RESUMEN
The synthesis and biological evaluation of eleven derivatives of the natural polyether ionophore monensin A (MON), modified at the C-26 position, is presented. Eight urethane and three ester derivatives were tested for their antimicrobial activity against different strains of Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli and Pseudomonas aeruginosa. In addition, their antiparasitic activity was also evaluated with bloodstream forms of Trypanosoma brucei. The majority of the modified ionophores were active against a variety of Gram-positive bacterial strains, including methicillin-resistant S. epidermidis, and showed better antibacterial activity than the unmodified MON. The phenyl urethane derivative of MON exhibited the most promising antibacterial activity of all tested compounds, with minimal inhibitory concentration values of 0.25-0.50 µg/ml. In contrast, none of the MON derivatives displayed higher antitrypanosomal activity than the unmodified ionophore.
Asunto(s)
Antibacterianos/farmacología , Monensina/farmacología , Tripanocidas/farmacología , Antibacterianos/síntesis química , Antibacterianos/química , Relación Dosis-Respuesta a Droga , Escherichia coli/efectos de los fármacos , Pruebas de Sensibilidad Microbiana , Estructura Molecular , Monensina/análogos & derivados , Monensina/química , Pruebas de Sensibilidad Parasitaria , Pseudomonas aeruginosa/efectos de los fármacos , Staphylococcus aureus/efectos de los fármacos , Staphylococcus epidermidis/efectos de los fármacos , Relación Estructura-Actividad , Tripanocidas/síntesis química , Tripanocidas/química , Trypanosoma brucei brucei/efectos de los fármacosRESUMEN
The targeted manipulation of polyketide synthases has in recent years led to numerous new-to-nature polyketides. For typeâ I polyketide synthases the response of post-polyketide synthases (PKS) processing enzymes onto the most frequently polyketide backbone manipulations is so far insufficiently studied. In particular, complex processes such as the polyether cyclisation in the biosynthesis of ionophores such as monensin pose interesting objects of research. We present here a study of the substrate promiscuity of the polyether cyclisation cascade enzymes in monensin biosynthesis in the conversion of redox derivatives of the nascent polyketide chain. LC-HRMS/MS2 -based studies revealed a remarkable flexibility of the post-PKS enzymes. They acted on derivatized polyketide backbones based on the three possible polyketide redox states within two different modules and gave rise to an altered polyether structure. One of these monensin derivatives was isolated and characterized by 2D-NMR spectroscopy, crystallography, and bioactivity studies.
Asunto(s)
Éteres/química , Monensina/química , Mutación Puntual , Sintasas Poliquetidas/genética , Antiinfecciosos/farmacología , Cromatografía Líquida de Alta Presión/métodos , Cromatografía de Fase Inversa , Cristalografía por Rayos X , Ciclización , Pruebas de Sensibilidad Microbiana , Estructura Molecular , Monensina/análogos & derivados , Monensina/farmacología , Resonancia Magnética Nuclear Biomolecular/métodos , Espectrometría de Masas en TándemRESUMEN
Monensin A (MON) is a polyether ionophore antibiotic, which shows a wide spectrum of biological activity, including anticancer activity. A series of structurally diverse monensin esters including its C-1 esters (1-9), C-26-O-acetylated derivatives (10-15), and lactone (16) was synthesized and for the first time evaluated for their antiproliferative activity against four human cancer cell lines with different drug-sensitivity level. All of the MON derivatives exhibited in vitro antiproliferative activity against cancer cells at micromolar concentrations. The majority of the compounds was able to overcome the drug resistance of LoVo/DX and MES-SA/DX5 cell lines. The most active compounds proved to be MON C-26-O-acetylated derivatives (10-15) which exhibited very good resistance index and high selectivity index.
Asunto(s)
Antineoplásicos , Proliferación Celular/efectos de los fármacos , Monensina , Neoplasias , Antineoplásicos/síntesis química , Antineoplásicos/química , Antineoplásicos/farmacología , Línea Celular Tumoral , Relación Dosis-Respuesta a Droga , Humanos , Monensina/análogos & derivados , Monensina/síntesis química , Monensina/química , Monensina/farmacología , Neoplasias/tratamiento farmacológico , Neoplasias/metabolismo , Neoplasias/patologíaRESUMEN
The incorporation of new-to-nature extender units into polyketide synthesis is an important source for diversity yet is restricted by limited availability of suitably activated building blocks in vivo. We here describe a straightforward workflow for the biogenic activation of commercially available new-to-nature extender units. Firstly, the substrate scope of a highly flexible malonyl co-enzyme A synthetase from Streptomyces cinnamonensis was characterized. The results were matched by in vivo experiments in which the said extender units were accepted by both the polyketide synthase and the accessory enzymes of the monensin biosynthetic pathway. The experiments gave rise to a series of predictable monensin derivatives by the exploitation of the innate substrate promiscuity of an acyltransferase and downstream enzyme functions.
Asunto(s)
Proteínas Bacterianas/metabolismo , Coenzima A Ligasas/metabolismo , Monensina/biosíntesis , Sintasas Poliquetidas/metabolismo , Aciltransferasas/química , Aciltransferasas/metabolismo , Monensina/análogos & derivados , Dominios Proteicos , Streptomyces/enzimología , Especificidad por SustratoRESUMEN
Essential oil (EO) from Brazilian red pepper fruit contains compounds with antimicrobial activity, and could be possible substitutes for the antibiotics commonly used in ruminant nutrition. The objectives of the present study were to evaluate the effects of the Brazilian red pepper fruit EO (Schinus terebinthifolius) as a substitute for monensin on performance, carcass characteristics and meat of lambs fed high concentrate diets. Forty-eight lambs were used, 24 males (20 ½ Dorper × ½ Santa Inês and 4 Santa Inês) and 24 females (24 ½ Dorper × ½ Santa Inês), with 21.54 ± 0.88 kg of initial body weight (BW) and 78 ± 2.4 days of age, in a randomized complete block design. The experiment lasted 56 days, divided into 2 periods of 28 days each. The treatments were defined by the inclusion in diets of 8 ppm of monensin (MON), and the doses 0.14% (14EO), 0.28% (28EO) and 0.42% (42EO) of red pepper fruit EO. The additives were included in a base diet with a 10:90 of forage to concentrate ratio. At the end of 56 days, 32 animals were slaughtered for the measurement of carcass parameters and meat composition. There was no interaction among treatments and periods for average daily gain (P = 0.08), DM intake (P = 0.36), feed efficiency (P = 0.24) and oocyst of Eimeria ssp. in feces (P = 0.46). The treatments did not affect (P > 0.05) the average daily gain (ADG), dry matter intake (DMI) and feed efficiency. Lambs fed diets containing monensin had less (P < 0.01) oocyst/g compared with the diet 14EO. There was no effect of diets on carcass characteristics. The treatments with higher doses of the Brazilian red pepper fruit EO had reduced mineral content of meat compared to monensin. The red pepper fruit EO demonstrated the potential to replace monensin in feedlot lambs fed high concentrate diets, maintaining performance and carcass characteristics. However, the monensin has greater capacity to control coccidiosis in feedlot lambs.
Os óleos essenciais (OE) dos frutos de aroeira possuem compostos com atividade antimicrobiana, sendo possíveis substitutos aos antibióticos comumente utilizados na nutrição de ruminantes. Os objetivos do presente estudo foram avaliar os efeitos da inclusão do óleo essencial de aroeira fruta (Schinus terebinthifolius) como substituto da monensina sobre o desempenho, características de carcaça e da carne de cordeiros alimentados com dietas contendo elevado teor de concentrado. Foram utilizados 48 cordeiros, 24 machos (20 ½ Dorper × ½ Santa Inês e 4 Santa Inês) e 24 fêmeas (24 ½ Dorper × ½ Santa Inês), com peso inicial de 21,54 ± 0,88 kg e 78 ± 2,4 dias de idade, em delineamento de blocos completos casualizados. O experimento teve duração de 56 dias, divididos em 2 períodos de 28 dias cada. Os tratamentos foram definidos pela inclusão na dieta de 8 ppm de monensina sódica (MON) e as doses de 0,14% (14EO), 0,28% (28EO) e 0,42% (42EO) de óleo essencial dos frutos da aroeira. As dietas experimentais foram compostas por 10% de volumoso e 90% de concentrado. Ao final dos 56 dias, 32 animais foram abatidos para a mensuração dos parâmetros de carcaça e análise química da carne. Não houve interação entre tratamento e período para o ganho médio diário (P = 0,08), consumo de MS (P = 0,36), eficiência alimentar (P = 0,24) e contagem de oocistos de Eimeria ssp. (P = 0,46). Não houve efeito (P > 0,05) dos tratamentos no ganho de peso médio diário (GMD), consumo de matéria seca (CMS) e eficiência alimentar (EA). Cordeiros alimentados com dietas contendo monensina tiveram menor (P < 0,01) contagem de oocistos/g de fezes comparado com a dieta 14OE. Não houve efeito das dietas sobre as características de carcaça. A inclusão de 0,28 e 0,42% de OE de aroeira fruto reduziram a concentração de matéria mineral da carne dos cordeiros comparados ao tratamento MON. O OE dos frutos da aroeira demonstrou capacidade de substituir a monensina, apresentando resultados similares com relação ao desempenho e características de carcaça. Entretanto, a monensina apresentou maior capacidade no controle de coccidiose
Asunto(s)
Animales , Aceites Volátiles/administración & dosificación , Ovinos/inmunología , Monensina/análogos & derivados , Anacardiaceae/enzimologíaRESUMEN
The objective of this research was to use data from multiple studies to comprehensively quantify the effects of feeding 1) laidlomycin propionate (LP), alone and/or in combination with chlortetracycline, compared with 2) monensin sodium (MS), alone and/or in combination with tylosin, at commercially approved dosages, on ADG, DMI, feed efficiency (FE), mortality, and carcass characteristics (HCW and liver abscesses). A secondary objective was to explore potential sources of heterogeneity among the comparative effectiveness studies. A systematic review of peer-reviewed literature and industry reports was used to identify studies that included direct comparisons of these treatments in finishing steers in North America. Random-effects meta-analysis models of performance, carcass, and health-related outcomes were fitted with extracted data, consisting of a total of 17 data sets comprising a total of 135 pens and 13,603 steers. Results showed that pens of steers fed LP had increased ADG (live and carcass adjusted), DMI, and HCW compared with those fed monensin ( < 0.05). However, liver abscesses were more common in LP-fed cattle than in MS-fed cattle ( < 0.05), presumably because of differences in the concurrently fed antimicrobials. No significant effects ( > 0.05) were identified for FE or for health-related outcomes (overall and cause-specific mortality). There was a substantial amount of heterogeneity in outcomes among studies, and when pen size and type of production setting were included in mixed-effects meta-regression models, they accounted for only a small proportion of the between-study heterogeneity found in the meta-analysis models. Therefore, caution should be exercised when interpreting summary estimates in the presence of substantial heterogeneity. However, these results provide comprehensive information on the comparative effects of different ionophores across multiple studies and multiple years, states, and production settings. These unique results can enable quantitative and informed decisions by potential end users of these feed additives that are widely used in the U.S. beef industry for reducing the costs of beef production through enhanced cattle performance.
Asunto(s)
Antibacterianos/farmacología , Bovinos/crecimiento & desarrollo , Clortetraciclina/farmacología , Monensina/análogos & derivados , Monensina/farmacología , Tilosina/farmacología , Animales , Antibacterianos/administración & dosificación , Composición Corporal/efectos de los fármacos , Bovinos/fisiología , Clortetraciclina/administración & dosificación , Absceso Hepático/tratamiento farmacológico , Absceso Hepático/prevención & control , Absceso Hepático/veterinaria , Masculino , Monensina/administración & dosificación , América del Norte , Ionóforos de Protónes/administración & dosificación , Ionóforos de Protónes/farmacología , Tilosina/administración & dosificaciónRESUMEN
The synthesis of laidlomycin is described. With an established stereocontrolled synthetic route to the aldehyde 5, the known ß-keto phosphonate 4 was coupled with 5 and the resulting enone was subjected to a sequential hydrogenolysis/hydrogenation and equilibration process to effect the correct spiroketalization for the natural product. The stereogenic carbons were elaborated by desymmetrization for C12, allylation for C13, vanadyl-induced epoxidation for C16, Zn(BH4)2 reduction for C17, a chiral building block for C18 and C24, Shi epoxidation for C20 and C21, Myers' alkylation for C22, and thermodynamic control for C25.
Asunto(s)
Monensina/análogos & derivados , Monensina/síntesis química , EstereoisomerismoRESUMEN
One hundred ninety-two steers (BW = 354 ± 23.5 kg) were used in a randomized block design to evaluate the effects of ionophore and ractopamine hydrochloride (RH) supplementation strategies on performance and carcass characteristics. Twelve pens of 4 steers were assigned to each of the following treatments: unsupplemented control (CON), laidlomycin propionate (12.1 mg/kg DM) with or without RH (LPRH and LP, respectively), and monensin sodium (36.4 mg/kg DM) with RH (MSRH). Steers were fed for 151 d, of which respective treatments received RH (Actogain; Zoetis, Florham Park, NJ) at a rate of 300 mg/(animal · d) for the final 32 d. Laidlomycin was removed from the LPRH treatment during this period, as no combination feeding has been approved. Upon harvest, carcass data were collected by trained personnel, and subsequent analysis of the LM was conducted to estimate tenderness using Warner-Bratzler shear force (WBSF). Prior to RH supplementation, both LP and LPRH had greater ADG ( ≤ 0.02) and G:F ( < 0.01) than CON, whereas MSRH was intermediate. During the final 32 d, MSRH improved G:F ( ≤ 0.02) compared to all other treatments and tended to increase ADG over unsupplemented controls ( = 0.05). Cattle receiving LP without RH had significantly greater BW at d 151 than CON ( = 0.02), whereas both RH treatments tended to improve final BW ( ≤ 0.09). Ionophores improved ADG ( ≤ 0.03) and G:F ( < 0.01) for the entire feeding period, and although LP-supplemented cattle had greater DMI for the final 32 d than both RH treatments ( ≤ 0.01), intakes for the 151-d trial were similar among treatments. Carcass weights were greater ( = 0.04) in cattle fed LP with no RH than CON, where cattle yielded an average of 12 kg more HCW. Ractopamine increased LM area in MSRH-supplemented cattle ( = 0.03) and tended to increase LM area for steers receiving LPRH ( = 0.07). Longissimus steaks of MSRH-supplemented cattle had greater WBSF values than CON ( = 0.04) after 7 d of postmortem aging and greater WBSF values than LPRH steaks after 28 d ( = 0.03). All other carcass and WBSF measurements were similar among treatments. The results of this study indicate that LP supplementation without RH may yield a performance similar to and carcass responses associated with the administration of a ß-agonist. These results also suggest that performance and carcass characteristics for cattle fed LP are similar to those of cattle fed monensin throughout the feeding period.
Asunto(s)
Composición Corporal/efectos de los fármacos , Bovinos/fisiología , Ionóforos/farmacología , Monensina/análogos & derivados , Fenetilaminas/farmacología , Agonistas Adrenérgicos beta/farmacología , Alimentación Animal/análisis , Fenómenos Fisiológicos Nutricionales de los Animales , Animales , Dieta/veterinaria , Suplementos Dietéticos , Masculino , Monensina/farmacología , Fenetilaminas/administración & dosificación , Compuestos de Trimetilsililo/farmacologíaRESUMEN
New tertiary amide derivatives of polyether ionophore Monensin A (MON) were synthesised and their anti-proliferative activity against cancer cell lines was studied. Very high activity (IC50=0.09 µM) and selectivity (SI=232) of MON against human biphenotypic myelomonocytic leukemia cell line (MV4-11) was demonstrated. The MON derivatives obtained exhibit interesting anti-proliferative activity, high selectivity index and also are able to break the drug-resistance of cancer cell line.
Asunto(s)
Amidas/química , Antineoplásicos/farmacología , Monensina/análogos & derivados , Monensina/farmacología , Amidas/farmacología , Antineoplásicos/química , Antineoplásicos/metabolismo , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Resistencia a Antineoplásicos/efectos de los fármacos , Ensayos de Selección de Medicamentos Antitumorales , Humanos , Estructura Molecular , Monensina/síntesis química , Monensina/química , Relación Estructura-ActividadRESUMEN
The polyether ionophore monensin is biosynthesized by a polyketide synthase that delivers a mixture of monensins A and B by the incorporation of ethyl- or methyl-malonyl-CoA at its fifth module. Here we present the first computational model of the fifth acyltransferase domain (AT5mon ) of this polyketide synthase, thus affording an investigation of the basis of the relaxed specificity in AT5mon , insights into the activation for the nucleophilic attack on the substrate, and prediction of the incorporation of synthetic malonic acid building blocks by this enzyme. Our predictions are supported by experimental studies, including the isolation of a predicted derivative of the monensin precursor premonensin. The incorporation of non-native building blocks was found to alter the ratio of premonensins A and B. The bioactivity of the natural product derivatives was investigated and revealed binding to prenyl-binding protein. We thus show the potential of engineered biosynthetic polyketides as a source of ligands for biological macromolecules.
Asunto(s)
Productos Biológicos/síntesis química , Monensina/análogos & derivados , Monensina/síntesis química , Sintasas Poliquetidas/química , Aciltransferasas/química , Biología Computacional , Escherichia coli/metabolismo , Fermentación , Malonatos/química , Modelos Moleculares , Monensina/farmacología , Conformación Proteica , Streptomyces/enzimología , Especificidad por SustratoRESUMEN
In this paper structural and microbiological studies on the ionophorous antibiotic monensin A and its derivatives have been collected. Monensin A is an ionophore which selectively complexes and transports sodium cation across lipid membranes, and therefore it shows a variety of biological properties. This antibiotic is commonly used as coccidiostat and nonhormonal growth promoter. The paper focuses on both the latest and earlier achievements concerning monensin A antimicrobial activity. The activities of monensin derivatives, including modifications of hydroxyl groups and carboxyl group, are also presented.
Asunto(s)
Antiinfecciosos/farmacología , Coccidiostáticos/farmacología , Monensina/química , Monensina/farmacología , Amidas/química , Antiinfecciosos/química , Cationes , Coccidiostáticos/química , Cristalografía por Rayos X , Diseño de Fármacos , Ionóforos/química , Pruebas de Sensibilidad Microbiana , Estructura Molecular , Monensina/análogos & derivados , Conformación Proteica , Relación Estructura-ActividadRESUMEN
Chemical investigation of the terrestrial Streptomyces sp. isolates GT2005/020 and ANK148 led to the isolation of two microbial furanone derivatives, 5-hydroxy-4-methylnaphtho[1,2-b]furan-3-one (1) and 4-hydroxy-5-methyl-furan-3-one (2), respectively, which have some similarity to quorum sensing molecules of the AI-2 type. In addition, the known compounds chalcomycin, ferulic acid, indole-3-acetic acid, uracil, thymine, 2'-deoxy-thymidin, monensin B (3), phencomycin, and 1-acetyl-beta-carboline were isolated. The structures of 1 and 2 were deduced from extensive studies of NMR (1D and 2D) and mass spectra. Additionally, the complete NMR shift assignments for monensin B (3) using H-H COSY, HMQC and HMBC experiments are reported here for the first time. We are describing the taxonomy and fermentation of the producing strains, the structure elucidation of the new metabolites and their bioactivity.
Asunto(s)
Furanos/análisis , Streptomyces/metabolismo , Furanos/química , Furanos/farmacología , Espectroscopía de Resonancia Magnética , Monensina/análogos & derivados , Monensina/análisis , Monensina/química , Streptomyces/químicaRESUMEN
A simple and highly sensitive LC/MS method was developed for the simultaneous determination of six ionophores--lasalocid, monensin, laidlomycin, maduramycin, salinomycin, and narasin--in feed. The procedure involved extraction of 1 g of feed with 4 mL of methanol-water (9 + 1, v/v) by shaking on a platform shaker for 45 min. After centrifugation, the extracts were diluted with methanol-water (75 + 25, v/v) and analyzed without any cleanup. The analysis was performed on a Betasil C18 column (150 x 4.6 mm id, 5 pm particle size) connected to an LC/MS system operated in the atmospheric pressure chemical ionization (APCI) mode. We believe this to be the first method that uses the APCI mode for the analysis of ionophores. The mobile phase consisted of 50 mM ammonium acetate as solvent A and acetonitrile-methanol (7 + 3, v/v) as solvent B in a gradient run. Excellent recoveries of 81-120% were found for all compounds at fortification levels of 1-200 microg/g, with RSD < or =15% (except 17% for maduramycin at 2 and 5 microg/g, and 16% for salinomycin at 1 microg/g). At 0.5 microg/g, recoveries of 87-119% were obtained, with RSD < or =20%. However, recovery of lasalocid was 133% and salinomycin 79% in sow and horse feed, respectively. Average RSD values of lasalocid and salinomycin were 22 and 21%, respectively. Finally, proficiency test samples analyzed with the method demonstrated favorable agreement with the certified values.
Asunto(s)
Alimentación Animal/análisis , Técnicas de Química Analítica/métodos , Cromatografía Liquida/métodos , Ionóforos/análisis , Lasalocido/análisis , Espectrometría de Masas/métodos , Monensina/análogos & derivados , Monensina/análisis , Piranos/análisis , Acetatos/química , Animales , Análisis de los Alimentos/métodos , Caballos , Iones , Lactonas/análisis , Metanol/química , Reproducibilidad de los Resultados , Solventes , Porcinos , Agua/químicaRESUMEN
Monensin A phenylurethane sodium salt (MON-UR1-Na) crystals were studied by the X-ray, NMR, FT-IR and PM5 semi-empirical methods. The X-ray data show that the compound forms a pseudocyclic structure, stabilized by three intramolecular hydrogen bonds, and the sodium cation coordinated by five oxygen atoms in the hydrophilic sphere. The NMR and FT-IR data demonstrate that this pseudocyclic structure is also conserved in CH(2)Cl(2) solution. This structure of MON-UR1-Na is significantly different than the ones previously proposed by Westley et al. and Tanaka et al. The semi-empirical calculations of the MON-UR1-Na structures indicate that the one of the crystal is the most energetically favorable one. Other parameters, such as the size, chemical and biological nature of the urethane substituent, and especially the free carbonyl urethane group, may have a role in the biological activity of MON-UR1-Na. The in vitro microbiological tests provide evidence that MON-UR1-Na shows higher antibacterial activity against human pathogenic bacteria, including antibiotic-resistant Staphylococcus aureus and Staphylococcus epidermidis than the parent unmodified antibiotic-Monensin A.
Asunto(s)
Monensina/análogos & derivados , Infecciones Estafilocócicas/tratamiento farmacológico , Staphylococcus aureus/efectos de los fármacos , Staphylococcus epidermidis/efectos de los fármacos , Infección Hospitalaria/tratamiento farmacológico , Infección Hospitalaria/microbiología , Cristalografía por Rayos X , Humanos , Espectroscopía de Resonancia Magnética , Espectrometría de Masas , Resistencia a la Meticilina , Pruebas de Sensibilidad Microbiana , Monensina/química , Monensina/farmacología , Monensina/uso terapéutico , Fenilcarbamatos/química , Infecciones Estafilocócicas/microbiología , Uretano/químicaRESUMEN
Concerns over the occurrence of the veterinary antibiotic monensin (MW 671Da) in animal food products and water have given rise to the need for a sensitive and rapid detection method. In this study, four monensin-specific single chain variable fragments (scFvs) were isolated from a hyperimmunized phage-displayed library originating from splenocytes of a mouse immunized with monensin conjugated to bovine serum albumin (BSA). The coding sequences of the scFvs were engineered in the order 5'-V(L)-linker-V(H)-3', where the linker encodes for Gly(10)Ser(7)Arg. Three rounds of selection were performed against monensin conjugated to chicken ovalbumin (OVA) and keyhole limpet hemocyanin (KLH), alternately. In the third round of selection, two different strategies, which differed in the number of washes and the concentration of the coating conjugates, were used to select for specific binders to monensin. A total of 376 clones from round two and three were screened for their specific binding to monensin conjugates and positive clones were sequenced. It was found that 80% of clones from round three contained a stop codon. After removing the stop codon by site-directed mutagenesis, ten binders with different amino acid sequences were subcloned into the vector pMED2 for soluble expression in Escherichia coli HB2151. Four of these scFvs bound to free monensin as determined using competitive fluorescence polarization assays (C-FPs). IC(50) values ranged from 0.031 and 231 microM. A cross-reactivity assay against salinomycin, lasalocid A, kanamycin and ampicillin revealed that the two best binders were highly specific to monensin.
Asunto(s)
Escherichia coli/genética , Monensina/análogos & derivados , Biblioteca de Péptidos , Albúmina Sérica Bovina/administración & dosificación , Anticuerpos de Cadena Única/metabolismo , Secuencia de Aminoácidos , Animales , Unión Competitiva , Bovinos , Femenino , Contaminación de Alimentos , Inmunización Secundaria , Ratones , Ratones Endogámicos BALB C , Datos de Secuencia Molecular , Monensina/sangre , Monensina/síntesis química , Monensina/inmunología , Mutagénesis Sitio-Dirigida , Conejos , Albúmina Sérica Bovina/síntesis química , Anticuerpos de Cadena Única/genética , Anticuerpos de Cadena Única/inmunologíaRESUMEN
Polyether antibiotics such as monensin and salinomycin have been primarily used as coccidiostat and growth promoter. Since residues of these antibiotic in food may pose a health risk for sensitive individuals, their use should be carefully monitored. An immunochemical method was developed for the determination of polyether antibiotic using monoclonal antibody (Mab) produced by immunized mice. Conjugates of monensin, salinomycin and laidlomycin were prepared with bovine serum albumin (BSA), keyhole limpet haemocyanine (KLH) and ovalbumin (OVA) by mixed anhydride method and then used as immunogene to produce Mab. Eight hybridoma cell lines were isolated that produced Mabs that competed with polyether antibiotic-protein conjugates in BALB/c-SP2/0 fusion system. Two hybridoma with higher sensitivity, designated as 4G11F and 1C8F1F, were cultured for mass production and then purified from ascites fluid. Antibiotic-protein conjugates were quantitavely analyzed by using the purified Mabs through a competitive enzyme-linked immunosorbent assay (ELISA).
Asunto(s)
Antibacterianos/análisis , Anticuerpos Monoclonales/biosíntesis , Ensayo de Inmunoadsorción Enzimática/métodos , Éteres/análisis , Animales , Antibacterianos/inmunología , Antibacterianos/farmacología , Especificidad de Anticuerpos , Línea Celular , Éteres/inmunología , Éteres/farmacología , Femenino , Hemocianinas/inmunología , Hibridomas/inmunología , Inmunización , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Staphylococcus aureus Resistente a Meticilina/crecimiento & desarrollo , Ratones , Ratones Endogámicos BALB C , Monensina/análogos & derivados , Monensina/análisis , Monensina/inmunología , Ovalbúmina/inmunología , Piranos/análisis , Piranos/inmunología , Albúmina Sérica Bovina/inmunologíaRESUMEN
The complexation of carboxylic acid Monensin A (MonH, 1a) with CoCl2.6H2O and MnCl2.4H2O leads to the formation of mononuclear complexes [Co(Mon)2(H2O)2], 2a and [Mn(Mon)2(H2O)2], 2b, respectively. The unique crystal structures of 2a and 2b were determined by X-ray crystallography. The complexes crystallize in the monoclinic space group P2 1 with an octahedrally coordinated transition metal center forming the crystallographically centrosymmetric chromophore CoO6 or MnO6, respectively. Two molecules of Monensin A act bidentately through their carboxylate moiety and a hydroxyl group, and two water molecules are additionally trans-coordinated. Although the transition metal ions are not bound into the cavity of the ligand, the unusual bidentate coordination mode of the ionophore induces its "pseudo-cyclization" forming 22-membered cycles further stabilized by a number of H-bonds. The complexes are the first example of divalent metal complexes of the monovalent polyether ionophore. The parallel study on the complexation ability of the potassium complex of Monensin A (MonK, 1b) towards Co(II) and Mn(II) showed the formation of the isostructural complexes 2a and 2b accompanied by loss of the potassium ion due to the new coordination mode of the ligand. The biological tests performed with the antibiotic MonH and the corresponding metal(II) complexes show greatly enhanced antimicrobial activity of complexes 2a-b against Gram(+)-bacteria.
Asunto(s)
Antibacterianos/química , Cloruros/química , Cobalto/química , Cristalografía por Rayos X , Ionóforos/química , Compuestos de Manganeso/química , Monensina/química , Antibacterianos/farmacología , Cloruros/farmacología , Cobalto/farmacología , Bacterias Grampositivas/efectos de los fármacos , Bacterias Grampositivas/crecimiento & desarrollo , Enlace de Hidrógeno , Ionóforos/farmacología , Compuestos de Manganeso/farmacología , Pruebas de Sensibilidad Microbiana , Modelos Moleculares , Estructura Molecular , Monensina/análogos & derivados , Monensina/farmacología , Análisis Espectral , Agua/químicaRESUMEN
This paper reports the first comparative study of the gas-phase fragmentation chemistry of monensin in negative ion mode electrospray and nanoelectrospray tandem mass spectrometry. The fragmentation was observed to occur at lower energies in nanoelectrospray than electrospray. The major product ions are proposed to be formed via an initial neutral elimination of methanol followed be subsequent fragmentation. The low-mass product ions were observed at the same m/z for both monensin A and B.
Asunto(s)
Monensina/análogos & derivados , Nanotecnología/métodos , Espectrometría de Masa por Ionización de Electrospray/métodos , Monensina/químicaRESUMEN
Culture broth of a streptomycete isolate, Streptomyces sp. CS684 showed antibacterial activity on methicillin resistant Staphylococcus aureus (MRSA) and vancomycin resistant enterococci (VRE). Among purified substances from the organism, CSU-1, which is active against MRSA and VRE, is a C37H62O12Na (M+, 721.3875), and identified as laidlomycin. The anti-MRSA and anti-VRE activity of CSU-1 was stronger than oxacillin and vancomycin. Phylogenetic analysis showed that strain CS684 is very similar to Streptomyces ardus NRRL 2817T, whereas the ability of Streptomyces sp. CS684 to produce laidlomycin was shown to be unique.
Asunto(s)
Antibacterianos/biosíntesis , Monensina/análogos & derivados , Staphylococcus aureus/efectos de los fármacos , Streptomyces/metabolismo , Antibacterianos/farmacología , Farmacorresistencia Bacteriana , Corea (Geográfico) , Resistencia a la Meticilina , Monensina/biosíntesis , Monensina/farmacología , Filogenia , Microbiología del Suelo , Streptomyces/clasificación , Resistencia a la VancomicinaRESUMEN
Monensin A is an ionophore able to carry protons and cations through the cell membrane. Its methyl ester (MON1) and its hydrates have been studied in acetonitrile, and its deuterated analogue by Fourier transform infrared (FTIR) and (1)H and (13)C NMR spectroscopies as well as by vapor pressure osmotic and PM5 semiempirical methods. Interestingly, these hydrates show new and unexpected biophysical and biochemical properties. The formation of the hydrates starts with a transfer of a proton from the O(IV)-H hydroxyl group of MON1 to an oxygen atom of a water molecule, which is subsequently hydrated by other water molecules forming the (MON1 + 3H(2)O) species. This hydrate exhibits a ringlike structure in which the water molecules form an almost linear hydrogen-bonded chain. Within this chain, the excess proton fluctuates very fast inside the water cluster as indicated by a continuous absorption in the FTIR spectra. The formation of the (MON1 + 3H(2)O) species is accompanied by a self-assembly process, leading to the formation of a proton channel made up of eight (MON1 + 3H(2)O) units with a length of 60 A, in which the proton can fluctuate over the whole distance. Semiempirical calculations suggest that due to the hydrophobic surface the channel can be incorporated readily in a lipid bilayer. This hypothetical new channel is thought to be able to transport protons through the cell membrane. Thus it is a suitable model for studying proton-transfer processes, and in addition, it may open interesting new fields of application.