Four new compounds from Neoboletus magnificus

Abstract

Four new compounds, compounds 1, 2, 4, 6, along with two known compounds 3, 5, were isolated from the methanol extract of the fruiting body of Neoboletus magnificus. The structures of compounds were elucidated by HRMS and NMR spectroscopic methods. The in vitro anti-inflammatory activity of the isolated compounds was evaluated.     

Mass spectrometry of fluorocarbon‐labeled glycosphingolipids

A method for generation of novel fluorocarbon derivatives of glycosphingolipids (GSLs) with high affinity for fluorocarbon phases has been developed, and their potential applications to mass spectrometry (MS)‐based methodologies for glycosphingolipidomics have been investigated. Sphingolipid ceramide N‐deacylase (SCDase) is used to remove the fatty acid from the ceramide moiety, after which a fluorocarbon‐rich substituent (F‐Tag) is incorporated at the free amine of the sphingoid. In initial trials, a neutral GSL, globotriaosylceramide (Gb₃Cer), three purified bovine brain gangliosides, and four fungal glycosylinositol phosphorylceramides (GIPCs) were de‐N‐acylated, derivatized by prototype F‐Tags, and recovered by solid phase extraction on fluorocarbon‐derivatized silica (F‐SPE). The efficacy of SCDase treatment of GIPCs was here demonstrated for the first time. Compatibility with subsequent per‐N,O‐methylation was established for the F‐tagged Gb₃ Cer and purified gangliosides, and extensive mass spectra (MS¹ and MS²) consistent with all of the expected products were acquired. The potential use of F‐tagged derivatives for a comprehensive MS based profiling application was then demonstrated on a crude ganglioside mixture extracted from bovine brain. Finally, a simple trial in microarray format demonstrated fixation of F‐tagged G_M1 ganglioside to a fluorous glass surface, with the glycan intact and available for interaction with a fluorescent derivative of cholera toxin B chain. The methods described thus provide a new avenue for rapid GSL recovery or cleanup, potentially compatible with a variety of platforms for mass spectrometric profiling and structure analysis, as well as parallel analysis of functional interactions. Copyright © 2010 John Wiley & Sons, Ltd.     

A world of sphingolipids and glycolipids in the brain--novel functions of simple lipids modified with glucose

Glycosphingolipids (GSLs) are present on cell surface membranes and are particularly abundant in the brain. Since over 300-400 GSLs are synthesized from glucosylceramide (GlcCer), GlcCer is believed to only serve as the source of most GSLs, including sialic acid-containing GSLs or gangliosides, in the brain. Recent studies, however, suggest that GlcCer itself plays a role in the heat stress response, as it functions as a glucose donor for the synthesis of cholesterylglucoside, a lipid mediator in heat stress responses in animals. GlcCer in adipose tissues is also thought to be involved in mechanisms that regulate energy (sugar and lipid) metabolism. Our extensive structural study revealed an additional novel glucosylated membrane lipid, called phosphatidylglucoside, in developing rodent brains and human neutrophils. These lipids, all modified with glucose, are enriched in lipid rafts and play important roles in basic cellular processes. Here, I summarize the recent progress regarding these glucosylated lipids and their biosynthesis and regulation in the central nervous system (CNS).     

基于鞘脂组学技术探究布洛芬对斑马鱼脑组织的立体选择性影响

以斑马鱼成鱼为研究对象,借助于鞘脂组学技术,探究了一种新型手性环境污染物布洛芬对斑马鱼脑组织中鞘脂含量的影响。建立了超高效液相色谱-三重四极杆-线性离子阱复合质谱检测斑马鱼成鱼脑组织中46种鞘脂的定量方法。借助于该方法对经布洛芬外消旋体及对映体暴露后的斑马鱼脑组织中的46种鞘脂进行了定量分析,通过考察主成分分析（PCA）、正交偏最小二乘法分析（OPLS-DA）及显著性差异分析（P）筛选出差异代谢物。同时,结合组间差异分析的结果可知,环境水平的布洛芬会导致斑马鱼脑组织中鞘脂代谢发生紊乱,且布洛芬的对映体之间存在立体选择性毒性。     

鞘氨醇的化学

动植物细胞中鞘脂及其代谢产物鞘氨醇等具有多种生理作用，是生命体传递信息的化学信使。鞘氨醇等的合成在有机合成界形成了一个经久不衰的热潮，应用各种新技术的合成方法不断出现。本文主要综述了鞘氨醇等衍生脂质的化学研究，特别是它们的化学合成进展。     

营养盐对假微型海链藻中鞘脂合成的影响

丝氨酸棕榈酰转移酶(Serine Palmitoyltransferase, SPT)是鞘脂合成途径中的关键酶, 其表达水平的高低影响生物体内鞘脂的含量. 该实验利用荧光定量PCR和液相色谱―质谱技术分析了营养盐对假微型海链藻中SPT表达及鞘脂合成的影响. 结果表明: SPT在微藻细胞中的表达水平直接影响其鞘脂的合成, 且P饥饿促进SPT的表达和细胞内神经酰胺的合成, 进而影响假微型海链藻的生长; 而N饥饿抑制SPT的表达和细胞内神经酰胺的合成及假微型海链藻的生长.     

Characterization of novel myelin components 3-O-acetyl-sphingosine galactosylceramides by electrospray ionization Q-TOF MS and MS/CID-MS of Li+ adducts

Glycosphingolipids with R(f) values higher than those of monoglycosylceramides (MGCs) in normal phase HPTLC appear to be normal components of myelin. A series of such low polarity components, referred to as 'fast moving cerebrosides' (FMCs), have been isolated from rat brain, and two of these fractions (FMC-1 and FMC-2) were found to be novel derivatives of galactosylceramide (GalCer) exhibiting O-acetylation at the 3-hydroxy group of the sphingoid moiety, and incorporating either non-hydroxy or 2-hydroxy fatty-N-acylation (Dasgupta S, Levery SB, Hogan EL. J. Lipid Res. 2002; 43: 751-761). Similar to the parent compounds, the 3-O-acetyl-sphingoid derivatives exhibit considerable diversity with respect to fatty-N-acyl chain length, manifested by heterogeneous molecular ion (Li(+) adduct) profiles. However, a detailed analysis of the individual molecular variants ('lipoforms'), e.g. by tandem MS/CID-MS analysis, was not carried out. In addition, several other FMCs distinguished by even lower polarity (higher HPTLC R(f) values) were isolated but have remained uncharacterized. For this study, analysis of both the known and unknown FMC components was carried out by positive ion ESI-MS and MS/CID-MS of their Li(+) adducts on a Q-TOF mass spectrometer. Since a Q-TOF instrument has not yet been applied to MS of lithiated cerebrosides and FMCs, MS/CID-MS spectra of bovine brain GalCer (both types) and the previously characterized rat brain FMCs (FMC-1 and FMC-2), having 3-O-acetylation of the sphingoid, were systematically acquired and their fragmentation behavior compared. This was followed by systematic analysis of previously uncharacterized FMC fractions (FMC-3 through FMC-5/6/7). The GalCer and FMC components proved to be amenable to analysis by this technique, and the data confirm that the latter are all related 3-O-acetyl-sphingoid derivatives, with the higher R(f) components carrying additional O-acetyl modifications on the galactosyl residue, which further reduce their polarity. The utility of the technique, the structures of unknown FMCs, and their characteristic fragmentation patterns are described.