Differential expression on mitochondrial tryparedoxin peroxidase (mTcTXNPx) in Trypanosoma cruzi after ferrocenyl diamine hydrochlorides treatments

Abstract Resistance to benznidazole in certain strains of Trypanosoma cruzi may be caused by the increased production of enzymes that act on the oxidative metabolism, such as mitochondrial tryparedoxin peroxidase which catalyses the reduction of peroxides. This work presents cytotoxicity assays performed with ferrocenyl diamine hydrochlorides in six different strains of T. cruzi epimastigote forms (Y, Bolivia, SI1, SI8, QMII, and SIGR3). The last four strains have been recently isolated from triatominae and mammalian host (domestic cat). The expression of mitochondrial tryparedoxin peroxidase was analyzed by the Western blotting technique using polyclonal antibody anti mitochondrial tryparedoxin peroxidase obtained from a rabbit immunized with the mitochondrial tryparedoxin peroxidase recombinant protein. All the tested ferrocenyl diamine hydrochlorides were more cytotoxic than benznidazole. The expression of the 25.5 kDa polypeptide of mitochondrial tryparedoxin peroxidase did not increase in strains that were more resistant to the ferrocenyl compounds (SI8 and SIGR3). In addition, a 58 kDa polypeptide was also recognized in all strains. Ferrocenyl diamine hydrochlorides showed trypanocidal activity and the expression of 25.5 kDa mitochondrial tryparedoxin peroxidase is not necessarily increased in some T. cruzi strains. Most likely, other mechanisms, in addition to the over expression of this antioxidative enzyme, should be involved in the escape of parasites from cytotoxic oxidant agents.

Support networks and people with physical disabilities: social inclusion and access to health services / Redes de apoio e pessoas com deficiência física: inserção social e acesso aos serviços de saúde

This study seeks to identify the formation of social support networks of people with physical disabilities, and how these networks can help facilitate access to health services and promote social inclusion. It is a cross-sectional study, with data collected via a form applied to physically disabled persons over eighteen years of age registered with the Family Health Teams of the municipal district of João Pessoa in the state of Paraíba. It was observed that the support networks of these individuals predominantly consist of family members (parents, siblings, children, spouses) and people outside the family (friends and neighbors). However, 50% of the interviewees declared that they could not count on any support from outside the family. It was observed that the support network contributes to access to the services and participation in social groups. However, reduced social inclusion was detected, due to locomotion difficulties, this being the main barrier to social interaction. Among those individuals who began to interact in society, the part played by social support was fundamental.

Este estudo objetiva identificar a constituição das redes de apoio social das pessoas com deficiência física e como estas podem contribuir para facilitar o acesso aos serviços de saúde e a inclusão social das mesmas. Trata-se de um estudo transversal, com dados coletados através de um formulário, aplicado em pessoas com deficiência física maiores de dezoito anos, cadastradas nas Equipes de Saúde da Família do município de João Pessoa (PB). Constatou-se que as redes de apoio dessas pessoas estão constituídas principalmente pelos componentes da dimensão familiar (pais, irmãos, filhos, cônjuges) e extrafamiliar (amigos e vizinhos). No entanto, 50% dos entrevistados relataram não contar com qualquer apoio fora da família. Verificou-se que a rede de apoio contribui para o acesso aos serviços e para a participação em grupos sociais. Evidenciou-se, porém, uma reduzida inserção social, decorrente da dificuldade de locomoção, sendo esta a principal barreira para a interação social. Entre as pessoas que começaram a interagir na sociedade o apoio social foi fundamental.

Enhancement of ligninolytic enzyme activities in a Trametes maxima-Paecilomyces carneus co-culture: Key factors revealed after screening using a Plackett-Burman experimental design

Background In the industrial biotechnology, ligninolytic enzymes are produced by single fungal strains. Experimental evidence suggests that co-culture of ligninolytic fungi and filamentous microfungi results in an increase laccase activity. In this topic, only the ascomycete Trichoderma spp. has been studied broadly. However, fungal ligninolytic-filamentous microfungi biodiversity interaction in nature is abundant and poorly studied. The enhancement of laccase and manganese peroxidase (MnP) activities of Trametes maxima as a function of time inoculation of Paecilomyces carneus and under several culture conditions using Plackett-Burman experimental design (PBED) were investigated. Results The highest increases of laccase (12,382.5 U/mg protein) and MnP (564.1 U/mg protein) activities were seen in co-cultures I3 and I5, respectively, both at 10 d after inoculation. This level of activity was significantly different from the enzyme activity in non-inoculated T. maxima (4881.0 U/mg protein and 291.8 U/mg protein for laccase and MnP, respectively). PBED results showed that laccase was increased (P < 0.05) by high levels of glucose, (NH4)2SO4 and MnSO4 and low levels of KH2PO4, FeSO4 and inoculum (P < 0.05). In addition, MnP activity was increased (P < 0.05) by high yeast extract, MgSO4, CaCl2 and MnSO4 concentrations. Conclusions Interaction between indigenous fungi: T. maxima-P. carneus improves laccase and MnP activities. The inoculation time of P. carneus on T. maxima plays an important role in the laccase and MnP enhancement. The nutritional requirements for enzyme improvement in a co-culture system are different from those required for a monoculture system.

Aflatoxin detoxification by manganese peroxidase purified from Pleurotus ostreatus

Manganese peroxidase (MnP) was produced from white rot edible mushroom Pleurotus ostreatus on the culture filtrate. The enzyme was purified to homogeneity using (NH4)2SO4 precipitation, DEAE-Sepharose and Sephadex G-100 column chromatography. The final enzyme activity achieved 81UmL-1, specific activity 78 U mg-1 with purification fold of 130 and recovery 1.2% of the crude enzyme. SDS-PAGE indicated that the pure enzyme have a molecular mass of approximately 42 kDa. The optimum pH was between 4-5 and the optimum temperature was 25 ºC. The pure MnP activity was enhanced by Mn2+,Cu2+,Ca2+ and K+ and inhibited by Hg+2 and Cd+2.H2O2 at 5 mM enhanced MnP activity while at 10 mM inhibited it significantly. The MnP-cDNA encoding gene was sequenced and determined (GenBank accession no. AB698450.1). The MnP-cDNA was found to consist of 497 bp in an Open Reading Frame (ORF) encoding 165 amino acids. MnP from P. ostreatus could detoxify aflatoxin B1 (AFB1) depending on enzyme concentration and incubation period. The highest detoxification power (90%) was observed after 48 h incubation at 1.5 U mL-1 enzyme activities.

Ultrastructural changes and oxidative stress markers in wild and cultivar Sesamum orientale L. following Alternaria sesami (Kawamura) Mohanty and Behera inoculation.

Alternaria sesami causes leaf spot disease in Sesamum orientale. Conidium germination, inoculation, penetration and colonization of the pathogen on the plant surfaces were studied using scanning electron microscopy. Electron microscopy analysis revealed multiple germ tubes from conidium that spread in all direction across the leaf surfaces. Penetration in the plant surface occured, directly through the epidermis or via stomata with or without the appressoria formation. Hyphal penetration continued through the substomata cavity and some of hyphal branches grew in the intercellular space of mesophyll tissue. Hyphal toxin, caused cell and cell wall damages. Changes in different biochemical parameters in the diseased sesame plants (both in wild and cultivar) were compared to control. Transmission electron microscopy showed structural changes in the chloroplast of diseased plants. Isozyme pattern and assays of different enzymes, namely catalase, acid phosphatase and peroxidase expressed varied level of activities. Meanwhile, esterase, polyphenol oxidase and superoxide dismutase in diseased plants showed remarkable levels compared to control. Due to the infection, chlorophyll content, carbohydrates and total soluble protein decreased whereas free amino acid, proline, phenols and disease-related proteins increased in the host plants. Differential SDS-PAGE band profiling of total soluble proteins were also observed in plants due to the infection.

Differential antioxidative response of tolerant and sensitive maize (Zea mays L.) genotypes to drought stress at reproductive stage.

The role of oxidative stress management was evaluated in two maize (Zea mays L.) genotypes — Parkash (drought-resistant) and Paras (drought-sensitive), subjected to drought stress during reproductive stage. Alterations in their antioxidant pools — glutathione (GSH) and ascorbic acid (AsA) combined with activities of enzymes glutathione reductase (GR), ascorbate peroxidase (APX), peroxidase (POX) and catalase (CAT) involved in defense against oxidative stress and stress parameters, namely chlorophyll (Chl), hydrogen peroxide (H2O2) and malondialdehyde (MDA) were investigated in flag leaves from silk emergence till maturity. The drought caused transient increase in GR, APX, POX and CAT activities in drought-tolerant genotype (Parkash) which decreased at later stages with the extended period of drought stress. However, in Paras, drought stress caused decrease in activities of GR and CAT from initial period of stress till the end of experiment, except for POX which showed slight increase in activity. A significant increase in GSH content was observed in Parkash till 35 days after silking (DAS), whereas in Paras, GSH content remained lower than irrigated till maturity. Parkash which had higher AsA and Chl contents, also showed lower H2O2 and MDA levels than Paras under drought stress conditions. However, at the later stages, decline in antioxidant enzyme activities in Parkash due to severe drought stress led to enhanced membrane damage, as revealed by the accumulation of MDA. Our data indicated that significant activation of antioxidant system in Parkash might be responsible for its drought-tolerant behavior under drought stress and helped it to cope with the stress up to a definite period. Thus, the results indicate that antioxidant status and lipid peroxidation in flag leaves can be used as indices of drought tolerance in maize plants and also as potential biochemical targets for the crop improvement programmes to develop drought-tolerant cultivars.

Grape stalks as substrate for white rot fungi, lignocellulolytic enzyme production and dye decolorization / Uso del escobajo como sustrato para el crecimiento de hongos de la pudrición blanca, la producción de enzimas ligninolíticas y la decoloración de tinturas

The aim of this work was to evaluate the potential of grape stalks, an agroindustrial waste, for growth and lignocellulolytic enzyme production via solid-state fermentation, using the following three white rot fungi: Trametes trogii, Stereum hirsutum and Coriolus antarcticus. The decolorization of several dyes by the above mentioned cultures was also investigated. Similar values of dry weight loss of the substrate were measured after 60 days (33-43 %). C. antarcticus produced the highest laccase and Mn-peroxldase activities (33.0 and 1.6 U/g dry solid). The maximum endoglucanase production was measured in S. hirsutum cultures (10.4 U/g), while the endoxylanase peak corresponded to T. trogii (14.6 U/g). The C. antarcticus/grape stalk system seems potentially competitive in bioremediation of textile processing effluents, attaining percentages of decolorization of 93, 86, 82, 82, 77, and 58 % for indigo carmine, malachite green, azure B, remazol brilliant blue R, crystal violet and xylidine, respectively, in 5 h.

El objetivo de este trabajo fue evaluar el potencial del escobajo, un residuo agroindustrial, como sustrato para el crecimiento y la producción de enzimas lignocelulósicas de tres hongos causantes de pudrición blanca en la madera: Trametes trogii, Stereum hirsutum y Coriolus antarcticus. Para ello se utilizaron técnicas de fermentación en estado sólido. También se ensayó la decoloración de colorantes industriales sobre estos cultivos. La pérdida de peso seco del sustrato fue similar después del día 60 (33-43 %). C. antarcticus produjo las mayores actividades de lacasa y Mn-peroxidasa (33,0 y 1,6 U/g peso seco). La mayor actividad endoglucanasa fue medida en cultivos de S. hirsutum (10,4 U/g), y la mayor actividad endoxilanasa en T. trogii (14,6 U/g). El sistema C. antarcticus/escobap mostró un importante potencial para su aplicación en la biorremediación de efluentes textiles, con porcentajes de decoloración de 93, 86, 82, 82, 77 y 58 % para índigo carmín, verde de malaquita, azure B, azul R brillante de remazol, cristal violeta y xilidina, respectivamente, en 5 h.

Pre-treatment of seeds with static magnetic field ameliorates soil water stress in seedlings of maize (Zea mays L.).

The effect of magnetic field (MF) treatments of maize (Zea mays L.) var. Ganga Safed 2 seeds on the growth, leaf water status, photosynthesis and antioxidant enzyme system under soil water stress was investigated under greenhouse conditions. The seeds were exposed to static MFs of 100 and 200 mT for 2 and 1 h, respectively. The treated seeds were sown in sand beds for seven days and transplanted in pots that were maintained at -0.03, -0.2 and -0.4 MPa soil water potentials under greenhouse conditions. MF exposure of seeds significantly enhanced all growth parameters, compared to the control seedlings. The significant increase in root parameters in seedlings from magnetically-exposed seeds resulted in maintenance of better leaf water status in terms of increase in leaf water potential, turgor potential and relative water content. Photosynthesis, stomatal conductance and chlorophyll content increased in plants from treated seeds, compared to control under irrigated and mild stress condition. Leaves from plants of magnetically-treated seeds showed decreased levels of hydrogen peroxide and antioxidant defense system enzymes (peroxidases, catalase and superoxide dismutase) under moisture stress conditions, when compared with untreated controls. Mild stress of -0.2 MPa induced a stimulating effect on functional root parameters, especially in 200 mT treated seedlings which can be exploited profitably for rain fed conditions. Our results suggested that MF treatment (100 mT for 2 h and 200 for 1 h) of maize seeds enhanced the seedling growth, leaf water status, photosynthesis rate and lowered the antioxidant defense system of seedlings under soil water stress. Thus, pre sowing static magnetic field treatment of seeds can be effectively used for improving growth under water stress.

Effect of exogenous H2O2 on antioxidant enzymes of Brassica juncea L. seedlings in relation to 24-epibrassinolide under chilling stress.

Hydrogen peroxide is most stable molecule among reactive oxygen species, which play a vital role in growth and development of plant as signaling molecule at low concentration in response to various abiotic and biotic stresses. Exogenous application of H2O2 is known to induce chilling tolerance in plants. Brassinosteroids are plant steroid hormones known for their anti-stress properties. In this study, effect of exogenous H2O2 on antioxidant defense system of Brassica juncea L. seedlings was investigated in 24-epibrassinolide (24-EBL) treated and untreated seedlings under chilling stress. The surface sterilized seeds of B. juncea L. were germinated in petriplates containing different concentrations of H2O2 alone and in combination with 10-8 M 24-EBL. Chilling treatment (4 ºC) was given to 10-days old seedlings grown in different treatments for 6 h daily up to 3 days. 24 h recovery period was given to chilling treated seedlings by placing at 25ºC ± 2ºC and harvested for antioxidant enzymes on 14th day after sowing (DAS). Treatment of 24-EBL in combination with H2O2 (15 and 20 mM) helped in reducing the toxicity of seed and seedlings due to H2O2 exposure on their germination rate, shoot and root length respectively. 24-EBL treatment at seed and seedling stage helped in alleviating the toxic effect of H2O2 through antioxidant defense system by increasing the activities of various enzymes involved in antioxidant defense system such as catalase (CAT, E.C. 1.11.1.6), ascorbate peroxidase (APOX, E.C. 1.11.1.11), and superoxide dismutase (SOD, E.C. 1.15.1.1). In conclusion, exogenous pretreatment of H2O2 to seeds of B. juncea L. adapted the seedlings to tolerate chilling stress, which was further ameliorated in combination of H2O2 with 24-EBL.

Industrial and biotechnological applications of ligninolytic enzymes of the basidiomycota: a review

Ligninolytic enzymes of the basidiomycetes play a crucial role in the global carbon cycle. The demand for application of ligninolytic enzymes complexes of white-rot fungi in industry and biotechnology is ever increasing due to their use in a variety of processes. Ligninolytic enzymes have potential applications in a large number of fields, including the chemical, fuel, food, agricultural, paper, textile, cosmetic industrial sectors and more. This ligninolytic system of white-rot fungi is also directly involved in the degradation of various xenobiotic compounds and dyes. Their capacities to remove xenobiotic substances and produce polymeric products make them a useful tool for bioremediation purposes. This paper reviews the applications of ligninolytic enzymes of basidiomycetes within different industrial and biotechnological area.

Biomolecular changes during in vitro organogenesis of Asteracantha longifolia (L.) Nees--a medicinal herb.

High frequency plant regeneration in A. longifolia (L.) was achieved from leaf explant implanted on MS basal medium supplemented with NAA (0.5 mg/l) + BA (2.0 mg/l) through intervening callus phase. Well-developed shoots (>3cm) were successfully rooted on MS medium supplemented with NAA (0.1 mg/l). Protein and total soluble sugar contents were maximum during organogenesis and multiple shoot induction phase compared with non-organogenic callus and root induction phase. Esterase and catalase activities were maximum during organogenic differentiation, while activities were minimum at non-differentiated callus stages. Peroxidase activities were higher during rhizogenesis. Contradiction to peroxidase activity, acid phosphatase activities were high during organogenesis and declined during rhizogenesis. SDS-PAGE analysis of total soluble proteins revealed expression of non-organogenic callus (97.9 kDa), organogenic callus (77.2, 74.1, 21.9 kDa), multiple shoot induction phase (106.6, 26.9, 11.6 kDa) and root induction phase (15.9 kDa) specific polypeptides. Esterase zymogram revealed one band (Rm 0.204) appeared in both organogenic callus and multiple shoot induction phase. Peroxidase zymogram detected two stage specific bands, one band (Rm 0.42) was specific to root induction phase, while another (Rm 0.761) was specific to multiple shoot induction. Catalase and acid phosphatase zymogram resolved one band (Rm 0.752 and 0.435, respectively) in differentiated stages including both multiple shoot induction phase and root induction phase, but absent in undifferentiated phases.

Antioxidative response of Lemna polyrrhiza L. to cadmium stress.

Growth, lipid peroxidation, different antioxidative enzymes and metal accumulation were studied in Lemna polyrrhiza treated with different concentrations (1-40 ppm) of CdSO4. The growth of the plant was slightly enhanced with 1 ppm, while higher concentrations retarted growth and multiplication of fronds, the effect being concentration and dose dependant. Increase in malondialdehyde content was insignificant after the first week but a prolonged exposure led to significant (p < 0.05) increase of about 38% and 45% over the control in 20 and 30 ppm, respectively after four weeks. Catalase (EC 1.11.1.6; CAT) activity increased at low concentration, but it declined to 42% and 54% at 40 ppm after 6 and 30 days, respectively Superoxide dismutase (EC 1.15.1.1; SOD), ascorbate peroxidase (EC 1.11.1.11;APx) and glutathione reductase (EC 1.6.4.2) increased at both low as well at high concentrations, but a prolonged exposure to high concentration of Cd (40 ppm) led to significant (p < 0.05) decline in the mean activities of these antioxidant enzymes. Accumulation of Cd in biomass was concentration and time dependant However at high concentration of 40 ppm, Cd accumulation did not increase significantly (p < 0.05) with time. Increased activities of antioxidant enzymes in Cd treated plants suggest that metal tolerance in L. polyrrhiza might be associated to the changes of antioxidant enzymatic activities.

Caracterización de los fagocitos mononucleares en la sangre de phrynops hilarii (Chelonia chelidae) / Characterization of blood mononuclear phagocytes in Phrynops hilarii (Chelonia chelidae)

The localization of peroxidase activity in different cell regions is used as a criterion for the classification of the stage of maturation of mammalian mononuclear phagocytes with a positive peroxidase reaction indicating the presence of monoblasts, promonocytes, monocytes and macrophages. In this study it was evaluated the peroxidase activity of blood mononuclear phagocytes of this turtle detected at different stages of differentiation. The present observations suggest that, in turtles, the differentiation of mononuclear phagocytes occur in the blood circulation, in contrast to animals, where only are monocytes in circulating blood and macrophage differentiation occurs in other body compartments.

La localization de la actividad de la peroxidasa en diversas regiones de la célula se utiliza como criterio para la clasificación de la etapa de maduración de fagocitos mononucleares. Una reacción positiva de peroxidasa indica la presencia de monoblastos, promonocitos, monocitos y macrófagos. En este estudio fue evaluada la actividad de la peroxidasa de los fagocitos mononucleares de la sangre de la tortuga Phrynops Hilarii detectada en diversas etapas de la diferenciación. Las actuales observaciones sugieren que, en tortugas, la diferenciación de fagocitos mononucleares ocurre en la circulación de la sangre, en contraste a los mamíferos, donde están solamente los monocitos en la sangre circulante y la diferenciación de los macrófagos ocurre en otras partes del cuerpo.

UV-B induced changes in antioxidant enzymes and their isoforms in cucumber (Cucumis sativus L.) cotyledons.

To assess the role of antioxidant defense system on exposure to ultra-violet-B (UV-B) radiation, the activities of antioxidant enzymes superoxide dismutase (SOD), ascorbic acid peroxidase (APX), glutathione reductase (GR) and guaiacol peroxidase (GPX), as well as the level of antioxidants ascorbic acid (AA) and alpha-tocopherol were monitored in cucumber (Cucumis sativus L. var long green) cotyledons. UV-B enhanced the activity of antioxidant enzymes as well as AA content, but decreased the level of alpha-tocopherol. Significant increase was observed in the activities of SOD and GPX. Analysis of isoforms of antioxidant enzymes by native-PAGE and activity staining revealed three isoforms of GPX in unexposed dark-grown cotyledons (control), and their intensity was enhanced by UV-B exposure. In addition, four new isoforms of GPX were observed in cotyledons after UV-B exposure. Although no new isoforms were observed for the other antioxidant enzymes, the activities of their existing isoforms were enhanced by UV-B.

The structural molecular biology network of the State of São Paulo, Brazil

Esse artigo descreve realizações do Programa SMolBNet (Rede de Biologia Molecular Estrutural) do Estado de São Paulo, apoiado pela FAPESP (Fundação de Apoio à Pesquisa do Estado de São Paulo). Ele reúne vinte grupos de pesquisa e é coordenado pelos pesquisadores do Laboratório Nacional de Luz Síncrotron (LNLS), em Campinas. O Programa SMolBNet tem como metas: Elucidar a estrutura tridimensional de proteínas de interesse aos grupos de pesquisa componentes do Programa; Prover os grupos com treinamento em todas as etapas de determinação de estrutura: clonagem gênica, expressão de proteínas, purificação de proteínas, cristalização de proteínas e elucidação de suas estruturas. Tendo começado em 2001, o Programa alcançou sucesso em ambas as metas. Neste artigo, quatro dos grupos descrevem suas participações, e discutem aspectos estruturais das proteínas que eles selecionaram para estudos.

Peripheral markers of oxidative stress in chronic mercuric chloride intoxication

The present study was designed to evaluate the time course changes in peripheral markers of oxidative stress in a chronic HgCl2 intoxication model. Twenty male adult Wistar rats were treated subcutaneously daily for 30 days and divided into two groups of 10 animals each: Hg, which received HgCl2 (0.16 mg kg-1 day-1), and control, receiving the same volume of saline solution. Blood was collected at the first, second and fourth weeks of Hg administration to evaluate lipid peroxidation (LPO), total radical trapping antioxidant potential (TRAP), and superoxide dismutase (Cu,Zn-SOD), glutathione peroxidase (GPx), glutathione-S-transferase (GST), and catalase (CAT). HgCl2 administration induced a rise (by 26 percent) in LPO compared to control (143 ± 10 cps/mg hemoglobin) in the second week and no difference was found at the end of the treatment. At that time, GST and GPx were higher (14 and 24 percent, respectively) in the Hg group, and Cu,Zn-SOD was lower (54 percent) compared to control. At the end of the treatment, Cu,Zn-SOD and CAT were higher (43 and 10 percent, respectively) in the Hg group compared to control (4.6 ± 0.3 U/mg protein; 37 ± 0.9 pmol/mg protein, respectively). TRAP was lower (69 percent) in the first week compared to control (43.8 ± 1.9 mM Trolox). These data provide evidence that HgCl2 administration is accompanied by systemic oxidative damage in the initial phase of the process, which leads to adaptive changes in the antioxidant reserve, thus decreasing the oxidative injury at the end of 30 days of HgCl2 administration. These results suggest that a preventive treatment with antioxidants would help to avoid oxidative damage in subjects with chronic intoxication.

Inactivación de la dihidrolipoamida deshidrogenasa de Trypanosoma cruzi por fenotiazinas en presencia de citocromo c y peróxido de hidrógeno: efectos de los antioxidantes / Trypanosoma cruzi dihydrolipoamide dehydrogenase is inactivated by phenothiazines in the presence of cytochrome c and hydrogen peroxide: effects of antioxidants

El citocromo c catalizó la oxidación de las fenotiazinas (FTZ) en presencia de peróxido de hidrógeno. La formación del radical catiónico de promazina (PZ+.) se demostró por espectrofo-tometría y por su conversión a promazina sulfóxido La dihidrolipoamida deshidrogenasa (LADH) del Trypanosoma cruzi es inhibida irreversiblemente por el sistema citocromo c/H2O2 complementado con fenotiazinas. La inactivación de la LADH del parásito varía según la estructura de las FTZ, el tiempo de incubación del sistema pro-oxidante con la LADH, y la presencia de un antioxidante supresor de radicales FTZ+. Entre las 12 FTZ ensayadas, la promazina (PZ), tioridazina (TRDZ) y trimeprazina (TMPZ) fueron las más efectivas produciendo inactivaciones de 82 por ciento,76 por ciento y 72 por ciento, respectivamente, a los 90 min de incubación. El efecto de PZ (con grupo alquilamino en la posición N 10) disminuyó por modificación de su estructura en la posición 2 (efecto inactivante de PZ > cloropromazina (CPZ) > propionilpromazina (PPZ) > trifluopromazina (TFPZ) o en la posición 10 ( efecto inactivante de PZ > TMPZ > prometazina (PMTZ).El efecto de las FTZ con sustituyente piperidinil en N 10 dependió del grupo de la posición 2 ( SCH3, en TRDZ de mayor efecto; CN, en propericiazina (PCYZ), la de menor efecto entre las FTZ estudiadas). Parece que la presencia del sustituyente piperazinil en posición N 10 no tiene función importante en el efecto inactivante de las FTZ, el cual dependió de la estructura del grupo en la posición 2. El efecto de los compuestos con Cl en posición 2 (CPZ, procloroperazina (PCP), perfenazina (PFZ)) fue mayor que el obtenido con los compuestos CF3 (TFPZ, trifluoroperazina (TFP), flufenazina (FFZ), e independiente de la estructura del sustituyente N 10.El efecto de las FTZ sobre la LADH de T. cruzi depende, por lo menos en parte, de la estabilidad de los radicales FTZ+. generados por la actividad peroxidasa. La LADH T c, en comparación con la LADH de mamífero...

Cytochrome c catalyzed the oxidation of phenothiazines (PTZ) in the presence of hydrogen peroxide. The transient formation of the promazine radical cation (PZ+.) has been demonstrated by light absorption measurements as well as by its conversión to promazine sulfoxide. Trypanosoma cruzi dihydrolipoamide dehydrogenase (LADH T c) was irreversibly inhibited by treatment with cytochrome c (cyt c)/H2O2 system supplemented with PTZ. LADH T c inactivation depended on a) The PTZ structure b) Time of incubación with the complete oxidant system c) The presence of an antioxidant that intercept free radicals. PZ, thioridazine (TRDZ) and trimeprazine (TMPZ), were the most effective systems out of twelve PTZ studied, with inactivation values of 82, 76 and 72%, respectively, after 90 min of incubation. LADH T c inactivation by PZ (with alkylamine substituent at N 10 position) decreased by its structural modification at 2 position (inactivation PZ > chlorpromazine (CPZ) > propionylpromazine (PPZ)>trifluopromazine (TFPZ)) or at N 10 position (inactivation PZ > TMPZ > promethazine (PMTZ)) PTZ activity with piperidinyl substituent at N10 position depended on the group at 2 position (TRDZ, with thiomethyl group, has high inactivating effect on LADH T c; propericyazine (PCYZ), with cyano group, is much less active). Apparently, piperazinyl substituent at the N10 position on the phenothiazine have not an important function in the compound's inactivating effect on LADH T c. The effect of PTZ with Cl at 2 position (CPZ, prochlorperazine (PCP), perphenazine (PFZ)) was higher than the effect of compounds with CF3 in the same position (TFPZ,trifluoperazine (TFP),fluphenazine (FFZ) ) independent on the structure of substituents at N10 position. Production of PTZ+. radicals was essential for LADH T c inactivation and this effect depended on the stability of these free radicals. Comparision of inactivation values for LADH T c and mammalian LADH demonstrated...

Biochemical studies of embryogenic and non-embryogenic callus of Cardiospermum halicacabum L.

Some physiological and biochemical changes were measured between embryogenic and non-embryogenic callus obtained from Cardiospermum halicacabum. Combination of auxin with cytokinin was more favourable for high amount of callus formation. 2,4-D played a key role in triggering somatic embryo formation. Embryogenic callus had more total carbohydrate and starch contents, total free amino acids, nucleic acids, phenols and ascorbic acid. Non-embryogenic callus exhibited high chlorophyll content, total soluble sugar, protein, ammonia and enzymes like peroxidase and polyphenol oxidase. Thus, the present study indicated that the process of somatic embryogenesis was characterized by some biochemical and physiological changes induced by plant growth regulators.

Protoporphyrin IX-induced structural and functional changes in human red blood cells, haemoglobin and myoglobin.

Protoporphyrin IX and its derivatives are used as photosensitizers in the photodynamic therapy of cancer. Protoporphyrin IX penetrates into human red blood cells and releases oxygen from them. This leads to a change in the morphology of the cells. Spectrophotometric studies reveal that protoporphyrin IX interacts with haemoglobin and myoglobin forming ground state complexes. For both proteins, the binding affinity constant decreases, while the possible number of binding sites increases, as the aggregation state of the porphyrin is increased. The interactions lead to conformational changes of both haemoglobin and myoglobin as observed in circular dichroism studies. Upon binding with the proteins, protoporphyrin IX releases the heme-bound oxygen from the oxyproteins, which is dependent on the stoichiometric ratios of the porphyrin : protein. The peroxidase activities of haemoglobin and myoglobin are potentiated by the protein-porphyrin complexation. Possible mechanisms underlying the relation between the porphyrin-induced structural modifications of the heme proteins and alterations in their functional properties have been discussed. The findings may have a role in establishing efficacy of therapeutic uses of porphyrins as well as in elucidating their mechanisms of action as therapeutic agents.