• Analytical Science and Technology
• /
• v.18 no.1
• /
• pp.85-88
• /
• 2005

Antiphase character of cross peaks in long-range COSY is modulated by changing the fixed delay time and used to assign diastereotopic methylene protons on rigid systems which could produce unpredictable NOE phenomena because of complicate coupling spins.

• Bulletin of the Korean Chemical Society
• /
• v.22 no.8
• /
• pp.789-790
• /
• 2001

• Journal of the Korean Magnetic Resonance Society
• /
• v.12 no.1
• /
• pp.14-25
• /
• 2008

To investigate the 3-bond connectivity of human brain metabolites by scalar coupling interaction through 2D-correlation spectroscopy (COSY) techniques using high field NMR spectroscopy. All NMR experiments were performed at 298K on Unity Inova 500 or 600 (Varian Inc.) equipped with a triple resonance probe head with z-shield gradient. Human brain metabolites were prepared with 10% $D_2O$. Two dimensional 2D COSY spectra were acquired with 4096 complex data points in $t_2$ and 128 or 256 increments in $t_1$ dimension. The spectral width was 9615.4 Hz and solvent suppression was achieved using presaturation using low power irradiation of the water resonance during 2s of relaxation delay. NMR data were processed using VNMRJ (Varian Instrument) software and all the chemical shifts were referenced to the methyl resonance of N-acetyl aspartate (NAA) peak at 2.0 ppm. Total 10 metabolites such as N-acetyl aspartate (NAA), creatine (Cr), choline (Cho), glutamine (Gln), glutamate (Glu), myo-inositol (Ins), lactate (Lac), taurine (Tau), ${\gamma}$-aminobutyricacid (GABA), alanine (Ala) were included for major target metabolites. Symmetrical 2D-COSY spectra were successfully acquired. Total 14 COSY cross peaks were observed even though there were parallel/orthogonal noisy peaks induced by water suppression. Except for Cr, all of human brain metabolites produced COSY cross peaks. The spectra of NAA methyl proton at 2.02 ppm and Glu methylene proton ($CH_2(3)$) at 2.11 ppm and Gln methylene proton ($CH_2(3)$) at 2.14 ppm were overlapped in the similar resonance frequency between 2.00 ppm and 2.15 ppm. The present study demonstrated that in vitro 2D-COSY represented the 3-bond connectivity of human brain metabolites by scalar coupling interaction. This study could aid in better understanding the interactions between human brain metabolites in vivo 2D-COSY study. Also it would be helpful to determine the molecular stereochemistry in vivo by using two-dimensional MR spectroscopy.

• Investigative Magnetic Resonance Imaging
• /
• v.12 no.1
• /
• pp.8-19
• /
• 2008

Purpose : To investigate the 3-bond and spatial connectivity of human brain metabolites by scalar coupling and dipolar nuclear Overhauser effect/enhancement (NOE) interaction through 2D- correlation spectroscopy (COSY) and 2D- NOE spectroscopy (NOESY) techniques. Materials and Methods : All 2D experiments were performed on Bruker Avance 500 (11.8 T) with the zshield gradient triple resonance cryoprobe at 298 K. Human brain metabolites were prepared with 10% $D_2O$. Two-dimensional spectra with 2048 data points contains 320 free induction decay (FID) averaging. Repetition delay was 2 sec. The Top Spin 2.0 software was used for post-processing. Total 7 metabolites such as N-acetyl aspartate (NAA), creatine (Cr), choline (Cho), lutamine (Gln), glutamate (Glu), myo-inositol (Ins), and lactate (Lac) were included for major target metabolites. Results : Symmetrical 2D-COSY and 2D-NOESY pectra were successfully acquired: COSY cross peaks were observed in the only 1.0-4.5 ppm, however, NOESY cross peaks were observed in the 1.0-4.5 ppm and 7.9 ppm. From the result of the 2-D COSY data, cross peaks between the methyl protons ($CH_3$(3)) at 1.33 ppm and methine proton (CH(2)) at 4.11 ppm were observed in Lac. Cross peaks between the methylene protons (CH2(3,$H{\alpha}$)) at 2.50ppm and methylene protons ($CH_2$,(3,$H_B$)) at 2.70 ppm were observed in NAA. Cross peaks between the methine proton (CH(5)) at 3.27 ppm and the methine proton (CH(4,6)) at 3.59 ppm, between the methine proton (CH(1,3)) at 3.53 ppm and methine proton (CH(4,6)) at 3.59 ppm, and between the methine proton (CH(1,3)) at 3.53 ppm and methine proton (CH(2)) at 4.05 ppm were observed in Ins. From the result of 2-D NOESY data, cross peaks between the NH proton at 8.00 ppm and methyl protons ($CH_3$) were observed in NAA. Cross peaks between the methyl protons ($CH_3$(3)) at 1.33 ppm and methine proton (CH(2)) at 4.11 ppm were observed in Lac. Cross peaks between the methyl protons (CH3) at 3.03 ppm and methylene protons (CH2) at 3.93 ppm were observed in Cr. Cross peaks between the methylene protons ($CH_2$(3)) at 2.11 ppm and methylene protons ($CH_2$(4)) at 2.35 ppm, and between the methylene protons($CH_2$ (3)) at 2.11 ppm and methine proton (CH(2)) at 3.76 ppm were observed in Glu. Cross peaks between the methylene protons (CH2 (3)) at 2.14 ppm and methine proton (CH(2)) at 3.79 ppm were observed in Gln. Cross peaks between the methine proton (CH(5)) at 3.27 ppm and the methine proton (CH(4,6)) at 3.59 ppm, and between the methine proton (CH(1,3)) at 3.53 ppm and methine proton (CH(2)) at 4.05 ppm were observed in Ins. Conclusion : The present study demonstrated that in vitro 2D-COSY and NOESY represented the 3-bond and spatial connectivity of human brain metabolites by scalar coupling and dipolar NOE interaction. This study could aid in better understanding the interactions between human brain metabolites in vivo 2DCOSY study.

• Applied Biological Chemistry
• /
• v.38 no.6
• /
• pp.577-580
• /
• 1995

During the screening for the antimicrobial agents against multidrug-resistant Staphylococcus aureus, we isolated an active compound produced by strain CNU30122. The active compound was purified from culture broth by HP-20 column chromatography, ethylacetate extraction. silica gel column and Sephadex LH-20 column chromatographies and HPLC. Based on various NMR studies including $^1H-^1H\;COSY$, $^1H-^{13}C\;COSY$ and HMBC experiments. the active compound was identified as fusidic acid.

• Korean Journal of Pharmacognosy
• /
• v.27 no.2
• /
• pp.123-128
• /
• 1996

From the leaves of Magnolia sieboldii a new aporphine-type alkaloid named magnoporphine was isolated. The structure of magnoporphine was all assigned by $^1H-^1H$COSY, $^1H-^{13}C$ COSY and $^1H-^{13}C$ long range NMR. In addition, costunolide, syringin, syringenin $4-O-{\beta}-cellobioside$ and echinacoside was isolated.

• Archives of Pharmacal Research
• /
• v.17 no.4
• /
• pp.284-286
• /
• 1994

A guaian type sesquiterpene, torilin, was isolated from the hexane extract of the fruits of Torilis japonica. The $^1H{\;}and{\;}^{13}C-sinals$ of this compound have been fully assigned utilizing $^1H-^1H$ COSY, HMQC, and HMBC experiments.

• Journal of Ginseng Research
• /
• v.19 no.1
• /
• pp.45-50
• /
• 1995

(20S)- and (20R)-protopanaxadiol were prepared from crude ginseng saponin by chemical treatment. The $^{1}H$- and $^{13}C$-NMR signals of these compounds were fully assigned by various NMR techniques such as DEPT, 1H-1H COSY, HMQC, HMBC and NOESY.

• Korean Architects
• /
• s.603
• /
• pp.80-89
• /
• 2019

• Journal of Life Science
• /
• v.9 no.2
• /
• pp.207-211
• /
• 1999

Biologically active compounds in Polygonatum sibiricum were extracted using organic solvents as hexane, CHCl$_3$, n-butanol corresponding each component. Compound I was purified from hexane layer and the chemical structure of compound I was characterized using 1H-NMR, 13C-NMR, DEPT135, COSY, HMQC, HMBC spectrum and MS-spectrum. Consequently, the chemical structure of compound I was determined as 9,12-(9E,l2E)-octade cadienoic acid.