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PubMed1995

A mechanistic study of the effects of the 1-alkyl-2-pyrrolidones on bilayer permeability of stratum corneum lipid liposomes: a comparison with hairless mouse skin studies.

The influence of a series of 1-alkyl-2-pyrrolidones (C2-C8) on the transport behavior of lipophilic and polar/ionic permeants across hairless mouse skin was recently investigated by employing a physical model approach that treats the stratum corneum barrier as a diffusional system of parallel lipoidal and pore pathways. In this previous study, the transport enhancement effects (enhancement factor, EHMS) on the lipoidal pathway of the stratum corneum were found to be essentially the same for all steroidal probe permeants investigated at various concentrations of these 1-alkyl-2-pyrrolidones. In the present research, the relationship between solute transport enhancement in the lipoidal pathway of hairless mouse skin and the transport enhancement in the stratum corneum lipid liposome bilayer was studied by comparing the enhancement factor for the lipoidal pathway in the hairless mouse skin, EHMS, with that for the stratum corneum lipid liposome, ESCLL, at equal solution concentrations of the 1-alkyl-2-pyrrolidones. The release rates of D-mannitol, D-glucose, 3-O-methyl-D-glucose, sucrose, and raffinose from stratum corneum lipid liposomes were determined, and the ESCLL values for these permeants were compared with the EHMS values obtained with hairless mouse skin using the steroidal permeants. An important finding in this study was a semiquantitative correlation between the enhancement effects induced by the 1-alkyl-2-pyrrolidones, except 1-ethyl-2-pyrrolidone, with the liposome bilayer using sugar molecules as permeants and those found with the lipoidal pathway in hairless mouse skin using steroid molecules as permeants.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2003

Alkyl chains acting as entropy reservoir in liquid crystalline materials.

The roles played by the conformational disordering of alkyl chains in determining the aggregation states of matter are reviewed for liquid crystalline materials from a thermodynamic perspective. Entropy, which is one of the most macroscopic concepts but which has a clear microscopic meaning, provides crucial microscopic information for complex systems for which a microscopic description is hard to establish. Starting from structural implication by absolute (third-law) entropy for crystalline solids, the existence of successive phase transitions caused by the successive conformational melting of alkyl chains in discotic mesogens is explained. An experimental basis is given for the "quasi-binary picture" of thermotropic liquid crystals, i.e., the highly disordered alkyl chains behave like a second component (solvent). A novel entropy transfer between the "components" of a molecule and the resulting "alkyl chains as entropy reservoir" mechanism are explained for cubic mesogens.

Journal Article↗
PubMed1998

Electrophoretic resolution of tubulin and tektin subunits by differential interaction with long-chain alkyl sulfates.

Tubulin dimers, formed from globular alpha and beta subunits, and the tektins, three equimolar alpha-helical proteins that form filaments, mutually associate to form the junctional regions of doublet and triplet microtubules. When evaluated by SDS-PAGE, the apparent molecular weights of these proteins can deviate substantially from their sequence molecular weights in a manner sensitive to both the source of SDS and the species of origin. The electrophoretic mobility of sperm tail flagellar tubulins and tektins from an echinoderm and a mollusc were studied systematically using detergent-free stacking and resolving gels with a running buffer containing pure sodium dodecyl sulfate augmented with fixed amounts of C10, C14, C16, or C18 alkyl sulfates. Although having no systematic effect on molecular weight standards, the presence of alkyl sulfates of increasing chain length progressively exaggerated the separation of tubulin subunits, similarly facilitated the separation of two normally comigrating tektins, yet minimally influenced the relative migration of adequately separated tektins. This phenomenon is most likely due to preferential binding of longer chain alkyl sulfates by specific hydrophobic regions of these otherwise similar proteins. The use of binary mixtures of pure alkyl sulfates, required in the running buffer alone, may prove useful for reproducibly separating other proteins that characteristically bind SDS anomalously.

Dimerization↗
PubMed1999

Self-Assembled Monolayers of Alkylammonium Ions on Mica: Direct Determination of the Orientation of the Alkyl Chains.

Near edge X-ray absorption fine structure spectroscopy was used to study the orientation of the alkyl chains in monolayers of R(1)(3)R(2)N(+) and R(1)(2)R(2)(2)N(+) (R(1) = methyl and R(2) = octadecyl), self-assembled on muscovite mica via ion exchange. The alkyl chains adopt a random orientation in the monooctadecylammonium ions. Dimethyldioctadecylammonium ions, however, form a well-ordered self-assembled monolayer. The average tilt angle between the alkyl chains and the surface normal is 38 degrees. The difference between the mono- and the dioctadecylammonium ions reflects at least partially the packing density of the alkyl chains. When adsorbed on muscovite mica, dimethyldioctadecylammonium ions establish monolayers that are similarly well ordered as alkanethiol monolayers on gold. Copyright 1999 Academic Press.

Journal Article↗
PubMed1975

Enzymic synthesis of 1-alkyl-2-acyl-sn-glycero-3-phosphorylethanolamine through ethanolaminephosphotransferase activity in the neuronal and glial cells of rabbit in vitro.

The transfer of radioactivity from cytidine-5'-diphosphate ethanolamine into 1-alkyl-2-acyl-sn-glycerophosphorylethanolamine of neuronal and glial cells from adult rabbit brain cortex has been investigated in vitro. The synthesis of 1-alkyl-2-acyl-sn-glycerophosphorylethanolamine in both cell populations was stimulated 23-25-fold by the addition of 6 mM alkylacylglycerol. The neuronal cell-enriched fraction was found to possess/unit protein a 1.7-1.8-fold ethanolaminephosphotransferase activity (EC 2.7.8.1), as compared to the glial fraction, when saturating concentrations (6 mM) of alkylacylglycerols were added in the incubation system. The neuronal/glial ratio was 2.6-2.8 in the absence of lipid acceptor or with low concentrations of alkylacylglycerol. Under most favorable conditions, 6.4 and 3.3 nmoles 1-alkyl-2-acyl-sn-glycerophosphorylethanolamine/mg protein/30 min was obtained for neurons and glia, respectively. Various kinetic properties of the 1-alkyl-2-acyl-sn-glycerophosphorylethanolamine synthesizing phosphotransferase activity were found to be similar both in neurons and glia.

Animals↗
PubMed1994

Alkyl glycerol monoethers in the marine sponge Desmapsamma anchorata.

1-O-Hexadecylglycerol (chimyl alcohol), 1-O-heptadecylglycerol and 1-O-octadecylglycerol (batyl alcohol) have been identified as the major native constituents of a mixture of free alkyl glycerol ethers isolated from the contained water and the methanolic extract of the sponge Desmapsamma anchorata. Minor components were the free C14, C15, C19, C20 and C21 alkyl glycerol monoethers. The alkyl glycerol monoethers were analyzed and identified by gas chromatography/mass spectrometry of their isopropylidene derivatives. This is the first report on the occurrence of free C15, C19, C20 and C21 alkyl glycerol monoethers in a sponge.

Animals↗
PubMed2001

Novel enzymatic assay for determination of alkyl polyglycosides with short chain fatty alcohols.

An enzymatic assay has been developed for the quantitative detection of alkyl polyglycosides after enzymatic hydrolysis with different carbohydrolases. A three-step enzymatic method was used for the quantification of alkyl polyglycosides. In the first step the enzymatic hydrolysis of alkyl polyglycosides was performed with different carbohydrolases, or an acid hydrolysis was used. The second step was quantification of free glucose with an enzyme electrode, which was covered with an immobilized glucose oxidase membrane; glucose was used as standard. The last step was the enzymatic quantification of fatty alcohols, which are the second substrate after enzymatic hydrolysis of alkyl polyglycosides. Surprisingly, the enzyme alcohol dehydrogenase ADH (E.C. 1.1.1.1) from bakers' yeast could efficiently oxidize a wide variety of aliphatic alcohols and had the highest catalytic specificity with short and medium fatty alcohol substrates, including octanol and decanol.

Alcohol Dehydrogenase↗
PubMed2000

Cytotoxicity, cell-cycle perturbations and apoptosis in human tumor cells by lipophilic N4-alkyl-1-beta-D-arabinofuranosylcytosine derivatives and the new heteronucleoside phosphate dimer arabinocytidylyl-(5'-->5')-N4-octadecyl-1-beta-D-arabinofuranosylcytosi ne.

The arabinofuranosylcytosine (AraC) derivative N4-octadecyl-1-beta-D-arabinofuranosylcytosine (NOAC) and its (5'-->5')-heterodinucleoside phosphate analog NOAC-AraC were compared with AraC for cytotoxicity, cell-cycle dependence, phosphorylation by deoxycytidine (dC) kinase and apoptosis induction in native, AraC- or NOAC-resistant HL-60 cells. NOAC was cytotoxic in all cells with three to seven-fold lower IC50 concentrations than those of NOAC-AraC or AraC. In contrast to NOAC-AraC, the lipophilic monomer NOAC overcame AraC resistance, inducing apoptosis in more than 80% of native and AraC-resistant HL-60 cells. This suggests that NOAC-AraC may be cleaved intracellularly only at very slow rates to AraC and NOAC or to the 5'-monophosphates, whereas NOAC exerts different mechanisms of action from AraC. In vitro the dimer was cleaved by phosphodiesterase or human serum to NOAC, AraC and AraC monophosphate. In contrast to AraC, N4-alkylated AraC derivatives with alkyl chains ranging from 6-18 C atoms were not substrates for dC kinase. Furthermore, treatment of the multidrug-resistant cell lines KB-ChR-8-5 and KB-V1 with the N4-hexadecyl-AraC derivative NHAC did not induce P-170 glycoprotein expression, suggesting that the N4-alkyl-AraC derivatives are able to circumvent MDR1 multidrug resistance. The in vivo activity of liposomal NOAC in a human acute lymphatic leukemia xenograft model confirmed the antitumor activity of this representative of the N4-alkyl-arabinofuranosylcytosines.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2006

Reaction between alkyl isocyanides and isopropylidene Meldrum's acid in the presence of bidentate nucleophiles.

The reaction between alkyl isocyanides and isopropylidene Meldrum's acid in the presence of 1,2-ethanediol leads to N (1)-(alkyl)-2-(5,7-dioxo-1,4-dioxepane-6-yl)-2-methylpropanamides. 1,3-Propanediol or 1,4-butanediol produce hydroxyalkyl 1-(tert-butyl)-4,4-dimethyl-2,5-dioxo-3-pyrrolidinecarboxylates. When the reaction was performed in the presence of catechol, bis(2-hydroxyphenyl) 2-[2-(tert-butylamino)-1,1-dimethyl-2-oxoethyl]malonate was obtained. 2-Aminophenols react with alkyl isocyanides in the presence of isopropylidene Meldrum's acid to produce 1-alkyl-N (3)-(2-hydroxyaryl)-4,4-dimethyl-2,5-dioxo-3-pyrrolidinecarboxamides in good yields.

Amides↗
PubMed1990

Amino and hydrazino alkyl benzoates as derivatizing agents for the separation and mass spectrometric analysis of oligosaccharides from bacterial lipooligosaccharides.

In an attempt to develop more sensitive and versatile methods for the structure analysis of oligosaccharides derived from lipooligosaccharides (LOS) of gram-negative bacteria, amino and hydrazino alkyl benzoate derivatives were prepared. These oligosaccharide derivatives were separated by HPLC and then analyzed by liquid secondary ion mass spectrometry (LSIMS). Both the amino and hydrazino alkyl benzoates react with the free reducing termini of acid-treated LOS, increasing the hydrophobicity of the released oligosaccharides and allowing them to be separated by reverse-phase HPLC. In addition, these oligosaccharide derivatives now contain a sensitive uv chromophore for subsequent peak detection and improve the quality of the LSIMS spectra compared to underivatized oligosaccharides. However, the amino alkyl benzoates reacted poorly compared to the analogous hydrazino alkyl benzoates with 3-deoxy-manno-2-keto octulosonic acid (KDO), and oligosaccharides with KDO at the reducing terminus, especially when the oligosaccharide also contained phosphoethanolamine. Derivatization with the hydrazino compounds can be carried out quickly and under mild conditions using a minimal amount of reagent, and is therefore suitable for microscale analyses. The chromatographic and mass spectrometric characteristics of these derivatives make them excellent alternatives to permethylation and peracetylation techniques for the structural analysis of complex bacterial oligosaccharides derived from glycolipids.

Aminobenzoates↗
PubMed1988

Isolation of a cytosolic beta-glucosidase from calf liver and characterization of its active site with alkyl glucosides and basic glycosyl derivatives.

A beta-glucosidase/beta-galactosidase with Mr 52,500 was isolated from calf liver cytosol by a four-step procedure incorporating affinity chromatography on N-(9-carboxynonyl)-deoxynojirimycin-AH-Sepharose. Its pH optimum was at 5.8 with half-maximal activity at pH 3.5 and 8.6. Affinity for gluco compounds expressed by Km or Ki of substrates and inhibitors was 2- to 10-fold higher than for the corresponding galacto compounds. Alkyl glucosides were hydrolyzed with lower Vmax than p-nitrophenyl and 4-methylumbelliferyl glucosides, but due to their higher affinity the alkyl glucosides displayed values for kcat/Km of the same magnitude of the aryl glucosides when the alkyl chains were longer than octyl. Glucosylsphingosine was bound with Ki (= Km) 2.2 microM and hydrolyzed with a Vmax that was 50-fold lower than the Vmax for 4-methylumbelliferyl beta-glucoside. The product sphingosine was inhibitory with Ki 0.30 microM. A systematic study with alkyl glucosides and glucosylamines defined the aglycon site as a narrow, strongly hydrophobic cleft able to accommodate up to 10 methylene groups. Each CH2 group contributed 3.1 kJ/mol to the standard free energy of binding. The inhibition by gluco- and galactosylamine and by 1-deoxynojirimycin and its D-galacto analog was approximately 200-fold better than by corresponding nonbasic compounds. pH dependence of the inhibition and comparison with permanently cationic glycosyl derivatives showed that the nonprotonated form was the inhibiting species. This feature puts the cytosolic beta-glucosidase in the large class of glycoside hydrolases which strongly bind basic glycosyl derivatives by their protonation at the active site and formation of a shielded ion pair with the carboxylate of an aspartic or glutamic side chain.

1-Deoxynojirimycin↗
PubMed1978

Structural requirements of alkyl acyldithiocarbazates for the uncoupling of oxidative phosphorylation in mitochondria.

A structure-activity relationship study on the uncoupling of alkyl acyldithiocarbazates was carried out. Greater activity was observed with increasing alkyl chain length, the optimum being C9. A further increase in alkyl chain length caused a decrease in the activity. Thione-thiol tautomeric forms with a dissociable proton were dound to be of primary importance for the uncoupling and the role of the acyl group was auxiliary. The reactivity of the SH group of alkyl acyldithiocarbazates with an SH-reagent was very low. These compounds facilitated the valinomycin-induced swelling of non-respiring mitochondria and non-sonicated lecithin liposomes in isotonic potassium acetate solution.

Animals↗
PubMed1975

Chromatographic purification of a mammalian histidine decarboxylase on charged and non-charged alkyl derivatives of agarose.

Histidine decarboxylase (EC 4.1.1.22) from a mouse mastocytoma has been purified by chromatography on charged and non-charged n-alkyl derivatives of agarose. The former was represented by the coupling product of CNBr-activated agarose and alkylmonoamines (alkylamino-agarose), the latter by the coupling of agarose and alkylglycidyl ehters (alkyl agarose). The choice of fractionation medium was restricted by the enzyme stability; excessively high ionic strength media could not be used. Under the conditions investigated, the best result was obtained with the non-charged ocytl agarose. The enzyme was adsorbed to this gel at a relatively high ionic strength, and on stepwise decrease in ionic stength of the eluting buffer it was desorbed with a total recovery of 80%. There was an approx. 10-fold increase in specific activity. The histidine decarboxylase, thus purified, retained 90-100% of its activity for 10 days or more at 6-8 degrees C. Some general comments on protein fractionation on charged and non-charged alkyl derivatives of agarose are given. The complexity of protein interaction with the charged alkyl derivatives is illustrated by experiments with a colored protein, phycoerythrin.

Animals↗
PubMed1983

1-O-alkyl-2-acyl-sn-glycero-3-phosphocholine: a novel source of arachidonic acid in neutrophils stimulated by the calcium ionophore A23187.

Rabbit peritoneal neutrophils incorporated [14C]arachidonic acid into seven molecular species of choline-containing phosphoglycerides. These 2-[14C]arachidonoyl species differed with respect to the alkyl ether or acyl residue bound at the sn-1 position; four of the seven were ether-linked. Stimulation with calcium ionophore A23187 induced a proportionate release of arachidonate from all seven molecular species: 40% of the released arachidonate came from alkyl ether species. Thus, 1-O-alkyl-2-arachidonoyl-sn-glycero-3-phosphocholine (GPC) is a significant source of metabolizable arachidonic acid. Since 1-O-alkyl-2-lyso-GPC is the metabolic precursor of platelet activating factor, these results further interrelate pathways forming arachidonate metabolites and platelet activating factor; they also supply a rationale for the observation that both classes of stimuli form concomitantly during cell activation.

Animals↗
PubMed1988

Alkyl-linked diglycerides inhibit protein kinase C activation by diacylglycerols.

Alkylacylglycerols are synthesized when choline-phospholipids are degraded by a phospholipase C. This class of compounds has been shown to have biological activities; however, the mechanism of action is unknown. A series of alkyl-linked diglycerides were synthesized and tested for activity in an in vitro assay for protein kinase C. When protein kinase C activity was stimulated with the synthetic diacylglyceride analog 1-oleoyl-2-acetyl-sn-glycerol, the addition of alkyl glycerides caused a concentration-dependent inhibition of protein kinase C activity. Comparison of the protein kinase C inhibition by this series of 1-O-alkyl-2-acyl analogs revealed that both saturated and unsaturated long-chain groups in position 1 were effective and that dietherglycerols with short-chain moieties in position 2 were also effective. It is concluded from these studies that the biological activity of alkyl-linked glycerides may be expressed through protein kinase C inhibition.

Cell Line↗
PubMed1992

Sulfated alkyl oligosaccharides with potent inhibitory effects on human immunodeficiency virus infection.

Compounds with medium relative molecular masses active against human immunodeficiency virus (HIV) were synthesized. Sulfated alkyl oligosaccharides such as sulfated octadecyl maltohexaoside, sulfated dodecyl laminaripentaoside and sulfated dodecyl laminari-oligomer caused 50% inhibition of virus infection in the EC50 range of 0.4-0.7 microgram/mL in vitro using the MT-4 cell line and HIV-1HTLV-IIIB virus isolate, though sulfated oligosaccharides without alkyl groups showed low anti-HIV activities. This anti-HIV activity was close to the EC50 of 0.43 microgram/mL for a highly active sulfated polysaccharide curdlan sulfate which was reported to inhibit completely the HIV infection at a concentration as low as 3.3 micrograms/mL. These compounds were also active against HIV-2 and a clinically isolated HIV-1 with reduced AZT sensitivity. For such sulfated alkyl oligosaccharides, the mechanism of inhibition of HIV infection was assumed to be the inhibition of HIV binding to the cell and to some extent the interaction of the alkyl portion with the lipid bilayer of the virus.

Amino Acid Sequence↗
PubMed1976

Synthesis and properties of 35S, 14C and 3H labeled S-alkyl glycerol ethers and derivatives.

Radioactive S-alkyl glycerol ethers have been synthesized with 35S, 14C and 3H labels as well as 3H/35S double labels. The synthesized compounds were converted to various derivatives which can serve to characterize the S-alkyl glycerol ethers. These included the isopropylidene derivative, oxidation with periodate to the aldehyde followed by reduction with LiAlH4 to the alcohol, and reaction of the alcohol with acetic anhydride to form the acetate derivative. Chemical analysis, IR, NMR, zonal TLC profile scans and GLC showed all the products to be greater than 99% pure. The GLC behavior of the aldehyde and acetate derivatives of both S-alkyl glycerol ethers and O-alkyl glycerol ethers on EGSS-X was compared.

Carbon Radioisotopes↗
PubMed1992

A facile synthesis of 1-O-alkyl-2-(R)-hydroxypropane-3-phosphonocholine (lyso-phosphono-platelet activating factor).

The synthesis of 1-O-alkyl-2-(R)-hydroxypropane-3-phosphonocholine is described. An efficient alkylation procedure using (NaH/DMSO) catalysis is also described and applied to the synthetic scheme. The key intermediate 1-O-alkyl-2-(R)-O-benzyl-3-bromopropane was phosphonylated using tris(methylsilyl)phosphite; the resulting phosphonic acid was coupled to choline using trichloroacetonitrile/pyridine or triisopropylbenzenesulfonyl chloride/pyridine followed by catalytic hydrogenation to yield 1-O-alkyl-2(R)-hydroxypropane-3-phosphonocholine.

Indicators and Reagents↗