular docking with LdNH and by NMR Saturation Transfer Difference studies. Kinetic studies demonstrate that the most potent inhibitor (3) acts by uncompetitive inhibition. This study reports for the first time the inhibition of LdNH by naturally sourced flavonoids.