Modulators of the glucocorticoid receptor also regulate mineralocorticoid receptor function

Modulators are proposed to be novel ether aminophosphoglycerides that stabilize unoccupied and occupied glucocorticoid receptor steroid binding and inhibit glucocorticoid receptor complex activation. Two isoforms, modulator 1 and modulator 2, have been purified from rat liver cytosol [Bodine, P.V., & Litwack, G. (1990) J. Biol. Chem. 265, 9544-9554]. Since the mineralocorticoid receptor is relatively resistant to activation, modulator's effect on rat distal colon mineralocorticoid receptor function was examined. Warming of unoccupied receptor decreased residual specific [3H]aldosterone binding by 86 +/- 2%. Both modulator isoforms completely prevented this destabilization with Km's of 2 +/- 1 microM modulator 1 and 24 +/- 5 microM modulator 2. Warming of occupied mineralocorticoid receptors decreased [3H]aldosterone binding by 56 +/- 3%. Modulator only partially stabilized occupied receptor binding with Km's of 10 +/- 2 microM modulator 1 and 68 +/- 8 microM modulator 2. Modulator inhibited receptor activation with Km's of 3 +/- 1 microM modulator 1 and 33 +/- 10 microM modulator 2. Double-reciprocal analysis showed linear kinetics, and mixing modulator isoforms together had additive effects on unoccupied and occupied receptor steroid binding stabilization and activation inhibition. Colon cytosol contained a low molecular weight, heat-stable factor(s) which inhibited receptor activation and stabilized occupied receptor steroid binding. Molybdate completely stabilized unoccupied mineralocorticoid receptor steroid binding and inhibited activation with half-maximal effects at 3-4 mM but only stabilized occupied receptor binding by approximately 40%. These data indicate that (i) apparent physiologic concentrations of modulator stabilize mineralocorticoid receptor steroid binding and inhibit receptor activation, (ii) an aldosterone-responsive tissue contains a modulator-like activity, and (iii) molybdate mimics the effects of modulator.(ABSTRACT TRUNCATED AT 250 WORDS)

The fatty acid composition of placenta in intrauterine growth retardation

To examine the impact of intrauterine growth retardation (IUGR) on essential fatty acids in human placenta, fatty acid composition in total acylglycerol and in the major phosphoglycerides phosphatidylcholine (PC) and phosphatidylethanolamine (PE), of 15 placentas from small for gestational age (SGA) births was compared with that of 7 control placentas. The acylglycerol fatty acid content was similar between the two groups, but the proportion of fatty acids of the linoleic acid series, including arachidonic acid, was significantly lower in SGA placentas. When the fatty acid composition in PC was studied, the reduction in fatty acids of the linoleic acid series was even more striking, and fatty acids of the linolenic acid series was also significantly less in the SGA group. These fatty acid changes in placenta membrane phospholipids can affect the transport of important nutrients to the fetal compartment. The decreased level of arachidonic acid and docosahexanoic acid might also lead to a disturbed formation of fetal thromboxane and prostacyclin. However, cord plasma PC fatty acid patterns were nearly identical in the two groups suggesting that in IUGR, the essential fatty acids will be transported to the fetus at the expense of the placenta.

[Chemical constituents of the pericarp of Trichosanthes rosthornii Harms]

Nine compounds were isolated from the pericarp of T. rosthornii and identified on the basis of spectral data to be palmitic acid, lignoceric acid, cerotic acid, montanic acid, melissic acid, L-(-)-alpha-monopalmitin, delta 7-stigmastenol, delta 7-stigmastenone-3 and delta 7-stigmatenol-3-beta-D-glucopyranoside. All but the last one are obtained from this species for the first time.

Volatile fraction of neem oil as a spermicide

The volatile, odorous fraction of neem oil coded as NIM-76 obtained by steam distillation was investigated for in vitro spermicidal activity. The data showed that the minimum concentration which inhibited spermatozoal motility was 0.25 mg/ml for rat and 25 mg/ml for human spermatozoa. The effect of the drug on spermatozoal motility was found to be dose-dependent. The activity of this drug was not altered in the presence of vaginal or cervical mucus. Intra-vaginal application of NIM-76 in rabbits showed no irritation to the vaginal mucosa.

Chromatographic resolution of chiral diacylglycerol derivatives: potential in the stereospecific analysis of triacyl-sn-glycerols

Diacylglycerols have been separated as their (S)-(+)-or (R)-(-)-1-(1-naphthyl)ethyl urethanes by high performance liquid chromatography (HPLC) on a column of silica gel with 0.5% 2-propanol in hexane as the mobile phase. The elution order of components derivatized with the (S)-form of the reagent was 1,3-, followed by 1,2-, and finally 2,3-diacyl-sn-glycerols. The elution order of 1,2- and 2,3-diasteromers was reversed when the (R)-form of 1-(1-naphthyl)ethyl isocyanate was used for derivatization. Single-acid 1,2- and 2,3-diastereomers were separated to the baseline with a resolution factor from 5.2-5.7, and the resolution factor between 1,3- and 1,2- or 2,3-diacyl-sn-glycerol derivatives was more than 23. Molecular species of single-acid diacylglycerol derivatives were separated in the sequence 18:1 less than 18:0 less than 18:2 less than 16.0. In order to assess this methodology as part of a procedure for the stereospecific analysis of triacyl-sn-glycerols, we prepared diacyl-rac-glycerols from maize oil, evening primrose oil and egg yolk triacylglycerols by partial hydrolysis with ethyl magnesium bromide. The 1,3-, 1,2- and 2,3-diacyl-sn-glycerols as (S)-(+)-1-(1-naphthyl)ethyl urethanes were isolated and their fatty acid compositions were determined. Although this only permitted an indirect determination of the compositions of positions sn-1, -2 and -3, it was sufficient to indicate the potential of the methodology because results comparable to those published earlier were achieved.

1-Butyryl-glycerol: a novel angiogenesis factor secreted by differentiating adipocytes

Differentiation of adipocytes is accompanied by secretion of molecules stimulating angiogenesis in vivo and endothelial cell growth and motility in vitro. We demonstrate that the angiogenic and motility-stimulating activities secreted by adipocytes are separable from the endothelial cell mitogenic activity by fractionation of adipocyte-conditioned medium. The major differentiation-dependent angiogenic molecule was purified and identified by GCMS as 1-butyryl-glycerol (monobutyrin). Monobutyrin levels increase at least 200-fold during adipocyte differentiation and represent a major fraction of the total angiogenic activity. Synthetic monobutyrin shows the same spectrum of biological activities as the adipocyte-derived factor: stimulation of angiogenesis in vivo and microvascular endothelial cell motility in vitro, with no effect on endothelial cell proliferation. Angiogenesis is stimulated at doses as low as 20 pg when tested in the chick chorioallantoic membrane assay. These results strongly suggest that monobutyrin is a key regulatory molecule in an angiogenic process linked to normal cellular and tissue development.

Release of dialkylglycerol from purple membrane phospholipids by phospholipase D

When the major polar lipid of purple membrane, a dialkyl analogue of phosphatidyl glycerophosphate, is treated with phospholipase D under the usual assay conditions for this enzyme, the reaction yields dialkylglycerol and glycerol bisphosphate, i.e. the kind of products that would be expected from a phospholipase C reaction. The effect is seen both in native purple membranes and with the pure phospholipid in the form of liposomes. The specific activity and kinetic parameters Km and Vmax of phospholipase D for the purple membrane phospholipid are similar to those for egg phosphatidylcholine. The presence of phospholipase C impurities in the phospholipase D preparations has been ruled out as an explanation for the above observations. A hypothesis is suggested, taking into account the peculiar headgroup structure of the bacterial lipid, to explain the seemingly anomalous enzyme behavior.

Structure of novel glyceroglycolipids in Adzuki bean (Vigna angularis) seeds

In addition to monoglycosyl diacylglycerol, three glyceroglycolipids with two to four hexose units were isolated from Adzuki bean seeds. Their structures were determined using enzymatic hydrolysis, permethylation analysis, nuclear magnetic resonance spectroscopy, and reversed-phase high pressure liquid chromatography, as folows: Gal(beta 1----3')- for the monoglycosyl diacyglycerol, Gal(alpha 1----6)-Gal(beta 1----3')- and Gal(beta 1----6)-Gal(beta1----3')- for the diglycosyl diacylglycerol, [Gal(beta 1----6]2-Gal(beta 1----3')- and Gal(beta 1----6)-Gal(alpha 1----6)-Gal(beta 1----3')- for the triglycosyl diacylglycerol, and [Gal(beta 1----6)]3-Gal(beta 1----3')- and [Gal(beta 1----6)]2-Gal(alpha 1----6)-Gal(beta 1----3')- for the tetraglycosyl diacylglycerol. Except for Gal(alpha 1----6)-Gal(beta 1----3')-diacylglycerol, all of the glycolipids with oligosaccharide moieties had novel glycosidic linkage patterns differing from those in the well-known glyceroglycolipids in nature. The predominant diacylglycerol species component was characterized as dilinolenin. However, the molecular species composition of the diacylglycerol moieties of the two diglycosyl isomers with different glycosidic linkage patterns were found to be qualitatively the same but different quantitatively, as follows: in the well-known isomer Gal(alpha 1----6)-Gal(beta 1----3')-, 39% dilinolenin, 15% palmitoyl linolenin, and 14% linoleoyl linolenin; and in the novel isomer Gal(beta 1----6)-Gal(beta 1----3')-, 35% dilinolenin, 24% dilinolein, and 21% linoleoyl linolenin.

Identification of 1-alkyl-2-acyl-3-(2',3'-diacylglycerol)glycerols, a new type of lipid class, in harderian gland tumors of mice

A new class of alkyl glycerolipids, 1-alkyl-2-acyl-3-(2',3'-diacylglycerol)glycerols, was identified in lipid extracts prepared from harderian gland tumors of mice. After saponification, this lipid class yielded 1-alkyl-3-(1'-glycerol)glycerols. Identification was based on mass spectrometry, proton nuclear magnetic resonance spectroscopy, infrared spectroscopy, and chromatography of various derivatives and appropriate standards that were synthesized. The alkyl moieties of this unique lipid class consisted of saturated aliphatic chains with chain lengths of 14 to 20 carbon atoms. The acyl moieties were mostly saturated and monounsaturated aliphatic chains ranging from 14 to 24 carbon atoms. The alkyl and acyl moieties of 1-alkyl-2-acyl-3-(2',3'-diacylglycerol)glycerols were similar to those of alkyldiacylglycerols present in the same tissue, except for the presence of monounsaturated alkyl moieties in the latter. 1-Alkyl-2-acyl-3-(2', 3'-diacylglycerol)glycerols were only found in trace amounts in the normal harderian glands of mice. The total quantity of the alkyl and acyl moieties with a chain length greater than 20 carbon atoms in the alkyldiacylglycerols from tumors were considerably lower than those found in normal harderian glands of mice. This is the first report of the presence of bisglyceryl ether lipids in mammalian tissue; its unique chemical structure is consistent with the type of ether-linked lipid products that could be synthesized in the reaction catalyzed by alkyldihydroxyacetone-P synthase.

Assay for triacylglycerol lipase by a rapid thin-layer chromatographic technique

A rapid and accurate assay for lipase-catalyzed hydrolysis of radioactively labeled triacylglycerols has been developed. Aliquots of reaction mixtures are applied directly, i.e., without extraction of the lipolysis products, to thin-layer chromatography plates coated with Silica Gel H containing 5% Na2CO3 (w/w), heated for 10 sec, and developed with diethyl ether-methanol 97:3 (v/v) to a height of 4-5 cm. About 98.5% of the fatty acids are immobilized as sodium salts at the origin of the chromatogram, whereas tri-, di-, and monoacylglycerols migrate close to the solvent front. Adsorbent at the origin and that at the remaining part of the chromatogram are then assayed for radioactivity without prior staining.

Comparison of the HPLC-separated species patterns of phosphatidic acid, CDP-diacylglycerol and diacylglycerol synthesized de novo in rat liver microsomes (a new method)

The species pattern of phosphatidic acid was compared with that of CDP-diacylglycerol and diacylglycerol synthesized de novo by glycerol 3-phosphate acylation in a CoA ester-generating system in liver microsomes. The similarity of the species patterns of phosphatidic acid and CDP-diacylglycerol indicated that the CTP-phosphatidyl cytidylyltransferase showed no selectivity for individual species of its phosphatidic acid substrate. Since the species pattern of diacylglycerol deviated from that of phosphatidic acid, a slight acyl selectivity of the phosphatidic acid phosphohydrolase or a slight inhomogeneity of its substrate pool might be assumed. For the determination of the molecular species of CDP-diacylglycerol, a new method was developed. By incubation of CDP-diacylglycerol with oligonucleate 5'-nucleotidohydrolase (phosphodiesterase), phosphatidic acid was produced. The CDP-diacylglycerol-derived phosphatidic acid was methylated with diazomethane and then separated by reverse-phase HPLC in 15 molecular species.

Rapid separations of diacyl- and dialkylglycerol enantiomers by high performance liquid chromatography on a chiral stationary phase

Rapid and practical separations of 1,2- and 2,3-diacyl- and dialkyl-sn-glycerol enantiomers as their 3,5-dinitrophenyl-urethane derivatives were carried out by normal-phase high performance liquid chromatography on a chiral stationary phase, N-(R)-1-(alpha-naphthyl)ethylaminocarbonyl-(S)-valine chemically bonded to gamma-aminopropyl silanized silica. Complete separations of the racemates into enantiomers were achieved for both of the diacyl- and dialkylglycerols within 10 min using a stainless steel column (25 cm long) packed with the 5-mu particles, an isocratic elution with a mixture of hexane/ethylene dichloride/ethanol as a mobile phase and a UV detector. The sn-1,2-enantiomers were eluted ahead of the corresponding sn-2,3-enantiomers. Satisfactory separation of the sn-1,3-diacylglycerols from the corresponding enantiomers and the separation of the homologues differing in acyl and alkyl groups were also observed. The formations of hydrogen bonding and charge transfer complex between the urethane derivatives and the stationary phase may contribute to the enantiomer separations.

Diglycosyl diacylglycerol of Mycobacterium tuberculosis

A diglycosyl diacylglycerol was isolated from Mycobacterium tuberculosis, and its structure was established by a combination of methylation analysis, 1H nuclear magnetic resonance, and fast atom bombardment-mass spectrometry. It is a 1,2-diacyl-[beta-D-glucopyranosyl(1"----6')-beta-D-glucopyranosyl(1'---- 3)]- sn-glycerol and exists in at least five molecular species differing in fatty acyl substituents. The major constituent fatty acids were identified as iso- and anteisopentadecanoate, iso- and n-hexadecanoate, and iso- and anteisoheptadecanoate. Although glycosyl diacylglycerols are common membrane components of gram-positive bacteria, this report represents the first substantial evidence for the presence of a glycosyl diacylglycerol within a member of the Mycobacterium genus. Although the glycolipid is not a major component of M. tuberculosis, it reacts readily in enzyme-linked immunosorbent assay against rabbit antibodies raised against whole bacteria and thus may be useful for the serodiagnosis of tuberculosis.

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.

Separation of some neutral lipids by normal-phase high-performance liquid chromatography on a cyanopropyl column: ubiquinone, dolichol, and cholesterol levels in sheep liver

The normal-phase high-performance liquid chromatographic separation of neutral lipids into molecular classes was carried out on a cyanopropyl (CN) column eluted with isopropanol in hexane. Cholesteryl, retinyl, and dolichyl esters, triglycerides and vitamin E, ubiquinone, dolichol, phytol, and cholesterol eluted as separate peaks with 0.05% isopropanol in hexane. Cholesterol, retinol, diglyceride, and monoglyceride eluted as separate peaks with 0.75% isopropanol in hexane. These separations could not be achieved on a silica gel column. The method was used to assay sheep liver ubiquinone, dolichol, and cholesterol levels, that were determined as 77, 108 and 1864 micrograms/g wet wt, respectively.

The characterization of 2,3-alkanediol diacyl esters obtained from the Harderian glands of Mongolian gerbil (Meriones unguiculatus)

A major lipid class in the Harderian glands of the Mongolian gerbil was investigated. The IR and 1H-NMR spectra suggested that it was a wax-like compound. Fatty acids present were capric, lauric, myristic, palmitic, stearic, arachidic, and behenic acids in ratios of 3.0%, 16.3%, 16.5%, 29.5%, 5.1%, 16.4%, and 9.8%, respectively. Odd-numbered, branched chain and unsaturated fatty acids were not present in large amounts. The structure of the alcohol moiety was elucidated to be 2,3-alkanediol with carbon chain lengths from C12 to C22 by GC-MS of the TMS and isopropylidine derivatives. Lemieux-von Rudloff oxidation of these alcohols confirmed the 2,3-diol structure, giving fatty acids two carbon units shorter.

Lipids associated with rat small-intestinal mucus glycoprotein

The lipid content and composition of rat small-intestinal mucus, and the purified mucus glycoprotein before and after Pronase digestion were investigated. The mucus, obtained by the instillation of intestine with 2M NaCl, was fractionated on Bio-Gel A-50 in the presence of 6M urea and the mucus glycoprotein free of noncovalently bound protein was isolated. A portion of the purified glycoprotein was subjected to Pronase digestion to yield glycopeptides. The native mucus, and the purified glycoprotein and glycopeptides were extracted with chloroform-methanol, and the lipids contained in the extracts were analyzed. The lipids accounted for 17.6 of the dry weight of mucus, 26.4 of the mucus glycoprotein, and 25.3% of the glycopeptides. In comparison to mucus, the lipids associated with mucus glycoprotein contained 1.9 times more phospholipids and 2.1 times more glycolipids, showed a 26% increase in neutral lipids, and were virtually free of glycosphingolipids. Treatment of the purified glycoprotein with Pronase led to a moderate (22.3%) loss in neutral lipids, 4.3-fold decrease in phospholipids, and 52.3% increase in glyceroglucolipids. The results indicate that while the interaction of mucus glycoprotein with phospholipids involves its Pronase-susceptible region, the interaction with glyceroglucolipids occurs in the glycosylated region of the glycoprotein that is resistant to proteolysis.

Structures and properties of acyl diglucosylcholesterol and galactofuranosyl diacylglycerol from Acholeplasma axanthum

Acholeplasma axanthum is one of the few procaryotes, and the only member of the Mollicutes, known to contain phosphosphingolipids. Examination of strain S743 for glycolipids revealed the presence of glucosides of cholesterol and galactosides of glycerol as the predominant glycolipids. The major component is acylated diglucosylcholesterol, followed by monogalactosyldiacylglycerol and monoglucosylcholesterol. The glucose residues of the sterol-based compounds appear to be alpha-linked pyranoses, while the galactose of the glycerol-based lipid is an alpha-linked furanose. The "glycolipid' fraction also contained N-(3-hydroxy)acyl sphinganines with varying degrees of O-acylation. None of these ceramide derivatives was linked to carbohydrate. The major glycolipid, tentatively identified as alpha-D-glucopyranosyl-(1 leads to 3)-(O-acyl)-alpha-D-glucopyranosyl-(1 leads to 3)-cholesterol, along with its deacylated derivative, appears to be the first reported instance of steryl diglycosides among procaryotes, in contrast to the steryl monoglycosides, which are common to other mycoplasmata and some spirochetes.

Strategy of glycerolipid separation and quantitation by complementary analytical techniques. Plenary lecture

Although improved systems for chromatographic resolution continue to be developed there is good reason to believe that no single method will be capable fo complete separation of all lipid mixtures including the geometric, positional and stereochemical isomers in each molecular species. Furthermore, the chromatographic systems giving the highest resolution usually yield the least complete recoveries of components and require separate procedures of quantitation. It is therefore necessary to develop appropriate strategies that yield the required resolution as a result of consecutive application of complementary analytical techniques. At the present time, the original combination of thin-layer and gas--liquid chromatography has been joined by the combination of thin-layer and liquid, and liquid and gas--liquid chromatography with both liquid and gas--liquid chromatography being frequently coupled to mass spectrometry with computerized data processing. Internal standardization with hydrogen flame ionization provides a simple quantitative detection for gas chromatography, while mass spectrometry serves a similar purpose in liquid chromatography, although a much more extensive calibration may be required for quantitation. Special advantages for both separation and quantitation of most neutral lipid mixtures are derived from enzymic and chemical modification of the samples prior to chromatography. With imaginative work-up of samples, superior qualitative and quantitative results can frequently be obtained by appropriate combination of chromatographic techniques of limited resolving power.