Alkyl Diacyl Glycerols Research Articles

Pharmacokinetics, Mass Balance, Excretion, and Tissue Distribution of Plasmalogen Precursor PPI-1011.

PPI-1011 is a synthetic plasmalogen precursor in development as a treatment for multiple plasmalogen-deficiency disorders. Previous work has demonstrated the ability of PPI-1011 to augment plasmalogens and its effects in vitro and in vivo, however, the precise uptake and distribution across tissues in vivo has not been investigated. The purpose of this study was to evaluate the pharmacokinetics, mass balance, and excretion of [14C]PPI-1011 following a single oral administration at 100 mg/kg in Sprague-Dawley rats. Further tissue distribution was examined using quantitative whole-body autoradiography after both single and repeat daily doses at 100 mg/kg/day. Non-compartmental analysis showed that following a single dose, PPI-1011 exhibited peak levels between 6 and 12 h but also a long half-life with mean t1/2 of 40 h. Mass balance showed that over 50% of the compound-associated radioactivity was absorbed by the body, while approximately 40% was excreted in the feces, 2.5% in the urine, and 10% in expired air within the first 24 h. Quantitative whole-body autoradiography following a single dose showed uptake to nearly all tissues, with the greatest initial uptake in the intestines, liver, and adipose tissue, which decreased time-dependently throughout 168 h post-dose. Following 15 consecutive daily doses, uptake was significantly higher across the entire body at 24 h compared to single dose and remained high out to 96 h where 75% of the initially-absorbed compound-associated radioactivity was still present. The adipose tissue remained particularly high, suggesting a possible reserve of either plasmalogens or alkyl diacylglycerols that the body can pull from for plasmalogen biosynthesis. Uptake to the brain was also definitively confirmed, proving PPI-1011’s ability to cross the blood-brain barrier. In conclusion, our results suggest that oral administration of PPI-1011 results in high uptake across the body, and that repeated dosing over time represents a viable therapeutic strategy for treating plasmalogen deficiencies.

Diagnostic application of lipidomics fingerprints to bladder carcinoma

Background: Bladder cancer is very diffuse especially in men aged about 65 years and the diagnosis is difficult and invasive. The identification of simple urine biomarkers that will enable diagnosis at an earlier stage of disease and accurately monitor for recurrence is a big challenge. The aim of this research is to find a simple urine test that may substitute or reduce the invasive and expensive cystoscopy. Methods: Voided urines collected in the morning before operation from 25 patients affected by papillary bladder carcinoma (Ta) were used after a short conservation at −80 ℃ and long conservation for more than 1 year. The lipids were extracted and analyzed using an Agilent Technologies. A statistical analysis of the results was performed with the specific software LipoStar. Results: The results show a clear difference in lipids between patients and controls that can be separated into two groups. In order to identify the lipid species, characteristic fragments of MS/MS spectra were used. On that basis, about 50% of 150 lipids selected were identified. This subset is mainly formed by triacylglycerols, alkyl diacylglycerols, cholesteryl ester and palmitoyl-sphingomyelin that are all present in high quantity in patients’ urine. These differences become less evident in samples saved for more than 1 year. Although the dataset is small, it appears that the urine lipids may be used as markers with good specificity and sensitivity. Conclusions: The relevance of lipids in tumorigenesis as well the possible alterations of chromatin lipids are discussed including also the possibility of miRNA influence. The development of a special kit for use in screening and for monitoring the appearance or reappearance of bladder tumors could prevent many deaths due to this disease and may reduce the current invasive and expensive diagnostic system.

Dimorphic expression of uncoupling protein‐3 in golden hamster harderian gland: Effects of castration and testosterone administration

Hamster (Mesocricetus auratus) harderian gland (HG) is a dimorphic orbital gland producing a copious lipid secretion. Two cell-types are present in hamster HG, type I in both sexes, type II only in males. In hamster HGs, we found a marked sexual dichotomy in the expression of uncoupling protein-3 (UCP3), a mitochondrial protein carrier, that probably exports fatty acid anions and fatty acid peroxides from the mitochondrial matrix. Following castration and/or testosterone treatment: (1) UCP3 levels correlated with the type II-cell percentage, not with testosterone levels, (2) in male HGs, UCP3 was comparable to female levels at 30 days post-castration (when the type II-cell percentage had fallen from 50 to 5%), although testosterone was already near zero at 15 days (when neither the type II-cell percentage nor the UCP3 level had fallen), and testosterone-replacement therapy prevented these changes. Testosterone-treated females possessed type II cells and a UCP3 level about twofold higher than in control females. Males displayed more intense UCP3 immunohistochemical positivity in type I HG cells than females. Hence, testosterone may indirectly control UCP3 expression by regulating the gland's morphological and lipid dimorphism. Straight-chain fatty acids [found in alkyl diacylglycerols (ADGs) in males] are oxidized predominantly in mitochondria, branched-chain fatty acids (abundant in ADGs in females) predominantly in peroxisomes, so we speculate that the higher UCP3 expression in males reflects greater fatty acid flux in HG mitochondria. This is supported by our finding that in female (not male) HGs, the peroxisome-rich fraction contained alpha-methylacyl-CoA racemase (AMACR), an enzyme important in the beta-oxidation of branched-chain fatty acids.

Lipids and fatty acids in Clione limacina and Limacina helicina in Svalbard waters and the Arctic Ocean: trophic implications

Lipid class and fatty acid compositions were determined in Limacina helicina and Clione limacina from an Arctic fjord and the marginal ice zone around Svalbard. C. limacina had higher levels of neutral lipids, including both alkyldiacylglycerols (ADG) and triacylglycerols (TAG), than L. helicina, which contained mainly TAG. However, considerable heterogeneity in the lipid classes and their fatty acids/alcohols were observed in C. limacina in that only two out of the seven specimens analysed were lipid-rich and contained both ADG and TAG, the others having only low percentages of TAG. In specimens of C. limacina containing ADG, 15:0 and 17:1n-8 were prominent fatty acids in both ADG and TAG. The fatty acids of the TAG of L. helicina were variable but 15:0 and 17:1n-8 were absent. We consider the heterogeneity in the fatty acid compositions of L. helicina to reflect temporal and spatial variability in the animals' predominantly phytoplanktonic and particulate diet, which occasionally includes small copepods. We further consider L. helicina to be the prime food for C. limacina and the noticeable amounts of 22:1 found in one sample of C. limacina to reflect significant input of Calanus either directly or indirectly through their prime food, L. helicina. We view the heterogeneity in the fatty acid compositions of both L. helicina and C. limacina, as well as the ability of C. limacina to biosynthesise WE, ADG, 15:0, and 17:1n-8, as adaptations to a large variation of food availability that enables C. limacina to synthesise lipids rapidly and flexibly. Thus, the lipid biochemistry of C. limacina is important in enabling the species to thrive in strong pulses in polar systems.

Sugar Surfactant-Based Solutions as Host Systems for Enzyme Activity Measurements

We used fluorogenic substrates, namely, alkyldiacyl glycerols labeled with a fluorophore and a fluorescence quencher, to measure lipase activities. For this optical lipase assay it is necessary that the water-insoluble fluorogenic substrates are dispersed in an aqueous medium in the presence of appropriate detergents in order to obtain well-defined and reproducible systems with high optical transparency. The activity of lipases critically depends on the supramolecular organization of the substrate. Therefore, we tested different solutions containing nonionic surfactants and organic phases for their potential use as host systems for fluorogenic lipids. We then determined the pseudoternary phase diagram for the system buffer−alkyl polyglucoside−hexanol, which showed the highest apparent enzyme activities, in the buffer corner. We performed structural investigations on micellar sugar surfactant solutions within the L1 phase with and without hexanol using small-angle neutron scattering (SANS), small-angle X-ray scattering (SAXS), and dynamic light scattering (DLS) in order to investigate a possible correlation between lipase activity and the structure of the aggregates present in the host system.

New fluorescent glycerolipids for a dual wavelength assay of lipase activity and stereoselectivity

A new type of fluorogenic alkyldiacyl glycerols was synthesized and used as fluorogenic substrates for the analysis of lipase activities and stereoselectivities. These compounds contain pyrene or perylene as a fluorophore and the trinitrophenyl-amino- (TNP) residue as a quencher. Both substituents are covalently bound to the ω-ends of the sn-2 and sn-1(3) acyl chains, respectively. Upon glycerolipid hydrolysis, the residues are separated from each other thus allowing determination of lipase activity from the continuous increase in fluorescence intensity which is caused by dequenching. Mixtures of enantiomeric fluorogenic alkyldiacyl glycerols, selectively labeled with pyrene or perylene as fluorophores, can be used for a dual-wavelength ‘stereoassay’ of lipases. Since absorption and emission maxima of both labels are clearly separated, hydrolysis of the respective enantiomeric substrates can be distinguished simultaneously, and the difference in their rates of hydrolysis can be taken as a parameter for the stereopreference of a lipase.

New fluorogenic triacylglycerol analogs as substrates for the determination and chiral discrimination of lipase activities

A new type of fluorogenic and isomerically pure 1(3)-O-alkyl-2,3 (3,2)-diacyl glycerols was synthesized that can be used as substrate for the determination of lipase activities. These compounds contain a fluorescent pyrene acyl chain and, as a potent quencher of pyrene fluorescence, a trinitrophenylamino acyl residue. In their intact form, the fluorogens show only low fluorescence intensity. Upon lipase-induced or chemical hydrolysis of the substrates, however, the fluorophore and quencher separate from each other. This leads to a gradual increase in pyrene fluorescence, reflecting the time-dependent progress of lipolysis and, under substrate saturation conditions, lipase activity. This lipase assay is continuous and does not require separation of substrate and reaction products. Short- and long-chain homologues as well as optical isomers of the fluorogenic alkyldiacyl glycerols were hydrolyzed by pancreatic lipase, hepatic lipase, and lipo-protein lipase at highly different rates depending on the substrate or enzyme preparation and source (e.g., postheparin plasma or cultured cells). It is proposed that a useful set of enantiomeric and/or homologous substrates in combination with appropriate reaction media might be applied to the selective determination of a lipase in a mixture of lipases, e.g., hepatic and lipoprotein lipase in PHP, for medical diagnostics.

Enantiomeric perylene-glycerolipids as fluorogenic substrates for a dual wavelength assay of lipase activity and stereoselectivity.

A new type of fluorogenic alkyldiacyl glycerols was synthesized and used as fluorogenic substrates for the analysis of lipase activities and stereoselectivities. These compounds contain perylene as a fluorophore and the trinitrophenylamino (TNP) residue as a quencher. Both substituents are covalently bound to the omega-ends of the sn-2 and sn-1 (3) acyl chains, respectively. Upon glycerolipid hydrolysis, the residues are separated from each other thus allowing determination of lipase activity by the continuous increase in fluorescence intensity which is caused by dequenching. Using enantiomeric pairs of these compounds, we were able to analyze lipase stereoselectivity depending on the reaction medium. Mixtures of enantiomeric fluorogenic alkyldiacyl glycerols, selectively labelled with pyrene or perylene as fluorophores, can be used for a dual-wavelength "stereoassay" of lipases. Since absorption and emission maxima of both labels are clearly separated, hydrolysis of the respective enantiomeric substrates can be determined simultaneously, and the difference in the rates of hydrolysis can be taken as a parameter for the stereopreference of a lipase. Hydrolysis rates measured with perylene-substituted lipids are generally lower than those obtained with the pyrene analogs. Thus, with a mixture of perylene and pyrene-substituted lipids, we observe a higher apparent stereoselectivity of lipases since we measure a combination of stereo- and substrate selectivity. In the presence of albumin, all microbial lipases tested so far exhibit stereopreference for the sn-1 glycerol position. In our assay, the apparent stereoselectivities are highest if in the presence of albumin, the sn-1 position carries pyrene and the sn-3 position is substituted with perylene. The lipase stereoselectivity assay described here requires the simultaneous measurement of the fluorescence intensities at two different wavelengths in a single cuvette and can thus be carried out using existing and cheap instrumentation that was developed for the fluorimetric analysis of Ca+2 concentrations.

Conformational effects on the fluorescence of pyrene-labeled alkyldiacyl glycerols in different model membranes

We synthesized two isomeric alkyldiacyl glycerols containing pyrene as a fluorescent reporter group bound to the omega end of both acyl chains. If located in the phospholipid monolayer of a vesicle both isomers showed intramolecular pyrene excimer fluorescence, indicating parallel orientation of both pyreneacyl chains in the lipid molecule. In micelles only pyrene monomer fluorescence was observed. Thus, in this system the labeled lipids adopt a conformation with both pyreneacyl chains extending into different directions. Using vesicles, lipase activities could be continuously determined from the increase of pyrene monomer fluorescence.

Distinctive selectivity for docosatetraenoic acid incorporation by Ehrlich ascites tumor cells

Three polyunsaturated fatty acids were incorporated into the lipids of Ehrlich ascites cells to examine the selectivity of the synthetic enzymes for chain length and the number of double bonds. Arachidonic acid (20:4 n-6) and timnodonic acid (20:5 n-6) showed approximately similar patterns of incorporation into neutral acylglycerols, choline glycerophospholipids and ethanolamine glycerophospholipids. Further division of the lipids into diacyl and alkylacyl categories established that 20:4 n-6 was incorporated at relatively lower amounts in the triacylglycerols and in the alkylacyl and alkenylacyl forms of the glycerophospholipids. The pattern of incorporation of radioactive 20:5 n-3 into the phospholipids was similar to that for 20:4 n-6, but there was no evidence for a selectively restrained incorporation into the triacylglycerols. The 22-carbon acid (22:4 n-6) differed greatly from its shorter homolog (20:4 n-6) in being incorporated in much greater amounts into triacylglycerols than into phospholipids. It did not appear to be present at an appreciably higher relative amount in either the alkyl diacylglycerols or in the ether-containing choline glycerophospholipids. Nevertheless, it occurred with exceptionally high specific acitivities in the alkylacyl and alkenylacyl forms of ethanolamine glycerophospholipids in a manner that suggests marked discrimination by the cytidine-mediated ethanolamine phosphotransferase. This distinctive selectivity provides evidence for special role for a 22-carbon acid in lipid metabolism.

Evidence for stereoselective lipolysis in a termite. Toxicity of enantiomeric ω-fluorinated alkyldiacylglycerols to Reticulitermes flavipes

Enantiomeric pairs of sn-1,2-0-diacyl-3-0-alkyl and sn-1-0-alkyl-2,3-0-diacyl glycerols containing ω-fluoroacyl or ω-fluoroalkyl groups were prepared and were fed to the Eastern subterranean termite. Insects fed the enantiomeric 1-0-(ω-fluoroalkyl) ethers showed similar mortality vs time courses and LC 50s (at four days), as did those fed the chiral alkyl diacyl glycerols bearing the ω-fluoroacyl group at the 2 position. However, the sn-1-0-(ω-fluoroacyl) showed lower toxicity and a slower time course for mortality than did the sn-3-0-(ω-fluoroacyl) enantiomer, consistent with a partially stereoselective lipolysis at the sn-3-position.

The effect of two isomeric octadecenoic acids on alkyl diacyl glycerides and neutral glycosphingolipids of novikoff hepatoma cells.

AbstractThe addition of 150 μg ofcis‐6‐octadecenoic acid (6–18∶1) per milliliter to the growth medium of Novikoff hepatoma cells reduced the rate of multiplication of these cells, whereas the same level ofcis‐9‐octadecenoic acid (9–18∶1) was without effect. The quantity of alkyl diacyl glycerols in cells grown in medium containing 100 μg/ml of either 6–18∶1 or 9–18∶1 was reduced to about 10% of that observed in cells grown in unsupplemented media. The presence of 6–18∶1 acid led to an increase in the concentration of the dihexosyl ceramide and a corresponding decrease in that of the monohexosyl ceramides of the cells; whereas the presence of 9–18∶1 resulted in an increase in the relative amount of tetraglycosyl ceramide and corresponding reductions in those of mono‐ and dihexosyl ceramide. Possible causes for these changes are discussed.

The metabolism of neutral lipids in the spur dogfish, Squalus acanthias.

AbstractCell free studies have shown that liver and intestine are the major sites of synthesis of triacyl glycerols inSqualus acanthias. The liver and to a lesser extent the intestine and stomach are major sites of wax ester synthesis. Muscle does not synthesize either triacyl glycerols or wax esters significantly. In vivo studies have shown that intravenously injected (3H) fatty alcohol is massively oxidized to (3H) fatty acid, the bulk of which appears in muscle. Liver appears to export both free fatty acids and triacyl glycerols to serum and thence to muscle. Free fatty acids, triacyl glycerols, wax esters and cholesteryl esters are all turned over within 48 hr inSqualus serum. The turnover of triacyl glycerols greatly exceeds the turnover of alkyl diacyl glycerols.

Metabolism of the enantiomeric 1- O-alkyl glycerol ethers in the rat intestinal mucosa in vivo; incorporation into 1- O-alkyl and 1- O-alk-1′-enyl glycerol lipids

1. 1. The incorporation of orally administered 1-O-(9,10-[ 3 H 2] octadecyl ) sn-glycerol and 3-O(1-[ 14 C] octadecyl ) sn-glycerol into alkyl acyl as well as alk-1′-enyl acyl glycerophosphoryl ethanolamine and alkyl diacyl glycerol of the rat intestinal mucosa was investigated in vivo. 2. 2. The enantiomers were found to be utilized to considerably different extents, the sn-1-isomer being the favored substrate in the above-mentioned biosynthetic reactions. 3. 3. The specific incorporation into alk-1′-enyl glycerol lipids of the 1- O-alkyl sn-glycerol as compared to the sn-3-isomer supports the view that the alk-1′-enyl glycerol bond is derived from the alkyl glycerol bond. 4. 4. The amount and chain length distribution of alkyl glycerol ethers naturally occurring in alkyl diacyl glycerols of the rat intestinal mucosa are reported.

Biosynthesis of alkyldiacylglycerols and triacylglycerols in a cell-free system from the liver of dogfish (Squalus acanthias).

Biosynthesis of alkyldiacylglycerols and triacylglycerols in a cell-free system from the liver of dogfish (Squalus acanthias).

The alkyl moieties in wax esters and alkyl diacyl glycerols af sharks

The alkyl moieties in wax esters and alkyl diacyl glycerols from the liver of the dogfish, soupfin shark, and silky shark are almost exclusively saturated and monounsaturated, the main alkyl moieties being the C(16) and C(18) chains in both lipid classes. However, the alkyl moieties in wax esters occur in a wider range of chain lengths. The unsaturated alkyl moieties in the two classes of lipids are mixtures of isomers. The distribution of isomeric octadecenyl moieties in wax esters and alkyl diacyl glycerols is almost the same.