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Biomedical subjects

N Durán

Publications and source records attributed to N Durán.

At least 19 recordsLinked to original sources
PubMed2006

In vitro studies on the release of isoniazid incorporated in poly(epsilon-caprolactone).

A polymeric micro- and nanosphere formulation using poly (epsilon-caprolactone) (PCL) to entrap an antituberculosis drug, isoniazid (INH), was developed and characterized. The microspheres were prepared by a solvent evaporation method using ethyl acetate, PCL and INH as the organic phase and water and Tween 40 as the aqueous phase. The nanospheres were prepared by a spontaneous emulsification solvent diffusion method using 40% ethanol in acetone (v/v), PCL and INH as the organic phase and water and Tween 40 as the aqueous phase. After freeze-drying, these systems were characterized by scanning electron microscopy (SEM), particle size analysis, determination of entrapped INH content, in vitro INH release and brine shrimp toxicity bioassay.

Animals↗
PubMed2005

Violacein cytotoxicity on human blood lymphocytes and effect on phosphatases.

Given the importance of protein phosphorylation in the context of cellular functions, abnormal protein phosphatase activity has been implicated in several diseases, including cancer. These critical roles of protein phosphatases qualify them as potential targets for the development of medicinal compounds that possess distinct modes of action such as violacein. In this work, studies with this natural indolic pigment at a concentration of 10.0 micromol L(-1) demonstrated a 20% activation of total protein phosphatase extracted from human lymphocytes. Although no alteration was observed on protein tyrosine phosphatase (CD45), 30% of inhibition was achieved in cytoplasmatic protein phosphatase activity after incubation with 10.0 micromol L(-1) violacein. Additionally, 5.0 micromol L(-1) of violacein inhibited by 50% the serum tartrate-resistant acid phosphatase activity. Violacein presented toxic effect on lymphocytes with IC50 values of 3 and 10 micromol L(-1) for protein content and protein phosphatase activity, respectively. These findings suggest an important role for protein phosphatases in the mechanisms controlling proliferation and cell death.

Cells, Cultured↗
PubMed2004

Trypanocidal activity of 2-propen-1-amine derivatives on trypomastigotes culture and in animal model.

The cis and trans isomers (either E or Z isomers) of the unsubstituted and bromo-2-propen-1-amine derivatives were evaluated in vitro on Trypanosoma cruzi. The results showed that cis is the most active isomeric form against trypomastigote forms of T. cruzi, indicating that it may contribute most to the trypanocidal effect. All mice which received 5 mg kg(-1) daily for 9 consecutive days, or 200 mg kg(-1) in a single dose of the bromo derivative of 2-propen-1-amine, survived after an infection with 10(4) trypomastigotes/ml of the Y-strain of T. cruzi. They also had a significantly lower parasitemia than the controls. However, with 100 mg kg(-1) of benznidazol for 9 consecutive days, 25% of the animals died by the end of the evaluation 40 days after infection. The involvement of the biosynthesis of ergosterol in the trypanocidal effect of the unsubstituted 2-propen-1-amine derivative was investigated on proliferative epimastigote forms of the parasite. The chromatographic analyses of the lipid extracts obtained from parasites treated with 2-propen-1-amine derivatives and controls (not treated) revealed that growth inhibition is correlated with the accumulation of squalene and the decrease of ergosterol levels. These results suggest that inhibition of the biosynthesis of ergosterol is an important target for the action of the 2-propen-1-amine derivative on T. cruzi through the inhibition of the enzyme squalene epoxidase.

Amines↗
PubMed2004

2-propen-1-amine derivatives and their synthetic intermediates: activity against pathogenic trypanosomatids.

The potential activity of three new derivatives of 3-(4'-Y-[1,1'-biphenyl]-4-yl)-3-(4-X-phenyl)-N,N-dimethyl-2-propen-1-amine (2-PAMs) was assayed against Trypanosoma cruzi and Leishmania amazonensis. They showed higher activity against trypomastigotes and epimastigotes of T. cruzi than the standard drugs, crystal violet and nifurtimox. Besides these derivatives, a series of eleven 2-PAMs derivatives and the corresponding intermediates, biphenyl methanones (BPMs) were assayed against promastigotes of L. amazonensis, showing that the 2-PAMs were remarkably more active than the BPMs. The PAMs 2c, 2e and 2j were about 2-fold more active that pentamidine isothionate and between 27.2- and 46.4-fold less toxic to V79 mammalian cells. The present results encourage further studies, especially against intracellular parasites and in experimental animals.

Animals↗
PubMed2002

A degradation and toxicity study of three textile reactive dyes by ozone.

Textile reactive dyes are very recalcitrant to biodegradation, causing aesthetic, acute and chronic toxicity problems in receiving waters. In this study, we present the degradation of three different reactive dyes (Reactive Black 5, Reactive Blue 19 and Reactive Blue 21) by ozone, at two different pH conditions. The ozonation process achieved a very fast decoloration rate for the studied dyes. The influence of pH in the ozonation of these dyes was only significant for Reactive Black 5. The toxicity of dyes, after pre-treatment, was evaluated using Vibrio fisheri (microtox). There was little change in toxicity for Reactive Black 5, but there was a reduction for Reactive Blue 19. A significant increase in toxicity for Reactive Blue 21 was verified, caused by the increase in the bioavailability of th e cooper ion that was in the complexed form before the treatment with ozone.

Animals↗
PubMed2002

Derivatives of dehydrocrotonin, a diterpene lactone isolated from Croton cajucara: cytotoxicity in rat cultured hepatocytes and in V79 cells.

Derivatives of dehydrocrotonin (DHC; Compound I) with different anti-ulcerogenic properties but less toxicity were produced by reducing the cyclohexenone moiety of DHC with NaBH4 (Compound II), reducing the cyclohexenone and lactone moieties with LiAlH4 (Compound III) and transforming the lactone moiety into an amide (Compound IV) using dimethylamine. Derivatives of DHC were assayed in cultured hepatocytes and V79 fibroblasts. Three independent endpoints assays for cytotoxicity were used, namely, the DNA content, tetrazolium reduction (MTT) and neutral red uptake (NRU). Compound III was less toxic than the other DHC derivatives in both cell cultures. ICso values ranging from 250 to 600 microM were obtained for Compounds II and IV in the NRU and DNA content tests evaluated in 4-hour hepatocyte cultures. Although Compound II showed relatively low cytotoxicity in rat hepatocytes based on the NRU and DNA content assays, a very high toxicity (IC50=10 microM) was observed in the MTT test. Metabolites of Compound II in conditioned medium from 4-hour old hepatocyte cultures enhanced the MTT-reducing ability of V79 fibroblasts. The cytotoxicity of the derivatives was greater in recently isolated hepatocytes (only a 4-hour incubation for cell attachment prior to treating with the derivatives) than in hepatocytes previously cultured (24-hour incubation) before the treatment. Thus, aging reduced the cytotoxic effects of DHC derivatives in isolated hepatocytes, suggesting that P450-mediated biotransformation of such derivatives may lead to the formation of more toxic metabolites.

Animals↗
PubMed2001

Cytotoxicity of derivatives from dehydrocrotonin on V79 cells and Escherichia coli.

New derivatives from dehydrocrotonin (DHC, compound I), with the same anti-ulcerogenic properties but less toxicity were synthesised by reducing the cyclohexenone moiety of DHC with NaBH(4) (compound II), by reducing the cyclohexenone and lactone moieties with LiAlH(4) (compound III) and by transforming the lactone moiety into an amide (compound IV) using dimethylamine. The cytotoxicity of these derivatives from DHC was assayed on V79 fibroblast cell line. Three independent endpoints for cytotoxicity were evaluated; namely, the nucleic acid content (NAC), tetrazolium reduction (MTT) and neutral red uptake (NRU). IC(50) values of 540 and 350 microM were obtained for compound II in the NRU and NAC tests, respectively. Compound III was less toxic than the other DHC derivatives (IC(50)=1800 microM) on V79 cells based on NAC assay. Compound IV showed an IC(50) ranging from 350 to 600 microM based on the three endpoints evaluated. The three compounds were less toxic on V79 cells than DHC. DHC, compounds II, III and IV did not change the respiration rate of Escherichia coli on the acute toxicity assay.

Animals↗
PubMed2001

Combined treatment of textile effluent using the sequence Phanerochaete chrysosporium-ozone.

Textile effluents cause a high environmental impact when released into the environment without correct treatment. In this work, we have evaluated the capacity of treatment of a textile effluent using a biological and a chemical method using the sequence Phanerochaete chrysosporium-ozone. The fungal treatment was performed by direct incubation of a fungus spore suspension in textile effluent for nine days. Then, the effluent was ozonized at pH 11 and room temperature. Color, total organic carbon, molecular mass distribution and total phenols were determined. In biological experiments, enzymatic activity (lignin peroxidase, manganese peroxidase and laccase) were also monitored. Toxicity tests were carried out with Scenedesmus subspicatus and with Escherichia coli. Good decoloration, total phenols reduction and textile effluent molecular mass reduction were obtained during the process. No significant total organic carbon reduction was observed. The toxicity of the textile effluent was reduced with both test organisms showing no inhibition at the end of the treatment.

Biodegradation, Environmental↗
PubMed2001

Kinetic studies on veratryl alcohol transformation by horseradish peroxidase.

A number of peroxidases, such as lignin peroxidase and manganese peroxidase have proved to be useful for industrial applications. Some studies on the effects of temperature and pH stability have been carried out. It is known that veratryl alcohol increases their stability in the range 28-50 degrees C and is oxidized, leading to veratryl aldehyde formation. Similar results with horseradish peroxidase (HRP) in the presence of cofactors were found, but the oxidation of veratryl alcohol in the absence of cofactors was extremely labile at acid pH and inactivated in a few minutes. Considering the growing industrial application of HRP, knowledge of its stability and denaturation kinetics is required. In this study, horseradish peroxidase pool (HRP-VI) and its isoenzymes HRP-VIII (acid) and HRP-IX (basic) have been shown to catalyze the oxidation of veratryl alcohol to veratryl aldehyde in the presence of hydrogen peroxide at pH 5.8 in the 35-45 degrees C range and in the absence of any cofactors. Heat and pH denaturation experiments in the presence and absence of veratryl alcohol incubation were conducted with HRP-VI and HRP-IX isoenzymes. HRP-IX was the most active isoenzyme acting on veratryl alcohol but HRP-VI was the most stable for the temperature range tested. At 35 degrees C the HRP pool presented decay constant (Kd) values of 5.5 x 10(-2) h(-1) and 1.4 10(-2) h(-1) in the absence and presence of veratryl alcohol, respectively, with an effective ratio of 3.9. These results present a new feature of peroxidases that opens one more interesting application of HRP to industrial processes.

Benzyl Alcohols↗
PubMed2001

Synthesis, antimycobacterial activities and cytotoxicity on V79 of 3-[4'-Y-(1,1'-biphenyl)-4-yl]-N,N-dimethyl-3-(4-X-phenyl)-2-propen-1-amine derivatives.

The derivatives of 3-(4'-bromo-[1,1'-biphenyl]-4-yl)-3-(4-X-phenyl)-N,N-dimethyl-2-propen-1-amine (5a-m) were synthesised through a Friedel-Crafts acylation followed by Wittig reaction. The effects of the compounds on standard strains of Mycobacterium sp. (ATCC) and M. tuberculosis isolated from clinical specimens were evaluated. Also the toxicity was determined on V79 cells line using neutral red uptake (NRU), nucleic acid content (NAC) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction to measure the cellular viability.

Alkenes↗
PubMed2001

Biodecolorization screening of synthetic dyes by four white-rot fungi in a solid medium: possible role of siderophores.

AIMS: Four selected fungi were screened for their ability to decolourize a textile effluent and commercial reactive dyes in a solid medium. METHODS AND RESULTS: Ligninolytic enzymes activities (lignin peroxidase, manganese peroxidase and laccase) and siderophores presence were monitored in decolourized plates. RESULTS: The results showed low lignin peroxidase activity and no manganese peroxidase activity was detected for all fungi. Laccase activity was observed in Reactive Blue 19 decolourized plates by Trametes versicolor and Trametes villosa. Siderophores presence was observed in Trametes versicolor, Phanerochaete chrysosporium and Lentinus edodes decolourized plates. CONCLUSION: Lentinus edodes displayed the greatest decolourization ability both in terms of extent and rapidity of decolourization. SIGNIFICANCE AND IMPACT OF THE STUDY: The transformation observed for dyes open the possibility to study siderophores to treat dyes and textile effluents.

Anthraquinones↗
PubMed2001

Violacein biotransformation by basidiomycetes and bacteria.

AIMS: The biotransformation study of the pigment (violacein) produced by Chromobacterium violaceum, was verified by its decolorization utilizing six different organisms in liquid and solid media. METHODS AND RESULTS: Lentinus edodes showed the fastest violacein decolorization (8th d) in solid medium whereas in a liquid medium, violacein was rapidly decolorized in 2 h by Azotobacter vinelandii. Adsorption experiments indicated no significant contribution for the decolorization process for all organisms in both media. CONCLUSIONS, SIGNIFICANCE AND IMPACT OF THE STUDY: The results showed poor lignin peroxidase activity in both media but manganese peroxidase and laccase activity varied according to the organism used. Siderophores presence was also detected in all organisms mainly in the liquid medium experiment.

Adsorption↗
PubMed2001

Remediation and toxicity removal from Kraft E1 paper mill effluent by ozonization.

The degradation of Kraft E1 pulp mill effluent was studied by four different ozonization oxidation systems (O3/pH3, O3/pH11, O3/pH11/H2O2, O3/pH11/UV). The investigation was focused on the reduction of total organic carbon (TOC), total phenols, color and acute toxicity (monitoring by inhibition of Escherichia coli respiration). For a reaction time of 90 minutes, the O3/pH11/UV was the most effective process for decoloration (45%). The O3/pH11/H2O2, O3/pH11/UV and O3/pH11 processes showed the best results for total phenols reduction (approximately/= 90%). None of the studied processes showed a significant TOC reduction. The O3/pH11/UV and O3/pH11 processes were effective for the acute toxicity reduction. Different kinetic parameters were also determined in order to quantify the reactivity of the effluent towards the applied oxidation systems.

Biological Assay↗
PubMed2001

Chromobacterium violaceum: a review of pharmacological and industiral perspectives.

Violet-pigmented bacteria, which have been described since the end of the 19th century, are occasionally the causative agent of septicemia and sometimes cause fatal infection in human and animals. Bacteria, producing violet colonies due to the production of a nondiffusible pigment violacein, were classified as a redefined genus Chromobacterium. Chromobacterium violaceum is gram-negative, and saprophyte from soil and water is normally considered nonpathogenic to human, but is an opportunistic pathogen of extreme virulence for human and animals. The biosynthesis and biological activities of violacein and the diverse effects of this pigment have been studied. Besides violacein, C. violaceum produces other antibiotics, such as aerocyanidin and aerocavin, which exhibit in vitro activity against both gram-negative and gram-positive bacteria. 3,6-Dihydroxyindoxazene and Y-TO678h exhibit a selective activity against gram-negative bacteria. Arphamenine A and B, and FR901228, that enhanced immunoresponse, and potentiators of beta-lactam antibiotics and chelators such as ferrioxamine exhibit important clinical potential applications. Lipopolysaccharides and polyhydroxyesters together with several enzymes appear as important metabolites with biotechnological applications. Many of these metabolites were already studied at the genome level.

Anti-Bacterial Agents↗
PubMed2001

Antimycobacterial activity of 4'-bromo-[1,1'-biphenyl]-4-yl 4-x-phenylmethanone derivatives, and their acute toxicity and cytotoxicity.

The antimycobacterial activity of nine biphenyl methanone (BPM) derivatives against standard strains of Mycobacterium kansasii, M. avium and M. malmoense was determined by colorimetric assay in microplates with the dye Alamar Blue. Acute toxicity of these compounds was also analyzed by determination of CO2 concentration in a respirometric assay using Escherichia coli. The compounds showed weak antimycobacterial activity with a minimal inhibitory concentration (MIC) over 0.038 mmol l-1 and no toxicity was found in E. coli up to 400 mmol l-1. No cytotoxicity was observed on V79 cells up to 0.35 mmol l-1 with 7 of the BPM derivatives, with two exceptions (X = SO2CH3, NO2) that showed some toxicity. The greatest antimycobacterial activity was observed with the SO2CH3 derivative and the application of Principal Component Analysis (PCA) showed a relationship between structure and antimycobacterial activity of the compounds. Two descriptors, nucleophilic superdelocalizability of carbon atom and pi-hydrophobic constant, were necessary to describe this relationship.

Animals↗
PubMed2000

Cytotoxicity of prodigiosin and benznidazole on V79 cells.

The cytotoxicity of prodigiosin, an antibiotic and potential trypanocide produced by Serratia marcescens, and Benznidazole, a trypanocidal drug, were assayed on V79 fibroblast cell line. Three independent endpoints for cytotoxicity were evaluated; namely, the nucleic acid content (NAC), MTT reduction and neutral red uptake (NRU). IC(50) values of 1-20 microM were obtained for prodigiosin in the NRU, MTT and NAC tests. Prodigiosin had greater trypanocidal activity (IC(50)=5 microM) than Nifurtimox (IC(50)=150 microM) a known trypanocide drug used in Chagas' disease therapy. Benznidazole was less toxic (IC(50)=2000 microM) than prodigiosin (IC(50)=1-20 microM) in V79 cells based on the MTT and NAC assays. Benznidazole stimulated the NRU until 2 mM. Indeed, the cell viability measured with the NRU was higher at all concentrations of benznidazole tested than that measured by MTT reduction and NAC assays.

Animals↗
PubMed2000

Myelopoietic response in tumour-bearing mice by an aggregated polymer isolated from Aspergillus oryzae.

The effects of magnesium ammonium phospholinoleate-palmitoleate anhydride (MAPA), a proteic aggregated polymer isolated from Aspergillus oryzae, on the growth and differentiation of granulocyte-macrophage progenitor cells (colony-forming unit-granulocyte-macrophage [CFU-GM]) in normal and Ehrlich ascites tumour-bearing mice were studied. Myelosuppression concomitant with increased numbers of spleen CFU-GM was observed in tumour-bearing mice. Treatment of these animals with MAPA (0.5-10 mg/kg) stimulated marrow myelopoiesis in a dose-dependent manner and reduced spleen colony formation. No changes were observed in total and differential marrow cell counts. The dose of 5.0 mg/kg MAPA, given prior or after tumour inoculation, was the optimal biologically active dose in tumour-bearing mice and this dose schedule also stimulated myelopoiesis in normal mice. MAPA significantly enhanced survival and concurrently reduced tumour growth in the peritoneal cavity. We propose that the modulatory effect of MAPA on the myelopoietic response may be related to its antitumour activity as a possible mechanism for regulation of granulocyte-macrophage production and expression of functional activities.

Animals↗