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au:CHAVES, OTAVIO A.

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Phytochemical profile of Cespedesia spathulata leaves (Ochnaceae) and its effect on tyrosinase enzyme
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OLIVEIRA, DÉBORA R. DE

; SILVA, MARIANA R. DA

; CHAVES, OTAVIO A.

; CASTRO, ROSANE N.

; OLIVEIRA, MARCIA C.C. DE

; BRAZ-FILHO, RAIMUNDO

; CARVALHO, MÁRIO G. DE

Anais da Academia Brasileira de Ciências

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2021, Volume 93 N. 4 elocation e20200443

Abstract: En | Text: En | PDF: En

Abstract Phytochemical studies of Cespedesia spathulata (Ochnaceae) leaves using 1H, 13C NMR, and GC-MS have led to the isolation of some metabolites identified for the first time in these species such as cathechin, epicatechin, vitexin, orientin, 6’’-O-acetyl-vitexin, sitosterol, stigmasterol, phytol, 4,5-dihydrovomifoliol and a mixture of aliphatic methyl esters, together with ochnaflavone, which was previously isolated from this plant. The modulating activity of some fractions and compounds from Cespedesia spathulata towards tyrosinase enzyme was assayed by spectroscopic and theoretical means/experiments. The dichloromethane fraction (133 μg mL-1) and ochnaflavone (333 μM) inhibited tyrosinase activity by 20 % and 2.0 %, respectively, whereas the ethyl acetate fraction (666 μg mL-1) and ±catechins (catechin and epicatechin - 800 μM) activated it by 104 % and 384 %, respectively. Quantum chemical calculations suggested that catechin and epicatechin are better activators than L-DOPA by interacting with Cu (II) ions. Molecular docking results suggested that hydrogen bonding and hydrophobic interactions are the main binding forces between each tyrosinase activator and the amino acid residues inside the active protein binding pocket.

https://doi.org/10.1590/0001-3765202120200443 86 downloads

Synthesis, Characterization, Spectroelectrochemical, Photophysical and HSA-Binding Properties of Novel and Versatile meso-Tetra(4-pyridylvinylphenyl)porphyrins Coordinated to Ruthenium(II)-Polypyridyl Derivatives
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Viecelli, Viviane

; Chaves, Otávio A.

; Araki, Koiti

; Martins, Paulo R.

; Iglesias, Bernardo A.

Journal of the Brazilian Chemical Society

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nov 2020, Volume 31 N. 11 Pages 2282 - 2298

Abstract: En | Text: En | PDF: En

The free-base meso-tetra(4-pyridylvinylphenyl)porphyrin (1a) and its zinc(II) complex were synthesized and then functionalized with [Ru(bpy)2Cl]+ units (2a and 2b) via conventional methods and evaluated in terms of photophysical, electrochemical and biological aspects. All porphyrins present moderate singlet oxygen production and fluorescence quantum yield, and did not show any aggregation process. The photo-oxidation ability of those porphyrins decreased in the order 2b > 1a > 2a. The electrochemical behavior of 2a and 2b modified electrodes was evaluated by electroanalytical methods. Also the 2b electrode showed a smaller charge transfer resistance (36.70 Ω) when compared to 2a electrode (45.17 Ω). In addition, even after 30 consecutive injections of nitrite solution (1.0 × 10−4 mol L−1) using the flow injection analysis (FIA) system, the modified 2b electrode showed an relative standard deviation (RSD, n = 30) of 1.36% exhibiting a great potential as amperometric sensor for nitrite. Moreover, the biological evaluation towards human serum albumin (HSA) indicated spontaneous, weak and ground-state association in the IB subdomain (site III) and possibily a second site, changing the conventional interaction mode of porphyrins with biomolecules as consequence of the longer arms (porphyrin ring substituents at meso-positions) ending with a ruthenium polypyridyl complex, that may enhance the photodynamic therapy (PDT) efficiency of photogenerated reactive oxygen species (ROS) species.

https://doi.org/10.21577/0103-5053.20200080 483 downloads

Antibacterial Activity of 2-Amino-1,4-naphthoquinone Derivatives against Gram-Positive and Gram-Negative Bacterial Strains and Their Interaction with Human Serum Albumin
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Silva, Carla C. da

; Chaves, Otávio A.

; Paiva, Rojane O.

; Costa, Gisela L. da

; Netto-Ferreira, José Carlos

; Echevarria, Aurea

Journal of the Brazilian Chemical Society

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sep 2020, Volume 31 N. 9 Pages 1838 - 1851

Abstract: En | Text: En | PDF: En

A series of 2-amino-1,4-naphthoquinone derivatives (NQA-NQF) was synthesized by alternative methods (ultrasonication and microwave irradiation), with yields ranging from 40 to 71%, and without the need of further recrystallization. Each compound was evaluated against four Gram-positive (Bacillus subtilis, Enterococcus faecalis, Staphylococcus aureus and Bacillus cereus) and five Gram-negative (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii and Klebsiella pneumoniae positive β-lactamase) bacteria strains. The NQF was the most active amino-naphthoquinone derivative with minimum inhibitory concentration (MIC) of 31.2 µg mL-1 against K. pneumoniae positive β-lactamase (a common intestinal bacteria which can cause life-threatening infections). On the other hand, NQA and NQC showed good activity as a potential antibiotic for the bacteria strains assayed, except for K. pneumoniae. In addition, the affinity of these three most active compounds (NQA, NQC, and NQF) for human serum albumin (HSA) was evaluated employing multiple spectroscopic techniques (steady-state, time-resolved, and synchronous fluorescence, as well as circular dichroism), combined with theoretical calculations (molecular docking). The interaction HSA:2-amino-1,4-naphthoquinones occurs spontaneously and moderately inside the subdomain IIA (Sudlow’s site I) via hydrogen bonding and van der Waals forces.

https://doi.org/10.21577/0103-5053.20200070 398 downloads

Design, Synthesis, Trypanocidal Activity, and Studies on Human Album in Interaction of Novel S-Alkyl-1,2,4-triazoles
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Franklim, Tatiany N.

; Freire-de-Lima, Leonardo

; Chaves, Otávio A.

; LaRocque-de-Freitas, Isabel F.

; Silva-Trindade, Joana D. da

; Netto-Ferreira, José C.

; Freire-de-Lima, Célio G.

; Decoté-Ricardo, Debora

; Previato, José O.

; Mendonça-Previato, Lucia

; Lima, Marco E. F. de

Journal of the Brazilian Chemical Society

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jul 2019, Volume 30 N. 7 Pages 1378 - 1394

Abstract: En | Text: En | PDF: En

Chagas disease is a neglected tropical disease caused by the hemoflagellated parasite Trypanosoma cruzi (Kinetoplastida). The only available drug to treat chagasic patients in Brazil, the nitroheterocycle benznidazole, is effective solely during the acute phase of the infection. There is accordingly a need to develop new therapeutic tools for the treatment of Chagas disease. This work reports the synthesis, trypanocidal evaluation and human serum albumin (HSA) interactions of a novel series of 1,2,4-triazoles. The new derivatives were synthesized via microwave irradiation in good yields. Most compounds showed toxic effects against T. cruzi with low toxicity to host cells. Three S-alkylated-triazoles showed the best activity profile against amastigotes, with half maximal inhibitory concentration (IC50) values of 3.95 ± 1.41, 4.15 ± 0.92 and 3.61 ± 0.65 µmol L-1, respectively. The interaction between HSA and 3-[(1E,3E)-4-(1,3-benzodioxol-5-yl)buta-1,3-dien-1-yl]-5-(butylthio)-4-cyclohexyl-4,5-dihydro-1H-1,2,4-triazole was investigated using multiple spectroscopic techniques and molecular docking, revealing that serum albumin is a potential endogenous carrier to this compound in the human bloodstream.

https://doi.org/10.21577/0103-5053.20190033 527 downloads

In vitro Analysis of the Interaction between Human Serum Albumin and Semi-Synthetic Clerodanes
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Chaves, Otávio A.

; Echevarria, Áurea

; Esteves-Souza, Andressa

; Maciel, Maria A. M.

; Netto-Ferreira, José C.

Journal of the Brazilian Chemical Society

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sep 2018, Volume 29 N. 9 Pages 1786 - 1795

Abstract: En | Text: En | PDF: En

The interaction between HSA and two semi-synthetic potential anti-cancer agents derived from trans -dehydrocrotonin-methyl-hydrazone (MHDCTN) and phenyl-hydrazone (PHDCTN) was evaluated under physiological conditions at 296, 303 and 310 K by multi-spectroscopic techniques and molecular docking calculations. Steady state fluorescence quenching indicated a ground state association (static quenching) for both samples; however, the quenching induced by PHDCTN was not essentially static and can be accompanied by a dynamic quenching mechanism. The binding is strong (modified Stern-Volmer binding constant (Ka) ca. 105 M-1), causing a very weak perturbation on the secondary structure of the protein and there is just one main binding site for both samples (Sudlow’s site I). Molecular docking results suggested hydrogen bonding and hydrophobic interactions as the main binding forces for both samples.

https://doi.org/10.21577/0103-5053.20180054 1035 downloads

Multiple Spectroscopic and Theoretical Approaches to Study the Interaction between HSA and the Antiparasitic Drugs: Benznidazole, Metronidazole, Nifurtimox and Megazol
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Chaves, Otávio A.

; Ferreira, Romulo C.

; Silva, Lorrayne S. da

; Souza, Bruna C. E. de

; Cesarin-Sobrinho, Dari

; Netto-Ferreira, José Carlos

; Sant’Anna, Carlos M. R.

; Ferreira, Aurélio B. B.

Journal of the Brazilian Chemical Society

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jul 2018, Volume 29 N. 7 Pages 1551 - 1562

Abstract: En | Text: En | PDF: En

The interaction between four antiparasitic drugs (benznidazole (BZL), metronidazole (MTZ), nifurtimox (NFX) and megazol (MZ)) with human serum albumin (HSA), the main vehicle of biodistribution of xenobiotics, hydrophobic, small and endogenous molecules in the bloodstream, was evaluated by multiple spectroscopic techniques and theoretical calculations. In all cases quenching of the fluorescence of HSA by these drugs involve a static mechanism, due to ground state association. There is just one main binding site in HSA for these four ligands (Sudlow’s site I); binding is spontaneous, moderate, does not have any effect on the polarity around the Tyr and Trp residues and does not perturb significantly the secondary structure of the protein. Molecular docking studies suggest hydrogen bonding and hydrophobic interactions as the main binding forces, i.e., BZL associates with the Trp-214 residue via hydrophobic interactions and with Gln-220, Arg-221 and Glu-449 residues via hydrogen bonding; whereas MTZ associates with Leu-197 and Leu-480 residues via hydrophobic interactions and with Trp-214, Glu-449 and Ser-453 via hydrogen bonding. Furthermore, electrostatic interactions were also suggested for HSA:MZ and HSA:NFX.

https://doi.org/10.21577/0103-5053.20180029 638 downloads

Studies of the Interaction between BSA and a Plumeran Indole Alkaloid Isolated from the Stem Bark of Aspidosperma cylindrocarpon (Apocynaceae)
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Chaves, Otávio A.

; Teixeira, Flávia S. M.

; Guimarães, Heloisa A.

; Braz-Filho, Raimundo

; Vieira, Ivo José C.

; Sant'Anna, Carlos Mauricio R.

; Netto-Ferreira, José Carlos

; Cesarin-Sobrinho, Dari

; Ferreira, Aurélio B. B.

Journal of the Brazilian Chemical Society

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jul 2017, Volume 28 N. 7 Pages 1229 - 1236

Abstract: En | Text: En | PDF: En

Binding between bovine serum albumin (BSA) and a plumeran indole alkaloid (PIA) isolated from the stem bark of Aspidosperma cylindrocarpon (Apocynaceae) was studied by spectroscopic techniques (UV-Vis absorption, circular dichroism, steady state and time-resolved fluorescence), combined with molecular docking. Steady state and time resolved fluorescence data revealed that PIA can quench the BSA fluorescence via a static mechanism: energy transfer from BSA to PIA occurs with high probability. The binding is strong (Kb ca. 105-106 L mol-1), spontaneous (ΔG° ca. -35.7 kJ mol-1 at 310 K) and entropy-driven (ΔS° = 0.146 kJ mol-1 K-1). There is just one main binding site (n ca. 1) for the BSA:PIA interaction and the α-helix content of the albumin does not suffer significant perturbation upon PIA binding. Molecular docking results suggest site I as the main binding site to PIA, which is able to interact with the Trp-212, Arg-217, Val-342 and Pro-446 residues.

https://doi.org/10.21577/0103-5053.20160285 924 downloads

A Study of the Interaction Between trans-Dehydrocrotonin, a Bioactive Natural 19-nor-Clerodane, and Serum Albumin
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Chaves, Otávio Augusto

; Soares, Breno A.

; Maciel, Maria Aparecida M.

; Sant'Anna, Carlos Maurício R.

; Netto-Ferreira, José Carlos

; Cesarin-Sobrinho, Dari

; Ferreira, Aurélio B. B.

Journal of the Brazilian Chemical Society

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oct 2016, Volume 27 N. 10 Pages 1858 - 1865

Abstract: En | Text: En | PDF: En

The interaction between 19-nor-clerodane trans-dehydrocrotonin (from Croton cajucara Benth.) and bovine serum albumin was studied, applying spectroscopic techniques (fluorescence and circular dichroism), combined with molecular modeling. Fluorescence quenching of albumin by the nor-clerodane (kq ca. 1011 mol L-1 s-1 and Stern-Volmer, KSV, increase with temperature) indicates a combination of static and dynamic quenching mechanism. The binding constant (Kb ca. 103 mol L-1) and circular dichroism data suggest that this association is weak and causes only a moderate change in the α-helix content of the protein. Thermodynamic parameters indicate a spontaneous (Gibbs free energy, ΔGº, ca. -21.28 kJ mol-1 at 310 K) and probably entropy-driven (ΔSº = 0.072 kJ mol-1 K-1) association, typical of hydrophobic interactions. The number of binding sites (n ca. 1) indicates one main binding site and molecular modeling suggests subdomain IIIA (Sudlow's site II) as the main binding site to the nor-clerodane, which is able to make hydrophobic interactions with leucine (Leu)-24, phenylalanine (Phe)-36, valine (Val)-40 and tryptophan (Trp)-134 residues.

https://doi.org/10.5935/0103-5053.20160069 930 downloads

Leukotoxicity of Aggregatibacter actinomycetemcomitans in generalized aggressive periodontitis in Brazilians and their family members
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Silveira, Virginia Regia Souza

; Nogueira, Marcia Viana Bessa

; Nogueira, Nadia Accioly Pinto

; Lima, Vilma

; Furlaneto, Flavia Aparecida Chaves

; Rego, Rodrigo Otavio

Journal of Applied Oral Science

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sep 2013, Volume 21 N. 5 Pages 430 - 436

Abstract: En | Text: En | PDF: En

OBJECTIVE: The purpose of this study was to examine the leukotoxin promoter types of Aggregatibacter actinomycetemcomitans clones in subjects with generalized aggressive periodontitis (GAgP) and in their family members (FM). MATERIAL AND METHODS: Thirty-five patients with GAgP (33.9±7.1 years), 33 of their FM (22.8±11.4 years), and 41 patients with chronic periodontitis (CP) (44.1±9.4 years) were clinically analyzed using the plaque index, gingival index, probing depth (PD), and clinical attachment level (CAL). Subgingival biofilm samples were collected from four interproximal periodontal sites (>PD and >CAL) of each patient. The presence of A. actinomycetemcomitans and its leukotoxic clone was confirmed by polymerase chain reaction (PCR). RESULTS: A. actinomycetemcomitans was observed in 23 (51.1%) GAgP patients and 16 (30.1%) CP patients. Thirty-seven (94.8%) patients showed minimally leukotoxic strains and 2 (5.1%) showed highly leukotoxic strains. In the FM group, 10 (30.3%) had aggressive periodontitis (AgP), 12 (36.3%) had CP, 11 (33.3%) were periodontally healthy or had gingivitis, and 12.2% were A. actinomycetemcomitans positive. Greater full mouth PD and CAL were observed in GAgP patients positive for the bacteria than those negative for it (p<;0.05), and the presence of A. actinomycetemcomitans positively correlated with GAgP (Odds ratio, 3.1; confidence interval, 1.4-7.0; p=0.009). CONCLUSIONS: The presence of A. actinomycetemcomitans was associated with the clinical condition of GAgP, with most patients exhibiting a generalized form of the disease and minimally leukotoxic clones. Most of the relatives of GAgP patients presented either CP or AgP.

https://doi.org/10.1590/1679-775720130252 1888 downloads

10.

IV Diretriz Brasileira sobre Dislipidemias e Prevenção da Aterosclerose: Departamento de Aterosclerose da Sociedade Brasileira de Cardiologia
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Sposito, Andrei C.

; Caramelli, Bruno

; Fonseca, Francisco A. H.

; Bertolami, Marcelo C.

; Afiune Neto, Abrahão

; Souza, Aguinaldo David

; Lottenberg, Ana Maria Pitta

; Chacra, Ana Paula

; Faludi, André A.

; Loures-Vale, Andréia A.

; Carvalho, Antônio Carlos

; Duncan, Bruce

; Gelonese, Bruno

; Polanczyk, Carisi

; Rodrigues Sobrinho, Carlos Roberto M.

; Scherr, Carlos

; Karla, Cynthia

; Armaganijan, Dikran

; Moriguchi, Emílio

; Saraiva, Francisco

; Pichetti, Geraldo

; Xavier, Hermes Toros

; Chaves, Hilton

; Borges, Jairo Lins

; Diament, Jayme

; Guimarães, Jorge Ilha

; Nicolau, José Carlos

; Santos, José Ernesto dos

; Lima, José Jayme Galvão de

; Vieira, José Luiz

; Novazzi, José Paulo

; Faria Neto, José Rocha

; Torres, Kerginaldo P.

; Pinto, Leonor de Almeida

; Bricarello, Liliana

; Bodanese, Luiz Carlos

; Introcaso, Luiz

; Malachias, Marcus Vinícius Bolívar

; Izar, Maria Cristina

; Magalhães, Maria Eliane C.

; Schmidt, Maria Inês

; Scartezini, Mariléia

; Nobre, Moacir

; Foppa, Murilo

; Forti, Neusa A.

; Berwanger, Otávio

; Gebara, Otávio C. E.

; Coelho, Otávio Rizzi

; Maranhão, Raul C.

; Santos Fº, Raul Dias dos

; Costa, Rosana Perim

; Barreto, Sandhi

; Kaiser, Sérgio

; Ihara, Silvia

; Carvalho, Tales de

; Martinez, Tania Leme Rocha

; Relvas, Waldir Gabriel Miranda

; Salgado, Wilson

Arquivos Brasileiros de Cardiologia

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apr 2007, Volume 88 Pages 2 - 19

Abstract: Pt | Text: Pt | PDF: Pt

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