Conversion Of Glycol Research Articles

Degradation of ethylene glycol using Fenton's reagent and UV

Oxidation of ethylene glycol in aqueous solutions was found to occur with the addition of Fenton's reagent with further conversion observed upon UV irradiation. The pH range studied was 2.5–9.0 with initial H 2O 2 concentrations ranging from 100 to 1000 mg/l. Application of this method to airport storm-water could potentially result in reduction of chemical oxygen demand by conversion of ethylene glycol to oxalic and formic acids. Although the amount of H 2O 2 added follows the amount of ethylene glycol degraded, smaller H 2O 2 doses were associated with increases in the ratio of ethylene glycol removed per unit H 2O 2 added indicating the potential of pulsed doses or constant H 2O 2 feed systems. Ethylene glycol removal was enhanced by exposure to UV light after treatment with Fenton's reagent, with rates dependent on initial H 2O 2 concentration. In addition to ethylene glycol, the principle products of this reaction, oxalic and formic acids, have been shown to be mineralized in other HO generating systems presenting the potential for ethylene glycol mineralization in this system with increased HO production.

Dose-dependent nonlinear pharmacokinetics of ethylene glycol metabolites in pregnant (GD 10) and nonpregnant Sprague-Dawley rats following oral administration of ethylene glycol.

The kinetics of orally administered ethylene glycol (EG) and its major metabolites, glycolic acid (GA) and oxalic acid (OX), in pregnant (P; gestation day 10 at dosing, GD 10) rats were compared across doses, and between pregnant and nonpregnant (NP) rats. Groups of 4 jugular vein-cannulated female rats were administered 10 (P and NP), 150 (P), 500 (P), 1000 (P), or 2500 (P and NP) mg (13)C-labelled EG/kg body weight. Serial blood samples and urine were collected over 24-hr postdosing, and analyzed for EG, GA, and OX using GC/MS techniques. Pharmacokinetic parameters including Cmax, Tmax, AUC, and betat((1/2)) were determined for EG and GA. Pregnancy status (GD 10-11) had no impact on the pharmacokinetic parameters investigated. Blood levels of GA were roughly dose-proportional from 10 to 150 mg EG/kg, but increased disproportionately from 500 to 1000 mg EG/kg. EG and GA exhibited dose-dependent urinary elimination at doses > or = 500 mg EG/kg, probably due to saturation of metabolic conversion of EG to GA, and of GA to downstream metabolites. The shift to nonlinear kinetics encompassed the NOEL (500 mg EG/kg) and LOEL (1000 mg EG/kg) for developmental toxicity of EG in rats, providing additional evidence for the role of GA in EG developmental toxicity. The peak maternal blood concentration of GA associated with the LOEL for developmental toxicity in the rat was quite high (363 microg/g or 4.8 mM blood). OX was a very minor metabolite in both blood and urine at all dose levels, suggesting that OX is not important for EG developmental toxicity.

EFFECT OF SEX HORMONES ON OXALATE-SYNTHESIZING ENZYMES IN MALE AND FEMALE RAT LIVERS

We studied the effect of changes in sex hormones on oxalate metabolism in rats. Adult male and female rats were administered a precursor of oxalate, and the relationship between dose and urinary oxalate was examined. Levels of sex hormones were varied in rats and glycolate oxidase (GO) and serine pyruvate aminotransferase (SPT) activities were measured under the conditions of being fed tap water or loading with 0.5% ethylene glycol. In addition, urinary oxalate excretion was evaluated. Ethylene glycol and glycolate increased urinary oxalate concentration in male rats dose-dependently but less in female rats. There was almost no change during glycine loading in either male or female rats. GO activity was significantly lower in intact female and gonadectomized male rats. SPT activity was slightly higher in the female than in the male controls. There were no differences in urinary oxalate excretions between male and female rats. During ethylene glycol loading, GO and SPT activities were similar to those with tap water intake. However, urinary oxalate excretion increased to two times the control value in male rats but only slightly increased in female rats. Sex-related differences exist in the metabolic conversion of glycolate to oxalate in rats, and GO activity is promoted by testosterone. Although difference in GO activity has no physiological effect on oxalate synthesis, GO activity affects urinary oxalate excretion during ethylene glycol loading. We could also conclude that estrogen decreases GO activity in male rats from our results.

American Academy of Clinical Toxicology Practice Guidelines on the Treatment of Ethylene Glycol Poisoning

Fomepizole (4-methylpyrazole, 4-MP, Antizol) is a potent inhibitor of alcohol dehydrogenase that was approved recently by the US Food and Drug Administration (FDA) for the treatment of ethylene glycol poisoning. Although ethanol is the traditional antidote for ethylene glycol poisoning, it has not been studied prospectively. Furthermore, the FDA has not approved the use of ethanol for this purpose. Case reports and a prospective case series indicate that the intravenous (i.v.) administration of fomepizole every 12 hours prevents renal damage and metabolic abnormalities associated with the conversion of ethylene glycol to toxic metabolites. Currently, there are insufficient data to define the relative role of fomepizole and ethanol in the treatment of ethylene glycol poisoning. Fomepizole has clear advantages over ethanol in terms of validated efficacy, predictable pharmacokinetics, ease of administration, and lack of adverse effects, whereas ethanol has clear advantages over fomepizole in terms of long-term clinical experience and acquisition cost. The overall comparative cost of medical treatment using each antidote requires further study.

Engineering Pichia pastoris for biocatalysis: co-production of two active enzymes

High levels of active glycolate oxidase from spinach (GO) and active catalase T from Saccharomyces cerevisiae (catT) have been co-produced in the methylotrophic yeast Pichia pastoris ( Pp). In sequential rounds of transformation using two selectable markers, multiple copies of the genes encoding GO and catT were integrated into the Pp chromosome under control of the methanol inducible alcohol oxidase I promoter, resulting in a strain designated MSP8.6. MSP8.6 is a second-generation biocatalyst used for the conversion of glycolate to glyoxylate in the presence of a reaction component which inhibits endogenous Pp catalase. This work demonstrates a significant advance in the utility of recombinant Pp for commercial bioprocess development.

Clofibrate feeding to Sprague-Dawley rats increases endogenous biosynthesis of oxalate and causes hyperoxaluria

The effects of clofibrate feeding (5 g/kg diet) on oxalate metabolism were investigated in male and female rats. Following clofibrate feeding, 24-hour urinary excretion of oxalate increased until 4 days and then reached a plateau. Whereas the contribution of dietary oxalate (1.4 g/kg diet, as potassium salt) to urinary oxalate was less than 5% in both control and clofibrate-treated male rats, the contribution of dietary glycolate (1.0 g/kg diet, as sodium salt) to urinary oxalate was six times higher in clofibrate-treated male rats compared with controls, indicating that the clofibrate-induced hyperoxaluria is due to increased endogenous biosynthesis of oxalate. This was supported by the increased lactate dehydrogenase (LDH) activity observed in liver supernatants of clofibrate-treated rats compared with controls, and the increased rate of conversion of glycolate and glyoxylate to oxalate by clofibrate-treated male rat liver supernatants. Female rats had lower excretion of urinary oxalate and lower levels of liver glycolic acid oxidase (GAO) as compared with males. Clofibrate-treated female rat liver supernatants had higher LDH levels and produced more oxalate from glyoxylate. Thus, it can be concluded that the increase in LDH activity may be the cause of the increased endogenous biosynthesis of oxalate leading to increased urinary excretion of oxalate in male and female rats treated with clofibrate.

Biochemical mechanism of action of pyridoxine in the prevention of glycolate induced hyperoxaluria in male albino rats

Sodium glycolate feeding (100 mg/100 g BW/day) to adult male rats for a period of six weeks resulted in significant hyperoxaluria which was due to enhanced activities of oxalate synthesising enzymes glycolic acid oxidase (GAO) and glycolic acid dehydrogenase (GAD) in the liver. Administration of pyridoxine (10 mg/100 g BW/day) along with sodium glycolate resulted in a significant decrease in urinary oxalate as compared to glycolate fed rats. Pyridoxine prevented glycolate induced hyperoxaluria by lowering the activities of GAO and GAD. The increased lactate dehydrogenase (LDH) activity in these animals promotes conversion of glycolate to glyoxylate which may be rapidly transminated to glycine by pyridoxal phosphate dependent aminotransferases. Pyridoxine administration also produced a significant increase in urinary citrate levels in glycolate fed rats.

Comparison of enzyme activities in oxalate synthesis betweenspinacia oleraceal. andbrassica campestrisL.

Abstract Enzymatic conversion of glycolate to oxalate was studied in detached leaves of Spinacia oleracea L. (spinach), an oxalate accumulator plant and Brassica campestris L. (komatsuna), an oxalate non-accumulator plant by the application of 2-14C-glycolate. The glycolate incorporated into leaves of the two species was rapidly metabolized. However, oxalate was not detected in the leaves of komatsuna. The in vitro experiment using crude enzyme extract from leaves of the two species failed to reveal any appreciable differences in the enzymatic properties of glycolate oxidase between the two species, Therefore, the oxalate synthesis by the crude enzyme in spinach and komatsuna was studied using glutamate or alanine as amino-group donor. In both plants, oxalate synthesis in the presence of amino-group donor was reduced compared with that in the absence of amino-group donor. In addition, the extent of the decrease was larger in komatsuna than in spinach.

Protein organization in the matrix of leaf peroxisomes. A multi-enzyme complex involved in photorespiratory metabolism.

This report is an investigation on how the compartmentation of peroxisomal metabolism, involved in the photorespiratory cycle, is accomplished. With isolated peroxisomes from spinach leaves the conversion of serine to glycerate, as coupled to the conversion of glycolate to glycine, was measured. Not only with intact but also with osmotically shocked peroxisomes, which had retained the aggregated state of the peroxisomal matrix but lost the integrity of the boundary membrane, the rates of glycerate synthesis were as high as required for the photorespiratory cycle in vivo. With both intact and shocked peroxisomes the intermediates glyoxylate and hydroxypyruvate did not equilibrate with the medium. It appears from these results that the apparent compartmentation of peroxisomal metabolism is not due to the function of the boundary membrane but to the organization of peroxisomal enzymes in multi-enzyme complexes. When glycolate was added to peroxisomes without transamination partners, glyoxylate was released from the peroxisomes while the peroxisomal matrix partially disintegrated. With solubilized peroxisomes a partial reconstitution of functional enzyme complexes was achieved by the addition of poly(ethylene glycol). The function of the apparently very stable peroxisomal multi-enzyme complexes in protecting the cells from the toxic intermediates H2O2 and glyoxylate is discussed.

Treatment of Ethylene Glycol Poisoning

In their recent article, Curtin et al 1 probably relied on a computer search to compile their bibliography. While computers and bibliographic software programs speed up literature searching, they do have their own pitfalls; chiefly, that the world's literature begins when the databases were started. Therefore, articles published earlier, are overlooked. I should like to point out that the use of ethyl alcohol to treat ethylene glycol poisoning goes back to 1963 when studies by Peterson et al 2 showed that ethylene glycol is a substrate of alcohol dehydrogenase and that ethyl alcohol inhibits its oxidation, thus preventing the conversion of ethylene glycol to toxic intermediates and oxalic acid. Moreover, in the same article, experiments carried out using squirrel monkeys proved that treatment of these animals with ethyl alcohol after supertoxic doses of ethylene glycol was successful. These studies were the basis for the first effective treatment of humans 3 that

Ion exchange resin catalysed etherification of ethylene and propylene glycols with isobutylene

Etherification of ethylene and propylene glycols with isobutylene was carried out in the presence of cation exchange resin catalysts, Amberlyst-15, Indion-130, and a homogeneous catalyst, p-toluene sulfonic acid. Kinetics of these reactions was studied in a magnetically stirred 1.0 × 10 −4 m 3 capacity autoclave in the temperature range 50–70°C. The maximum conversion of glycols was obtained at 60°C and 10% loading of Amberlyst-15 catalyst. Aspects of mono- and di-etherification and etherification of primary versus secondary OH groups in monopropylene glycol were studied. A pseudohomogeneous model fitted the data very well. Optimum values of the rate constants were obtained numerically. The ethers formed could be deetherified easily at 120°C with the same catalyst.

Novel Biotreatment Process for Glycol Waters

Propylene oxide (PO), propylene glycol (PG), and polyols are produced from propylene via propylene chlorohydrin. Effluents from these plants contain biological oxygen demand/chemical oxygen demand (BOD/COD) loads besides high chloride concentrations. The high salinity poses severe problem to adopt conventional methods like activated sludge processes. Presently, a simple, economically viable and versatile microbiological process has been developed to get more than 90% biodegradation in terms of BOD/COD, utilizing specially developed Pseudomonas and Aerobacter. The process can tolerate high salinity up to 10 wt% NaCl or 5 wt% CaCl2 and can withstand wide variations in pH (5.5-11.0) and temperature (15-45 degrees C). The biodegradation of glycols involves two steps. The enzymatic conversion of glycols to carboxylic and hydroxycarboxylic acids is aided by Pseudomonas. Further degradation to CO2 and H2O by carboxylic acid utilizing Aerobacter, and possible metabolic degradative pathway of glycols are discussed. Various process parameters obtained in the lab scale (50 L bioreactor) and pilot scale (20 m3 bioreactor), and unique features of our process are also discussed.

Glycolate determination detects type I primary hyperoxaluria in dialysis patients

The detection of type I primary hyperoxaluria is based on the finding of exceedingly high oxalate excretion which is associated with increased glycolate excretion. The differential diagnosis of this disease may become a difficult task once end-stage renal disease (ESRD) and anuria have supervened. The various procedures thus far proposed to obviate this circumstance are complex, inaccurate or not reproducible. In this paper we propose the accurate liquid chromatographic determination of glycolate in blood and dialysate as a means to detect type I primary hyperoxaluria in patients on maintenance hemodialysis (RDT). The method is based on the enzymatic conversion of glycolate to glyoxylate coupled with alpha-keto acid derivatization with phenylhydrazine. The resulting phenylhydrazone is then resolved by high-performance liquid chromatograph (HPLC). With this method, plasma glycolate in 12 healthy controls was 7.8 +/- 1.7 mumol/liter, almost twentyfold less than previously reported. Five dialysis patients with high serum oxalate, of whom four with primary hyperoxaluria and one with Crohn's disease and presumed enteric oxalate hyperabsorption, were checked by this method and compared to nine patients with oxalosis-unrelated ESRD. The patients with hyperoxalemia were also evaluated for their response to pyridoxine therapy. The measurement of glycolate in blood drawn prior to and at the end of the dialysis session as well as in the dialysate soundly discriminated the patients with type I hyperoxaluria from all the other dialysis patients. Glycolate measurement was shown to be much more powerful than oxalate in that patients with oxalosis-induced ESRD exhibited an almost two hundred and fiftyfold increase compared to the oxalosis-unrelated patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Copper catalyzed amination of ethylene glycol

The amination of ethylene glycol by dimethylamine on alumina supported copper has been studied in a continuous fixed-bed reactor at atmospheric pressure. Main reaction products were 2-dimethylaminoethanol, N,N,N′,N′-tetramethyl-1,2-diaminoethene (enamine) and N,N,N′,N′-tetramethylethylenediamine (diamine). The selectivity to 2-dimethylaminoethanol exhibited a maximum at 230°C, reaching more than 70 wt%. Selectivities to the enamine and to the diamine were much lower and did not show a maximum in the range 190° – 250°C. Ethylene glycol conversion was virtually independent of the hydrogen partial pressure and of the reactant ratio, dimethylamine : glycol, in the range 1.25 – 2.25. In contrast, the selectivities to 2-dimethylaminoethanol and to the enamine were markedly influenced when the reactant ratio was changed in this range. The selectivity to the enamine could be increased to 55 %, when hydrogen was substituted by nitrogen in the feed.

Oxaloacetate acetylhydrolase activity in virulent and hypovirulent strains of Endothia (Cryphonectria) parasitica

Extracts of three virulent strains of Endothia (Cryphonectria) parasitica and three hypovirulent strains derived from them were assayed for enzyme activities that would produce oxalate. Oxaloacetate acetylhydrolase (E.C. 3.7.1.1), the enzyme that converts oxaloacetate to oxalate and acetate, was at least four times higher in extracts of the virulent strains than in extracts of the hypovirulent strains. The level of activity of this enzyme could account for the formation of all the oxalate produced by the virulent cultures. When extracts of hypovirulent strains were added to extracts of virulent strains, the measured rate was less than the sum of the two rates. The inhibition did not change when the hypovirulent extract was either dialysed or boiled. No enzyme activity for the conversion ofglycolate or glyoxylate to oxalate could be detected in any of the extracts. There was no apparent difference between the virulent and hypovirulent strains of the fungus on the basis of intracellular organic acid content except that fumarate concentration was lower in extracts of hypovirulent strains. The amounts of oxalate produced by the virulent strains when grown on solid medium with malate (an immediate precursor of oxaloacetate) and fumarate were much higher than when they were grown on solid medium with glycolate. Two of the hypovirulent strains produced no oxalate on any of the substrates. However, the hypovirulent strain which had the highest oxaloacetate acetylhydrolase activity produced oxalate cultured on malate and fumarate but none on glycolate.

Mitochondrial Metabolism of Glycolate in the Alga Eremosphaera viridis

In Eremosphaera glycolate is synthesized and can either be excreted or metabolized by the cells. All the enzymes required for the conversion of glycolate to glycerate are present in this organism. In contrast to higher plants and also to some other algae the enzymes of glycolate metabolism are located exclusively in the mitochondria. Oxidation of glycolate is catalyzed by a dehydrogenase which also has a high affinity for D-lactate. Glycolate as well as D-lactate supplied in the culture medium can be taken up and metabolized by the whole cells. The metabolism of both substrates causes an increase in respiration activity. With D-lactate the oxygen consumption is much higher than with glycolate.

Metabolism of Glycolate and Glyoxylate in Intact Spinach Leaf Peroxisomes

Intact and broken (osmotically disrupted) spinach (Spinacia oleracea) leaf peroxisomes were compared for their enzymic activities on various metabolites in 0.25 molar sucrose solution. Both intact and broken peroxisomes had similar glycolate-dependent o(2) uptake activity. In the conversion of glycolate to glycine in the presence of serine, intact peroxisomes had twice the activity of broken peroxisomes at low glycolate concentrations, and this difference was largely eliminated at saturating glycolate concentrations. However, when glutamate was used instead of serine as the amino group donor, broken peroxisomes had slightly higher activity than intact peroxisomes. In the conversion of glyoxylate to glycine in the presence of serine, intact peroxisomes had only about 50% of the activity of broken peroxisomes at low glyoxylate concentrations, and this difference was largely overcome at saturating glyoxylate concentrations. In the transamination between alanine and hydroxypyruvate, intact peroxisomes had an activity only slightly lower than that of broken peroxisomes. In the oxidation of NADH in the presence of hydroxypyruvate, intact peroxisomes were largely devoid of activity. These results suggest that the peroxisomal membrane does not impose an entry barrier to glycolate, serine, and O(2) for matrix enzyme activity; such a barrier does exist to glutamate, alanine, hydroxypyruvate, glyoxylate, and NADH. Furthermore, in intact peroxisomes, glyoxylate generated by glycolate oxidase is channeled directly to glyoxylate aminotransferase for a more efficient glycolate-glycine conversion. In related studies, application of in vitro osmotic stress to intact or broken peroxisomes had little effect on their ability to metabolize glycolate to glycine.

A Study of Formate Production and Oxidation in Leaf Peroxisomes during Photorespiration

When glycolate was metabolized in peroxisomes isolated from leaves of spinach beet (Beta vulgaris L., var. vulgaris) formate was produced. Although the reaction mixture contained glutamate to facilitate conversion of glycolate to glycine, the rate at which H(2)O(2) became "available" during the oxidation of [1-(14)C]glycolate was sufficient to account for the breakdown of the intermediate [1-(14)C]glyoxylate to formate (C(1) unit) and (14)CO(2). Under aerobic conditions formate production closely paralleled (14)CO(2) release from [1-(14)C]glycolate which was optimal between pH 8.0 and pH 9.0 and was increased 3-fold when the temperature was raised from 25 to 35 C, or when the rate of H(2)O(2) production was increased artificially by addition of an active preparation of fungal glucose oxidase.When [(14)C]formate was added to these preparations it was oxidized directly to (14)CO(2) by the peroxidatic action of peroxisomal catalase; however, the breakdown of formate was slow relative to the rate of formate production. For example, when [(14)C]formate was generated from [2-(14)C]glycolate it was not readily oxidized to (14)CO(2) in these organelles. Because the activity of formate-NAD(+) dehydrogenase in cell-free leaf extracts was low compared with that of formyl tetrahydrofolate synthetase it is suggested that most of the formate produced during glycolate oxidation could be metabolized via the one carbon pool and not oxidized directly to CO(2).At 25 C the rate of release of (14)CO(2) from [2-(14)C]glycolate in leaf discs was 40 to 50% of the rate from [1-(14)C]glycolate. Isonicotinyl hydrazide inhibited (14)CO(2) release from both [1-(14)C]- and [2-(14)C]glycolate; but this inhibitor was more effective in blocking (14)CO(2) release from [2-(14)C]glycolate. It is argued that the oxidation of the methylene carbon group of glycolate does not occur as a direct consequence of formate (C(1) unit) breakdown, but is a product of the further metabolism of formate and glycine, possibly, via serine.

Photooxidative Damage in Photosynthetic Activities of Chromatium vinosum

The capacity of photosynthetic CO(2) fixation in the anaerobic purple-sulfur bacterium, Chromatium vinosum is markedly impaired by strong illumination (9 x 10(4) lux) in the presence of 100% O(2). In the absence of HCO(3) (-), decline in activity occurred gradually, with about 40% of the initial activity remaining after a 1-hour incubation. The addition of 50 millimolar HCO(3) (-) to the incubation medium resulted in a measurable delay (about 30 minutes) of the inactivation process. Ribulose-1,5-bisphosphate carboxylase activity and light-dependent O(2) uptake (electron flow) or crude extracts prepared after pretreatment of the bacterial cells with O(2) and light were not affected but the photophosphorylation capacity of either bacterial cells or chromatophores was drastically reduced. The inhibition of photophos-phorylation in the chromatophore preparations was significantly reduced by the addition of either an O(2) (-) scavenger, Tiron, or an (1)O(2) scavenger, alpha-tocopherol. These results suggest that the active O(2) species, O(2) (-) or (1)O(2), might take part in the observed inactivation.The pretreatment of the bacteria with O(2) and light inhibited CO(2) assimilation through the Calvin-Benson cycle, while relatively stimulating the formation of aspartate and glutamate. It also inhibited the conversion of glycolate to glycine, resulting in a sustained extracellular excretion of glycolate. The inactivation of photosynthetic CO(2) fixation by intact cells was enhanced by low temperature, KCN, or methylviologen addition during the pretreatment with O(2) and light. The mechanism(s) of O(2)-dependent photoinactivation of photosynthetic activities in Chromatium are discussed in relation to the possible role of photorespiration as a means of producing CO(2) in the photosynthetic system.

Nonenzymic model of the dioldehydratase reaction. Initiation of conversion of ethylene glycol into acetaldehyde on anaerobic photolysis of organocobalamins in the presence of SH-compounds

Anaerobic photolysis of adenosyl- and methyl-cobalamins in an aqueous KCl–HCl buffer (pH 2·0) in the presence of SH-compounds (e.g. dihydrolipoic acid amide) causes conversion of ethylene glycol into acetaldehyde, and provides a model for the dioldehydratase enzymic reaction.