Polyol Formation Research Articles

New developments in the field of synthetic lubricants from natural sources

AbstractOils derivedfrom natural sources like vegetable and animal fats are constituted by a variety of triglycerides. The major drawbacks as compared to petroleum lubricants is poor stability under operating conditions, caused by (1) presence of β‐hydrogen in the glyceride radical; (2) unsaturation in acyl radicals, which is linked to hydroxide formation and oxidation stability; (3) linear structure of the fatty acid which has poor resistance to hydrolysis and emulsification.There are several reactions in oleochemistry by which the structure of triglycerides could be modified, and so liquids with good lubrication properties produced. These include hydrogenation, dimerization, alkylation, polyol formation and transesterification. This paper deals with the application of transesterfication for the modification of the glyceride structure into a lubricant. This permits preparation of a semisynthetic lubricant directly from natural glycerides. Molecular structure, molecular weight, polarity, rheological properties, thermal and hydrolytic stability of transesterification products are reported.

Elution characteristics of polyol—borate eluents in anion-exchange chromatography : I. Eluent strength of sugar—, uronate—borate eluents

Eleven polyol compounds including monosaccharides, disaccharides and acidic polyol compounds were investigated as additives to a boric acid eluent in anion-exchange chromatography. It was expected that boric acid eluents containing polyol compounds would have new characteristics because the latter compounds form ester-like complexes with boric acid. The addition of polyol compounds increased the eluent strength of boric acid. In particular, acidic polyol compounds gave stronger eluents when they were used with boric acid than when they were used alone. This promotion of the eluent strength is due to the formation of polyol—borate complexes.

Monosaccharides in health and disease.

In healthy persons, glucose homeostasis maintains blood glucose levels between 70 and 130 mg/dl despite perturbations by meals, fasting, and exercise. Long-term follow-up of diabetic patients has suggested that "good control" of blood sugar levels minimizes the long-term complications of diabetes, such as retinopathy, nephropathy, and atherosclerosis. It now seems likely the products of insulin-independent metabolic pathways in epithelial and endothelial cells leading to polyol formation and protein glycosylation may be factors in the genesis of retinopathy, neuropathy, nephropathy, and premature atherosclerosis of diabetic patients. Dietary complex carbohydrates of various type, including those rich in dietary fiber, which are the cell walls of fruits, vegetables, and cereals, may slow the rate of absorption of glucose from those diets and contribute to a lowering of the postprandial glucose peak. Glycemic responses to various foods compared to glucose have been studied and show a large variation, which is dependent upon gastric emptying, overall effects on rate of hydrolysis and absorption of glucose from food mixtures. Dietary sucrose seems to cause a degree of insulin resistance. The active part of the disaccharide is fructose, which does not elicit an acute insulin response, but appears indirectly to increase insulin levels in both animals and man. Sucrose in animals appears to promote obesity more than glucose because of its lack of stimulation of thermogenesis. Xylitol has been used as a sweetener and as a sugar substitute in total parenteral nutrition. It is a paradox that the most physiological of sugars (glucose) can be a menace at high concentrations. The use of nonphysiological sugars or their derivatives in diabetics and patients with special needs, such as TPN, requires much more investigation to develop a sound rationale in nutrition management.

Patterns of translocation, changes in invertase activity, and polyol formation in susceptible and resistant flax infected with the rust fungus Melampsora lini

In two near-isogenic lines of flax ( Linum usitatissimum L.) displaying resistance and susceptibility, respectively, to race 1 of the flax rust, Melampsora lini (Ehrenb.) Lév., retention of photoassimilates at infection sites and increased import of assimilates towards these sites were detected in susceptible cotyledons bearing a localized rust infection. No alterations in translocation patterns were detected in infected resistant seedlings. Increases in the activity of both soluble and insoluble acid invertases occurred from 6 days after inoculation in the susceptible host, but no increases were detected in the resistant variety. Fungal polyols, both hexitols and penitols, were detected in the susceptible host from five days after inoculation. By day 11 after inoculation they represented 45% of the labelled products 30 min after exposing infected cotyledons to 14CO 2. Only trace amounts of labelled polyols were detected in the rust-infected resistant variety, representing only 9% of the labelled products at 11 days after inoculation. A chemical method failed to detect any chitin formation in the rust-infected resistant host. However histological examination showed definite increases in rust colony area in resistant tissue. Increase in fungal chitin in the susceptible host was correlated with a similar increase in activity of acid invertase.

The stereochemistry of complex formation of polyols with borate and periodate anions, and with metal cations

In alkaline solution, periodate ions form complexes with three consecutive hydroxyl groups in an axial-equatorial-axial arrangement but not with three syn-axial hydroxyl groups. Borate ions form complexes with three syn-axial hydroxyl groups but not with the ax eq ax sequence. Accordingly, cis-inositol gives a 1,2,3-periodate and a 1,3,5-borate complex. Cations form complexes with either type of conformation, but complex formation provides little energy towards achieving it by ring inversion. Lanthanide ions have been used to establish the sites of complex formation.

Variation von Glycerin, Sorbit und anderen Metabolitgehalten infolge von Temperaturstress bei Larven von Callitroga macellaria

Sorbitol, sorbitol phosphate, glycerol, α-glycerol phosphate, lactic and pyruvic acid were determined after storing of non-feeding Callitroga larvae hot or cold. Compared with controls, the high levels of pyruvic acid and lactic acid indicate the increase of anaerobic metabolism by temperature stress. At the same time glycerol increased about threefold, sorbitol increased about seventeenfold after heating and about thirty-fourfold after cooling. The level of glycerol phosphate is lowered after heating and after cooling. Sorbitol phosphate shows after heating a trend to decrease. Heat causes a great standard error. Based on this and other facts it is supposed that different kinds of stress result in a lack of metabolic energy. Thus the pathway of glucose phosphate to direct oxidation and formation of triose phosphate by the pentose phosphate cycle is energetically favoured because the phosphorylation of hexose phosphate to hexose diphosphate is avoided. Triose phosphate can enter the glycolytic pathway. The reduced coenzyme nicotinamide adenine dinucleotide phosphate (NADPH) is generated by the formation of polyols (or polyolphosphates).

End-group Analysis of Some Polyether Polyols and Polyester Polyols by Nuclear Magnetic Resonance Spectroscopy

Ring-opening polymerization of monosubstituted ethylene oxides Cl J results in formation of polyether polyols with either primary C 2or secondary terminal hydroxyl group C3D, depen- ding on the mode of C-O-C bond cleavage.This end-group structure is significant, since it is closely related to the reactivity of polyols and affects the properties of polyurethane resin prepared from those polyols and diisocyanates. The application of NMR technique to the analysis of primary hydroxyl groups in polyol are studied in this paper when the hydroxyl is converted into urethane, and it proves to be a simple and convenient method. We also employed the time-average technique of NMR with a Mnemotron Computer of Average Transient to analysis of terminal unsaturation in polyols. It was revealed that poly (oxypropylene)glycol prepared by KOH catalyst contains substan- tially on or a small amount of primary hydroxyl, but more than 40% primary hydroxyl is found in polyether which was prepared by BF, --catalyzed, polymerization, and no matter what the polymerization catalyst is the amount of terminal unsaturation in the resultant polyethers increases by the molecular weight increase of polyether.

The serum polyol pattern and the urinary polyol excretion in diabetic and in uremic patients

A gas-liquid chromatographic method, based on acetylation of polyols, was applied to a study of polyols in urine and in serum. The profile of the normal urinary polyol excretion was described and the formation of additional polyols was demonstrated by treating samples with sodium borohydride prior to chromatography. In diabetes mellitus the urinary excretion of mannitol and myo-inositol was elevated. In cases of chronic renal failure the retention of polyols in serum was demonstrated and the level of myo-inositol was shown to be increased both in serum and in urine. The design of the experimental conditions eliminated the errors due to the intake of exogenous polyols. The metabolic significance of the findings is still to be determined.

CARBOHYDRATE METABOLISM IN THE EGGS OF THE SILKWORM, BOMBYX MORI. I. ABSENCE OF PHOSPHOFRUCTOKINASE IN THE DIAPAUSING EGG

In the diapausing eggs of the silkworm, Bombyx mori, glycogen is rapidly converted to sorbitol and glycerol, and this conversion is reversed at termination of the diapause (Chino, 1958). To elucidate the pathway leading to this polyol formation and its regulatory mechanisms, enzymes concerning carbohydrate metabolism were surveyed in diapausing as well as in developing eggs of the silkworm. Most of the enzyme activities concerning citric acid cycle are low at the beginning of the embryogenesis and during diapause, but increase at the later stages of the development. Making an exception, reduction rate of malate and fumarate was rather high from the onset of the embryonic development. Several glycolytic enzymes were also studied. Most remarkable fact is that phosphofructokinase activity could not be demonstrated in the diapausing and also in the early stages of the developing eggs. Other enzymes, viz.α-glycerophosphate dehydrogenase, aldolase, glyceraldehyde-3-phosphate dehydrogenase were detected from the beginning of the embryogenesis. Absence of phosphofructokinase, together with the high activity in glucose-6-phosphate dehydrogenase, suggests that predominant pathway in carbohydrate metabolism in the early stages of embryogenesis and in the diapause period is by way of pentose phosphate pathway. This supposition is confirmed by the experiments using labeled glucose. Incorporation of the label into glycerol of the diapausing eggs was three to four fold when G-6-14C was injected into pupae as compared with the case of G-1-14C injection. The above experiments provide evidence supporting the theory that glycogen is converted into sorbitol and glycerol mostly by way of the pentose phosphate pathway in the diapausing eggs.

Carbon balance of a mannitol fermentation and the biosynthetic pathway.

The carbon balance was determined for a fermentation in which mannitol is produced from glucose by an Aspergillus species. The products found were: cells (17% of carbon input), CO(2) (26%), mannitol (35%), glycerol (10%), erythritol (2.5%), glycogen (1%), and unidentified compounds (8%). Thus, 92% of the carbon input was accounted for. Cell-free enzyme studies showed that mannitol was synthesized via the reduction of fructose-6-phosphate and not by the direct reduction of fructose. If the cell yield from glucose was assumed to be 50% and the theoretical conversion efficiency from glucose to polyols was 90%, as calculated from the energy balance, then 34% of the glucose carbon was used for growth and 53% was used for polyol formation.

Carbon Balance of a Mannitol Fermentation and the Biosynthetic Pathway

The carbon balance was determined for a fermentation in which mannitol is produced from glucose by an Aspergillus species. The products found were: cells (17% of carbon input), CO(2) (26%), mannitol (35%), glycerol (10%), erythritol (2.5%), glycogen (1%), and unidentified compounds (8%). Thus, 92% of the carbon input was accounted for. Cell-free enzyme studies showed that mannitol was synthesized via the reduction of fructose-6-phosphate and not by the direct reduction of fructose. If the cell yield from glucose was assumed to be 50% and the theoretical conversion efficiency from glucose to polyols was 90%, as calculated from the energy balance, then 34% of the glucose carbon was used for growth and 53% was used for polyol formation.

Gas chromatography of sugars and other polyhydroxy compounds

Aldose reductase (AR) and Advanced glycation end product (AGE) are known to play important roles in the development of diabetic complications. The inhibitors of AR and AGE would be potential agents for the prevention of diabetic complications.The present study was aimed to evaluate the aldose reductase (AR) and advanced glycation end product (AGE) inhibitory potential of pterostilbene for its possible role in the treatment of diabetic complications such as cataract.The compound was studied for its inhibitory activity against rat lens AR (RLAR) and rat kidney AR (RKAR) in vitro along with its ability to inhibit the formation of AGEs. Anticataract activity of pterostilbene was demonstrated using sugar induced lens opacity model in isolated cattle lens. Further, the involvement of pterostilbene in galactosemia in rats was investigated by assessing the key markers in the polyol pathway and the results were compared with that of a potent AR inhibitor, fidarestat.Pterostilbene exhibited inhibitory activity against RLAR and RKAR with IC50 values of 5.49 mg/ml (21.4 mM) and 6.40 mg/ml (25.02 mM), respectively. In sugar-induced lens opacity model, pterostilbene displayed a significant protective effect by preventing opacification and formation of polyols in cattle lens. Besides, the compound exhibited in vivo inhibition of galactitol accumulation in lens and sciatic nerves of galactose fed rats.The results obtained in the study underline the potential of pterostilbene as possible therapeutic agent against long-term diabetic complications.

Formation of Polyols by the Lens of the Rat with ‘Sugar’ Cataract

CATARACT (opacity) of the lens inevitably develops in young rats fed xylose or galactose1, or in young diabetic rats if the blood glucose is maintained at a level above 2.5 mgm./ml. blood2. These three forms of cataract which resemble each other closely in clinical and histological appearance, are known as ‘sugar’ cataracts because in all cases there is a raised level of monosaccharides in the blood. The early metabolic changes within the lens, which lead to gradual loss of transparency, are unknown. It was decided to examine the carbohydrates and their derivatives in normal and cataractous lenses to see if changes occurred in ‘sugar’ cataract, and if so whether there was any similarity in this respect between the three forms of cataract.