Structural analysis of leech galactocerebrosides using 1D and 2D NMR spectroscopy, gas chromatography–mass spectrometry, and FAB mass spectrometry1

Zipser, Birgit; Bradford, James J; Hollingsworth, Rawle I.

doi:10.1016/s0008-6215(98)00055-x

Cited by 6 publications

(4 citation statements)

References 18 publications

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“…In particular, cerebrosides, whose head groups have OH groups exposed at the surface of phospholipid cell membranes, are a major lipid component of WM and are 4‐fold more abundant in WM than GM (34, 35). These lipids, whose OH groups have substantial frequency shifts (36), have been shown to cause large magnetization transfer effects that have been attributed to chemical exchange (34) based on their pH‐dependence. As well as being affected by pH, chemical exchange rates are affected by temperature and tissue oxygenation (33, 37).…”

Section: Discussionmentioning

confidence: 99%

The contribution of chemical exchange to MRI frequency shifts in brain tissue

Shmueli

Dodd

et al. 2010

Magnetic Resonance in Med

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Recent high-field MRI studies based on resonance frequency contrast have revealed brain structure with unprecedented detail. Although subtle magnetic susceptibility variations caused by iron and myelin seem to be important to this contrast, recent research on protein solutions suggests that chemical exchange between water and macromolecular protons may contribute substantially to the observed gray-white matter frequency contrast. To investigate this, we performed spectroscopic MRI experiments at 14 T on samples of fixed human visual cortex and fresh pig brain. To allow direct observation of any exchange-induced frequency shifts, these samples were soaked in reference chemicals (TSP and dioxane) that are assumed not to be involved in exchange. For both fresh and fixed tissues and with both reference chemicals, substantial negative exchange-induced gray-white matter frequency contrast (-6.3 to -13.5 ppb) was found, whereas intracortical contrast was negligible. The sign of the graywhite matter exchange-induced frequency difference was opposite to the overall gray-white matter frequency difference observed in vivo. This suggests that exchange contributes to, but is not sufficient to explain, the frequency contrast in vivo and tissue susceptibility differences may have a greater contribution than previously thought. The exchange-dependent contribution may report on tissue chemical composition and pH. Magn Reson Med 65:35-43,

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Section: Discussionmentioning

confidence: 99%

The contribution of chemical exchange to MRI frequency shifts in brain tissue

Shmueli

Dodd

et al. 2010

Magnetic Resonance in Med

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“…Scrutiny of GC, FAB-MS, and 1D and 2D NMR data allowed a partial characterization of the structures composed typically of a β-galactose motif and a ceramide residue carrying an unusual polyunsaturated sphingosine chain 2-amino-1,3-dihydroxydocosatriene. 60 This is the first report describing the isolation of cerebrosides without any phosphocholine-related motif.…”

Section: Annelidamentioning

confidence: 95%

The cerebrosides

Tan

Chen

2003

Nat. Prod. Rep.

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“…An increased interest in the clinical use of leeches as an adjunct to modern medical and surgical therapy has created a need to determine various methods of analysis of bio-molecules such as lipids in H. manillensis. Several chromatographic studies have been published for the determination of bio-molecules in the medicinal leech, based on gas-liquid chromatography (GLC) (16,17,18,19), high-performance liquid chromatography (9,11), high-performance thin-layer chromatography (21,22,23), thinlayer chromatography (TLC) (20) and mass spectroscopy (16,19,20); however, there are no reported methods regarding stability-indicating analysis of free sterols in the Asian medicinal leech, H. manillensis. Hence, in the present investigation, we have proposed a stability-indicating validated analytical methodology for the estimation of lipids with reference to cholesterol in the extract of Asian medicinal leech (H. manillensis).…”

Section: Introductionmentioning

confidence: 99%

“…Zipser et al used TLC, one-dimensional and two-dimensional nuclear magnetic resonance spectroscopy (double quantum filtered-correlated spectroscopy and heteronuclear multiple quantum coherence), gas chromatography-mass spectroscopy and fast-atom-bombardment mass spectrometry (FABMS) to prove that cholesterol is the major free sterol present in H. medicinalis (16,19). Additionally, TLC analysis by Rabinowitz determined free fatty acids and phophatidic acid as the largest groups of lipids (20).…”

Section: Introductionmentioning

confidence: 99%

Development and Validation of a Stability-Indicating Method for Determination of Free Sterols in the Asian Medicinal Leech Hirudo manillensis

Hasan¹,

Khar²,

Ahmad³

et al. 2012

Journal of Chromatographic Science

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A rapid, simple, sensitive, selective, precise and robust thin-layer chromatography densitometric method for the determination of free sterols in leech was developed and validated on silica gel layer using carbon tetrachloride-methanol-formic acid (9.5:1.5:0.55, v/v/v). Spectrodensitometric scanning was carried using a Camag TLC scanner III at 366 nm after spraying 2% methanolic sulphuric acid, which gave compact spots for cholesterol (R(F) = 0.35 ± 0.02). The regression analysis data for calibration plot implied a good linear relationship (r(2) = 0.99958) between response and concentration over the range 100-600 ng per spot with respect to peak area. The limits of detection and quantification were found to be 13.8 ± 0.51 and 45.01 ± 1.29 ng per spot, respectively. Validation was in accordance to the International Conference on Harmonization guidelines. Cholesterol was subjected to forced stress conditions of oxidation, hydrolysis and heat. Degradation products resulting from the forced stress did not interfere with detection because the degradant peaks were well separated from the cholesterol peak. The densitometric method can be regarded as stability-indicating and can be used for quality control assay of cholesterol in leech extract.

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Structural analysis of leech galactocerebrosides using 1D and 2D NMR spectroscopy, gas chromatography–mass spectrometry, and FAB mass spectrometry1

Cited by 6 publications

References 18 publications

The contribution of chemical exchange to MRI frequency shifts in brain tissue

The contribution of chemical exchange to MRI frequency shifts in brain tissue

The cerebrosides

Development and Validation of a Stability-Indicating Method for Determination of Free Sterols in the Asian Medicinal Leech Hirudo manillensis

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