RESUMEN
Flavonoids are metabolized in vivo to monocyclic phenolic acids. We investigated whether 18 phenolic acids of the benzoic, phenylacetic, phenylpropanoic or cinnamic series-known or potential metabolites of flavonoids-inhibit reactive oxygen species (ROS) released by human polymorphonuclear neutrophils (PMNs). Chemiluminescence was measured after PMN stimulation with three agents (N-fMetLeuPhe, phorbol myristate acetate (PMA), or opsonised zymosan) using two probes (lucigenin or luminol) with or without horseradish peroxidase (HRP) in order to derive specificity profiles for each test compound. The profiles of the phenolic acids and flavonoids were compared by a multivariate (correspondence) factor analysis. Overall, the phenolic acids were less specific than the flavonoids and, with a few exceptions, less potent. Phenolic acids had virtually no effect on the chemiluminescence related to O2- formation that is measured by lucigenin but inhibited luminol luminescence. Inhibition for all but two phenolic acids was sensitive to HRP and might be explained by a scavenger mechanism. Few structure-activity relationships emerged suggesting that simple properties such as radical scavenging and/or redox activity rather than overall structure might be the key determinants of chemiluminescence inhibition. Whatever the mechanism, however, we conclude that part of the in vivo pharmacological activity of flavonoids may readily be accounted for by phenolic acids.
Asunto(s)
Flavonoides/farmacología , Hidroxibenzoatos/farmacología , Neutrófilos/efectos de los fármacos , Adulto , Humanos , Mediciones Luminiscentes , Neutrófilos/metabolismoRESUMEN
Guaiacol moiety has been found in antiinflammatory compounds present in traditional african or chinese medicine. As the activity of these products could be due to reactions with the reactive oxygen species (ROS) or enzymes involved in the inflammatory reaction, a comparative study has been done between biological and physico-chemical investigations. Antioxidant properties of six guaiacol derivatives were measured in vitro by the inhibition of cyclooxygenase activities in human platelets and of the release of ROS by human polymorphonuclear leucocytes (PMNs). PMNs were stimulated by the bacterial peptide N-fMetLeuPhe (FMLP) and the protein kinase C activator phorbol myristate acetate (PMA) using luminol as chemiluminescent probe. Electron Spin Resonance (ESR) and the technique of spin-trapping with 5,5-dimethyl-pyrroline-N-oxide (DMPO) have been used to quantify hydroxyl and superoxide scavenging activities. Hydroxyl radicals were generated by the Fenton's reaction (Fe2+/H2O2) and the superoxide anion by the acetaldehyde/xanthine oxydase system (AC/XOD). The PMNs tests revealed that curcumin and methyl ferulate appeared as the most active compounds. Platelet cycloxygenase activity was inhibited by curcumin and cyclovalone. ESR studies showed a better ROS scavenging activity for vanillin, methyl ferulate and curcumin. Whatever test we used, curcumin and methylferulate appeared as the most interesting antioxidative compounds.
Asunto(s)
Antioxidantes/farmacología , Guayacol/análogos & derivados , Guayacol/farmacología , Plaquetas/enzimología , Fenómenos Químicos , Química Física , Inhibidores de la Ciclooxigenasa/farmacología , Espectroscopía de Resonancia por Spin del Electrón , Humanos , Técnicas In Vitro , Mediciones Luminiscentes , Neutrófilos/química , Óxido Nítrico/sangreRESUMEN
In the present study we measured the inhibition by 34 compounds, either flavonoids or related substances, of the release of reactive oxygen species by human neutrophils after stimulation by three agents: the bacterial peptide N-fMetLeuPhe (FMLP), the protein kinase C activator phorbol myristate acetate (PMA) or opsonized zymosan (OZ), using two chemiluminescent probes, lucigenin or luminol in the presence or absence of horseradish peroxidase (HRP). The data matrix (34 x 7) was submitted to multivariate analysis: first, a correspondence factorial analysis to uncover levels of correlation among the biochemical parameters and the specificity of action of the test-compounds and second, a minimum spanning tree analysis that classified the chemical structures into a network describing both specificity and amplitude of the inhibition of the chemiluminescence response. The major conclusions of the analyses were: (a) opposition between inhibition of poly-morphonuclear leukocytes (PMNs) stimulated by FMLP and of PMNs stimulated by PMA or OZ implying that, for the molecules under study, there was a fundamental difference in the manner in which this inhibition occurred and, conversely, a difference in the nature of the stimulatory action of these activators. Molecules lacking hydroxyl groups on ring B, i.e. chrysin, chalcone, flavone and galangin, molecules glycosylated in position 7, i.e. hesperidin and naringin and ring B mono-hydroxylated molecules were, for the most part, at the origin of this dichotomy and might interfere with the membrane FMLP receptor; (b) a marked difference in chemiluminescence inhibition in the presence or absence of HRP that can be explained by the differential action of catechins compared to flavone and flavonol derivatives; (c) a similarity in biological profile between non-flavonoids such as chalcone and phloretin and low mean-activity flavonoids such as chrysin and galangin and between the non-flavonoid curcumin and the highly active flavonoid isorhamnetin; (d) a reaffirmation of the importance of ring A (C5,7) and ring B (C3',4') dihydroxylation, ring C (C3) hydroxylation, but also of the presence of a methoxy group on ring B in engendering high potency. This potency is generally decreased by C2-C3 saturation and by glycosylation. The most active molecules identified in this study provide valuable information for the selection of simpler molecules (e.g. metabolites accounting for the potency of orally administered flavonoids) for further structure-activity relationship (SAR) studies that could lead to the design of novel drugs or prodrugs.
Asunto(s)
Benzopiranos/farmacología , Flavonoides/farmacología , Neutrófilos/efectos de los fármacos , Especies Reactivas de Oxígeno/metabolismo , Acridinas , Benzopiranos/química , Diseño de Fármacos , Flavonoides/química , Glicosilación , Peroxidasa de Rábano Silvestre , Humanos , Mediciones Luminiscentes , Luminol , Análisis Multivariante , N-Formilmetionina Leucil-Fenilalanina/farmacología , Neutrófilos/metabolismo , Relación Estructura-Actividad , Acetato de Tetradecanoilforbol/farmacología , Zimosan/farmacologíaRESUMEN
The present study addresses the question whether nervonic acid (24:1n-9) accumulation in sphingomyelin (SM) of red blood cells (RBC) could yield information on cerebrum maturation in premature infants. The study included 28 premature eutrophic infants of 31.5 wk gestational age. Eleven were fed with human milk, nine with a regular formula and eight with an alpha-linolenate-enriched formula. The fatty acid composition of the SM fraction was determined by gas-liquid chromatography on a 50-m fused silica capillary column. At 32 wk gestational age, the main fatty acids in SM were 16:0, 18:0, 20:0, 22:0, 24:0 and 24:1n-9. After five weeks of feeding, at week 37 of postconceptional age, the most striking variation was a rise in 24:1n-9, from 9.9 +/- 0.7 to 12.8 +/- 0.9 (P < 0.02), regardless of regimen in all three feeding groups. The rise in 24:1n-9 after birth in premature eutrophic infants is the beginning of a trend toward the higher levels in 24:1n-9 observed in mature newborns and older infants. The 24:1n-9 level in SM of RBC from premature infants may reflect 24:1n-9 levels in SM of brain and could thus reflect brain maturity.
Asunto(s)
Eritrocitos/metabolismo , Ácidos Grasos Monoinsaturados/metabolismo , Recien Nacido Prematuro/metabolismo , Esfingomielinas/metabolismo , Biomarcadores , Encéfalo/crecimiento & desarrollo , Encéfalo/fisiología , Ácidos Grasos/metabolismo , Femenino , Humanos , Recién Nacido , Recien Nacido Prematuro/crecimiento & desarrollo , MasculinoRESUMEN
Flavonoids are known to reduce reactive oxygen species released by polymorphonuclear neutrophils (PMNs) in vitro. We have studied the effects of S5682 (Daflon 500 mg), a purified flavonoid fraction composed of 90% diosmin and 10% hesperidin. S5682 produced a dose-dependent inhibition of the luminol chemiluminescence (CL) induced by phorbol myristate acetate on PMNs (IC50 = 5 x 10(-5) M), with no effect on superoxide anion (O2.-) formation and on cellular superoxide dismutase activity as determined by lucigenin-amplified CL. The CL results were confirmed by the hydrogen peroxide (H2O2) determination showing that S5682 reduced H2O2 formed through either PMN stimulation (IC50 = 1.6 x 10(-6) M) or an in vitro enzymatic mechanism (IC50 = 2 x 10(-6) M). S5682 inhibited luminol-dependent CL induced by H2O2 (IC50 = 5 x 10(-6) M). However, O2 was not formed from H2O2 in contact with S5682 and the UV spectrum of this compound was not modified. In contrast, S5682 inhibited luminol-dependent CL induced by H2O2 in the presence of horseradish peroxidase (IC50 = 3 x 10(-6) M), and the UV spectrum of S5682 was modified. Luminol-dependent CL induced by hypochlorite (OCl- 10(-5) M) was also inhibited by S5682 (IC50 = 7 x 10(-5) M). This inhibitory effect was similar to that of sodium azide on myeloperoxidase activity. Moreover, OCl- 5 x 10(-4) M also altered the UV spectrum of S5682 10(-4) M. These results indicate that S5682 could be active on the H2O2-OCl(-)-myeloperoxidase system.