RESUMEN
Eugenia dysenterica DC (cagaiteira) is a native tree from Cerrado biome. Cagaita fruits are known and consumed in natura, mainly by inhabitants from Cerrado. In this study, we evaluated the antioxidant activity of leaves of this plant. For this evaluation we used four methods, the reduction of phosphomolybdenum, scanning by hydrogen peroxide, DPPH radical scavenging assay and determination of electrochemical parameters by differential pulse voltammetry. The results indicate that all extracts from leaves of this species have significant antioxidant potential, following the order: crude ethanol extract CEE) >crude aqueous extract (CAE) >crude hexane extract (CHE). The voltammetric approaches were also applied in order to evaluate the redox behavior of the hydrophilic extracts, as well as of their sub-extracts. Thus, the results suggest the presence of catechol-like polyphenols, which were confirmed by chromatography and phytochemical methods. Voltammetric analysis showed to be a reliable and fast method to determine redox behavior of E. dysenterica extracts.
Asunto(s)
Antioxidantes/farmacología , Catecoles/farmacología , Eugenia/química , Extractos Vegetales/farmacología , Antioxidantes/aislamiento & purificación , Compuestos de Bifenilo/química , Catecoles/aislamiento & purificación , Técnicas Electroquímicas , Etanol/química , Hexanos/química , Interacciones Hidrofóbicas e Hidrofílicas , Oxidación-Reducción , Fitoterapia , Picratos/química , Extractos Vegetales/aislamiento & purificación , Hojas de la Planta , Plantas Medicinales , Solventes/química , Espectrofotometría , Agua/químicaRESUMEN
Polyvinylpolypyrrolidone (PVPP) is a fining agent, widely used in winemaking and brewing, whose mode of action in removing phenolic compounds has not been fully characterised. The aim of this study was to evaluate the experimental and theoretical binding affinity of PVPP towards six phenolic compounds representing different types of phenolic species. The interaction between PVPP and phenolics was evaluated in model solutions, where hydroxyl groups, hydrophobic bonding and steric hindrance were characterised. The results of the study indicated that PVPP exhibits high affinity for quercetin and catechin, moderate affinity for epicatechin, gallic acid and lower affinity for 4-methylcatechol and caffeic acid. The affinity has a direct correlation with the hydroxylation degree of each compound. The results show that the affinity of PVPP towards phenols is related with frontier orbitals. This work demonstrates a direct correlation between the experimental affinity and the interaction energy calculations obtained through computational chemistry methods.
Asunto(s)
Alimentos , Modelos Teóricos , Fenoles/química , Povidona/análogos & derivados , Adsorción , Catequina/química , Catequina/aislamiento & purificación , Catecoles/química , Catecoles/aislamiento & purificación , Alimentos/normas , Ácido Gálico/química , Ácido Gálico/aislamiento & purificación , Estructura Molecular , Fenoles/aislamiento & purificación , Extractos Vegetales/química , Extractos Vegetales/aislamiento & purificación , Povidona/química , Quercetina/química , Quercetina/aislamiento & purificación , SolucionesRESUMEN
Presently, natural products, such as Piper umbellata L. (Piperaceae), have been evaluated as sources of antimicrobial agents with efficacies against microorganisms. The in vitro antimicrobial activity was performed by broth micro-dilution susceptibility assay, according to the protocols of the National Committee for Clinical Laboratory Standards, and described the antibacterial and antifungal activities of crude ethanolic extract and fractions obtained by partitions sequentially among water-methanol, methylene chloride and ethyl acetate, as well as the major constituent, 4-nerolidylcatechol from the aerial parts of P. umbellata L. Amphotericin B and ciprofloxacin were used as controls. Among the microorganism cultures, hydromethanol fraction demonstrated the pre-eminent antifungal activity. 4-Nerolidylcathecol was the only tested plant component that exhibited activity against all the selected microorganisms, suggesting its great potential as a source for the development of new drugs. In order to estimate the antimalarial activity of P. umbellata L., a micro-dilution method protocol, parasite lactate dehydrogenase assay, with a Plasmodium falciparum Sierra Leone (D6) clone was utilised. The antimalarial agent artemisinin was used as control. 4-Nerolidylcathecol exhibited the best antimalarial activity; however, it was not significant when compared with control. These in vitro results do not justify the use of P. umbellata L. in malaria patients. However, there is a possibility of 4-nerolidylcathecol, after biotransformation, exhibiting a significant antimalarial activity in in vivo assays. However, 4-nerolidylcathecol demonstrated to possess a broad antimicrobial activity which is, in fact, a promising source for the development of new therapeutic agents.
Asunto(s)
Antiinfecciosos/farmacología , Antimaláricos/farmacología , Catecoles/farmacología , Piper/química , Componentes Aéreos de las Plantas/química , Extractos Vegetales/farmacología , Antiinfecciosos/aislamiento & purificación , Antimaláricos/aislamiento & purificación , Catecoles/aislamiento & purificación , Evaluación Preclínica de Medicamentos , L-Lactato Deshidrogenasa/metabolismo , Espectroscopía de Resonancia Magnética , Pruebas de Sensibilidad Microbiana , Extractos Vegetales/aislamiento & purificaciónRESUMEN
Current work was conducted to evaluate the vasorelaxant effect of dihydrospinochalcone-A (1) and isocordoin (2), compounds type chalcone isolated from Lonchocarpus xuul, an endemic tree of the Yucatan Peninsula, Mexico. Compounds 1 and 2 were found to induce significant relaxant effect in a concentration-dependent manner on aortic rat rings pre-contracted with noradrenaline (NA, 0.1 µM). Compound 1 was the most active and its effect was endothelium-dependent (Emax=79.67% and EC50=21.46 µM with endothelium and Emax=23.58% and EC50=91.8 µM without endothelium, respectively). The functional mechanism of action for 1 was elucidated. Pre-incubation with L-NAME (unspecific nitric oxide synthase inhibitor), indomethacin (unspecific COX inhibitor), ODQ (soluble guanylyl cyclase inhibitor), atropine (cholinergic receptor antagonist), TEA (unspecific potassium channel blocker) reduced relaxations induced by 1. Oral administration of 50 mg/kg of compound 1 exhibited significant decrease in diastolic and systolic blood pressure in SHR rats. The heart rate was not modified. Compound 1 was docked with a crystal structure of eNOS. Dihydrospinochalcone-A showed calculated affinity with eNOS in the C1 binding pockets, near the catalytic site; Trp449, Trp447 and His373 through aromatic and π-π interactions, also His463 and Arg367 are the residues that make hydrogen bonds with the carbonyl and hydroxyl groups. In conclusion, dihydrospinochalcone-A induces a significant antihypertensive effect due to its direct vasorelaxant action on rat aorta rings, through NO/sCG/PKG pathway and potassium channel opening.
Asunto(s)
Antihipertensivos/farmacología , Presión Sanguínea/efectos de los fármacos , Catecoles/farmacología , Chalconas/farmacología , Fabaceae/química , Óxido Nítrico/biosíntesis , Vasodilatadores/farmacología , Animales , Antihipertensivos/aislamiento & purificación , Aorta Torácica/efectos de los fármacos , Atropina/farmacología , Catecoles/aislamiento & purificación , Chalconas/aislamiento & purificación , Relación Dosis-Respuesta a Droga , Endotelio Vascular/efectos de los fármacos , Guanilato Ciclasa/antagonistas & inhibidores , Frecuencia Cardíaca/efectos de los fármacos , Indometacina/farmacología , México , NG-Nitroarginina Metil Éster/farmacología , Óxido Nítrico Sintasa de Tipo III/metabolismo , Norepinefrina , Extractos Vegetales/química , Extractos Vegetales/farmacología , Bloqueadores de los Canales de Potasio/farmacología , Unión Proteica , Ratas , Ratas Endogámicas SHR , Ratas Wistar , Receptores Citoplasmáticos y Nucleares/antagonistas & inhibidores , Guanilil Ciclasa Soluble , Vasoconstricción/efectos de los fármacos , Vasodilatadores/aislamiento & purificaciónRESUMEN
This paper describes the synthesis and characterization of PEI-coated gold nanoparticles (PEI-AuNP), which were applied as a new platform in the immobilization of laccase (LAC) originating from Aspergillus oryzae. This material (PEI-AuNP-LAC) was used in the construction of a biosensor based on a glassy carbon electrode coated with a bio-nanostructured film. The occurrence of direct electron transfer (DET) between the electroactive center of LAC and the electrode surface was observed by cyclic voltammetry (CV), suggesting that the presence of AuNP in the film acts as a bridge for electron transfer. In acetate buffer solution (pH 5.0), LAC shows a pair of well-defined redox waves with a formal potential (E°') of 0.226V vs. Ag/AgCl (3M KCl). The biosensor response indicated a surface-controlled process with an apparent electron transfer rate constant (k(s)) of 0.4 s⻹, charge transfer coefficient (α) of 0.5, and surface coverage concentration (Γ) of 3.45×10⻹° mol cm⻲. The optimized biosensor showed the following limits of detection (LOD) for the phenolic compounds tested: 0.03 µM for catechol and guaiacol; 0.14 µM for pyrogallol and 0.21 µM for hydroquinone, using square-wave voltammetry (SWV). The proposed biosensor demonstrated high sensitivity, good repeatability and reproducibility, and long-term stability (only 20% decrease in response over 90 days and after 150 measurements by SWV for each film formed). This biosensor was successfully applied to catechol quantification in spiked water samples. Furthermore, this method showed great potential for application in the development of new devices for biosensing.
Asunto(s)
Técnicas Biosensibles/métodos , Catecoles/aislamiento & purificación , Oro/química , Lacasa/química , Nanopartículas del Metal/química , Carbono/química , Catálisis , Electroquímica/métodos , Electrodos , Enzimas Inmovilizadas/química , Iminas/química , Límite de Detección , Oxidación-Reducción , Polietilenos/química , Agua/químicaRESUMEN
Stenotrophomonas maltophilia is an emerging nosocomial pathogen. Despite the broad spectrum of syndromes associated with S. maltophilia infections, little is known about its virulence factors, including siderophore production. The aims of this work were to detect S. maltophilia siderophores and to determine their chemical nature. We studied 31 S. maltophilia isolates from device-associated infections, recovered over the period 2006-2011 at Hospital de Clínicas José de San Martín, Buenos Aires, Argentina, and the strain K279a, whose genome has been fully sequenced. The production of siderophores was screened by the chrome azurol S (CAS) agar assay, previously modified to detect siderophores in this species. When grown on modified CAS agar plates, all the clinical isolates and K279a were CAS-positive for siderophore production. In order to determine the chemical nature of siderophores, the Csáky (hydroxamate-type) and Arnow (catechol-type) assays were used. All S. maltophilia isolates produced catechol-type siderophores, but hydroxamate-type siderophores were not detected.
Asunto(s)
Catecoles/aislamiento & purificación , Infecciones por Bacterias Gramnegativas/microbiología , Sideróforos/aislamiento & purificación , Stenotrophomonas maltophilia/química , 2,2'-Dipiridil/farmacología , Argentina/epidemiología , Bacteriemia/microbiología , Técnicas Bacteriológicas , Líquido del Lavado Bronquioalveolar/microbiología , Infecciones Relacionadas con Catéteres/microbiología , Colorimetría , Colorantes , Enfermedades Transmisibles Emergentes/microbiología , Infección Hospitalaria/epidemiología , Infección Hospitalaria/microbiología , Infecciones por Bacterias Gramnegativas/epidemiología , Humanos , Indicadores y Reactivos , Hierro/análisis , Quelantes del Hierro/farmacología , Neumonía Asociada al Ventilador/microbiología , Stenotrophomonas maltophilia/aislamiento & purificación , Tráquea/microbiología , Cateterismo Urinario/efectos adversosRESUMEN
This study describes an optimization of [6]-, [8]- and [10]-gingerol isolation and purification in semi-preparative HPLC scale and their anti-proliferative activity. The gingerols purification was carried out in HPLC system using a Luna-C18 and the best mobile phase evaluated was MeOH/H2O (75:25, v/v). This new methodology for the gingerols isolation was very effective, since considerable amounts (in the range of milligrams) with a good purity degree (â¼98%) were achieved in 30 min of chromatographic run. [6]-, [8]- and [10]-Gingerol purified by this methodology inhibited the proliferation of MDA-MB-231 tumor cell line with IC50 of 666.2±134.6 µM, 135.6±22.6 µM and 12.1±0.3 µM, respectively. These substances also inhibited human fibroblasts (HF) cell proliferation, however in concentrations starting from 500 µM. In conclusion, our results demonstrate an optimization of gingerols isolation and their specific anti-proliferative activities against tumor cells, suggesting their use as important models for drug design in an attempt to develop new compounds with fewer side effects when compared to conventional chemotherapy.
Asunto(s)
Catecoles/aislamiento & purificación , Catecoles/farmacología , Alcoholes Grasos/aislamiento & purificación , Alcoholes Grasos/farmacología , Zingiber officinale/química , Análisis de Varianza , Catecoles/química , Línea Celular , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Cromatografía Líquida de Alta Presión/métodos , Alcoholes Grasos/química , HumanosRESUMEN
Isocordoin (1) and 2',4'-dihydroxy-3'-(gamma,gamma-dimethylallyl)-dihydrochalcone (7), chalcones isolated from the root of Lonchocarpus xuul, together with six analogues of 1 were tested in vitro against promastigotes of Leishmania mexicana and epimastigotes of Trypanosoma cruzi. Additionally, cytotoxic studies with MDCK cells were carried out using the MTT method. Among these derivatives, 2',4'-diacetoxy-3'-(3-methylbut-2-enyl)-chalcone (2) and 2',4'-dimethoxy-3'-(3-methylbut-2-enyl)-chalcone (3) showed the strongest antiprotozoal activity and lower cytotoxicity in comparison with isocordoin at a concentration in the microM range. Derivative 3 had the strongest trypanocidal activity with IC(50) values lower than those of nifurtimox and benznidazole, the common drugs used against these parasites. The selectivity index calculated for 3 (SI 109.3) confirms the selective trypanocidal activity of this metabolite.
Asunto(s)
Antiprotozoarios/farmacología , Catecoles/farmacología , Fabaceae/química , Leishmania mexicana/efectos de los fármacos , Trypanosoma cruzi/efectos de los fármacos , Animales , Antiprotozoarios/química , Antiprotozoarios/aislamiento & purificación , Ascomicetos , Catecoles/química , Catecoles/aislamiento & purificación , Línea Celular , Perros , Concentración 50 Inhibidora , Extractos Vegetales/químicaRESUMEN
Butadiene is marketed containing p-tertbutylcatechol (p-TBC), a polymerization inhibitor that should be removed before butadiene utilization in synthetic rubber production. p-TBC can be removed from butadiene by washing with sodium hydroxide (NaOH) solution, producing a wastewater with pH 14, which contains high amounts of p-TBC, a toxic chemical compound. The aim of this work was to develop a treatment process that could reduce the content of p-TBC from the wastewater. Since p-TBC is very soluble in basic, but not in neutral and acid solutions, acidification tests were performed with phosphoric acid (H3PO4) to precipitate p-TBC. Reaction between NaOH and H3PO4 can result in crystallization of large amounts of salt without p-TBC precipitation. Under selected acidifying conditions p-TBC precipitates and the wastewater COD is highly reduced (> 90/o). Chromatographic determinations showed that the precipitated p-TBC could be recovered with 99% purity.
Asunto(s)
Butadienos/química , Catecoles/aislamiento & purificación , Elastómeros/química , Residuos Industriales , Catecoles/análisis , Catecoles/química , Precipitación Química , Concentración de Iones de Hidrógeno , Ácidos Fosfóricos/química , Hidróxido de Sodio/químicaRESUMEN
Exposure to UV radiation up-regulates the synthesis of matrix metalloproteinases (MMPs), a group of matrix-degrading enzymes. MMPs are regarded as promising therapeutic targets and the development of effective inhibitors is an important research focus. The plant Pothomorphe umbellata has been shown to exert a potent antioxidant activity on the skin and to delay the onset and reduce the incidence of UVB-induced chronic skin damage. The aim of the present study was to determine the effect of P. umbellata ethanolic root extract on MMP-2 and MMP-9. The in vitro inhibition of MMP-2 and MMP-9 was measured by gelatin zymography in the presence of different concentrations of P. umbellata extract, as well as in the presence of its isolated active principle 4-nerolidylcatechol (4-NC). The inhibitory effect of the P. umbellata extract was stronger than that of 4-NC. Gelatin zymography and histological analysis revealed that P. umbellata was able to inhibit constitutive MMP-9 activity in vivo in mice sacrificed 2 h after UVB irradiation. The intensity of the MMP-2 band was unchanged. Our data contribute to the elucidation of the mechanism of prevention of photoaging by P. umbellata and may provide a rational basis for the use of this plant in prophylaxis against and treatment of skin cancer.
Asunto(s)
Inhibidores de la Metaloproteinasa de la Matriz , Piperaceae/química , Extractos Vegetales/farmacología , Raíces de Plantas/química , Protectores contra Radiación/farmacología , Piel/enzimología , Animales , Catecoles/aislamiento & purificación , Relación Dosis-Respuesta a Droga , Inhibidores Enzimáticos/farmacología , Gelatina/química , Metaloproteinasa 2 de la Matriz/metabolismo , Metaloproteinasa 9 de la Matriz/metabolismo , Metaloproteinasas de la Matriz/metabolismo , Ratones , Ratones Pelados , Fitoterapia/métodos , Extractos Vegetales/química , Traumatismos Experimentales por Radiación/patología , Traumatismos Experimentales por Radiación/prevención & control , Factores de Tiempo , Rayos UltravioletaRESUMEN
In this study, the production of siderophores by Xylella fastidiosa from the citrus bacteria isolate 31b9a5c (FAPESP - ONSA, Brazil) was investigated. The preliminary evidence supporting the existence of siderophore in X. fastidiosa was found during the evaluation of sequencing data generated in our lab using the BLAST-X tool, which indicated putative open reading frames (ORFs) associated with iron-binding proteins. In an iron-limited medium siderophores were detected in the supernatant of X. fastidiosa cultures. The endophytic bacterium Methylobacterium extorquens was also evaluated. Capillary electrophoresis was used to separate putative siderophores produced by X. fastidiosa. The bacterial culture supernatants of X. fastidiosa were identified negative for hydroxamate and catechol and positive for M. extorquens that secreted hydroxamate-type siderophores.
Asunto(s)
Hierro/metabolismo , Sideróforos/biosíntesis , Xylella/crecimiento & desarrollo , Xylella/metabolismo , Catecoles/aislamiento & purificación , Medios de Cultivo/análisis , Medios de Cultivo/química , Electroforesis Capilar , Ácidos Hidroxámicos/aislamiento & purificación , Proteínas de Unión a Hierro/análisis , Espectrometría de Masa por Láser de Matriz Asistida de Ionización DesorciónRESUMEN
Three new biphenyl derivatives, clusiparalicolines A (1), B (2), and C (3), were isolated from the roots of Clusia paralicola by bioassay-directed fractionation using the DNA strand-scission and the KB human cancer cell line cytotoxicity assays. Compounds 1 and 2 were found to be active in the DNA strand-scission assay, whereas all three compounds exhibited modest cytotoxicity against the KB cell line. The structures of 1-3 were elucidated by spectroscopic methods including 1D and 2D NMR techniques.
Asunto(s)
Antineoplásicos Fitogénicos/aislamiento & purificación , Benzopiranos/aislamiento & purificación , Catecoles/aislamiento & purificación , ADN de Neoplasias/efectos de los fármacos , Fenoles/aislamiento & purificación , Plantas Medicinales/química , Antineoplásicos Fitogénicos/farmacología , Benzopiranos/farmacología , Catecoles/farmacología , Supervivencia Celular/efectos de los fármacos , América Central , Humanos , Células KB , Espectroscopía de Resonancia Magnética , Fenoles/farmacología , Raíces de Plantas/química , América del Sur , Espectrofotometría InfrarrojaRESUMEN
The total reactive antioxidant potential (TRAP) and total antioxidant reactivity (TAR) of 4-nerolidylcatechol (4-NC) and methanolic extracts of Pothomorphe umbellata and P. peltata were determined by monitoring the intensity of luminol enhanced chemiluminescence by peroxyl radicals derived from thermolysis of 2,2'-azobis(2-amidinopropane). The highest antioxidant potential was measured in the extract of P. umbellata (TRAP = 97.2 microM) while the highest reactivity was observed in the extract of P. peltata (TAR = 5.0 microM), measured as equivalents of Trolox concentration. These results were higher than those obtained for 4-NC (TRAP = 33.6 microM, TAR = 4.9 microM). DNA sugar damage induced by Fe(II) salts was also used to determine the capacity of 4-NC to suppress hydroxyl radical-mediated degradation of DNA. Calculated IC50 values for 4-NC and catechin, used as a standard, were 25 and 17 microM, respectively.
Asunto(s)
Catecoles/farmacología , Daño del ADN , Compuestos Ferrosos/toxicidad , Depuradores de Radicales Libres/farmacología , Hojas de la Planta/química , Catecoles/aislamiento & purificación , Depuradores de Radicales Libres/aislamiento & purificaciónRESUMEN
Analysis of a clinical isolate of Acinetobacter baumannii showed that this bacterium was able to grow under iron-limiting conditions, using chemically defined growth media containing different iron chelators such as human transferrin, ethylenediaminedi-(o-hydroxyphenyl)acetic acid, nitrilotriacetic acid, and 2,2'-bipyridyl. This iron uptake-proficient phenotype was due to the synthesis and secretion of a catechol-type siderophore compound. Utilization bioassays using the Salmonella typhimurium iron uptake mutants enb-1 and enb-7 proved that this siderophore is different from enterobactin. This catechol siderophore was partially purified from culture supernatants by adsorption chromatography using an XAD-7 resin. The purified component exhibited a chromatographic behavior and a UV-visible light absorption spectrum different from those of 2,3-dihydroxybenzoic acid and other bacterial catechol siderophores. Furthermore, the siderophore activity of this extracellular catechol was confirmed by its ability to stimulate energy-dependent uptake of 55Fe(III) as well as to promote the growth of A. baumannii bacterial cells under iron-deficient conditions imposed by 60 microM human transferrin. Polyacrylamide gel electrophoresis analysis showed the presence of iron-regulated proteins in both inner and outer membranes of this clinical isolate of A. baumannii. Some of these membrane proteins may be involved in the recognition and internalization of the iron-siderophore complexes.