Antioxidant activity in heterogeneous and homogeneous system of the resinous exudates from Heliotropium stenophylum and H. sinuatum and of 3-O-methylgalangin their main component / Actividad antioxidante en sistema heterogéneo y homogéneo de los exudados resinosos de Heliotropium stenophyllum y H. sinuatum y de 3-O-methylgalangina su componente mayoritario

The antioxidant activity of resinous extracts obtained from H. stenophylum and H. sinuatum species, was evaluated through ORAC index (Oxygen Radical Absorbance Capacity) in water phase and in presence of Triton X-100 micelles, using as test molecules to pyrogallol red (PGR) and evaluating their reduction by the action of peroxyl radicals obtained from thermolysis of AAPH. The results show that these extracts protect to PGR of the action of the radicals. This protection is reduced drastically in the presence of Triton X-100 micelles. The same effect was observed with the main flavonoid of these extracts (3-O-methylgalangin). These results show the importance of the media of reaction of pure compounds and/or extracts at the time of to take into account their use as antioxidants.

La actividad antioxidante de exudados resinosos obtenidos desde las especies H. stenophylum y H. sinuatum, fue evaluada a través del ensayo ORAC (Oxygen Radical Absorbance Capacity) en fase acuosa y en presencia de micelas de Triton X-100, usando como molécula prueba a pirogalol rojo (PGR) y evaluando su reducción frente a la acción de radicales peróxidos obtenidos desde la termólisis de AAPH. Los resultados muestran que estos extractos protegen al PGR de la acción de los radicales. Esta protección es reducida drásticamente en presencia de micelas de Tritón X-100. El mismo efecto fue observado con el flavonoide mayoritario de estos extractos (3-O-metilgalangina). Estos resultados muestran la importancia de considerar el medio de reacción de compuestos puros y/o extractos al momento de tomar en cuenta su uso como antioxidantes.

Mecanismos moleculares da ação tóxica pró-oxidante de 1,4-diamino-2-butanona, um análogo de putrescina, sobre células de mamíferos e Trypanosoma cruzi / The Molecular mechanisms of pro-oxidant activity of 1,4-diamino-2-butanone, a putrescine analogue, to mammalian cells and Trypanosoma cruzi

Compostos α-aminocarbonilícos como ácido 5-aminolevulínico (ALA) e aminoacetona (AA) apresentam um grande potencial pró-oxidante, pois sofrem reações de enolização e subseqüente oxidação aeróbica, com a formação de espécies radicalares de oxigênio, íons NH4+ e α-oxoaldeídos potencialmente citotóxicos. A α-aminocetona 1,4-diamino-2-butanona (DAB), um análogo da putrescina, é um agente microbicida de vários parasitas incluindo Trypanosoma cruzi. Acredita-se que o mecanismo de morte desencadeado por DAB nos parasitas seja por meio da inibição competitiva da ornitina descarboxilase (ODC), importante enzima do metabolismo de poliaminas, muito embora tenha sido observado de igual forma danos oxidativos nestes parasitas quando tratados com DAB. O objetivo deste trabalho é esclarecer o mecanismo de oxidação química de DAB e sua ação pró-oxidante à cultura de células de mamíferos (LLC-MK2 e RKO), assim como sua atividade microbicida contra tripomastigotas de Trypanosoma cruzi. Demonstramos aqui que DAB, quimicamente similar ao ALA e AA, sofre reação de oxidação catalisada por íons fosfato, e por íons de metais de transição como Fe(II) e Cu(II), resultando na formação de radicais de oxigênio, H2O2, NH4+, 2-oxo-4-aminobutanal como produto principal da oxidação de DAB e de compostos ciclicos de caracter pirrólico. Danos oxidativos observados em ferritina, apotransferrina e liposomos de cardiolipina e fosfatidilcolina (20:80) contribuem para a nossa hipótese de ação pró-oxidante de DAB. O tratamento de células de mamíferos das linhagens LLC-MK2 (IC50 1,5 mM, tratamento de 24 h) e RKO (IC50 0,3 mM, tratamento de 24 h) com DAB levou à alteração do balanço redox celular, à ativação de resposta antioxidante e ao desencadeamento de morte celular via apoptose e parada de ciclo celular. Em culturas de tripomastigotas de T. cruzi o tratamento com DAB culminou na redução da motilitidade e viabilidade destes parasitas (IC50 0,2 mM, tratamento de 4 h), assim como depleção do...

α-Aminocarbonyl componds such as 5-aminolevunilic acid (ALA) and aminoacetone (AA) have been shown to exhibit pro-oxidant properties. These compounds undergo phosphate-catalyzed enolization in physiological pH and subsequent aerobic oxidation, yielding reactive oxygen species, NH4+ ions and an α-oxoaldehyde highly cytotoxic. The α-aminoketone 1,4-diamino-2-butanone (DAB) is a putrescine analogue and a microbicidal agent to various parasites including Trypanosoma cruzi. The mechanism of DAB toxicity to these parasites is attributed to DAB competitive inhibition of ornithine decarboxylase (ODC), a key enzyme on polyamine biosynthesis, although it has also been shown DAB isto implicated in oxidative damage to these parasites. Our aim is to clarify the mechanism of DAB aerobic oxidation and of its putative pro-oxidant activity to mammalian cell cultures (LLC-MK2 and RKO cell linages) and to Trypanosoma cruzi trypomastigotes. Here we show that, similar to ALA and AA, DAB undergoes aerobic oxidation in presence of phosphate ions and of transition metal ions such as Fe(II) and Cu(II), yielding oxygen radicals, H2O2, NH4+ and 2-oxo-4-aminobutanal accompanied by its condensation cyclic products displaying pyrrolic characteristics. Oxidative alterations to ferritin, apotransferrin and liposomes of cardiolipin and phosphatidylcholine (20:80) were observed under DAB treatment strongly supporting our hypothesis of DAB pro-oxidative activity. DAB treatment of mammalian cultured cells LLC-MK2 (IC50 1.5 mM, 24 h incubation) and RKO (IC50 0.3 mM, 24 h incubation) resulted in redox imbalance, induction of antioxidant response, activation of apoptosis pathway and cell cycle arrest. DAB is shown here to trigger Trypanosoma cruzi trypomastigotes decreased parasite motility and viability (IC50 0.2 mM, 4 h incubation), as well as redox thiol imbalance parallel to increase TcSOD activity. In addition, DAB efficiently hampered host cell (LLC-MK2) invasion by trypomastigotes...

Biologically active free radicals and their scavengers: a review

Free radicals are continuously generated in almost all aerobic cells. If they are not scavenged by the integrated comprehensive array of endogenous antioxidant mechanisms, tissue damage occurs. It has been widely accepted that free radicals are implicated in a large number of medical disorders including cancer, inflammation, atherosclerosis, coronary heart disease and diabetes. Low levels of one or more of the essential antioxidants have been shown to be associated with many of these disorders. Thus, in such cases, the administration of exogenous antioxidants seems to be salutary. Nowadays, a great deal of effort being expended to find effective antioxidants for the treatment or prevention of free radical-mediated deleterious effects. The effectiveness of currently used exogenous antioxidant therapy stems most probably from the augmentation of the endogenous free radical scavengers such as enzymes [superoxide dismutase and selenium-dependent glutathione peroxidase] and vitamins [alpha-tocopherol, ascorbic acid and beta-carotene]. Many drugs have been also found to possess free radical scavenging activity. Among these are probucol, gliclazide, allopurinol and some calcium channel blockers. The free radical scavenging property exerted by drugs might account, at least in part, for some of their beneficial pharmacological actions

Especies reactivas de oxígeno en el espermatozoide / Oxygen reactive species in the spermatozoa

Los radicales libres de oxígeno son especies químicas de este elemento formadas mediante reacciones enzimáticas y no enzimáticas y han sido implicados en muchos procesos patológicos y fisiológicos. Las especies químicas de oxígeno más reactivas son el peróxido de hidrógeno y los radicales libres anión superóxido e hidróxilo, siendo este último el más reactivo. El espermatozoide de mamíferos, incluyendo el del humano producen radicales libres de oxígeno y peróxido de hidrógeno; sin embargo esta última célula normalmente posee mecanismos enzimáticos para protegerse del posible daño que pudiera causarle estos agentes tóxicos. A pesar de ello, el espermatozoide es bastante suceptible al "estrés oxidativo", probablemente debido a su alto contenido de ácidos grasos insaturados. Este hecho puede tener importancia en la patología de ciertos tipos de infertilidad masculina como lo es la oligozoospermia, ya que se ha demostrado que en estos casos, se presenta una producción incontrolada de especies reactivas de oxígeno por parte del espermatozoide