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At least 19 recordsLinked to original sources
PubMed1997

Inulin hydrogels as carriers for colonic drug targeting: I. Synthesis and characterization of methacrylated inulin and hydrogel formation.

PURPOSE: Vinyl groups were introduced in inulin chains in order to form hydrogels of this sugar polymer by free radical polymerization. METHODS: Inulin was reacted with glycidyl methacrylate in N,N-dimethylformamide in the presence of 4-dimethylaminopyridine as catalyst. 1H and 13C NMR spectroscopy were used for the characterization of the obtained reaction product. Solid state 13C NMR spectroscopy revealed the conversion of the incorporated vinyl groups into covalent cross-links upon free radical polymerization of aqueous solutions of the derivatized inulin. RESULTS: During reaction of inulin with glycidyl methacrylate, transesterification occurred, leading to the direct attachment of the methacryloyl group to inulin. Consequently, the obtained reaction product is methacrylated inulin. The extent of chemical modification of inulin could be tuned by varying the molar ratio of glycidyl methacrylate to inulin in the reaction mixture. Aqueous solutions of methacrylated inulin were converted into cross-linked hydrogels by free radical polymerization using ammonium persulphate and N,N,N',N'-tetramethylethylenediamine as initiating system. CONCLUSIONS: Inulin hydrogels can be formed by free radical polymerization of aqueous solutions of methacrylated inulin.

4-Aminopyridine↗
PubMed2003

Optimal sampling strategies to assess inulin clearance in children by the inulin single-injection method.

BACKGROUND: Glomerular filtration rate in patients can be determined by estimating the plasma clearance of inulin with the single-injection method. In this method, a single bolus injection of inulin is administered and several blood samples are collected. For practical and convenient application of this method in children, it is important that a minimal number of samples are drawn. The aim of this study was to develop and validate sampling strategies with fewer samples for reliable prediction of inulin clearance in pediatric patients by the inulin single-bolus-injection method. METHODS: Complete inulin plasma concentration-time curves of 154 patients were divided into an index (n = 100) and a validation set (n = 54). A population pharmacokinetic model was developed for the index set. Optimal sampling times were selected based on D-optimality theory. For the validation set, Bayesian estimates of clearance were generated using the derived population parameters and concentrations at two to four sampling times. Bayesian estimates of clearance were compared with the individual reference values of clearance. RESULTS: The strategies with samples taken at 10/30/90/240 min, 10/30/240 min, 10/90/240 min, 30/90/240 min, and 90/240 min allowed accurate prediction of inulin clearance (bias <3% and not significantly different from 0; imprecision <15%). CONCLUSIONS: Strategies involving two to four samples, including a sample at 240 min after administration of inulin, in the inulin single-injection method allow accurate prediction of inulin clearance in pediatric patients. Even one blood sample at 240 min showed acceptable performance. The proposed strategies are practical and convenient to children, and reduce repetitive blood sampling without compromising accuracy.

Adolescent↗
PubMed2002

Characterization of a novel fructosyltransferase from Lactobacillus reuteri that synthesizes high-molecular-weight inulin and inulin oligosaccharides.

Fructosyltransferase (FTF) enzymes produce fructose polymers (fructans) from sucrose. Here, we report the isolation and characterization of an FTF-encoding gene from Lactobacillus reuteri strain 121. A C-terminally truncated version of the ftf gene was successfully expressed in Escherichia coli. When incubated with sucrose, the purified recombinant FTF enzyme produced large amounts of fructo-oligosaccharides (FOS) with beta-(2-->1)-linked fructosyl units, plus a high-molecular-weight fructan polymer (>10(7)) with beta-(2-->1) linkages (an inulin). FOS, but not inulin, was found in supernatants of L. reuteri strain 121 cultures grown on medium containing sucrose. Bacterial inulin production has been reported for only Streptococcus mutans strains. FOS production has been reported for a few bacterial strains. This paper reports the first-time isolation and molecular characterization of (i) a Lactobacillus ftf gene, (ii) an inulosucrase associated with a generally regarded as safe bacterium, (iii) an FTF enzyme synthesizing both a high molecular weight inulin and FOS, and (iv) an FTF protein containing a cell wall-anchoring LPXTG motif. The biological relevance and potential health benefits of an inulosucrase associated with an L. reuteri strain remain to be established.

Amino Acid Sequence↗
PubMed1994

Purification of inulin fructotransferase (DFA I-producing) from Arthrobacter sp. MCI2493 and production of DFA I from inulin by the enzyme.

An extracellular enzyme that produces di-D-fructofuranose-2',1;2,1' dianhydride from inulin was purified from the culture broth of Arthrobacter sp. MCI2493. The molecular weight of the enzyme was 40,000 by gel filtration and SDS polyacrylamide gel electrophoresis. The enzyme had maximum activity at pH 6.0 and 50 degrees C. Using this purified enzyme, 100 g/liter inulin was converted into 60 g/liter of DFA I, nystose, and 1-F-fructofuranosyl-nystose after incubation for 30 h.

Arthrobacter↗
PubMed1991

Suitability of tritiated inulin for determination of glomerular filtration rate.

Purity of different batches of [3H]inulin delivered from leading manufacturers was elevated with a chromatographic method (Sephadex G-25 column) that allowed simultaneous analysis of cold inulin, [3H]inulin, and [14C]inulin in the same run. Among four batches of [3H]inulin received within 5 mo, two were found relatively pure, whereas two were partly decomposed to lower-molecular-weight fragments. The chromatographic profile of pure isotopes was not significantly affected by redistribution and freeze drying, nor by subsequent storage in the freeze-dried state at -20 degrees C for up to 5 mo, nor by incubation in aqueous solution at 37 degrees C for 24 h. Three batches of [3H]inulin with different grades of decomposition (noninulin percentages 13%, 38%, and 61%, respectively) were selected for clearance experiments and infused simultaneously with cold and undecomposed [14C]inulin to conscious rats. [14C]inulin had a significantly higher clearance than cold inulin (+7.6 +/- 0.6%) and relatively pure [3H]inulin (+12.4 +/- 0.4%). Decomposed [3H]inulin isotopes progressively underestimated clearance of cold inulin to an extent related to the degree of decomposition. Thus at the end of the 5-h clearance experiment, ratios between clearance of tracer and of cold inulin were 0.92, 0.71, and 0.60 for the three 3H isotopes, respectively. This study indicates that [3H]inulin delivered from leading manufacturers may be decomposed to an extent that invalidates its use as a marker for glomerular filtration rate (GFR). It is thus necessary to check the purity routinely before use. Within the same rat, clearance of undecomposed [3H]inulin and [14C]inulin may differ by 12%, and for this reason they should not be used interchangeably as GFR markers.

Animals↗
PubMed1995

Recovery of inulin from Jerusalem artichoke (Helianthus tuberosus L.) in the small intestine of man.

The recovery of inulin, a naturally occurring beta (2-->1)-fructan isolated from Jerusalem artichoke (Helianthus tuberosus L.), in the small intestine of man was studied in ileostomy subjects. The ileostomists were given a low-dietary-fibre diet based on white wheat bread and virtually free of inulin, and the same diet with the addition of 10 g and 30 g inulin product respectively, and the recovery and mean transit time (MTT) of inulin were estimated by tracking inulin in ileal effluent. The recovery of inulin was approximately 87% at both ingestion levels. MTT was 4.9 (SE 0.6) h at an intake of 10 g inulin product decreasing to 3.4 (SE 0.3) h at an intake of 30 g inulin product. A significant change in the fructose:glucose ratio of inulin from ingestion (4.1) to recovery in ileal effluent (4.5-4.7) and a lower recovery of the glucose residue than of the fructose residue of inulin indicate that the low-molecular-weight inulins are more sensitive to hydrolysis than the high-molecular-weight fragments. The loss of inulin during passage through the small intestine is presumably due to hydrolysis by either acids or enzymes and to microbial degradation by the microflora permanently colonizing the distal small intestine. The concentrations of lactic acid (LA) and short-chain fatty acids (SCFA) in frequently collected ileal effluents on the control day were approximately 6 nmol/l and approximately 55 mmol/l respectively. During periods with inulin ingestion the concentration of LA increased to 18-26 mmol/l (P < 0.052), while the concentration of SCFA ran converse and decreased to 18-32 mmol/l (P < 0.023). The osmotic loads (68 and 204 mosmol/l) associated with the ingestion of inulin product caused minor malabsorption of low-molecular-weight sugars.

Adult↗
PubMed1991

High propionic acid fermentations and mineral accumulation in the cecum of rats adapted to different levels of inulin.

The digestive and metabolic effects of inulin (from chicory) were studied in rats adapted to semipurified diets containing 0, 5, 10 or 20% inulin (wt/wt). Moderate levels of inulin (5-10%) did not significantly affect food intake or body weight gain. Dietary inulin resulted in considerably greater cecal fermentation and a significantly greater intraluminal concentration of propionate (peaking at 58.4 mmol/L). A lower concentration of acetate (42.6 mmol/L) was observed in rats fed 20% inulin. Lactic fermentations were observed in rats fed the 10 or 20% inulin diets. The cecal pool of volatile fatty acids tended to reach a plateau in rats fed diets containing more than 10% inulin (up to 600-700 mumol), but volatile fatty acid absorption was a slightly hyperbolic function of the dietary inulin level. Butyrate absorption was proportionally lower than that of propionate. Inulin-containing diets induced an enlargement of the cecal pool of calcium, phosphate and (to a lesser extent) magnesium. There was also an enhanced absorption of these divalent cations. The cecal pool of bile acids was greater in rats fed inulin, and this oligosaccharide displayed a slight hypocholesterolemic effect, even in rats fed the 5% inulin diet. However, plasma triglycerides were depressed only in rats fed the 20% inulin diet. In conclusion, inulin seems very effective in promoting propionic fermentation and in enhancing the calcium content of the large intestine. However, high levels of inulin (greater than 10%) may affect growth in rats and lead to acidic (pH 5.65) cecal fermentation.

Adaptation, Physiological↗