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PubMed1984

Thickness dependence of monoglyceride bilayer membrane conductance.

We have studied the conductance properties of unmodified monoglyceride membranes as a function of monoglyceride chain length. As membrane thickness decreases from 31 to 20 nm, the steepness of the current-voltage (I-V) curve increases from 80 mV per e-fold current increase to 52 mV per e-fold current increase. The zero-voltage conductance increases more than 1,000-fold and the apparent activation energy of conductance decreases from 18.4 to 14.2 kcal/mol. We have analyzed our results using both the Nernst-Planck equation and absolute rate theory. Both approaches are consistent with our results and give consistent values for the parameters describing the I-V curves. We conclude that both the surface ion concentration and the distance from the surface of the membrane at which the energy of an ion rises appreciably above its value in solution (position of the barrier) are invariant with thickness.

Electric Conductivity↗

PubMed2002

A role for monoglyceride lipase in 2-arachidonoylglycerol inactivation.

2-Arachidonoylglycerol (2-AG) is a naturally occurring monoglyceride that activates cannabinoid receptors and meets several key requisites of an endogenous cannabinoid substance. It is present in the brain (where its levels are 170-folds higher than those of anandamide), is produced by neurons in an activity- and calcium-dependent manner, and is rapidly eliminated. The mechanism of 2-AG inactivation is not completely understood, but is thought to involve carrier-mediated transport into cells followed by enzymatic hydrolysis. We examined the possible role of the serine hydrolase, monoglyceride lipase (MGL), in brain 2-AG inactivation. We identified by homology screening a cDNA sequence encoding for a 303-amino acid protein, which conferred MGL activity upon transfection to COS-7 cells. Northern blot and in situ hybridization analyses revealed that MGL mRNA is unevenly present in the rat brain, with highest levels in regions where CB1 cannabinoid receptors are also expressed (hippocampus, cortex, anterior thalamus and cerebellum). Immunohistochemical studies in the hippocampus showed that MGL distribution has striking laminar specificity, suggesting a presynaptic localization of the enzyme. Adenovirus-mediated transfer of MGL cDNA into rat cortical neurons increased the degradation of endogenously produced 2-AG in these cells, whereas no such effect was observed on anandamide degradation. These results indicate that hydrolysis via MGL may be a primary route of 2-AG inactivation in intact neuronal cells.

Amidohydrolases↗

PubMed2001

Exon-intron organization and chromosomal localization of the mouse monoglyceride lipase gene.

Monoglyceride lipase (MGL) functions together with hormone-sensitive lipase to hydrolyze intracellular triglyceride stores of adipocytes and other cells to fatty acids and glycerol. In addition, MGL presumably complements lipoprotein lipase in completing the hydrolysis of monoglycerides resulting from degradation of lipoprotein triglycerides. Cosmid clones containing the mouse MGL gene were isolated from a genomic library using the coding region of the mouse MGL cDNA as probe. Characterization of the clones obtained revealed that the mouse gene contains the coding sequence for MGL on seven exons, including a large terminal exon of approximately 2.6 kb containing the stop codon and the complete 3' untranslated region. Two different 5' leader sequences, diverging 21 bp upstream of the predicted translation initiation codon, were isolated from a mouse adipocyte cDNA library. Western blot analysis of different mouse tissues revealed protein size heterogeneities. The amino acid sequence derived from human MGL cDNA clones showed 84% identity with mouse MGL. The mouse MGL gene was mapped to chromosome 6 in a region with known homology to human chromosome 3q21.

3' Untranslated Regions↗

PubMed2002

Preparation and structural investigations of colloidal dispersions prepared from cubic monoglyceride-water phases.

Dispersions of bicontinuous cubic monoglyceride-water phases, so-called 'cubosomes', have been proposed as parenteral sustained release delivery systems. For the present study, dispersions of monoolein-rich monoglycerides (MO), with or without purified soya phospholipids (PL), were prepared by equilibration of a MO/(PL)/water cubic phase, subsequent fragmentation with a poloxamer 407 (P407) solution, sonication and homogenization. This yielded systems of very different macroscopic appearance: Almost transparent dispersions, slightly turbid systems, opaque dispersions or milky emulsions. The mean z-average particle diameters ranged from 80 nm to well above 350 nm. Considerable particle growth could be detected in most systems during storage at room temperature. Storage at 5 degrees C resulted in the formation of ointment-like gels, which may be attributed to the crystallization of MO. Freeze-fracture transmission electron micrographs of MO dispersions revealed predominantly spherical particles with a low fracturing tendency. Synchrotron radiation X-ray diffraction indicated that high energy input during disintegration of the cubic phase leads to very complex systems in which particles with a cubic structure and MO/(PL) vesicles may coexist. The characteristic reflections of cubic systems were absent in the diffraction patterns of almost transparent or slightly turbid dispersions. The results indicate a strong dependence of ultrastructure of the dispersions on the preparation parameters.

Chemistry, Pharmaceutical↗

PubMed2002

Bactericidal effects of fatty acids and monoglycerides on Helicobacter pylori.

The susceptibility of Salmonella spp., Escherichia coli and Helicobacter pylori to fatty acids and monoglycerides was studied. None of the lipids showed significant antibacterial activity against Salmonella spp. and E. coli but eight of 12 lipids tested showed high activity against H. pylori, monocaprin and monolaurin being the most active. The high activity of monoglycerides against H. pylori suggests that they may be useful as active ingredients in pharmaceutical formulations.

Anti-Bacterial Agents↗

PubMed1974

A new assay procedure for monoglyceride acyltransferase.

1. A new assay system is described for monoglyceride acyltransferase (acylglycerol palmitoyltransferase, EC 2.3.1.22) in which palmitoyl-CoA is generated from palmitoyl-(-)-carnitine. 2. With the microsomal fraction from homogenates of guinea-pig intestinal mucosa, the V(max.) of this enzyme decreased with different acyl acceptors in the order 2-monopalmitoylglycerol>2-hexadecylglycerol>rac-1-monopalmitoylglycerol. 3. There were highly significant correlations between the monoglyceride acyltransferase activity as measured with these three substrates. This demonstrates that each of these substrates can be used to measure the same enzyme activity. 4. The advantages of using generated palmitoyl-CoA with 2-hexadecylglycerol and rac-1-monopalmitoylglycerol as model substrates for this enzyme are discussed.

Acyltransferases↗

PubMed1996

Monoglycerides in membrane systems.

Monoglycerides are used abundantly in food systems, ingested and produced in vivo, and recognized as significant mediators in many biochemical processes, yet their function in various membrane systems is only understood at a hypothetical level. This paper provides a comprehensive review of the effects of monoglycerides in membrane systems from three diverse disciplines: nutrition, food science, and membrane biochemistry. An analysis of the data ranging from feeding studies to physical chemistry is given, detailing the role of these common molecules in biological membranes.

Chylomicrons↗

PubMed1998

In vitro inactivation of Chlamydia trachomatis by fatty acids and monoglycerides.

The antichlamydial effects of several fatty acids and monoglycerides were studied by incubating Chlamydia trachomatis bacteria with equal volumes of lipid solutions for 10 min and measuring the reduction in infectivity titer compared with that in a control solution without lipid. Caprylic acid (8:0), monocaprylin (8:0), monolaurin (12:0), myristic acid (14:0), palmitoleic acid (16:1), monopalmitolein (16:1), oleic acid (18:1), and monoolein (18:1) at concentrations of 20 mM (final concentration, 10 mM) had negligible effects on C. trachomatis. In contrast, lauric acid (12:0), capric acid (10:0), and monocaprin (10:0) caused a greater than 10,000-fold (>4-log10) reduction in the infectivity titer. When the fatty acids and monoglycerides were further compared at lower concentrations and with shorter exposure times, lauric acid was more active than capric acid and monocaprin was the most active, causing a greater than 100, 000-fold (>5-log10) inactivation of C. trachomatis at a concentration of 5 mM for 5 min. The high levels of activity of capric and lauric acids and particularly that of monocaprin are notable and suggest that these lipids have specific antichlamydial effects. The mode of action of monocaprin was further studied by removal of the lipid by centrifugation before inoculation of Chlamydia onto host cells and by electron microscopy. The results indicate that the bacteria are killed by the lipid, possibly by disrupting the membrane(s) of the elementary bodies. A 50% effective concentration of 30 microgram/ml was found by incubation of Chlamydia with monocaprin for 2 h. The rapid inactivation of large numbers of C. trachomatis organisms by monocaprin suggests that it may be useful as a microbicidal agent for the prevention of the sexual transmission of C. trachomatis.

Cells, Cultured↗

PubMed1999

In vitro susceptibilities of Neisseria gonorrhoeae to fatty acids and monoglycerides.

The susceptibility of Neisseria gonorrhoeae to several medium-chain fatty acids and their 1-monoglycerides was tested at a short inactivation time of 1 min. The results indicate that monocaprin, a monoglyceride of capric acid (10 carbon atoms, no double bonds), causes the fastest and most effective killing of all strains of N. gonorrhoeae tested.

Colony Count, Microbial↗

PubMed2006

Stable concentrated emulsions of the 1-monoglyceride of capric acid (monocaprin) with microbicidal activities against the food-borne bacteria Campylobacter jejuni, Salmonella spp., and Escherichia coli.

Of 11 fatty acids and monoglycerides tested against Campylobacter jejuni, the 1-monoglyceride of capric acid (monocaprin) was the most active in killing the bacterium. Various monocaprin-in-water emulsions were prepared which were stable after storage at room temperature for many months and which retained their microbicidal activity. A procedure was developed to manufacture up to 500 ml of 200 mM preconcentrated emulsions of monocaprin in tap water. The concentrates were clear and remained stable for at least 12 months. They were active against C. jejuni upon 160- to 200-fold dilution in tap water and caused a >6- to 7-log(10) reduction in viable bacterial count in 1 min at room temperature. The addition of 0.8% Tween 40 to the concentrates as an emulsifying agent did not change the microbicidal activity. Emulsions of monocaprin killed a variety of Campylobacter isolates from humans and poultry and also killed strains of Campylobacter coli and Campylobacter lari, indicating a broad anticampylobacter activity. Emulsions of 1.25 mM monocaprin in citrate-lactate buffer at pH 4 to 5 caused a >6- to 7-log(10) reduction in viable bacterial counts of Salmonella spp. and Escherichia coli in 10 min. C. jejuni was also more susceptible to monocaprin emulsions at low pH. The addition of 5 and 10 mM monocaprin emulsions to Campylobacter-spiked chicken feed significantly reduced the bacterial contamination. These results are discussed in view of the possible utilization of monocaprin emulsions in controlling the spread of food-borne bacteria from poultry to humans.

Animal Feed↗

PubMed1978

Effect of sugar and monoglyceride on fatty acid esterification.

The effect of hexose and monoolein on fatty acid esterification was studied in everted rings of rat jejunum. By use of [3H]oleic acid and [U-14C]glucose, esterification via both phosphatidic acid and monoglyceride pathways was quantified. Our results showed that 1) metabolizable sugars stimulate fatty acids esterification regardless of their mode of transport; 2) in the presence of glucose alone, in vitro fatty acid esterification is mediated entirely by the phosphatidic acid pathway; 3) glucose stimulates both esterification pathways in the presence of monoolein; 4) monoolein stimulates only the monoglyceride pathway and has no effect on the phosphatidic acid pathway; and 5) the rate-limiting factor in the presence of monoolein alone is the formation of acyl-CoA, whereas in the presence of glucose alone, the rate-limiting factor is the formation of alpha-glycerophosphate.

Acyl Coenzyme A↗

PubMed2002

Lymphatic absorption of docosahexaenoic acid given as monoglyceride, diglyceride, triglyceride, and ethyl ester in rats.

Lymphatic absorption of docosahexaenoic acids (DHA) given as monoglyceride (MG), consisting of 1(or 3)-species (9 1.4%), 2-species (4.2%) and diglyceride (DG) consisting of 1,3-species (70.8%), 1(or 3),2-species (28.6%), were investigated in comparison with that of triglyceride (TG) and ethyl ester (EE). Rats were infused with a lipid emulsion containing 200 mg of DHA-MG, DG, TG, or EE via a gastric cannula. Lymph was collected through the thoracic lymph duct at 2 h intervals for 10 h and at a single collection from 10 to 30 h. Physiological saline containing glucose was infused (2 mL/h) throughout the lymph collection. The overall recovery of DHA at 30 h after its infusion was significantly higher in the rank order DHA-MG>DG>TG=EE. Moreover, time-dependent changes in recovery rates from 2 to 10 h of DHA given as MG were significantly higher than those of the corresponding DG, TG, and EE. These results indicate that DHA-MG and DG are absorbed and transported more effectively than TG and EE forms under restricted water supply, even if they mainly consist of 1(or 3)-species. Lymph lipids were mainly transported as TG, and a large amount of DHA was incorporated into a TG fraction in all fat types examined. Furthermore, the intramolecular distribution of DHA in lymph TG was similar in all groups. docosahexaenoic acid, monoglyceride, diglyceride triglyceride, ethyl ester

Analysis of Variance↗

PubMed1979

Digestion and absorption of lipids in chicks fed triglycerides or free fatty acids: synthesis of monoglycerides in the intestine.

Digestion and absorption of lipids were determined in 3-week-old chicks fed diets containing triglycerides, free fatty acids, or free fatty acids with added glycerol. The 91YCl3 was present as a non-absorbed reference substance. Overall absorption of total fatty acids was highest in triglyceride-fed chicks and lowest in chicks receiving fatty acids. Net secretion of endogenous fatty acids from biliary phospholipids was observed in the duodenum of triglyceride fed chicks, whereas in the other treatments net absorption was observed at this site. Fractionation of the intestinal lipids by thin layer chromatography showed that triglycerides were almost completely hydrolyzed in the duodenum. Monoglycerides were present at high levels in the duodenum of triglyceride fed chicks and at lower levels in chicks receiving free fatty acids and glycerol and at trace levels in free fatty acid-fed chicks. Total micellar fatty acids were lowest in the duodenum of free fatty acid-fed chicks. In vitro incubation of pancreatic homogenate with oleic acid, glycerol, phosphatidyl choline, and taurocholate revealed synthesis of monoglycerides. The poorer fat absorption observed on feeding acidulated soapstock instead of triglycerides is partially explained by less efficient micellarization when free fatty acids are fed.

Animals↗

PubMed2001

Analysis of monoglyceride synthetic reaction in a solvent-free two-phase system catalyzed by a monoacylglycerol lipase from Pseudomonas sp. LP7315.

Kinetics of monoglyceride synthesis catalyzed by a monoacylglycerol lipase (MGL) isolated from Pseudomonas sp. LP7315 was studied at 65 degrees C in a solvent-free two-phase system, in which fatty acid droplets were dispersed in a glycerol phase containing a small amount of water. The initial rate of the synthetic reaction depended on several factors: the amounts of fatty acid and glycerol, and the concentration of MGL in the glycerol phase. To analyze the effects of these factors, a kinetic model was developed based on the assumption that the adsorption equilibrium of MGL molecules at the interface between the two phases is the crucial factor for the synthetic reaction. The model was found to yield good approximations of the initial synthetic rate under various reaction conditions. The analysis suggests that the adsorption behavior of MGL onto the interface had a large effect on the initial rate of the monoglyceride synthesis.

Journal Article↗

PubMed2005

Development of a virucidal cream containing the monoglyceride monocaprin.

The lipid monocaprin (1-monoglyceride of capric acid) has been shown to be effective against enveloped viruses such as herpes simplex virus HSV in vitro. As it is known that HSV can develop resistance to acyclovir which is the most common treatment used, it was considered to be of interest to formulate a cream containing the lipid monocaprin as the active substance against HSV. The aim of this study was to develop an o/w-emulsion (cream) containing monocaprin and to evaluate the effects of formulation variables on the virucidal activity of monocaprin as well as the in vitro release rate of the monoglyceride from the formulations. The results show that release rate and extent of monocaprin release as well as the microbicidal properties of the the o/w-emulsion formulations are affected by the proportion of the oil phase and the amount of carbomer in the aqueous phase. Reducing the oil volume fraction increased antiviral effect and release of monocaprin from the formulation.

Antiviral Agents↗

PubMedDate not supplied

Simple method for derivatization of monoglycerides and diglycerides.

A method has been developed for derivatization of monoglycerides and diglycerides to their propyl esters by using propionic anhydride in the presence of pyridine. The derivatives are volatile and thus can be separated and identified by gas chromatography (GC). Completion of the reaction is monitored by thin-layer chromatography. Monoglyceride propyl esters were positively identified by gas chromatography and by gas chromatography/mass spectrometry. No side products were observed in the derivatization reaction which requires 35 min at 75 degrees C. GC analysis of the mono- and diglyceride propyl esters can be completed in approximately 30 min.

Chemical Phenomena↗

PubMed1966

Synthesis and characterization of 1- and 2-monoglycerides of anteiso fatty acids.

The branched-chain fatty acids D-(+)-12-methyltetradecanoic acid (C(15) anteiso) and D-(+)-14-methylhexadecanoic acid (C(17) anteiso) were isolated from the lipids of Listeria monocytogenes and their 1- and 2-monoglycerides were prepared. Reaction intermediates and products were purified without isomerization by column chromatography. Thin-layer chromatography on Florisil impregnated with boric acid and nuclear magnetic resonance were used in characterizing the 1- and 2-monoglycerides. The value of the latter method for analyzing glyceride structure is discussed.

Chemical Phenomena↗

PubMed1969

Evidence for separate monoglyceride hydrolase and triglyceride lipase in post-heparin human plasma.

Post-heparin plasma contains an enzyme or enzymes with both triglyceride lipase (TGL) and monoglyceride hydrolase (MGH) activities. A simple and reproducible radioactive assay for measurement of MGH activity was developed and used, with a previously reported assay for TGL, to study lipolysis in plasma. After the injection of heparin, enzymatic activity against both tri- and monoglycerides appeared and disappeared from plasma at approximately the same rates. However, in contrast to TGL activity, MGH activity was: (a) much greater, (b) considerably less heat-sensitive, (c) unaffected by three inhibitors (NaCl, protamine, and pyrophosphate), (d) not influenced by radical changes in fat and carbohydrate content of the diet, and (e) normal in familial Type I hyperlipoproteinemia. The dichotomy between MGH and TGL activities in patients with genetic deficiency of TGL constitutes strong evidence that these are two different enzymes. The findings further indicate that when post-heparin lipolytic activity is measured for the purpose of detecting TGL deficiency, it may be necessary to perform the assay with a substrate free from partial glycerides.

Diet↗