Activities of two key enzymes of gangliosides biosynthesis were determined in rat testes during development. GD3 synthase activity was low and showed small variations with age. GM2 synthase activity increased 10-fold in testes from 10- to 30-d-old animals, showing a maximum activity at 30 d, followed
by a small decrease until 45 d and then a constant activity up to adulthood. These developmental changes in the activity of
both glycosyltransferases were related to the increasing complexity in the ganglioside pattern observed in rats testes during
the period of sexual development. 相似文献
Gangliosides play a critical role in human brain development and function. Human breast milk (HBM) is an important dietary source of gangliosides for the growing infant. In this study, ganglioside concentrations were measured in the breast milk from a cross‐sectional sample of Chinese mothers over an 8‐month lactation period. The average total ganglioside concentration increased from 13.1 mg/l during the first month to 20.9 mg/l by 8 months of lactation. The average concentration during the typically solely breast‐feeding period of 1?6 months was 18.9 mg/l. This is the first study to report the relative distribution of the individual ganglioside molecular species through lactation for any population group. The ganglioside molecular species are made up of different fatty acid moieties that influence the physical properties of these gangliosides, and hence affect their function. The GM3 molecular species containing long‐chain acyl fatty acids had the most prominent changes, increasing in both concentration and relative distribution. The equivalent long‐chain acyl fatty acid GD3 molecular species typically decreased in concentration and relative distribution. The lactational trends for both concentration and relative distribution for the very long‐chain acyl fatty acid molecular species were more varied. The major GM3 and GD3 molecular species during lactation were d40:1 and d42:1, respectively. An understanding of ganglioside molecular species distribution in HBM is essential for accurate application of mass spectrometry methods for ganglioside quantification. 相似文献
Gangliosides are a large family of glycosphingolipids that are abundant in the brain, and have been shown to affect neuronal
plasticity during development, adulthood, and aging. We developed a fast, efficient, and sensitive liquid chromatography–mass
spectrometry method to quantify eight different classes of gangliosides (GM1, GM2, GM3, GD3, GD1a, GD1b, GT1b, GQ1b) in the brains of 2-day-old and 80-day-old Wistar rats. The gangliosides were extracted from rat brain using a modified Svennerholm
and Fredman method. After ganglioside class separation using a hydrophilic high performance liquid chromatography (HPLC) column,
the resolving power of the LTQ-Orbitrap™ mass spectrometer was used to extract and sum the major species of each ganglioside
class, generating fully resolved extracted ion current peaks for both standards and samples. The flexibility and the specificity
of this method are such that it can be applied to the analysis of other ganglioside species/classes not discussed in this
paper, provided appropriate standards are available. The method had good repeatability (coefficient of variation 4.8–12.3%)
and mean recoveries in the range 92–107%. 相似文献
Gangliosides from bovine optic nerve were analyzed. The optic nerve contained 129, 98, 97, 80, 31 and 12 μg of GM1, GD1a, GD1b, GT1b, GD3 and GQ1 gangliosides, respectively, per g of tissue wet wt. These 6 gangliosides altogether contributed 97% of the total sialic acid.
GM3 and GM2 gangliosides contributed the remaining 3% of total sialic acid. Stearoyl (18∶0) was the predominant acyl group (61–76%) in
all gangliosides. There was a marked variation in acyl group composition between GT1 and most of the other major gangliosides except GD3. In comparison to the other gangliosides, GT1 contained a lower proportion of the stearoyl group and a higher proportion of the oleoyl, nervonoyl and the long chain acyl
groups. Both GT1 and GD3 gangliosides contained proportionately higher levels of long chain acyl groups (20∶0→24∶0) than did other gangliosides. GD3 gangliosides showed 2 bands on thin layer chromatography, and the upper band was more distinct than the lower band. 相似文献
Acetone powders of fresh-frozen pineals were extracted with chloroform/methanol mixtures. By column chromatography on silicic
acid, mild alkaline methanolysis, ion-exchange high performance liquid chromatography and a final thin layer chromatography
on silicic acid, the major glycosphingolipids were purified from the extracts of a total of 300 bovine pineal bodies. Chromatographically
purified fractions were characterized by gas chromatographic analysis. The most prominent glycosphingolipid appeared to be
cerebroside. In addition, five different gangliosides were found in detectable levels. The two major gangliosides have the
chromatographic and component characteristics of GD3 and GM3, with disialoganglioside predominating. Gangliosides indistinguishable from purchased standards of GM1 and GD1a were third and fourth, respectively, in amount. The fatty acid profiles of the two lactosyl gangliosides are similar and
significantly different from those of the two gangliotetraose gangliosides. The fifth most prominent ganglioside, present
at a level of 1.09% of total recovered ganglioside sialic acid, appears to be a novel trisialoganglioside, called GTx. This new molecule has a component ratio of gal:glc:sialic acid:amino sugar of approximately 1∶2∶3∶1. Similarities between
bovine pineal and rod outer segments are discussed. 相似文献
The viscosity of plasma and extracellular fluid has been shown to be a regulator of lipoprotein production both in cultured
hepatocytes and in vivo. The possibility that this extracellular effect on cell function involves modulation of cell surface
membrane components was examined. In the present work, we studied the effect of medium viscosity on liver cell gangliosides
known to be involved in various membrane functions and to be located predominantly at the cell surface membrane. Cultivation
of isolated hepatocytes as primary cultures markedly reduced the ganglioside content, but this reduction process was attenuated
by increasing the viscosity of the culture medium. Elevation of extracellular fluid viscosity inhibited the degradation of
the cell gangliosides and secretion of lysosomal enzymes involved in ganglioside degradation. The cellular activity of these
enzymes as well as the activity of enzymes involved in ganglioside synthesis, CMP-NANA:GM1 sialyltransferase, CMP-NANAP:GM3 sialyltransferase and UDP-galactose:GD2 galactosyltransferase, were not affected bymodulation of the extracellular medium viscosity. It is proposed that the modulation
of cell ganglioside content by extracellular fluid viscosity is due to an effect on enzymes involved in ganglioside catabolism. 相似文献
The transfer hydrogenation of 2‐substituted bicyclic and monocyclic ketimines using HCO2H/ Et3N as the hydrogen source and TsDPEN‐based Ru(II) and Ir(III) catalysts proceeds with dynamic kinetic resolution to afford the corresponding cis‐cycloalkylamines with moderate to excellent levels of diastero‐ and enantioselectivity. A “one‐pot” procedure starting from ketones as starting materials with in situ formation of the reacting imines has also been developed. 相似文献
The ganglioside and neutral glycosphingolipid composition of adult monkey small and large intestinal mucosa were characterized
and compared. GM3, GM2 and GD1A were found to be the principal gangliosides in each of these tissues. Dihexosylceramide was the major neutral glycosphingolipid
of both organs. The total content of gangliosides and neutral glycolipids/ceramide, however, was ca. four-fold and two-fold
higher, respectively, in small intestinal than colonic mucosa.
While all glycosphingolipids examined contained hydroxy and nonhydroxy fatty acids, the former fatty acids accounted for 60–90%
of the total fatty acids in both organs. Sphingosine was the predominant long chain base of ceramide, mono-, di-, tri- and
tetrahexosylceramide, whereas phytosphingosine was the major base of GM3 in both tissues. The results of these studies demonstrate that while many similarities of monkey small and large intestinal
glycosphingolipids exist, qualitative and quantitative differences are present along the length of the monkey gut. These differences
may be at least partially responsible for certain of the well-recognized variations in normal physiological and pathological
processes that occur in these organs. 相似文献
The ganglioside and neutral glycosphingolipid composition of fetal and adult sheep colonic mucosa were characterized and compared.
Mono- and tetrahexosylceramide were the major neutral glycolipids of both fetal and adult colons. Adult, but not fetal, mucosa
also possessed di- and trihexosylceramide. Similarly, GD1a, GM3 and GM2 were found to be the principal gangliosides in fetal and adult tissue. Adult colonic mucosa possessed significant amounts
of GT1a not present in fetal tissue.
Analysis of the hydroxy and nonhydroxyfatty acids as well as of the long chain bases of the major glycosphingolipids revealed
differences between these lipophilic components of glycolipids in fetal and adult colonic mucosa. The present results, therefore,
indicate that both quantitative and qualitative differences in glycosphingolipid composition exist between fetal and adult
sheep colonic mucosa. 相似文献
Mixed brain gangliosides or individual ganglioside GM1 were dissolved in one of the following solvents: (a) water, (b) 0.1 M aqueous KC1, or (c) methanol-aqueous 0.1 M KC1 at concentrations
ranging from 10−8 to 10−3 M, and were submitted to dialysis against distilled water for up to 4 days. No significant loss of gangliosides on dialysis
was observed when gangliosides were dissolved in water or 0.1 M aqueous KC1, but a loss occurred when the ganglioside solution
contained methanol; the loss was greater at the lowest ganglioside concentration. However, losses ceased to occur after 1
day when methanol was removed from the dialysis sac. 相似文献
α‐Substituted β‐acetyl amides could undergo C C bond cleavage to form α‐keto amides when treated with copper(II) chloride (CuCl2) and boron trifluoride diethyl etherate (BF3⋅OEt2) under an oxygen atmosphere. The yield can be increased by the addition of tert‐butyl hydroperoxide which alone can also effect the reaction. The reaction provides a new protocol for the synthesis of α‐keto amides.
The goal of this work was to alter the composition of amide-linked FA of bovine buttermilk gangliosides, particularly the
disialoganglioside GD3, to adjust lipid sources to special food specifications and pharamacological or cosmetic applications. The chemical transacylation
of amide-linked FA of buttermilk gangliosides with free arachidic acid (20∶0) by a combination of basic hydrolysis and diethylphosphorylcyanide/triethylamine-catalyzed
reacylation was compared to an enzymatic sphingolipid ceramide N-deacylase (EC 3.5.1.23)-catalyzed FA exchange by GC analysis
and nano electrospray ionization-MS. The buttermilk predominantly contained the disialoganlioside GD3 and the monosialoganglioside GM3. The heterogeneity of FA that are incorporated into gangliosides, mainly palmitic acid (29.4 wt%), stearic acid (16.9 wt%),
oleic acid (17.8 wt%), and myristic acid (8.5 wt%), was effectively altered by both transes-terification techniques. Arachidic
acid, which was not integrated into the initial buttermilk gangliosides, was transacylated to total gangliosides with 23.2
wt% (GD3, 6.7 wt%) by the chemical process and with 8.7 wt% (GD3, 13.8 wt%) when catalyzed enzymatically. Mainly behenic acid and lignoceric acid of GD3 were exchanged chemically, and stearic acid was exchanged by the enzymatic process. This observation might depend on hydrolytic
sensitivities of amide-linked very long chain saturated FA or specific enzyme subtrate affinities, respectively. Results of
chemical hydrolysis indicated there was a risk of sialic acid decomposition and unspecific degradations. Regarding specificity
and avoidance of critical agents, the enzymatic transesterification is recommended for industrial-scale production of consumer
goods. 相似文献
The reaction of the Cu(II) bis N,O‐chelate‐complexes of L‐2,4‐diaminobutyric acid, L‐ornithine and L‐lysine {Cu[H2N–CH(COO)(CH2)nNH3]2}2+(Cl–)2 (n = 2–4) with terephthaloyl dichloride or isophthaloyl dichloride gives the polymeric complexes {‐OC–C6H4–CO–NH–(CH2)n–CH(nh2)(COO)Cu(OOC)(NH2)CH–CH2)n–NH‐}x 1 – 5 . From these the metal can be removed by precipitation of Cu(II) with H2S. The liberated ω,ω′‐N,N′‐diterephthaloyl (or iso‐phthaloyl)‐diaminoacids 6 – 10 react with [Ru(cymene)Cl2]2, [Ru(C6Me6)Cl2]2, [Cp*RhCl2]2 or [Cp*IrCl2]2 to the ligand bridged bis‐amino acidate complexes [Ln(Cl)M–(OOC)(NH2)CH–(CH2)nNH–CO]2–C6H4 11 – 14 . 相似文献
The highly catalytic asymmetric α‐hydroxylation of 1‐tetralone‐derived β‐keto esters and β‐keto amides using tert‐butyl hydroperoxide (TBHP) as the oxidant was realized by a chiral N,N′‐dioxide‐magnesium ditriflate [Mg(OTf)2] complex. A series of corresponding chiral α‐hydroxy dicarbonyl compounds was obtained in excellent yields (up to 99%) with excellent enantioselectivities (up to 98% ee). The products were easily transformed into useful building blocks and the precursor of daunomycin was achieved in an asymmetric catalytic way for the first time. 相似文献
Feline omental lipid extracts, previously reported to be angiogenic in the cornea of rabbits, were fractionated and the major
lipid components characterized. Approximately 97% of the chloroform/methanol extract consisted of triglycerides containing
primarily 16∶0, 18∶0, 18∶1 and 18∶2 fatty acids. Trace quantities of free fatty acids, cholesterol, di- and monoglycerides
were also detected. The phospholipid fraction, obtained by solvent partition and Unisil column chromatography and characterized
by high performance liquid chromatography (HPLC)-mass spectrometry, was found to consist of phosphatidylcholine, sphingomyelin,
phosphatidylethanolamine and phosphatidylserine. The neutral glycolipids, isolated by solvent partition and Unisil column
chromatography and identified by high performance thin layer chromatography and HPLC of their perbenzoylated derivatives,
were found to consist of glucosyl- and galactosylceramides, galabiosylceramide, lactosylceramide, globotriaosylceramide and
globotetraosylceramide. The complex glycolipid fraction, obtained from Folch upper phase solvent partition, was found to consist
primarily of Forssman glycolipid and gangliosides GM3 and GD3. Smaller amounts of GM1 and other unidentified gangliosides were also present.
The ganglioside nomenclature is according to the system of Svennerholm (J. Neurochem. 10, 613–623, 1963) 相似文献
The activation of 1,2‐diols through formation of boronate esters was found to enhance the selective oxidation of 1,2‐diols to their corresponding α‐hydroxy ketones in aqueous medium. The oxidation step was accomplished using dibromoisocyanuric acid (DBI) as a terminal chemical oxidant or an electrochemical process. The electrochemical process was based on the use of platinum electrodes, methylboronic acid [MeB(OH)2] as a catalyst and bromide ion as a mediator. Electro‐generated OH− ions (EGB) at the cathode acted as a base and “Br+” ion generated at the anode acted as an oxidant. Various cyclic and acyclic 1,2‐diols as substrates were selectively oxidized to the corresponding α‐hydroxy ketones via their boronate esters by the two oxidative methods in good to excellent yields.
Condensation products of L‐histidine with the 3‐oxoenolethers diethyl‐ethoxymethylene‐malonate ( 1 ) and ethyl‐ethoxymethylene‐cyanoacetate ( 2 ) react with copper(II) as di‐anionic ligands to give neutral 1:1 complexes Cu‐ His1 and Cu‐ His2 . Both complexes crystallize as oligonuclear units, even from strongly donating solvents like N‐methylimidazole (Meim) (Cu‐ His1 ) and pyridine (Cu‐ His2 ). X‐ray structure analyses show supramolecular structures, formed of two (Cu‐ His1 ) or four (Cu‐ His2 ) formula units of the complex, which arrange to macrocycles by means of intermolecular coordination of the imidazole‐N. Strong H‐bridges result in a face‐to‐face orientation of the hydrophilic sites of two great rings. ESI‐MS investigations in pyridine solution give evidence for the existence of dimeric, tetrameric and – in case of Cu‐ His2 – trimeric units, besides the monomeric adducts with one pyridine. In contrast to the dimeric or tetrameric (“cubane‐like”) copper(II) complexes of amino alcohols and their β‐ketoenamines, the complexes Cu‐ His1 and Cu‐ His2 show no significant spin coupling from room temperature down to 4 K. The complexes Cu‐ His1 and Cu‐ His2 give no electrochemically reversible CuII/I reduction in pyridine. However, the isolation of a stable diamagnetic copper(I) complex of the methylester derivative, CuI‐ HisMe1 , supports the assumption, that similar histidine‐derived copper complexes should display reversible redox behaviour and catalytic activity in reactions with O2. 相似文献
The ytterbium(III) triflate [Yb(OTf)3]‐catalyzed diastereoselective cascade reaction of m‐N,N‐dimethylaminophenyl α,β‐unsaturated carbonyls with cyclopropane 1,1‐diesters under mild reaction conditions afforded highly substituted cis‐ and trans‐tetralins. The reaction of m‐N,N‐dimethylaminophenyl α,β‐unsaturated ketones with cyclopropane 1,1‐diesters provided tetralins with a trans orientation of the 1,4‐substitutents on the cyclohexyl ring; cis‐tetralins were obtained from m‐N,N‐dimethylaminophenyl substituted methylidenemalonates with high diastereoselectivities.
The formation of 4‐alkoxy‐2(5H)‐furanones was achieved via tandem alkoxylation/lactonization of γ‐hydroxy‐α,β‐acetylenic esters catalyzed by 2 mol% of [2,6‐bis(diisopropylphenyl)imidazol‐2‐ylidine]gold bis(trifluoromethanesulfonyl)imidate [Au(IPr)(NTf2)]. The economic and simple procedure was applied to a series of various secondary propargylic alcohols allowing for yields of desired product of up to 95%. In addition, tertiary propargylic alcohols bearing mostly cyclic substituents were converted into the corresponding spiro derivatives. Both primary and secondary alcohols reacted with propargylic alcohols at moderate temperatures (65–80 °C) in either neat reactions or using 1,2‐dichloroethane as a reaction medium allowing for yields of 23–95%. In contrast to [Au(IPr)(NTf2)], reactions with cationic complexes such as [2,6‐bis(diisopropylphenyl)imidazol‐2‐ylidine](acetonitrile)gold tetrafluoroborate [Au(IPr)(CH3CN)][BF4] or (μ‐hydroxy)bis{[2,6‐bis(diisopropylphenyl)imidazol‐2‐ylidine]gold} tetrafluoroborate or bis(trifluoromethanesulfonyl)imidate – [{Au(IPr)}2(μ‐OH)][X] (X=BF4, NTf2) – mostly stop after the alkoxylation. Analysis of the intermediate proved the exclusive formation of the E‐isomer which allows for the subsequent lactonization. 相似文献
Triterpenes of betulinic acid type exhibit many interesting biological activities. Therefore a series of new 3α‐hydroxy‐lup‐20(29)‐ene‐23,28‐dioic acid derivatives 2a—22 with putative pharmacological activities were synthesized. As starting compounds 3α‐hydroxy‐lup‐20(29)‐ene‐23,28‐dioic acid ( 1a ), isolated from Schefflera octophylla, or its 3‐O‐acetyl derivative 1b were used. Mono‐ and diesters ( 2a—b from 1a , and 4d from 4c ) were prepared with CH2N2. Oxidation of the isopropenyl side chain with OsO4 yielded the 20,29‐diols ( 4a—b from 1b , and 19 from 17 ), which were in the case of 4b further transformed to the 29‐norketones 8a/mdash;b . Oxidation of the isopropenyl side chain with m‐chloroperbenzoic acid afforded the 20,29‐epoxide 12 (from 1b ) and the 29‐aldehydes and a‐hydroxy aldehydes ( 13a—c from 2a, 14a—c from 2b , and 16a—c from 15a ). Ring A was modified by a tosylation—elimination sequence using p‐TsCl/NaOAc, which afforded diolefin 15a (from 2a ) with Δ2,20(29) double bonds or 23‐nor‐Δ3,20(29)diolefin 17 (from 1a ). Compounds 4b, 4c , and 8a were coupled with L ‐methionin, L ‐phenylalanin, L ‐alanin, L ‐serin, and L ‐glutaminic acid via amide bonds at positions 23 and 28 to afford the amino acid conjugates 5a—7b and 9a—11 . 相似文献