title: Antioxidant effects of JM-20 on rat brain mitochondria and synaptosomes: mitoprotection against Ca²⁺-induced mitochondrial impairment.
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.
authors.affiliation: Centro de Investigación y Desarrollo de Medicamentos, Ave 26, No. 1605 Boyeros y Puentes Grandes, CP 10600, La Habana, Cuba.
authors.forename: Yanier
authors.initials: Y
authors.lastname: Nuñez-Figueredo
authors.affiliation: 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. Electronic address: gilbertopardo@infomed.sld.cu.
authors.forename: Gilberto L
authors.initials: GL
authors.lastname: Pardo-Andreu
authors.affiliation: Centro de Investigación y Desarrollo de Medicamentos, Ave 26, No. 1605 Boyeros y Puentes Grandes, CP 10600, La Habana, Cuba.
authors.forename: Jeney
authors.initials: J
authors.lastname: Ramírez-Sánchez
authors.affiliation: Centro de Investigación y Desarrollo de Medicamentos, Ave 26, No. 1605 Boyeros y Puentes Grandes, CP 10600, La Habana, Cuba.
authors.forename: René
authors.initials: R
authors.lastname: Delgado-Hernández
authors.affiliation: 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.
authors.forename: Estael
authors.initials: E
authors.lastname: Ochoa-Rodríguez
authors.affiliation: 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.
authors.forename: Yamila
authors.initials: Y
authors.lastname: Verdecia-Reyes
authors.affiliation: 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.
authors.forename: Zeki
authors.initials: Z
authors.lastname: Naal
authors.affiliation: 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.
authors.forename: Alexandre Pastoris
authors.initials: AP
authors.lastname: Muller
authors.affiliation: 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.
authors.forename: Luis Valmor
authors.initials: LV
authors.lastname: Portela
authors.affiliation: 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.
authors.forename: Diogo O
authors.initials: DO
authors.lastname: Souza
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001569:Benzodiazepines / Q000494:pharmacology*; D002118:Calcium / Q000633:toxicity*; D002374:Catalase / Q000494:pharmacology; D045304:Cytochromes c / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008297:Male; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D009525:Niacin / Q000031:analogs & derivatives* / Q000494:pharmacology; D009840:Oligomycins / Q000494:pharmacology; D010100:Oxygen / Q000378:metabolism; D016548:Prosencephalon / Q000648:ultrastructure*; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D013574:Synaptosomes / Q000187:drug effects*
chemical_list: C000591456:3-ethoxycarbonyl-2-methyl-4-(2-nitrophenyl)-4,11-dihydro-1H-pyrido(2,3-b)(1,5)benzodiazepine; D000975:Antioxidants; D004791:Enzyme Inhibitors; D009840:Oligomycins; D017382:Reactive Oxygen Species; D013481:Superoxides; D001569:Benzodiazepines; D009525:Niacin; D000255:Adenosine Triphosphate; D045304:Cytochromes c; D002374:Catalase; D010100:Oxygen; D002118:Calcium
keywords: Antioxidant; Brain ischemia; JM-20; Mitochondria; Neuroprotector; Synaptosomes