In studies designed to investigate the metabolism of erythritol in vivo in healthy volunteers and to compare the fermentation of erythritol by human fecal flora in vitro with that of glucose and lactitol, four male and two female volunteers aged 21-25 undertook an overnight fast and were then chosen at random to receive a single dose of 25 g (13)C-erythritol, (13)C-glucose, and (13)C-lactitol in 250 mL of water with at least three days between each treatment. Breath samples were taken for analysis of (13)C-carbon dioxide and hydrogen gas before treatment and at 30 min intervals up to 6 hr after treatment. The ratio of (13)C:(12)C-carbon dioxide was measured by isotope-ratio mass spectrometry. ... In order to maintain a constant metabolic rate, the subjects remained at rest during the study. For the assay of fermentation in vitro, fecal samples were collected from six healthy volunteers (sex and age not specified) who ate a normal western diet. None of the subjects complained of gastrointestinal symptomsand none had used antibiotics in the past six months. The samples were incubated under anaerobic conditions for 6 hr, and then the hydrogen gas concentration was measured in the head-space of the incubation vials. ... After a 6 hr incubation with erythritol, the amount of hydrogen gas formed by the fecal flora was comparable to that in control vials, but significantly (p < 0.001) more hydrogen gas was produced in the glucose and lactitol vials than in either control or erythritol.
Groups of three Wistar rats of each sex were given a single dose of 0.1 g/kg bw (14)C-erythritol by gavage, as follows: germ-free rats were kept under sterile conditions until administration of commercial (14)C-erythritol; adapted conventional rats received diets containing weekly increases of 5, 10, and 20% erythritol for three weeks before administration of commercial (14)C-erythritol; unadapted conventional rats were kept on CIVO stock diet before administration of commercial (14)C-erythritol; or germ-free rats were kept under sterile conditions until dosing with purified (14)C-erythritol. Rats were not fasted before dosing. Immediately after treatment, the rats were placed in individual metabolism cages to allow collection of expired carbon dioxide, urine, and feces over 24 hrs. ... In rats that received commercial (14)C-erythritol, 2.5-2.9% of the radiolabel was erythrose and 0.2-0.35% was glucose. In germ-free rats that received purified (14)C-erythritol, less radiolabel was associated with erythrose. No volatile radioactive components were identified by lyophilization of the urine samples.
Groups of 11 male Wistar rats were fed control diet or control diet containing 10% erythritol (added at the expense of corn starch) for two weeks. They were then sacrificed, the caecal contents were collected and pooled by group, and the contents were suspended. Samples of each suspension were incubated with 12 mg (14)C-erythritol (10 uCi) for 6 hr under anaerobic conditions, and the incubation mixture was analyzed for erythritol, short-chain fatty acids, and carbon dioxide 1, 2, 4, and 6 hr after the beginning of incubation. The total recoveries of radiolabel were comparable for control and treated groups at the end of incubation, but the proportions of all (14)C-labelled products of fermentation differed significantly ( p < 0.01) between the two groups: in the controls, 84% of the radiolabel was present as unchanged erythritol, and carbon dioxide, acetic acid, propionic acid, and butyric acid each accounted for < 2% of the radiolabel; in contrast, < 1% of the radiolabel in the caecal contents of treated rats was present as erythritol at the end of incubation, 17% of the administered dose was released as (14)C-carbon dioxide within 2 hr of incubation, and 24% of the radiolabel was recovered as (14)C-carbon dioxide by the end of the incubation period. Succinic, acetic, propionic, and butyric acids were identified as fermentation products and accounted for about 60% of the radiolabel at the end of the incubation period. Succinic acid was detectable after 1 hr but not subsequently, suggesting that it was fermented to other products.
/SRP:/ Immediate first aid: Ensure that adequate decontamination has been carried out. If patient is not breathing, start artificial respiration, preferably with a demand-valve resuscitator, bag-valve-mask device, or pocket mask, as trained. Perform CPR as necessary. Immediately flush contaminated eyes with gently flowing water. Do not induce vomiting. If vomiting occurs, lean patient forward or place on left side (head-down position, if possible) to maintain an open airway and prevent aspiration. Keep patient quiet and maintain normal body temperature. Obtain medical attention. /Higher alcohols (>3 carbons) and related compounds/
/SRP:/ Basic Treatment: Establish a patent airway (oropharyngeal or nasopharyngeal airway, if needed). Suction if necessary. Watch for signs of respiratory insufficiency and assist ventilations if necessary. Administer oxygen by nonrebreather mask at 10 to 15 L/min. Monitor for shock and treat if necessary ... . Monitor for pulmonary edema and treat if necessary ... . Anticipate seizures and treat if necessary ... . For eye contamination, flush eyes immediately with water. Irrigate each eye continuously with 0.9% saline (NS) during transport ... . Do not use emetics. For ingestion, rinse mouth and administer 5 ml/kg up to 200 ml of water for dilution if the patient can swallow, has a strong gag reflex, and does not drool. Administer activated charcoal ... . /Higher alcohols (>3 carbons) and related compounds/
/SRP:/ Advanced Treatment: Consider orotracheal or nasotracheal intubation for airway control in the patient who is unconscious, has severe pulmonary edema, or is in severe respiratory distress. Positive-pressure ventilation techniques, with a bag-valve-mask device, may be beneficial. Consider drug therapy for pulmonary edema ... . Monitor cardiac rhythm and treat arrhythmias as necessary ... . Start IV administration of D5W /SRP: "To keep open", minimal flow rate/. Use 0.9% saline (NS) or lactated Ringer's (LR) if signs of hypovolemia are present. For hypotension with signs of hypovolemia, administer fluid cautiously. Consider vasopressors if patient is hypotensive with a normal fluid volume. Watch for signs of fluid overload ... . Monitor for signs of hypoglycemia (decreased LOC, tachycardia, pallor, dilated pupils, diaphoresis, and/or dextrose strip or glucometer readings below 50 mg) and administer 50% dextrose if necessary ... . Treat seizures with diazepam or lorazepam ... . Use proparacaine hydrochloride to assist eye irrigation ... . /Higher alcohols (>3 carbons) and related compounds/
/HUMAN EXPOSURE STUDIES/ In order to investigate the effects of repeated doses of erythritol on blood glucose control and renal function in patients with non-insulin-dependent diabetes mellitus, three male out-patients (mean age, 65 +/- 6 years) and eight female out-patients (mean age, 50 +/- 14 years) consumed 20 g of erythritol in a solution throughout the day daily for 14 days with their usual diet, but without specific restriction on timing or division of the daily dose. Food intake was monitored for three days before the test and three days before the end of the test. Body weights before and after administration and blood glucose and hemoglobin A1c after fasting were determined in all participants as indices of control of diabetes. In four or five of the subjects, blood urea nitrogen, creatinine, beta-2-microglobulin, and urinary proteins (not specified) were measured as indices of renal function before and after erythritol treatment. None of the participants reported diarrhea or any other subjective symptoms during treatment. The blood glucose concentrations after fasting, reported for nine subjects (sex not specified), decreased from 181 +/- 60 mg/dL before administration to 165 +/- 57 mg/dL after administration, which was not significant. The hemoglobin A1c concentrations after fasting, reported for all 11 participants, were the same as those before treatment for four, decreased in six, and increased in one subject after erythritol treatment. The large decreases in two subjects resulted in a decrease in the group mean value after treatment, to 7.5 +/- 1.6% from 8.5 +/- 1.5% before administration. Blood urea nitrogen, creatinine, and beta -2-microglobulin values were reported for only five or fewer subjects, but erythritol had no effect on these parameters. Urinary proteins, as measured colorimetrically for an unspecified number of participants, were reported not to be affected by erythritol treatment. ...
/HUMAN EXPOSURE STUDIES/ The gastrointestinal tolerance and diuretic response to repeated doses of erythritol were examined in a double-blind, two-way cross-over study in which healthy men consumed erythritol and, for comparison, sucrose. Twelve men aged 22-46 and weighing 65-98 kg consumed each test material for seven days, comprising a two-day adaption period at home and a five-day test period under supervision. The men consumed 0.3 g/kg bw erythritol or 0.6 g/kg bw sucrose in test foods during the first and second day of adaptation, respectively, and 1 g/kg bw per day of erythritol or sucrose in yoghurt, biscuits, soft drinks, or chocolate under supervision. In order to attain the correct dose, fixed amounts were given in test foods at each meal except the evening meal, when individual doses of the test compounds were administered in order to reach the nominal dose of 1 g/kg bw for each subject. Beverages such as mineral water and fruit juice were allowed ad libitum, but consumption of caffeine-containing drinks was limited to four cups per day. ... The entire urine volume was collected at five 3-hr intervals during the day and one 9-hr interval overnight throughout the test period, and sodium, potassium, chlorine, calcium, phosphorus, citrate, gamma-glutamyl transpeptidase and N-acetylglucosamine activities, beta-2-microglobulin, urea, and creatinine were determined. The concentration of erythritol was determined in a separate aliquot. The daily dose 1 g/kg bw per day erythritol was well tolerated, with no increase in the reported incidence of gastrointestinal symptoms such as flatulence, abdominal cramps, and diarrhea. One man reported thirst during treatment with erythritol, but there were no differences in the subjective judgements of the frequency and quantity of urine production. Fluid intake varied considerably among the study participants, from 800 to 6600 mL/man per day, and the averages for both treatment periods were reported to be high in comparison to usual intakes, but there was no significant difference between the two periods. Urine production was about 7% higher during erythritol treatment, but the increase was not statistically significant. Urinary excretion of erythritol resulted in significantly (p < 0.001) increased urine osmolarity and hourly output of osmotically active solutes, but urinary pH and the excretion of creatinine, urea, citrate, sodium, potassium, and chlorine were not affected. Marginal but statistically significant increases in calcium concentration, microalbumin, beta-2-microglobulin, and N-acetylglucosamine activity were noted consistently over the five-day period after ingestion of erythritol, although the values for these parameters remained within reference intervals and below values that would be considered clinically relevant. The data on gamma-glutamyl transpeptidase activity were considered unreliable and were therefore not reported. Thus, 1 g/kg bw of erythritol was consumed as part of the regular diet over five days without adverse gastrointestinal symptoms. Urine volume and urinary electrolyte and protein excretion were not significantly affected at this dose, suggesting the absence of a diuretic effect, although the high fluid consumption of the participants and the consumption of coffee and/or tea (up to four cups per day) may have prevented the detection of any diuretic effect of erythritol.
In 12 male subjects who consumed 1 g/kg bw per day erythritol in a variety of foods during a five-day test period under controlled conditions, the mean urinary excretion was 61-88% of the nominal ingested dose, with an average of 78%.
The peak serum concentration of erythritol in five non-insulin-dependent diabetic patients (sex not indicated) who consumed a single dose of 20 g erythritol in solution occurred 1 hr after administration and was 650 +/= 37 ug/mL. On average, 82, 88, and 88% of the administered erythritol was recovered in the urine 24, 48, and 72 hrs after dosing, respectively.
After 12 male and 12 female volunteers received a dose of 0.4 or 0.8 g/kg bw erythritol in a chocolate snack, the plasma erythritol concentrations increased rapidly, reaching peaks of 3 and 5 mmol/L 1 and 2 hrs after dosing with 0.4 and 0.8 g/kg bw, respectively. Starting 2 hrs after treatment, the plasma erythritol concentrations were significantly (p < 0.05) higher in the group given 0.8 g/kg bw than in that given 0.4 g/kg bw. At both doses, erythritol appeared in the urine within 2 hrs of dosing, the largest quantities being collected between 2 and 4 hrs after administration. Erythritol was still present in urine 22 hrs after treatment. The concentration of erythritol in the urine of individuals given 0.8 g/kg bw was about twice and significantly (p < 0.05) greater than that in the urine of people given 0.4 g/kg bw. On average, 61 and 62% of the administered erythritol was recovered in the urine after the 0.4 and 0.8 g/kg bw doses, respectively, within 22 hrs.
The kinetics of erythritol in plasma and urine were investigated in three men and three women after an overnight fast. Each subject ingested a single oral dose of 1 g/kg bw dissolved in 250 mL of water, and blood samples were taken 5, 10, 15, 30, 45, 60, 90, 120, 180, and 240 min after dosing for determination of plasma concentrations of erythritol. Plasma creatinine concentrations were determined in a blood sample taken before treatment. Urine was collected over 0-30 min, 30-60 min, 1-2 hr, 2-3 hr, and 3-24 hr after treatment for determination of the volume and of the erythritol and creatinine concentrations. Erythritol was detected in the plasma 10 min after dosing, and the mean plasma concentrations increased steadily from 15 min after treatment to a peak of 2.2 mg/mL after 90 min. The urine volume and erythritol concentration reached a maximum during 1-2 hr after ingestion, at about the same time that the plasma concentration of erythritol peaked. Urinary recovery of erythritol over the 24 hr collection period accounted for 78% of the administered dose, with 30% collected after 3 hr. During 1 and 2 hr after administration, the clearance of erythritol was about half that of creatinine, indicating tubular reabsorption of erythritol by the kidney.
Bronsted acid catalyzed oxidation of certain sugar alcohols (polyols) has been studied by quinolinium dichromate (QDC) using aqueous sulfuric, perchloric, and hydrochloric acids at different temperatures. At constant acidity, reaction kinetics revealed the second‐order kinetics with a first order in [Alcohol] and [QDC]. Zucker‐Hammett, Bunnett, and Bunnett‐Olsen criteria were used to analyze acid‐dependent
Multiple Forms of Xylose Reductase in <i>Candida intermedia</i>: Comparison of Their Functional Properties Using Quantitative Structure−Activity Relationships, Steady-State Kinetic Analysis, and pH Studies
The xylose-fermenting yeast Candida intermedia produces two isoforms of xylose reductase: one is NADPH-dependent (monospecific xylose reductase; msXR), and another is shown here to prefer NADH approximately 4-fold over NADPH (dual specific xylose reductase; dsXR). To compare the functional properties of the isozymes, a steady-statekineticanalysis for the reaction d-xylose + NAD(P)H + H(+) <--> xylitol
Conversion of sugars to ethylene glycol with nickel tungsten carbide in a fed-batch reactor: high productivity and reaction network elucidation
作者：Roselinde Ooms、Michiel Dusselier、Jan A. Geboers、Beau Op de Beeck、Rick Verhaeven、Elena Gobechiya、Johan A. Martens、Andreas Redl、Bert F. Sels
DOI：10.1039/c3gc41431k
日期：——
Bifunctional nickel tungsten carbide catalysis was used for the conversion of aqueous sugar solutions into short-chain polyols such as ethylene glycol. It is shown that very concentrated sugar solutions, viz. up to 0.2 kg L−1, can be converted without loss of ethylene glycol selectivity by gradually feeding the sugar solution. Detailed investigation of the reaction network shows that, under the applied reaction conditions, glucose is converted via a retro-aldol reaction into glycol aldehyde, which is further transformed into ethylene glycol by hydrogenation. The main byproducts are sorbitol, erythritol, glycerol and 1,2-propanediol. They are formed through a series of unwanted side reactions including hydrogenation, isomerisation, hydrogenolysis and dehydration. Hydrogenolysis of sorbitol is only a minor source of ethylene glycol. To assess the relevance of the fed-batch system in biomass conversions, both the influence of the catalyst composition and the reactor setup parameters like temperature, pressure and glucose addition rate were optimized, culminating in ethylene glycol yields up to 66% and separately, volume productivities of nearly 300 gEG L−1 h−1.
We present new approaches to the (C2) chiral and meso 1,4-diamino-2,3-butanediol (1) and 2,3-diamino-1,4-butanediol (2) and derivatives. Reactions of these compounds with aldehydes to form the novel 1,5-dioxa-3,7-diazadecalin (DODAD) and 1,5-diaza-3,7-dioxadecalin (DADOD) classes of compounds (7, 9, 11–15) are also reported. These reactions are diastereospecific, i.e., erythro (meso) or threostarting
