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1.
Br J Nutr ; 113(2): 225-38, 2015 Jan 28.
Artículo en Inglés | MEDLINE | ID: mdl-25498469

RESUMEN

Wheat bran extract (WBE), containing arabinoxylan-oligosaccharides that are potential prebiotic substrates, has been shown to modify bacterial colonic fermentation in human subjects and to beneficially affect the development of colorectal cancer (CRC) in rats. However, it is unclear whether these changes in fermentation are able to reduce the risk of developing CRC in humans. The aim of the present study was to evaluate the effects of WBE on the markers of CRC risk in healthy volunteers, and to correlate these effects with colonic fermentation. A total of twenty healthy subjects were enrolled in a double-blind, cross-over, randomised, controlled trial in which the subjects ingested WBE (10 g/d) or placebo (maltodextrin, 10 g/d) for 3 weeks, separated by a 3-week washout period. At the end of each study period, colonic handling of NH3 was evaluated using the biomarker lactose[15N, 15N']ureide, colonic fermentation was characterised through a metabolomics approach, and the predominant microbial composition was analysed using denaturing gradient gel electrophoresis. As markers of CRC risk, faecal water genotoxicity was determined using the comet assay and faecal water cytotoxicity using a colorimetric cell viability assay. Intake of WBE induced a shift from urinary to faecal 15N excretion, indicating a stimulation of colonic bacterial activity and/or growth. Microbial analysis revealed a selective stimulation of Bifidobacterium adolescentis. In addition, WBE altered the colonic fermentation pattern and significantly reduced colonic protein fermentation compared with the run-in period. However, faecal water cytotoxicity and genotoxicity were not affected. Although intake of WBE clearly affected colonic fermentation and changed the composition of the microbiota, these changes were not associated with the changes in the markers of CRC risk.


Asunto(s)
Fibras de la Dieta/análisis , Disbiosis/prevención & control , Microbioma Gastrointestinal , Extractos Vegetales/uso terapéutico , Prebióticos , Semillas/química , Triticum/química , Adulto , Anticarcinógenos/efectos adversos , Anticarcinógenos/uso terapéutico , Bélgica/epidemiología , Biomarcadores/análisis , Neoplasias Colorrectales/epidemiología , Neoplasias Colorrectales/metabolismo , Neoplasias Colorrectales/microbiología , Neoplasias Colorrectales/prevención & control , Estudios Cruzados , Método Doble Ciego , Disbiosis/metabolismo , Disbiosis/microbiología , Heces/química , Heces/microbiología , Femenino , Fermentación , Fármacos Gastrointestinales/efectos adversos , Fármacos Gastrointestinales/uso terapéutico , Humanos , Masculino , Extractos Vegetales/efectos adversos , Prebióticos/efectos adversos , Riesgo , Adulto Joven
2.
J Pediatr Gastroenterol Nutr ; 58(5): 647-53, 2014 May.
Artículo en Inglés | MEDLINE | ID: mdl-24368315

RESUMEN

OBJECTIVES: We assessed whether wheat bran extract (WBE) containing arabinoxylan-oligosaccharides (AXOS) elicited a prebiotic effect and modulated gastrointestinal (GI) parameters in healthy preadolescent children upon consumption in a beverage. METHODS: This double-blind randomized placebo-controlled crossover trial evaluated the effects of consuming WBE at 0 (control) or 5.0 g/day for 3 weeks in 29 healthy children (8-12 years). Fecal levels of microbiota, short-chain fatty acids, branched-chain fatty acids, ammonia, moisture, and fecal pH were assessed at the end of each treatment and at the end of a 1-week run-in (RI) period. In addition, the subjects completed questionnaires scoring distress severity of 3 surveyed GI symptoms. Finally, subjects recorded defecation frequency and stool consistency. RESULTS: Nominal fecal bifidobacteria levels tended to increase after 5 g/day WBE consumption (P = 0.069), whereas bifidobacteria expressed as percentage of total fecal microbiota was significantly higher upon 5 g/day WBE intake (P = 0.002). Additionally, 5 g/day WBE intake induced a significant decrease in fecal content of isobutyric acid and isovaleric acid (P < 0.01), markers of protein fermentation. WBE intake did not cause a change in distress severity of the 3 surveyed GI symptoms (flatulence, abdominal pain/cramps, and urge to vomit) (P > 0.1). CONCLUSIONS: WBE is well tolerated at doses up to 5 g/day in healthy preadolescent children. In addition, the intake of 5 g/day exerts beneficial effects on gut parameters, in particular an increase in fecal bifidobacteria levels relative to total fecal microbiota, and reduction of colonic protein fermentation.


Asunto(s)
Fibras de la Dieta , Tracto Gastrointestinal/microbiología , Microbiota/efectos de los fármacos , Oligosacáridos/administración & dosificación , Extractos Vegetales/administración & dosificación , Xilanos/administración & dosificación , Dolor Abdominal/etiología , Amoníaco/análisis , Bifidobacterium/aislamiento & purificación , Niño , Estudios Cruzados , Fibras de la Dieta/análisis , Método Doble Ciego , Ácidos Grasos/análisis , Ácidos Grasos Volátiles/análisis , Heces/química , Heces/microbiología , Femenino , Flatulencia/inducido químicamente , Tracto Gastrointestinal/efectos de los fármacos , Humanos , Concentración de Iones de Hidrógeno , Masculino , Oligosacáridos/análisis , Cooperación del Paciente , Placebos , Extractos Vegetales/efectos adversos , Prebióticos , Xilanos/análisis
3.
Br J Nutr ; 108(12): 2229-42, 2012 Dec 28.
Artículo en Inglés | MEDLINE | ID: mdl-22370444

RESUMEN

Wheat bran extract (WBE) is a food-grade soluble fibre preparation that is highly enriched in arabinoxylan oligosaccharides. In this placebo-controlled cross-over human intervention trial, tolerance and effects on colonic protein and carbohydrate fermentation were studied. After a 1-week run-in period, sixty-three healthy adult volunteers consumed 3, 10 and 0 g WBE/d for 3 weeks in a random order, with 2 weeks' washout between each treatment period. Fasting blood samples were collected at the end of the run-in period and at the end of each treatment period for analysis of haematological and clinical chemistry parameters. Additionally, subjects collected a stool sample for analysis of microbiota, SCFA and pH. A urine sample, collected over 48 h, was used for analysis of p-cresol and phenol content. Finally, the subjects completed questionnaires scoring occurrence frequency and distress severity of eighteen gastrointestinal symptoms. Urinary p-cresol excretion was significantly decreased after WBE consumption at 10 g/d. Faecal bifidobacteria levels were significantly increased after daily intake of 10 g WBE. Additionally, WBE intake at 10 g/d increased faecal SCFA concentrations and lowered faecal pH, indicating increased colonic fermentation of WBE into desired metabolites. At 10 g/d, WBE caused a mild increase in flatulence occurrence frequency and distress severity and a tendency for a mild decrease in constipation occurrence frequency. In conclusion, WBE is well tolerated at doses up to 10 g/d in healthy adults volunteers. Intake of 10 g WBE/d exerts beneficial effects on gut health parameters.


Asunto(s)
Fibras de la Dieta/análisis , Tracto Gastrointestinal/efectos de los fármacos , Promoción de la Salud , Oligosacáridos/administración & dosificación , Extractos Vegetales/administración & dosificación , Xilanos/administración & dosificación , Adulto , Bifidobacterium/crecimiento & desarrollo , Cresoles/orina , Estudios Cruzados , Método Doble Ciego , Ácidos Grasos Volátiles/análisis , Heces/química , Heces/microbiología , Femenino , Fermentación , Enfermedades Gastrointestinales/inducido químicamente , Humanos , Concentración de Iones de Hidrógeno , Masculino , Persona de Mediana Edad , Oligosacáridos/metabolismo , Placebos , Extractos Vegetales/efectos adversos , Extractos Vegetales/química , Xilanos/metabolismo
4.
Int J Toxicol ; 29(5): 479-95, 2010.
Artículo en Inglés | MEDLINE | ID: mdl-20884858

RESUMEN

Wheat bran extract (WBE) is a food-grade preparation that is highly enriched in arabinoxylan-oligosaccharides. As part of the safety evaluation of WBE, its genotoxic potential was assessed in a bacterial reverse mutagenicity assay (Ames test) and a chromosome aberration assay on Chinese hamster lung fibroblast cells. These in vitro genotoxicity assays showed no evidence of mutagenic or clastogenic activity with WBE. The safety of WBE was furthermore evaluated in a subchronic toxicity study on rats that were fed a semisynthetic diet (AIN 93G) containing 0.3%, 1.5%, or 7.5% WBE for 13 weeks, corresponding to an average intake of 0.2, 0.9, and 4.4 g/kg body weight (bw) per day, with control groups receiving the unsupplemented AIN 93G, AIN 93G with 7.5% inulin, or AIN 93G with 7.5% wheat bran. Based on this rat-feeding study, the no-observed-adverse-effect level (NOAEL) for WBE was determined as 4.4 g/kg (bw)/d, the highest dose tested.


Asunto(s)
Fibras de la Dieta , Oligosacáridos/análisis , Extractos Vegetales/química , Extractos Vegetales/toxicidad , Semillas/química , Triticum/química , Xilanos/análisis , Animales , Biotransformación , Línea Celular , Cricetinae , Cricetulus , Relación Dosis-Respuesta a Droga , Escherichia coli/efectos de los fármacos , Femenino , Inocuidad de los Alimentos , Masculino , Pruebas de Mutagenicidad , Nivel sin Efectos Adversos Observados , Extractos Vegetales/metabolismo , Ratas , Ratas Wistar , Salmonella typhimurium/efectos de los fármacos , Pruebas de Toxicidad
5.
J Am Coll Nutr ; 27(4): 512-8, 2008 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-18978172

RESUMEN

OBJECTIVE: Arabinoxylooligosaccharides (AXOS) are non-digestible in the upper gastrointestinal tract and have been shown to exert prebiotic effects in animals. The aim of this study was to characterize the influence of AXOS with an average degree of polymerization of 15 and an average degree of arabinose substitution of 0.26 (AXOS-15-0.26) on gastrointestinal motility and colonic bacterial metabolism in healthy human volunteers. METHODS: Twelve healthy volunteers received five test meals, containing different amounts of AXOS-15-0.26, with one week intervals between each test meal. Breath tests were used to measure gastric emptying rate, oro-cecal transit time (OCTT) and hydrogen excretion. Colonic bacterial metabolism was estimated using the biomarkers lactose-[(15)N, (15)N']-ureide ((15)N-LU) and p-cresol. RESULTS: Gastric emptying and OCTT were not influenced by addition of varying amounts of AXOS-15-0.26. Administration of 2.2g or 4.9 g AXOS-15-0.26 significantly decreased the urinary (15)N-excretion (respectively p = 0.008 and p = 0.035) as compared to the baseline, whereas fecal (15)N-excretion was significantly increased (respectively p = 0.034 and p = 0.019). This shift from urinary to fecal (15)N-excretion suggests a higher uptake or incorporation by bacteria due to the stimulation of colonic bacterial growth and/or metabolic activity. Furthermore, a significant increase in hydrogen excretion after administration of 2.2g (p = 0.002) and 4.9 g (p = 0.004) AXOS-15-0.26 was observed. No influence on urinary p-cresol excretion was observed. CONCLUSION: These findings suggest that a minimal dose of 2.2g AXOS-15-0.26 favorably modulates the colonic bacterial metabolism in healthy humans. However, long term studies are required to confirm a possible prebiotic effect.


Asunto(s)
Colon/metabolismo , Colon/microbiología , Motilidad Gastrointestinal/efectos de los fármacos , Oligosacáridos/farmacología , Extractos Vegetales/farmacología , Probióticos/farmacología , Adulto , Biomarcadores/análisis , Relación Dosis-Respuesta a Droga , Grano Comestible , Femenino , Alimentos Fortificados , Tránsito Gastrointestinal , Humanos , Isótopos/análisis , Masculino , Oligosacáridos/administración & dosificación , Adulto Joven
6.
Plant Physiol ; 128(4): 1346-58, 2002 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-11950983

RESUMEN

We developed a method for expression in Arabidopsis of a transgene encoding a cleavable chimeric polyprotein. The polyprotein precursor consists of a leader peptide and two different antimicrobial proteins (AMPs), DmAMP1 originating from Dahlia merckii seeds and RsAFP2 originating from Raphanus sativus seeds, which are linked by an intervening sequence ("linker peptide") originating from a natural polyprotein occurring in seed of Impatiens balsamina. The chimeric polyprotein was found to be cleaved in transgenic Arabidopsis plants and the individual AMPs were secreted into the extracellular space. Both AMPs were found to exert antifungal activity in vitro. It is surprising that the amount of AMPs produced in plants transformed with some of the polyprotein transgene constructs was significantly higher compared with the amount in plants transformed with a transgene encoding a single AMP, indicating that the polyprotein expression strategy may be a way to boost expression levels of small proteins.


Asunto(s)
Antiinfecciosos/aislamiento & purificación , Péptidos Catiónicos Antimicrobianos/genética , Arabidopsis/genética , Defensinas , Proteínas de Plantas/genética , Poliproteínas/genética , Secuencia de Aminoácidos , Antiinfecciosos/farmacología , Antifúngicos/aislamiento & purificación , Antifúngicos/farmacología , Fusarium/efectos de los fármacos , Regulación de la Expresión Génica de las Plantas , Glucosafosfato Deshidrogenasa/metabolismo , Impatiens/genética , Datos de Secuencia Molecular , Extractos Vegetales/química , Plantas Modificadas Genéticamente , Plásmidos/genética , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/aislamiento & purificación , Alineación de Secuencia
7.
Plant J ; 29(2): 131-40, 2002 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-11862946

RESUMEN

An Arabidopsis thaliana mutant, esa1, that shows enhanced susceptibility to the necrotrophic pathogens Alternaria brassicicola, Botrytis cinerea and Plectosphaerella cucumerina, but has wild-type levels of resistance to the biotrophic pathogens Pseudomonas syringae pv. tomato and Peronospora parasitica. The enhanced susceptibility towards necrotrophic pathogens correlated with a delayed induction of phytoalexin accumulation and delayed induction of the plant defensin gene PDF1.2 upon inoculation with pathogens. Two reactive oxygen generating compounds, paraquat and acifluorfen, were found to cause induction of both phytoalexin accumulation and PDF1.2 expression in wild-type plants, but this induction was almost completely abolished in esa1. This finding suggests that esa1 may somehow be involved in transduction of signals generated by reactive oxygen species.


Asunto(s)
Alternaria/patogenicidad , Arabidopsis/microbiología , Defensinas , Enfermedades de las Plantas/genética , Especies Reactivas de Oxígeno/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Ciclopentanos/farmacología , Etilenos/farmacología , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Inmunidad Innata/efectos de los fármacos , Indoles/farmacología , Mutación , Nitrobenzoatos/farmacología , Oxilipinas , Paraquat/farmacología , Enfermedades de las Plantas/microbiología , Extractos Vegetales/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Salicilatos/farmacología , Sesquiterpenos , Terpenos , Tiazoles/farmacología , Fitoalexinas
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