Previously, the metabolism of alpha-tocopherol was considered to involve the opening of the chroman structure because of its oxidation to tocopherylquinone. In contrast, we describe here 2,5,7,8-tetramethyl-2(2'-carboxyethyl)-6-hydroxychroman (alpha-CEHC) as the major urinary metabolite of alpha-tocopherol that appears in human urine after vitamin E supplementation. It is formed directly from alpha-tocopherol without previous oxidative splitting of the chroman ring. The correlation of alpha-tocopherol intake, plasma alpha-tocopherol concentrations, and urinary excretion of alpha-CEHC in human volunteers supplemented with RRR-alpha-tocopherol dosages ranging from 0 to 800 mg/d was examined. HPLC and gas chromatography-mass spectroscopy analysis revealed that alpha-CEHC was only excreted when a plasma threshold of 7-9 mumol alpha-tocopherol/g total lipid was exceeded. This concentration was obtained by a daily intake of approximately 50-150 mg alpha-tocopherol. We suggest that alpha-CEHC excretion indicates a saturated binding capacity of vitamin E in the plasma and thus may be considered to be a marker of optimum vitamin E intake.
R . L a n g e , W . S c h u m a n n , M . P e i r z i k a , H . B u s c h u n d R . M a r q u a r d * Lucas Meyer GmbH, Hamburg, Landesforschungsanstali fur Landwirtschaft und Fischerei Mecklenburg-Vorpommern, Giilzow, Deutsches Institut fur Ernahrungsforschung, Bergholz-Rehbriicke, Deutsche Saaiveredelung, Salzkoiten-Thiile und Insiiiui fur Pflanzenbau und Pflanzenziichtung I , GiepenDie Studie berichtet iiber Art und Menge der Glucosinolate (GLS) in Leindottersaaten. Im Vergleich zur Literatur wird gezeigt. daO neben dem Glucocamelinin ( LO-Methylsulfinyldecyl-GLS) zwei weitere Thioglucoside vorkommen. Durch GC/MS-und Thermospray/MS-Untersuchungen wurden sie als 9-Methylsufinylnonyl-bzw. 11-Methylsulfinylundecyl-GLS identifiziert. Der Gesamt-GLS-Gehalt der untersuchten Prilparate wurde zwischen 21 und 34 pmollg Samen gefunden. Haupt-GLS ist Glucocamelinin (60%) gefolgt vom 9-(20%) und 11-Homologen (15 %). Variationen im Gehalt zeigen insbesondere die Minorkomponenten. Glucosiaolates in Linseed DodderThe study deals with typ and level of glucosinolates (GLS) occurring in Cumelina soriva seeds. In comparison to literature it could be shown that beside glucocamelinin (10-methylsulfinyldecyl-GLS) two other thioglucosides occur. They were identified by gdms-and thermospraylms-investigations as 9-methylsulfinylnonyI-respectively ll-rnethylsulfinylundecyl-GLS. The total-glucosinolate content of the seeds was found between 21 and 34 pmollg. Main-GLS is glucocamelinin (60%). Minor compounds are the 9-(20%) and 11-homologous (15%). Especially the minor compounds show variations in the content.
In IDDM, the gluconeogenic turnover of amino acids is increased even if glycemia is well controlled and may be restored to normal by means of prehepatic insulin substitution. Therefore, the present study was designed 1) to investigate the influence of route of insulin administration (portal versus peripheral) on the urea production rate, which is considered to measure amino acid catabolism, and 2) to elucidate the impact of different food-protein intake. Paired studies were conducted in chronic insulin-dependent diabetic dogs maintained normoglycemic. Diabetic animals and nondiabetic controls were fed either a high-protein diet (46% of energy intake provided by proteins; study 1) or a low-protein carbohydrate-supplemented diet (20% of energy intake provided by protein; study 2) for 2 days, and flux rates of glucose and urea were measured using isotope dilution techniques. In both studies, the diabetic animals were maintained normoglycemic by glucose-controlled insulin infusion delivered either systemically or portally. In study 1 versus study 2, the animals showed lower alpha-amino nitrogen levels and concentrations of gluconeogenic amino acids, predominantly alanine. There were no significant differences in plasma glucose and glucose turnover between the experimental groups on either systemic or portal insulin infusion versus controls; however, peripheral insulin levels were higher for diabetic animals maintained with systemic versus portal insulin delivery (P < 0.05). No significant differences in glucagon, lactate, pyruvate, nonesterified fatty acids, or beta-hydroxybutyrate were observed. Urea production was significantly higher in study 1 compared with study 2: 7.48 +/- 0.83 vs. 5.97 +/- 0.59 micromol / kg / min (normal dogs); 12.97 +/- 1.86 vs. 5.54 +/- 0.60 micromol / kg / min (diabetic dogs on portal insulin); 16.11 +/- 2.59 vs. 6.82 +/- 0.70 micromol / kg / min (diabetic dogs on systemic insulin infusion); P < 0.05 for all. The diabetic dogs maintained normoglycemic with systemic insulin infusions had significantly higher rates of urea synthesis than those with portal insulin infusion (P < 0.05). It is concluded that in IDDM, even if normoglycemia is managed, there is significantly increased amino acid catabolism with posthepatic systemic insulin treatment. This increased catabolic rate is more pronounced during high-protein nourishment.
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