RESUMEN
The prenylated flavanone 2'-4'-dihidroxy-5'-(1" '-dimethylallyl)-6-prenylpinocembrin) (6PP), isolated from the roots of Dalea elegans, shows antimicrobial activity. The aim of this study was to evaluate mitochondrial toxicity and antioxidant properties of 6PP. Addition of micromolar concentrations of 6PP to rat liver mitochondria, stimulated O2 uptake in state 4 and inhibited it in state 3 when malate-glutamate was the respiratory substrate, and inhibited O2 uptake in state 3 when succinate was the substrate. Highest concentration of 6PP also inhibited O2 uptake in state 4 in the latter case; in both conditions, respiratory control index values were decreased. This flavanone collapsed the mitochondrial membrane potential in a concentration-dependent manner. 6PP also inhibited F0F1-ATPase activity in coupled mitochondria and in submitochondrial particles. In the latter, this compound also inhibited NADH oxidase and succinate dehydrogenase activities. HEp-2 cells were incubated for 24 h with 6PP in presence or absence of 0.5% albumin. As measured by reduction of the mitochondrial-related probe MTT, in the albumin-free condition, 6PP was cytotoxic in a concentration-dependent manner; on the other hand, albumin decreased 6PP effect. In addition, in rat liver microsomes 6PP: (1) inhibited the enzymatic lipid peroxidation, (2) exhibited significant scavenging activity, measured by DPPH reduction assay and (3) demonstrated significant antioxidant activity by decreasing the reduction of Mo(VI) to Mo(V). We suggest that 6PP impairs the hepatic energy metabolism by acting as mitochondrial uncoupler and by inhibiting enzymatic activities linked to the respiratory chain. 6PP also exerts both antioxidant and antiradical activities. Due to its cytotoxicity, this molecule, and its future structure developments, can be considered as a potentially promising therapeutic agent, for instance in cancer chemotherapy.
Asunto(s)
Antineoplásicos/farmacología , Antioxidantes/farmacología , Inhibidores Enzimáticos/farmacología , Fabaceae/química , Flavanonas/farmacología , Flavonoides/farmacología , Mitocondrias Hepáticas/efectos de los fármacos , Animales , Antineoplásicos/química , Antineoplásicos/aislamiento & purificación , Antioxidantes/química , Antioxidantes/aislamiento & purificación , Supervivencia Celular/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Ensayos de Selección de Medicamentos Antitumorales , Activación Enzimática/efectos de los fármacos , Inhibidores Enzimáticos/química , Inhibidores Enzimáticos/aislamiento & purificación , Flavanonas/química , Flavanonas/aislamiento & purificación , Flavonoides/química , Flavonoides/aislamiento & purificación , Humanos , Peroxidación de Lípido/efectos de los fármacos , Masculino , Mitocondrias Hepáticas/metabolismo , Membranas Mitocondriales/efectos de los fármacos , Membranas Mitocondriales/metabolismo , Estructura Molecular , Complejos Multienzimáticos/antagonistas & inhibidores , NADH NADPH Oxidorreductasas/antagonistas & inhibidores , Oxígeno/antagonistas & inhibidores , Oxígeno/metabolismo , Extractos Vegetales/química , Extractos Vegetales/aislamiento & purificación , Extractos Vegetales/farmacología , Raíces de Plantas/química , Prenilación , ATPasas de Translocación de Protón/antagonistas & inhibidores , Ratas , Ratas Wistar , Succinato Deshidrogenasa/antagonistas & inhibidores , Células Tumorales CultivadasRESUMEN
This study was undertaken to investigate the free radical-scavenging and antioxidant activities of various structurally related hydroquinones including hydroxynaphthalenones and dihydroxyanthracenones. Electron spin resonance spectroscopy and spin trapping techniques were used to evaluate the ability of hydroquinones to scavenge hydroxyl, diphenylpicrylhydrazyl, and galvinoxyl radicals. In addition, the oxygen radical absorbing capacity assay using fluorescein (ORAC-FL) was used to obtain the relative antioxidant capacity of these radicals. The rate constants of the first H atom abstraction by 2,2-diphenyl-2-picrylhydrazyl (k(2)), were obtained under pseudo-first-order conditions. The free radical-scavenging activities and k(2) values discriminate well between hydroxynaphthalenones and dihydroxyanthracenones, showing that the latter have better antioxidant properties. The aforementioned experimental data agree with quantum-chemical results demonstrating the relevance of intramolecular H bonding to radical-scavenging activities.
Asunto(s)
Antracenos/química , Antioxidantes/química , Depuradores de Radicales Libres/química , Naftalenos/química , Oxígeno/química , Animales , Antracenos/farmacología , Antioxidantes/farmacología , Línea Celular Tumoral , Espectroscopía de Resonancia por Spin del Electrón/métodos , Depuradores de Radicales Libres/farmacología , Enlace de Hidrógeno , Cinética , Ratones , Estructura Molecular , Naftalenos/farmacología , Oxígeno/antagonistas & inhibidores , Oxígeno/metabolismo , Especies Reactivas de Oxígeno/química , Especies Reactivas de Oxígeno/metabolismo , Reproducibilidad de los Resultados , Sensibilidad y EspecificidadRESUMEN
The production and role of reactive oxygen species (ROS) in the expanding zone of maize (Zea mays) leaf blades were investigated. ROS release along the leaf blade was evaluated by embedding intact seedlings in 2',7'-dichlorofluorescein-containing agar and examining the distribution of 2',7'-dichlorofluorescein fluorescence along leaf 4, which was exposed by removing the outer leaves before embedding the seedling. Fluorescence was high in the expanding region, becoming practically non-detectable beyond 65 mm from the ligule, indicating high ROS production in the expansion zone. Segments obtained from the elongation zone of leaf 4 were used to assess the role of ROS in leaf elongation. The distribution of cerium perhydroxide deposits in electron micrographs indicated hydrogen peroxide (H(2)O(2)) presence in the apoplast. 2',7'-Dichlorofluorescein fluorescence and apoplastic H(2)O(2) accumulation were inhibited with diphenyleneiodonium (DPI), which also inhibited O*(2)(-) generation, suggesting a flavin-containing enzyme activity such as NADPH oxidase was involved in ROS production. Segments from the elongation zone incubated in water grew 8% in 2 h. KI treatments, which scavenged H(2)O(2) but did not inhibit O*(2)(-) production, did not modify growth. DPI significantly inhibited segment elongation, and the addition of H(2)O(2) (50 or 500 microM) to the incubation medium partially reverted the inhibition caused by DPI. These results indicate that a certain concentration of H(2)O(2) is necessary for leaf elongation, but it could not be distinguished whether H(2)O(2), or other ROS, are the actual active agents.
Asunto(s)
Hojas de la Planta/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Zea mays/metabolismo , Pared Celular/efectos de los fármacos , Pared Celular/metabolismo , Fluoresceínas/química , Fluoresceínas/metabolismo , Fluoresceínas/farmacología , Peróxido de Hidrógeno/antagonistas & inhibidores , Peróxido de Hidrógeno/metabolismo , Peróxido de Hidrógeno/farmacología , Meristema/crecimiento & desarrollo , Meristema/metabolismo , Microscopía Electrónica , Compuestos Onio/farmacología , Oxígeno/antagonistas & inhibidores , Oxígeno/metabolismo , Hojas de la Planta/crecimiento & desarrollo , Hojas de la Planta/ultraestructura , Cloruro de Potasio/farmacología , Yoduro de Potasio/farmacología , Especies Reactivas de Oxígeno/antagonistas & inhibidores , Zea mays/efectos de los fármacos , Zea mays/crecimiento & desarrolloRESUMEN
The generation of electronically excited molecular oxygen 1O2 has been shown to occur in several biological systems, such as photooxidation of a variety of biological compounds and xenobiotics ("photodynamic action") and also enzymatic reactions. The high reactivity of 1O2 with unsaturated compounds, sulfides and amino groups arises from its electrophilicity and relatively long lifetime. Thus, biological targets for 1O2 having the above functional groups include unsaturated fatty acids, proteins, enzymes and DNA. There is interest in the role of nutrition in the prevention and pathogenesis of cancer. Epidemiological studies in humans have suggested that carotenoids aid in cancer prevention. Lycopene and oxycarotenoids are present at significant levels in cells and plasma. Extensively conjugated biomolecules such as carotenoids act largely on physical quenching of 1O2 and in much lesser extent on chemical reaction. In this study we observed the protective effect of beta-carotene and lycopene entrapped in human albumin (HSA) against the oxidative 1O2 attack of 2'-deoxyguanosine (dGuo). Photosensitization with methylene blue associated with Chelex resine or Polymer-Rose bengal (Sensitox) and thermodecomposition of water-soluble endoperoxide 3,3'-(1,4-naphthylidene)dipropionate were employed to generate 1O2. The detection of 8-oxo-7,8-dihydro-2'-deoxyguanosine(8-oxodGuo) and 4-hydroxy-8-oxo-7,8-dihydro-2'-deoxyguanosine(4-OH-8-oxodGuo) were performed using reversed phase HPLC with UV, electrochemical detection and by electrospray ionization mass spectrometry. Results showed a significant decrease in the amount of 8-oxodGuo in the presence of lycopene. The percentages of 4-OH-8-oxodGuo and 8-oxodGuo measured were 50% and 70% lower than the control, respectively. These data indicate that carotenoids entrapped in albumin can be an efficient quencher of 1O2 and may be of interest in protecting against the deleterious effect of this excited state molecule.