A new method for monitoring the contamination of glycerol with diethylene glycol

A quartz crystal microbalance has been used to check the purity of glycerol. The experimental procedure involves no derivatization or other preliminary step except determination of water content. The protocol consists of the direct reading of the frequency of a quartz crystal with one face in contact with an aqueous solution of the glycerol to be tested. The method is inexpensive, simple, rapid, and highly sensitive; diethylene glycol contamination at the 3.61% level could be detected.

New acetylenic enol ethers of glycerol from the sponge Petrosia sp

Ten acetylenic enol ethers of glycerols, including six new compounds (1-6) and a linear acetylenic alcohol (7), have been isolated from a sponge of the genus Petrosia. The structures of the novel compounds were elucidated by spectroscopic methods. The absolute stereochemistry of 1-7 was determined by chemical transformations and the Mosher method. Some of these compounds exhibited weak cytotoxicity against a human leukemia cell-line (K-562).

Anti-tumour-promoting glyceroglycolipids from the green alga, Chlorella vulgaris

Two new monogalactosyl diacylglycerols were isolated from the freshwater green alga, Chlorella vulgaris, as anti-tumour promoters, together with three monogalactosyl diacylglycerols and two digalactosyl diacylglycerols. The new monogalactosyl diacylglycerol containing (7Z,10Z)-hexadecadienoic acid showed a more potent inhibitory effect toward tumour promotion than the other glycerolipids isolated.

Mass spectra of fatty acid derivatives, of isopropylidenes of novel glyceryl ethers of cod muscle and of phenolic acetates obtained with the Finnigan MAT Ion Trap Detector

The applicability of the Finnigan MAT Ion Trap Detector (ITD) mass spectrometer for structure determination in some selected fatty acids and their derivatives has been investigated. Isopropylidene derivatives of novel glyceryl ethers isolated from cod flesh and of phenolic acetates are included to indicate the potential for diverse structures and to clarify the protonation of ions. The ITD is a simple and unsophisticated gas liquid chromatograph-mass spectrometer, but the spectra obtained are in most respects comparable to those from more conventional electron impact mass spectrometers. However, due to the comparatively high background pressure (approximately 10(-3) torr) in the ionization chamber of the ITD, there is a tendency for both neutral and ionized molecules to acquire protons from other molecules or fragments through collision. In many cases, the molecular ion was observed as the protonated molecular ion (M + 1), as in chemical ionization mass spectrometry. These interactions can be minimized if the sample load is decreased. Phenolic acetates exhibit not only protonation of the molecular ion, but also protonation of stable fragmented neutral molecules or ions.

Optimizing aerobic conversion of glycerol to 3-hydroxypropionaldehyde

When cells of Klebsiella pneumoniae NRRL B-199 (ATCC 8724) were grown aerobically on a rich glycerol medium and then suspended in buffer supplemented with semicarbazide and glycerol, aerobic conversion of glycerol to 3-hydroxypropionaldehyde (3-HPA) ensued. Depending on conditions, 0.38 to 0.67 g of 3-HPA were formed per gram of glycerol consumed. This means that up to 83.8% of the carbon invested as glycerol could potentially be recovered as the target product, 3-HPA. Production of 3-HPA was sensitive to the age of cells harvested for resuspension and was nonexistent if cells were cultivated on glucose instead of glycerol as the sole carbon source. Compared with 24- and 72-h cells, 48-h cells produced 3-HPA at the highest rate and with the greatest yield. The cell biomass concentration present during the fermentation was never particularly critical to the 3-HPA yield, but initial fermentation rates and 3-HPA accumulation displayed a linear dependence on biomass concentration that faded when biomass exceeded 3 g/liter. Fermentation performance was a function of temperature, and an optimum initial specific 3-HPA productivity occurred at 32 degrees C, although the overall 3-HPA yield increased continuously within the 25 to 37 degrees C range studied. The pH optimum based on fermentation rate was different from that based on overall yield; 8 versus 7, respectively. Initial glycerol concentrations in the 20 to 50 g/liter range optimized initial 3-HPA productivity and yield.

Structural elucidation of a unique macrocyclic membrane lipid from a new, extremely thermophilic, deep-sea hydrothermal vent archaebacterium, Methanococcus jannaschii

The membrane lipid of a new deep-sea hydrothermal vent methanogen, Methanococcus jannaschii, was isolated, purified, and structurally characterized. The total lipid extract, amounting to 32.2 micrograms/mg, dry cell weight, was fractionated on silica gel into a neutral lipid and polar lipid fraction. The neutral lipid fraction consisted of a series of isoprenoid hydrocarbons and free (nonphospholipid) alkylglycerol ethers. The polar phospholipid and glycolipid fraction (8.44 micrograms/mg, dry cell weight) was hydrolyzed with methanolic HCl, and the resulting alkylglycerol ethers were analyzed by a combination of chemical and spectroscopic techniques. The hydrolyzed polar lipid was primarily (95%) a unique, macrocyclic glycerol diether, heretofore unknown. High-field (250 MHz) proton nuclear magnetic resonance and infrared spectra of this novel macrocyclic compound are nearly identical and overlapping those of the known bis-(phytanyl)glycerol diether and bis-(diphytanyl)diglycerol tetraether. A field desorption mass spectrum revealed a molecular weight of 650 for the macrocyclic glycerol diether, 2 mass units less than that of bis-(phytanyl)glycerol diether. Degradation of the macrocyclic ether with boron tribromide resulted in diphytanyl dibromide, and further reaction of this dibromide with lithium aluminium hydride resulted in diphytane as determined by gas chromatography-mass spectrometry. The significance of the predominance of this structure in M. jannaschii is discussed. A survey of selected methanogenic Archaebacteria, including three thermophiles, failed to indicate the presence of the macrocyclic glycerol diether in any other microorganism, including two species of order Methanococcales, one species of Methanobacteriales, and three strains belonging to the order Methanomicrobiales.

Studies on (Na+ + K+)-activated ATPase. XLIX. Content and role of cholesterol and other neutral lipids in highly purified rabbit kidney enzyme preparation

(1) The neutral lipids and the free and bound fatty acids of a highly purified (Na+ + K+)-ATPase preparation from rabbit kidney outer medulla have been analysed. (2) On a dry weight basis, the total lipid content is nearly the same as the total protein content, and consists for 66% of phospholipids and for 34% of neutral lipids and free fatty acids. In the latter category cholesterol is the main component (71%). (3) On a molar basis the enzyme preparation contains 382 mol phospholipids, 67 mol free fatty acids, 9, 16 and 12 mol mono-, di- and triacylglycerols, 249 and 19 mol free and esterified cholesterol per mol enzyme. (4) The fatty acid composition of each lipid and of the free fatty acid fraction, present in the enzyme preparation, is reported. (5) All cholesterol and part of the phospholipids can be removed by hexane extraction, leaving 66% of the (Na+ + K+)-ATPase activity. Oxidation of all cholesterol to cholest-4-en-3-one by cholesterol oxidase leaves 85% of the (Na+ + K+)-ATPase activity. These results indicate that cholesterol is not essential for (Na+ + K+)-ATPase activity.

Determination of epimeric 1-(3-indolyl) propane -1,2,3-triol isolated from Balansia epichloe

Investigations into diseases in cattle grazing on grass pastures infected with clavicipitaceous fungi have resulted in the isolation and characterization of erythro and threo 1-(3-indolyl) propane-1,2,3-triol from cultures of Balansia epichloë (Weese). Gas chromatography-mass spectroscopy analyses of synthetic and natural epimers as their trimethylsilyl derivatives is described. Toxicity studies with fertile chicken eggs demonstrated that the threo epimer was the more active compound. The ratio of erythro to threo was calculated at 3:2 in the natural isolate.

Chylomicron formation and composition in unanaesthetised rabbits

Emulsified lipid was infused steadily into the upper small intestine of unanaesthetised rabbits for 6 h and 24 h periods. Lymph was collected from a thoracic duct cannula, the output of infused lipids was measured and the lymph chylomicrons were isolated. Recovery of infused triacylglycerol was 63 +/- 6.4% and recovery of infused radioactive cholesterol was 24 +/- 4.2% during a 24 h period. There was considerable dilution of radioactive exogenous cholesterol with endogenous cholesterol. Provided that absorption was well-established most exogenous lipid was present in the lymph in the form of chylomicrons, and there was a close relationship between lipid content of the lymph and the presence of chylomicrons. During absorption of fats of differing fatty acid composition chylomicrons remained the predominant transport form in the lymph. Chylomicrons obtained during absorption of several fats have been analysed in detail. The protein, phospholipid, free and esterified cholesterol content of these chylomicrons varies within narrow limits. The fatty acid composition of chylomicron triacylglycerols reflects the type of fat in the test meal but the composition of chylomicron phospholipids and cholesteryl esters shows clear discrimination. During absorption of coconut oil there is a strong negative discrimination towards lauric acid both for cholesteryl esters and for phospholipids.