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González-Durruthy M, Alberici LC, Curti C, Naal Z, Atique-Sawazaki DT, Vázquez-Naya JM, González-Díaz H, Munteanu CR. Experimental-Computational Study of Carbon Nanotube Effects on Mitochondrial Respiration: In Silico Nano-QSPR Machine Learning Models Based on New Raman Spectra Transform with Markov-Shannon Entropy Invariants. J Chem Inf Model 2017; 57:1029-1044. [PMID: 28414908 DOI: 10.1021/acs.jcim.6b00458] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The study of selective toxicity of carbon nanotubes (CNTs) on mitochondria (CNT-mitotoxicity) is of major interest for future biomedical applications. In the current work, the mitochondrial oxygen consumption (E3) is measured under three experimental conditions by exposure to pristine and oxidized CNTs (hydroxylated and carboxylated). Respiratory functional assays showed that the information on the CNT Raman spectroscopy could be useful to predict structural parameters of mitotoxicity induced by CNTs. The in vitro functional assays show that the mitochondrial oxidative phosphorylation by ATP-synthase (or state V3 of respiration) was not perturbed in isolated rat-liver mitochondria. For the first time a star graph (SG) transform of the CNT Raman spectra is proposed in order to obtain the raw information for a nano-QSPR model. Box-Jenkins and perturbation theory operators are used for the SG Shannon entropies. A modified RRegrs methodology is employed to test four regression methods such as multiple linear regression (LM), partial least squares regression (PLS), neural networks regression (NN), and random forest (RF). RF provides the best models to predict the mitochondrial oxygen consumption in the presence of specific CNTs with R2 of 0.998-0.999 and RMSE of 0.0068-0.0133 (training and test subsets). This work is aimed at demonstrating that the SG transform of Raman spectra is useful to encode CNT information, similarly to the SG transform of the blood proteome spectra in cancer or electroencephalograms in epilepsy and also as a prospective chemoinformatics tool for nanorisk assessment. All data files and R object models are available at https://dx.doi.org/10.6084/m9.figshare.3472349 .
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Affiliation(s)
| | | | | | | | | | - José M Vázquez-Naya
- RNASA-IMEDIR, Computer Science Faculty, University of A Coruna , Campus de Elviña s/n, 15071 A Coruña, Spain
| | - Humberto González-Díaz
- Department of Organic Chemistry II, Faculty of Science and Technology, University of the Basque Country UPV/EHU , 48940, Leioa, Bizkaia, Spain.,IKERBASQUE, Basque Foundation for Science , 48011, Bilbao, Bizkaia, Spain
| | - Cristian R Munteanu
- RNASA-IMEDIR, Computer Science Faculty, University of A Coruna , Campus de Elviña s/n, 15071 A Coruña, Spain.,Instituto de Investigación Biomédica de A Coruña (INIBIC), Complexo Hospitalario Universitario de A Coruña (CHUAC) , A Coruña, 15006, Spain
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2
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Possato B, Deflon VM, Naal Z, Formiga ALB, Nikolaou S. An extended π-system and enhanced electronic delocalization on symmetric [Ru3O(CH3COO)6(L)3]n complexes combined with azanaphthalene ligands. Dalton Trans 2017; 46:7926-7938. [DOI: 10.1039/c7dt01152k] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The electronic density of the metallic core relies on the basicity of the ligands through σ-donation, while part of this electronic density is delocalized to the periphery through π-interactions.
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Affiliation(s)
- Bruna Possato
- Departamento de Química – Faculdade de Filosofia
- Ciências e Letras de Ribeirão Preto - Universidade de São Paulo – Av. Bandeirantes
- Ribeirão Preto
- Brazil
| | - Victor M. Deflon
- Departamento de Química e Física Molecular - Instituto de Química de São Carlos - Universidade de São Paulo - Av. Trabalhador São Carlense
- São Carlos
- Brazil
| | - Zeki Naal
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto - Universidade de São Paulo – Av. do Café s/no
- Ribeirão Preto
- Brazil
| | | | - Sofia Nikolaou
- Departamento de Química – Faculdade de Filosofia
- Ciências e Letras de Ribeirão Preto - Universidade de São Paulo – Av. Bandeirantes
- Ribeirão Preto
- Brazil
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3
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González-Durruthy M, Monserrat JM, Alberici LC, Naal Z, Curti C, González-Díaz H. Mitoprotective activity of oxidized carbon nanotubes against mitochondrial swelling induced in multiple experimental conditions and predictions with new expected-value perturbation theory. RSC Adv 2015. [DOI: 10.1039/c5ra14435c] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Mitochondrial Permeability Transition Pore (MPTP) is involved in neurodegeneration, hepatotoxicity, cardiac necrosis, nervous and muscular dystrophies.
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Affiliation(s)
- Michael González-Durruthy
- Institute of Biological Science (ICB)
- Universidade Federal do Rio Grande (FURG)
- Porto Alegre
- Brazil
- ICB-FURG Post-graduate Program Physiological Sciences – Comparative Animal Physiology, Brazil
| | - Jose Maria Monserrat
- Institute of Biological Science (ICB)
- Universidade Federal do Rio Grande (FURG)
- Porto Alegre
- Brazil
- ICB-FURG Post-graduate Program Physiological Sciences – Comparative Animal Physiology, Brazil
| | - Luciane C. Alberici
- Department of Physic-Chemistry
- Faculty of Pharmacy of Ribeirão Preto
- University of São Paulo (USP)
- 14040-903 Ribeirão Preto
- Brazil
| | - Zeki Naal
- Department of Physic-Chemistry
- Faculty of Pharmacy of Ribeirão Preto
- University of São Paulo (USP)
- 14040-903 Ribeirão Preto
- Brazil
| | - Carlos Curti
- Department of Physic-Chemistry
- Faculty of Pharmacy of Ribeirão Preto
- University of São Paulo (USP)
- 14040-903 Ribeirão Preto
- Brazil
| | - Humberto González-Díaz
- Department of Organic Chemistry II
- Faculty of Science and Technology
- University of the Basque Country UPV/EHU
- Leioa
- Spain
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Nuñez-Figueredo Y, Pardo-Andreu GL, Ramírez-Sánchez J, Delgado-Hernández R, Ochoa-Rodríguez E, Verdecia-Reyes Y, Naal Z, Muller AP, Portela LV, Souza DO. Antioxidant effects of JM-20 on rat brain mitochondria and synaptosomes: mitoprotection against Ca²⁺-induced mitochondrial impairment. Brain Res Bull 2014; 109:68-76. [PMID: 25305343 DOI: 10.1016/j.brainresbull.2014.10.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Revised: 09/25/2014] [Accepted: 10/01/2014] [Indexed: 12/31/2022]
Abstract
Because mitochondrial oxidative stress and impairment are important mediators of neuronal damage in neurodegenerative diseases and in brain ischemia/reperfusion, in the present study, we evaluated the antioxidant and mitoprotective effect of a new promising neuroprotective molecule, JM-20, in mitochondria and synaptosomes isolated from rat brains. JM-20 inhibited succinate-mediated H₂O₂ generation in both mitochondria and synaptosomes incubated in depolarized (high K(+)) medium at extremely low micromolar concentration and with identical IC₅₀ values of 0.91 μM. JM-20 also repressed glucose-induced H₂O₂ generation stimulated by rotenone or by antimycin A in synaptosomes incubated in high sodium-polarized medium at extremely low IC₅₀ values of 0.395 μM and 2.452 μM, respectively. JM-20 was unable to react directly with H₂O₂ or with superoxide anion radicals but displayed a cathodic reduction peak at -0.71V, which is close to that of oxygen (-0.8V), indicating high electron affinity. JM-20 also inhibited uncoupled respiration in mitochondria or synaptosomes and was a more effective inhibitor in the presence of the respiratory substrates glutamate/malate than in the presence of succinate. JM-20 also prevented Ca(2+)-induced mitochondrial permeability transition pore opening, membrane potential dissipation and cytochrome c release, which are key pathogenic events during stroke. This molecule also prevented Ca(2+) influx into synaptosomes and mitochondria; the former effect was a consequence of the latter because JM-20 inhibition followed the patterns of carbonyl cyanide p-trifluoromethoxyphenyl hydrazone (FCCP), which is a classic mitochondrial uncoupler. Because the mitochondrion is considered an important source and target of neuronal cell death signaling after an ischemic insult, the antioxidant and protective effects of JM-20 against the deleterious effects of Ca(2+) observed at the mitochondrial level in this study may endow this molecule with the ability to succeed in mitochondrion-targeted strategies to combat ischemic brain damage.
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Affiliation(s)
- Yanier Nuñez-Figueredo
- Centro de Investigación y Desarrollo de Medicamentos, Ave 26, No. 1605 Boyeros y Puentes Grandes, CP 10600, La Habana, Cuba
| | - Gilberto L Pardo-Andreu
- Centro de Estudio para las Investigaciones y Evaluaciones Biológicas, Instituto de Farmacia y Alimentos, Universidad de La Habana, Ave 23, No. 21425 e/214 y 222, La Coronela, La Lisa, CP 13600, La Habana, Cuba.
| | - Jeney Ramírez-Sánchez
- Centro de Investigación y Desarrollo de Medicamentos, Ave 26, No. 1605 Boyeros y Puentes Grandes, CP 10600, La Habana, Cuba
| | - René Delgado-Hernández
- Centro de Investigación y Desarrollo de Medicamentos, Ave 26, No. 1605 Boyeros y Puentes Grandes, CP 10600, La Habana, Cuba
| | - Estael Ochoa-Rodríguez
- Laboratorio de Síntesis Orgánica de La Facultad de Química de La Universidad de La Habana, Zapata s/n entre G y Carlitos Aguirre, Vedado Plaza de la Revolución, CP 10400, La Habana, Cuba
| | - Yamila Verdecia-Reyes
- Laboratorio de Síntesis Orgánica de La Facultad de Química de La Universidad de La Habana, Zapata s/n entre G y Carlitos Aguirre, Vedado Plaza de la Revolución, CP 10400, La Habana, Cuba
| | - Zeki Naal
- Department of Physics and Chemistry, Faculty of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ave. Café s/n, 14040-903 Ribeirão Preto, SP, Brazil
| | - Alexandre Pastoris Muller
- Departamento de Bioquímica, PPG em Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600 anexo, Porto Alegre 90035-003, RS, Brazil
| | - Luis Valmor Portela
- Departamento de Bioquímica, PPG em Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600 anexo, Porto Alegre 90035-003, RS, Brazil
| | - Diogo O Souza
- Departamento de Bioquímica, PPG em Bioquímica, PPG em Educação em Ciência, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600 anexo, Porto Alegre 90035-003, RS, Brazil
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Amaral MF, Deliberto LA, de Souza CR, Naal RM, Naal Z, Clososki GC. Synthesis, photophysical, and electrochemical properties of 2,5-diaryl-indolizines. Tetrahedron 2014. [DOI: 10.1016/j.tet.2013.11.105] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Kabeya LM, Fuzissaki CN, Taleb-Contini SH, da C. Ferreira AM, Naal Z, Santos EO, Figueiredo-Rinhel AS, Azzolini AEC, Vermelho RB, Malvezzi A, -do Amaral AT, Lopes JLC, Lucisano-Valim YM. 7-Hydroxycoumarin modulates the oxidative metabolism, degranulation and microbial killing of human neutrophils. Chem Biol Interact 2013; 206:63-75. [DOI: 10.1016/j.cbi.2013.08.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Revised: 07/14/2013] [Accepted: 08/17/2013] [Indexed: 11/30/2022]
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Nuñez-Figueredo Y, García-Pupo L, Ramírez-Sánchez J, Alcántara-Isaac Y, Cuesta-Rubio O, Hernández R, Naal Z, Curti C, Pardo-Andreu G. Neuroprotective Action and Free Radical Scavenging Activity of Guttiferone-A, a Naturally Occurring Prenylated Benzophenone. ACTA ACUST UNITED AC 2012; 62:583-9. [DOI: 10.1055/s-0032-1327612] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
| | - L. García-Pupo
- Centro de Investigación y Desarrollo de Medicamentos, La Habana, Cuba
| | | | | | - O. Cuesta-Rubio
- Departamento de Farmacia, Instituto de Farmacia y Alimentos, Universidad de La Habana, La Habana, Cuba
| | - R. Hernández
- Centro de Investigación y Desarrollo de Medicamentos, La Habana, Cuba
| | - Z. Naal
- Departamento de Física y Química, Facultad de Ciencias Farmacéuticas de Ribeirao Preto, Universidad de Sao Paulo, Ribeirao Preto, SP, Brasil
| | - C. Curti
- Departamento de Física y Química, Facultad de Ciencias Farmacéuticas de Ribeirao Preto, Universidad de Sao Paulo, Ribeirao Preto, SP, Brasil
| | - G. Pardo-Andreu
- Centro de Estudio para las Investigaciones y Evaluaciones Biológicas, Instituto de Farmacia y Alimentos, Universidad de La Habana, Ciudad Habana, Cuba
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Vessecchi R, Naal Z, Lopes JNC, Galembeck SE, Lopes NP. Generation of naphthoquinone radical anions by electrospray ionization: solution, gas-phase, and computational chemistry studies. J Phys Chem A 2011; 115:5453-60. [PMID: 21561138 DOI: 10.1021/jp202322n] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Radical anions are present in several chemical processes, and understanding the reactivity of these species may be described by their thermodynamic properties. Over the last years, the formation of radical ions in the gas phase has been an important issue concerning electrospray ionization mass spectrometry studies. In this work, we report on the generation of radical anions of quinonoid compounds (Q) by electrospray ionization mass spectrometry. The balance between radical anion formation and the deprotonated molecule is also analyzed by influence of the experimental parameters (gas-phase acidity, electron affinity, and reduction potential) and solvent system employed. The gas-phase parameters for formation of radical species and deprotonated species were achieved on the basis of computational thermochemistry. The solution effects on the formation of radical anion (Q(•-)) and dianion (Q(2-)) were evaluated on the basis of cyclic voltammetry analysis and the reduction potentials compared with calculated electron affinities. The occurrence of unexpected ions [Q+15](-) was described as being a reaction between the solvent system and the radical anion, Q(•-). The gas-phase chemistry of the electrosprayed radical anions was obtained by collisional-induced dissociation and compared to the relative energy calculations. These results are important for understanding the formation and reactivity of radical anions and to establish their correlation with the reducing properties by electrospray ionization analyses.
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Affiliation(s)
- Ricardo Vessecchi
- Departamento de Química, Faculdade de Filosofia Ciências e Letras, Universidade de São Paulo, Ribeirão Preto, SP 14040-901, Brasil.
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Figueredo YN, García-Pupo L, Cuesta Rubio O, Delgado Hernández R, Naal Z, Curti C, Pardo Andreu GL. A strong protective action of guttiferone-A, a naturally occurring prenylated benzophenone, against iron-induced neuronal cell damage. J Pharmacol Sci 2011; 116:36-46. [PMID: 21512303 DOI: 10.1254/jphs.10273fp] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
Guttiferone-A (GA) is a natural occurring polyisoprenylated benzophenone with several reported pharmacological actions. We have assessed the protective action of GA on iron-induced neuronal cell damage by employing the PC12 cell line and primary culture of rat cortical neurons (PCRCN). A strong protection by GA, assessed by the 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carbox-anilide (XTT) assay, was revealed, with IC(50) values <1 µM. GA also inhibited Fe(3+)-ascorbate reduction, iron-induced oxidative degradation of 2-deoxiribose, and iron-induced lipid peroxidation in rat brain homogenate, as well as stimulated oxygen consumption by Fe(2+) autoxidation. Absorption spectra and cyclic voltammograms of GA-Fe(2+)/Fe(3+) complexes suggest the formation of a transient charge transfer complex between Fe(2+) and GA, accelerating Fe(2+) oxidation. The more stable Fe(3+) complex with GA would be unable to participate in Fenton-Haber Weiss-type reactions and the propagation phase of lipid peroxidation. The results show a potential of GA against neuronal diseases associated with iron-induced oxidative stress.
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Affiliation(s)
- Yanier Núñez Figueredo
- Laboratorio de Farmacología Molecular, Centro de Investigación y Desarrollo de Medicamentos, Ciudad Habana, Cuba
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Pardo-Andreu GL, Sánchez-Baldoquín C, Avila-González R, Yamamoto ETS, Revilla A, Uyemura SA, Naal Z, Delgado R, Curti C. Interaction of Vimang (Mangifera indica L. extract) with Fe(III) improves its antioxidant and cytoprotecting activity. Pharmacol Res 2006; 54:389-95. [PMID: 17000117 DOI: 10.1016/j.phrs.2006.08.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2006] [Revised: 07/11/2006] [Accepted: 08/03/2006] [Indexed: 11/27/2022]
Abstract
A standard aqueous stem bark extract from selected species of Mangifera indica L. (Anacardiaceae)--Vimang, whose major polyphenolic component is mangiferin, displays potent in vitro and in vivo antioxidant activity. The present study provides evidence that the Vimang-Fe(III) mixture is more effective at scavenging 2,2-diphenyl-1-picrylhydrazyl (DPPH) and superoxide radicals, as well as in protecting against t-butyl hydroperoxide-induced mitochondrial lipid peroxidation and hypoxia/reoxygenation-induced hepatocytes injury, compared to Vimang alone. Voltammetric assays demonstrated that Vimang, in line with the high mangiferin content of the extract, behaves electrochemically like mangiferin, as well as interacts with Fe(III) in close similarity with mangiferin's interaction with the cation. These results justify the high efficiency of Vimang as an agent protecting from iron-induced oxidative damage. We propose Vimang as a potential therapy against the deleterious action of reactive oxygen species generated during iron-overload, such as that occurring in diseases like beta-thalassemia, Friedreich's ataxia and haemochromatosis.
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Affiliation(s)
- Gilberto L Pardo-Andreu
- Departamento de Investigaciones Biomédicas, Centro de Química Farmacéutica, Calle 200, Esq. 21, Playa, Ciudad de La Habana, Cuba.
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Pardo-Andreu GL, Cavalheiro RA, Dorta DJ, Naal Z, Delgado R, Vercesi AE, Curti C. Fe(III) Shifts the Mitochondria Permeability Transition-Eliciting Capacity of Mangiferin to Protection of Organelle. J Pharmacol Exp Ther 2006; 320:646-53. [PMID: 17068204 DOI: 10.1124/jpet.106.112003] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mangiferin acts as a strong antioxidant on mitochondria. However, when in the presence of Ca(2+), mangiferin elicits mitochondrial permeability transition (MPT), as evidenced by cyclosporin A-sensitive mitochondrial swelling. We now provide evidence, by means of electrochemical and UV-visible spectroscopical analysis, that Fe(III) coordinates with mangiferin. The resulting mangiferin-Fe(III) complex does not elicit MPT and prevents MPT by scavenging reactive oxygen species. Indeed, the complex protects mitochondrial membrane protein thiols and glutathione from oxidation. Fe(III) also significantly increases the ability of mangiferin to scavenge the 2,2-diphenyl-1-picrylhydrazyl radical, as well as to display antioxidant activity toward antimycin A-induced H(2)O(2) production and t-butyl hydroperoxide-promoted membrane lipid peroxidation in mitochondria. We postulate that coordination with Fe(III) constitutes a potential protective mechanism toward the prooxidant action of mangiferin and other catechol-containing antioxidants regarding MPT induction. Potential therapeutic relevance of this finding for conditions of pathological iron overload is discussed.
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Affiliation(s)
- Gilberto L Pardo-Andreu
- Departamento de Investigaciones Biomédicas, Centro de Química Farmacéutica, Calle 200, Esq. 21, Playa, Ciudad de La Habana, Cuba.
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Choi PS, Naal Z, Moore C, Casado-Rivera E, Abruña HD, Helmann JD, Shapleigh JP. Assessing the impact of denitrifier-produced nitric oxide on other bacteria. Appl Environ Microbiol 2006; 72:2200-5. [PMID: 16517672 PMCID: PMC1393196 DOI: 10.1128/aem.72.3.2200-2205.2006] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2005] [Accepted: 01/09/2006] [Indexed: 11/20/2022] Open
Abstract
A series of experiments was undertaken to learn more about the impact on other bacteria of nitric oxide (NO) produced during denitrification. The denitrifier Rhodobacter sphaeroides 2.4.3 was chosen as a denitrifier for these experiments. To learn more about NO production by this bacterium, NO levels during denitrification were measured by using differential mass spectrometry. This revealed that NO levels produced during nitrate respiration by this bacterium were in the low muM range. This concentration of NO is higher than that previously measured in denitrifiers, including Achromobacter cycloclastes and Paracoccus denitrificans. Therefore, both 2.4.3 and A. cycloclastes were used in this work to compare the effects of various NO levels on nondenitrifying bacteria. By use of bacterial overlays, it was found that the NO generated by A. cycloclastes and 2.4.3 cells during denitrification inhibited the growth of both Bacillus subtilis and R. sphaeroides 2.4.1 but that R. sphaeroides 2.4.3 caused larger zones of inhibition in the overlays than A. cycloclastes. Both R. sphaeroides 2.4.3 and A. cycloclastes induced the expression of the NO stress response gene hmp in B. subtilis. Taken together, these results indicate that there is variability in the NO concentrations produced by denitrifiers, but, irrespective of the NO levels produced, microbes in the surrounding environment were responsive to the NO produced during denitrification.
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Affiliation(s)
- Peter S Choi
- Cornell University, Department of Microbiology, Wing Hall, Ithaca, NY 14853, USA
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Guaratini T, Vessecchi RL, Lavarda FC, Maia Campos PMBG, Naal Z, Gates PJ, Lopes NP. New chemical evidence for the ability to generate radical molecular ions of polyenes from ESI and HR-MALDI mass spectrometry. Analyst 2004; 129:1223-6. [PMID: 15565222 DOI: 10.1039/b412154f] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report here new chemical evidence for the generation of radical molecular ions of compounds with a conjugated pi-system (polyene) in ESI and HR-MALDI mass spectrometry. The oxidation potential of the neutral polyenes was calculated by cyclic-voltammetry and the results compared with those previously published for other complex conjugated compounds that have also been shown to form M*+ in ESI-MS. This study clearly demonstrates the correlation between the oxidation potential and the formation of the M*+ for the polyenes studied.
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Affiliation(s)
- Thais Guaratini
- Universidade de São Paulo, Faculdade de Ciências Farmaceuticas de Ribeirão Preto, Via do Café S/N, CEP 14040-903, Ribeirão Preto-SP, Brazil
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Naal Z, Park JH, Bernhard S, Shapleigh JP, Batt CA, Abruña HD. Amperometric TNT biosensor based on the oriented immobilization of a nitroreductase maltose binding protein fusion. Anal Chem 2002; 74:140-8. [PMID: 11795782 DOI: 10.1021/ac010596o] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The preparation and characterization of an amperometric 2,4,6-trinitrotoluene (TNT) biosensor based on the surface immobilization of a maltose binding protein (MBP) nitroreductase (NR) fusion (MBP-NR) onto an electrode modified with an electropolymerized film of N-(3-pyrrol-1-ylpropyl)-4,4'-bipyridine (PPB) are described. The MBP domain of MBP-NR exhibits a high and specific affinity toward electropolymerized films of PPB with the immobilized enzyme retaining virtually all of its enzymatic activity. Under similar conditions, the wild-type NR enzyme (i.e., without the MBP domain) loses most of its enzymatic activity. The kinetics of the catalytic reaction between the biosensor and TNT and 2,4-dinitrotoluene (DNT) were characterized using rotated disk electrode and cyclic voltammetry techniques, and values of 1.4 x 10(4) and 7.1 x 10(4) M(-1) s(-1) were obtained for TNT and DNT, respectively. The apparent Michaelis-Menten constants (KM) for MBP-NR in solution and on the surface, using TNT as substrate, were determined to be 27 and 95 microM, respectively. The corresponding value for "wild-type" NR in solution containing TNT was 78 microM, which is very close to the value obtained for MBP-NR on the surface. The limits of detection for both TNT and DNT were estimated to be 2 microM, and the sensitivities were determined to be 205 and 222 nA/microM, respectively.
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Affiliation(s)
- Z Naal
- Department of Chemistry & Chemical Biology, Cornell University, Ithaca, New York 14853, USA
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