APPLICATION OF 6-NITROCOUMARIN AS A SUBSTRATE FOR THE FLUORESCENT DETECTION OF NITROREDUCTASE ACTIVITY IN Sporothrix schenckii / Aplicação de 6-nitrocumarina como substrato fluorescente para detecção de atividade nitroredutásica em Sporothrix schenckii

Introduction Sporothrix schenckii is a thermal dimorphic pathogenic fungus causing a subcutaneous mycosis, sporotrichosis. Nitrocoumarin represents a fluorogenic substrate class where the microbial nitroreductase activity produces several derivatives, already used in several other enzyme assays. The objective of this study was the analysis of 6-nitrocoumarin (6-NC) as a substrate to study the nitroreductase activity in Sporothrix schenckii. Methods Thirty-five samples of S. schenckii were cultivated for seven, 14 and 21 days at 35 °C in a microculture containing 6-nitrocoumarin or 6-aminocoumarin (6-AC) dissolved in dimethyl sulfoxide or dimethyl sulfoxide as a negative control, for posterior examination under an epifluorescence microscope. The organic layer of the seven, 14 and 21-day cultures was analyzed by means of direct illumination with 365 nm UV light and by means of elution on G silica gel plate with hexane:ethyl acetate 1:4 unveiled with UV light. Results All of the strains showed the presence of 6-AC (yellow fluorescence) and 6-hydroxylaminocoumarin (blue fluorescence) in thin layer chromatography, which explains the green fluorescence observed in the fungus structure. Conclusion The nitroreductase activity is widely distributed in the S. schenckii complex and 6-NC is a fluorogenic substrate of easy access and applicability for the nitroreductase activity detection. .

Introdução Sporothrix schenckii é um fungo dimórfico térmico, agente etiológico de micose subcutânea, a esporotricose. Nitrocumarina representa classe de substratos fluorogênicos em que a atividade nitroredutásica microbiana produz vários derivados, já utilizados em vários outros ensaios enzimáticos. O objetivo deste estudo foi analisar 6-nitrocumarina (6-NC) como substrato para estudo da atividade nitroredutásica em Sporothrix schenckii. Métodos Trinta e cinco isolados de S. schenckii foram cultivados por sete, 14 e 21 dias a 35 °C em um microcultivo contendo 6-nitrocumarina ou 6-aminocumarina (6-AC) solubilizada em dimetilsulfóxido ou dimetilsulfóxido como controle negativo, para posterior análise em microscópio de epifluorescência. A fase orgânica da cultura de sete, 14 e 21 dias foi analisada por meio de iluminação direta com luz UV de 365 nm e por eluição em placas de sílica gel G com hexano:acetato de etila 1:4 e revelada com luz UV. Resultados Todos os isolados mostraram a presença de 6-AC (fluorescência amarela) e 6-hidroxilaminocumarina (fluorescência azul) em cromatografia em camada delgada, que explica a fluorescência verde observada na estrutura dos fungos. Conclusão A atividade nitroredutásica é amplamente distribuída no complexo S. schenckii e 6-NC é um substrato fluorogênico de fácil obtenção e aplicabilidade para detecção da atividade nitroredutásica. .

IP3 production in the hypersensitive response of lemon seedlings against Alternaria alternata involves active protein tyrosine kinases but not a G-protein

IP3 increase and de novo synthesis of scoparone are produced in the hypersensitive response (HR) of lemon seedlings against the fungus Alternaria alternata. To elucidate whether a G-protein and/or a protein tyrosine kinase (PTK) are involved in signal transduction leading to the production of such a defensive response, we studied the HR in this plant system after treatment with G-protein activators alone and PTK inhibitors in the presence of fungal conidia. No changes in the level of IP3 were detected in response to the treatment with the G-protein activators cholera toxin or mastoparan, although the HR was observed in response to these compounds as determined by the scoparone synthesis. On the contrary, the PTK inhibitors lavendustin A and 2,5-dihidroxy methyl cinnamate (DHMC) not only prevented the IP3 changes observed in response to the fungal inoculation of lemon seedlings but also blocked the development of the HR. These results suggest that the IP3 changes observed in response to A. alternata require a PTK activity and are the result of a G-protein independent Phospholipase C activity, even though the activation of a G-protein can also lead to the development of a HR. Therefore, it appears that more than one signaling pathway may be activated for the development of HR in lemon seedlings: one involving a G-protein and the other involving a PTK-dependent PLC.

Optimization of wedelolactone accumulation in shoot cultures of Eclipta alba.

Influence of different environmental factors on accumulation of wedelolactone, a potential anti-hepatotoxic principle of E. alba in shoot cultures was investigated. A significant increase in the content of wedelolactone due to kinetin treatment, temperature change and photoperiod alteration in shoot cultures was observed. Incorporation of phenylalanine in the medium also increased content of wedelolactone significantly in a dose-dependent manner.

Permeabilization and in situ adsorption studies during growth and coumarin production in hairy root cultures of Cichorium intybus L.

Effect of addition of a permeabilizing agent dimethyl sulfoxide (DMSO) and a solid adsorbent, XAD -7, on growth and coumarin production in hairy root cultures of C. intybus was studied. Continuous permeabilization of the hairy root cultures of C. intybus with DMSO has been shown to be an effective strategy for enhanced release of coumarins while preserving the root viability. DMSO at 0.2% (v/v) level showed the maximum growth and coumarin production but was less as compared to control on day 28. Treatment of cells with increasing concentrations of DMSO (0.3 - 0.6 % v/v) to hairy root cultures of C. intybus, showed an inverse relationship with growth and coumarin production. Growth and production of coumarins increased with 1% media filtrate (MF) of cultures of Phytopthora parasitica var. nicotiana treatment. It was observed that treatment with DMSO (0.2% v/v) and 1% MF of P. parasitica showed the better growth and coumarin production with an increased release of coumarins as compared to the control and other treatments. It was observed that treatment of hairy root cultures with XAD-7 resulted in lesser growth and coumarin production as compared to control during the culture period. Addition of XAD-7 along with 1% MF of P. parasitica showed enhanced growth, coumarin production and increased adsorption as compared to control and lone XAD-7 treatment. Combined addition of DMSO/XAD-7 with fungal elicitor showed synergistic response in terms of biomass and coumarin production. Excretion of coumarins in both the cases was dependent on the presence of DMSO/XAD-7. These results showed that continuous permeabilization of hairy root cultures of C. intybus by using DMSO at 0.2% (v/v) level coupled with 1% MF of P. parasitica maintained viability of tissues and produced coumarins at higher level.

Participation of the phosphoinositide metabolism in the hypersensitive response of Citrus limon against Alternaria alternata

Lemon seedlings inoculated with Alternaria alternata develop a hypersensitive response (HR) that includes the induction of Phenylalanine ammonia-lyase (PAL, E. C. 4.3.1.5) and the synthesis of scoparone. The signal transduction pathway involved in the development of this response is unknown. We used several inhibitors of the Phosphoinositide (PI) animal system to study a possible role of Inositol-1,4,5-triphosphate (IP3) in the transduction of the fungal conidia signal in Citrus limon. The HR was only partially inhibited by EGTA, suggesting that not only external but internal calcium as well are necessary for a complete development of the HR. In this plant system, Alternaria alternata induced an early accumulation of the second messenger IP3. When lemon seedlings were watered long term with LiCl, an inhibitor of the phosphoinositide cycle, the IP3 production was reduced, and the LiCl-watered plants could neither induce PAL nor synthesize scoparone in response to fungal conidia. Furthermore, neomycin, a Phospholipase C (PLC, E. C. 3.1.4.3) inhibitor, also inhibited PAL induction and scoparone synthesis in response to A. alternata. These results suggest that IP3 could be involved in the signal transduction pathway for the development of the HR of Citrus limon against A. alternata.

Efecto en el ciclo celular de líneas de adenocarcinoma pulmonar por cumarina y 7-hidroxicumarina / Effects of cumarine and 7-hydroxicumarine on the cell cycle of pulmonary adenocarcinoma cell lines

Introducción: Las cumarinas son compuestos ampliamente distribuidos en la naturaleza. En el humano el principal metabolito de la cumarina es la 7-hidroxicumarina. Estos compuestos presentan actividad antitumoral in vitro e in vivo. Previamente reportamos que la cumarina y la 7-hidroxicumarina ejercen actividad citostática en líneas de adenocarcinoma; sin embargo, se desconocen los aspectos relacionados a la fase del ciclo celular en la que estos compuestos pueden actuar.Objetivo: Determinar el efecto de la cumarina y la 7-hidroxicumarina en la transición del ciclo celular en líneas de adenocarcinoma pulmonar.Material y métodos: Tres líneas de adenocarcinoma pulmonar (SK-LU-1, 1.3.15 y 3A5A) y células mononucleares de individuos sanos estimuladas con fitohemaglutinina, se incubaron por 24h y 40h respectivamente, con 100 µg/mL de cumarina o 7-hidroxicumarina. Las perturbaciones en el ciclo celular se evaluaron por medio de la determinación de contenido de DNA por citometría de flujo.Resultados: Posterior al tratamiento, las líneas celulares presentaron acumulación significativa de células en la fase G0/G1, disminuyendo proporcionalmente la población de células en la fase S. En cambio, las células mononucleares no presentaron cambios significativos después del tratamiento.Conclusiones: Estos resultados demuestran que los compuestos cumarínicos causan un arresto de las células tumorales en la fase G0/G1. El conocimiento de las perturbaciones en el ciclo celular, inducidas por estos productos, puede facilitar la elaboración de esquemas de tratamiento mediante combinaciones con otros fármacos que arresten en distinta(s) fase(s) del ciclo. Además, esta metodología permite evaluar la susceptibilidad de las células tumorales a los agentes quimioterapéuticos.

Deconvolution of the fluorescence spectra into its component Gaussians: a method to analyze the binding of coumarin to bovine serum albumin.

7-N,N-Diethylamino-4-methylcoumarin, (cou-1), a readily available laser dye binding to bovine serum albumin (BSA), at room temperature has been studied by steady state fluorescence spectroscopy. Existing methods of analysis of the binding to obtain the binding parameters are based on the change in fluorescence intensity at a particular wavelength. These methods are not convenient when there is a gradual shift in the emission maxima for increasing protein concentration. In this paper we present a method to obtain the binding constants of cou-1 to BSA using a Windows '95 based package to deconvolute the asymmetrical spectrum (fluorescence intensity versus wave number curve) into two Gaussians, each corresponding to the binding of the fluorophore to a particular site. This method is convenient to analyze the binding constant data and obtain the binding parameters of each binding site, and can also provide information about the microenvironment of each site, relating micropolarity and microviscosity.

Comparison between the effect of pyrazole, cobalt and tin on hepatic and renal microsomal cytochrome P450 concentration and metabolism of coumarin and 7 ethoxycoumarin

Recently, the metabolism of coumarin and 7-ethoxycoumarin were reported to be enhanced several folds in the mouse liver after pretreatment with either N-containing heteroaromatic compounds [e.g. pyrazole, PL] or heavy metals [e.g. Cobalt, Co and Tin, Sn]. The effect of these compounds on the mouse renal microsomes is not thoroughly investigated. Accordingly the present study was designed to compare the effect of pyrazole. cobalt and tin on hepatic and renal microsomes. The study revealed that in both kidney and liver microsomes, the concentration of Cyt P450 was decreased to about the same extent after pretreatment of male mice [NMRI-type] with these compounds. In contrary the metabolism of 7-ethoxy-coumarin and of Coumarin were increased several folds. In the liver microsomes, the highest increase in the metabolism of the coumarin derivatives, were observed after pretreatment of mice with Sn [Sn > PL > Co]. On the other hand, in the kidney microsomes, the most potent inducer was found to be PL [PL> Co>Sn]. These results indicate that PL, Co or Sn enhance the hepatic and renal metabolism of coumarin derivatives by different rates. Accordingly, these data suggested the different regulation of the coumarin derivatives metabolizing enzymes in the -liver from that in the kidney

Enhancement of O-dealkylation in Mouse Liver by Dietary Administrations of BHA and BHT: Studies with Isolated Perfused Livers and Hepatic Microsomes

Effects of feeding 2(3)-tert-butyl 4-hydroxyanisole (BHA) and 3, 5-di-tert-butyl 4-hydroxytoluene (BHT) on the rates of mixed function oxidation and conjugation enzyme reactions have been determined using isolated hepatic microsomal fractions and isolated perfused livers of mice. The treatments with either of the antioxidants have increased the rates of O-demethylation for p-nitroanisole and of O-deethylation for 7-ethoxycoumarin up to 2-fold, both in microsomes and in perfused liver. Analysis of the perfusate showed that the increased amounts of p-nitrophenol and 7-hydroxycoumarin produced by the elevated mixed-function oxidase activities were reflected by the increase in the amounts of glucuronide conjugates and not in the increase for the amounts of the sulfate ester conjugates. Comparison of results also indicated that in the perfused liver, the maximal rate of metabolite conjugation is limited by the maximal rates of the initial mixed function oxidase activities.