Electrospray positive ionization tandem mass spectrometry of Amadori compounds

Full text of DOI:10.1002/jms.1290

JOURNAL OF MASS SPECTROMETRY
J. Mass Spectrom. 2008; 43: 262–264
Published online 12 October 2007 in Wiley InterScience
(www.interscience.wiley.com) DOI: 10.1002/jms.1290
JMS Letters
Dear Sir,
room temperature, the precipitates were removed by filtration (the
unreacted glucose and amino acid were filtered off). Each filtrate was
concentrated to approximately 15 ml in vacuo. Dropwise addition of
anhydrous acetone to the ice-cooled filtrate yielded the Amadori
product as a hygroscopic solid. Then the melted solids were filtered
out and washed with acetone a few times. The viscous solids were
transferred into a flask and acetone (8 ml) was added to the flask.
After the system was dried under reduced pressure, the amorphous
solids were obtained. The products were stored under nitrogen.
Owing to the hygroscopic nature of the Amadori products in air, all
solid compounds (1 mg) were quickly weighed and then dissolved
in water (100 ml), respectively. The solutions were used in the
following experiment.
Electrospray positive ionization tandem mass spectrometry of
Amadori compounds
The Maillard reaction, the nonenzymatic interaction between
reducing sugars and amino acids, is one of the most important
reactions in food and human bodies.1,2 Amadori compounds are
N-substituted 1-amino-1-deoxyketoses, which are formed in the
initial phase of the Maillard reaction by Amadori rearrangement,
representing a key class of Maillard intermediates.3,4 The importance
of Amadori compounds results from the fact that their formation as
well as decomposition can occur under physiological conditions
and during food processing and storage. Amadori compounds
The ESI-MS/MS spectra were obtained using the 4000 Q-
Trap mass spectrometer (AB/MDS Sciex, Concord, Canada). An
Agilent-1200 system including a quaternary pump, autosampler,
and thermostatted column compartment was integrated with the
play
a central role in the production of aroma, taste, and
color.5–9 Furthermore, it has been shown that these compounds
are accompanied by a reduction in the nutritive value and the
formation of toxic compounds, which have a remarkable effect on
the health of human, and so this type of compounds has attracted
considerable attention.10–13
Table 1. Optimized declustering potential and collision
Many methods have been used to analyze Amadori com-
pounds, such as gas chromatography with sample derivatization
prior to analysis,14 high-performance liquid chromatography,14
high-performance anion exchange chromatography with an electro-
chemical detector,15 and so on. However, the analysis of Amadori
compounds was still a challenging task because they are numer-
ous and their structures are similar. With the development of
soft ionization technology applied in the field of mass spectrom-
etry over the past decade, fast atom bombardment tandem mass
spectrometry16 and the coupling of tandem mass spectrometry to
capillary electrophoresis17 were successfully used to identify a few
glucose-derived Amadori compounds. Recently, electrospray ion-
ization tandem mass spectrometry has become an important means
of analysis of organic molecules. High-performance ion exchange
chromatography coupled to tandem mass spectrometry18 has been
applied to analyze several Amadori compounds. But the systemized
research of mass spectrometry of Amadori compounds and the frag-
mentation modes of the compounds under electrospray ionization
condition have not been developed yet. In this paper, the 18 Amadori
compounds were prepared from the reactions between the 18 com-
mon amino acids found in food and human bodies with glucose.
After purification by high-performance liquid chromatography, the
mass spectrometry (ESI-MS/MS) of these compounds was carried
out. Moreover, their main fragmentation pathways are summarized.
The preparation of Amadori compounds is shown in Scheme
1. Samples of individual Amadori compounds were prepared by
refluxing powdered anhydrous glucose (20 mmol), malonic acid
(5 mol), and the corresponding amino acid (20 mmol) in methanol
(30 ml) under nitrogen for 6 h. After the solutions were cooled to
energy of Amadori compounds
No.
Amadori compounds
DP (V)
CE (V)
1
2
3
4
5
Fru-Gly
Fru-Ala
Fru-Val
Fru-Leu
Fru-Ile
50
42
46
48
48
42
42
48
43
47
42
55
49
48
33
49
45
42
20
18
20
20
20
18
23
23
20
20
20
22
20
20
20
20
20
28
6
7
8
9
10
11
12
13
14
15
16
17
18
Fru-Pro
Fru-Phe
Fru-Tyr
Fru-Met
Fru-Ser
Fru-Thr
Fru-Try
Fru-Asn
Fru-Gln
Fru-Asp
Fru-Glu
Fru-His
Fru-Arg
Note: N-(1-deoxy-D-fructos-1-yl)glycine was abbreviated
as Fru-Gly. The same abbreviation method was appropri-
ate to other Amadori compounds.
ŁCorrespondence to: J. Wang, Technical Center, ChangYang Road
717#, Shanghai 200 082, P. R. China. E-mail: chwj75@163.com
CH2OH
O
OH
O
OH
CH2(COOH)2
MeOH
OH
+
H2N CHCOOH
R
OH
OH
OH
CHCOOH
R
NH
OH
OH
No. AA
No.
6
AA
No.
11
12
13
14
15
AA
No. AA
1
2
3
4
5
Gly
Ala
Val
Leu
Ile
Pro
Phe
Tyr
Met
Ser
Thr
Try
Asn
Gln
Asp
16
17
18
Glu
His
Arg
7
8
9
10
AA denotes amino acids.
Scheme 1. Preparation of the Amadori compounds.
Copyright  2007 John Wiley & Sons, Ltd.

JMS letters 263
Table 2. MS/MS spectral data of [M C H]C and the significant fragment ions of Amadori
compounds
Amadori
compounds
Precursor ion (m/z)
[M C H]C
Significant fragment ions
No.
[MS2] (m/z)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
Fru-Gly
Fru-Ala
Fru-Val
Fru-Leu
Fru-Ile
238
252
280
294
294
278
328
344
312
268
282
367
295
309
296
310
318
337
220, 202, 192, 184, 174, 156, 154, 88, 76
234, 216, 206, 198, 188, 170, 168, 102, 90
262, 244, 234, 226, 216, 198, 196, 130, 118
276, 258, 248, 240, 230, 212, 210, 144, 132
276, 258, 248, 240, 230, 212, 210, 144, 132
260, 242, 232, 224, 214, 196, 194, 128, 116
310, 292, 282, 274, 264, 246, 244, 178, 166
326, 308, 298, 290, 280, 262, 260, 194, 182
294, 276, 266, 258, 248, 230, 228, 162, 150
250, 232, 222, 214, 204, 186, 184, 118, 106
264, 246, 236, 228, 218, 200, 198, 132, 120
349, 331, 321, 313, 303, 283, 217, 205
277, 259, 249, 241, 231, 213, 211, 145, 133
291, 273, 263, 255, 245, 225, 159, 147
278, 260, 250, 242, 232, 214, 212, 146, 134
292, 274, 264, 256, 246, 228, 226, 160, 148
300, 282, 272, 264, 254, 236, 234, 168, 156
319, 301, 291, 283, 273, 187, 175
Fru-Pro
Fru-Phe
Fru-Tyr
Fru-Met
Fru-Ser
Fru-Thr
Fru-Try
Fru-Asn
Fru-Gln
Fru-Asp
Fru-Glu
Fru-His
Fru-Arg
Scheme 2. Proposed fragmentation pathways of Amadori compounds.
mass spectrometer. Purification of the Amadori samples was carried
out on a C-18 column (RESTEK Pinnacle-II, 5 µm, 250 ð 4.6 mm).
The elution condition was at a flow rate of 0.65 ml/min and the
mixture of 0.1% (V/V) aqueous formic acid (40%) with methanol
injection volume was 8 µl. The Amadori compounds were analyzed
in positive electrospray ionization mode using product ion (MS2)
°
experiment. The turbo ion-spray source was operated at 550 C with
an ion-spray voltage at 5500 V, curtain gas (N2) at 20 psi, ion source
nebulizer gas at 45 psi, ion source heater gas at 55 psi, and collision
°
(60%) as eluent. The column temperature was set at 25 C. The
Copyright  2007 John Wiley & Sons, Ltd.
J. Mass Spectrom. 2008; 43: 262–264
DOI: 10.1002/jms

264
JMS letters
gas at medium pressure. In the experiment, the entrance potential
was set at 10 V, collision cell exit potential at 10 V, focusing lens
at ꢀ11.0 V, and prefilter at ꢀ17.0 V. Declustering potential (DP)
and collision energy (CE) were optimized according to Amadori
compounds. The results of voltages are shown in Table 1. The Scan
time was equal to 1 s. Data were treated with the manufacturer’s
Analyst 1.4.1 software.
3. Hodge JE. The Amadori rearrangement. Advances in Carbohydrate
Chemistry and Biochemistry 1955; 10: 169.
4. Wrodnigg TM, Eder B. The Amadori and Heyns rearrangement:
landmarks in the history of carbohydrate chemistry or unrecog-
nized synthetic opportunities. Topics in Current Chemistry 2001;
215: 115.
5. Martins S, Jongen W, Boekel M. A review of Maillard reaction
in food and implications to kinetic modelling. Trends in Food
Science and Technology 2001; 11: 364.
The MS/MS tandem spectral data of the [M C H]C ions and
the significant fragment ions of the 18 Amadori compounds are
summarized in Table 2.
From the MS/MS spectral data of the Table 2, it was found
that the MS2 spectra of [M C H]C ions of the Amadori compounds
showed characteristic fragment ions at m/z [M C H ꢀ 18]C, [M C
H ꢀ 36]C, [M C H ꢀ 46]C, [M C H ꢀ 54]C, [M C H ꢀ 64]C, [M C
H ꢀ 82]C, [M C H ꢀ 84]C, [M C H ꢀ 150]C, and [M C H ꢀ 162]C.
According to the characteristic structure of the Amadori molecules,
in which there are carbonyl and hydroxide groups, the fragmentation
patterns can be deduced. The fragment ions at m/z [M C H ꢀ 18]C,
[M C H ꢀ 46]C, [M C H ꢀ 36]C, and [M C H ꢀ 64]C are [M C H ꢀ
H2O]C, [M C H ꢀ H2O ꢀ CO]C, [M C H ꢀ 2H2O]C, and [M C H ꢀ
2H2O ꢀ CO]C ions, respectively. The ions at m/z [M C H ꢀ 54]C,
[M C H ꢀ 82]C, and [M C H ꢀ 84]C belong to [M C H ꢀ 3H2O]C,
[M C H ꢀ 3H2O ꢀ CO]C and [M C H ꢀ 3H2O ꢀ H2CO]C ions. The
ions at m/z [M C H ꢀ 150]C and [M C H ꢀ 162]C are [AA ꢀ H C
CH2]C and [AA C H]C ions, which derive from the cleavage of
Amadori compounds between the sugar and amino acid moieties by
pathway aorpathway b. According to the observed rulesofcleavage,
the proposed fragmentation pathways of Amadori compounds are
summarized in Scheme 2.
After being further purified by high-performance liquid chro-
matography, the Amadori precursor ions have been selected in terms
of their mass and then every selected ion has been subjected to MS2.
The cleavage rules were summarized from the ESI-MS/MS spectra.
There are remarkable characteristic rules in the main fragmenta-
tion pathways of the positive ions of the Amadori compounds. The
rules are typical for the analysis and identification of Amadori com-
pounds. The positive ion ESI-MS/MS spectrometry is an excellent
method for the study of Amadori compounds.
6. Ames JM. Applications of the Maillard reaction in the food
chemistry. Food Chemistry 1998; 62: 431.
7. Blank I, Devaud S, Matthey-Doret W, Robert F. Formation of
odorants in Maillard systems based on L-Proline as affected by
PH. Journal of Agricultural and Food Chemistry 2003; 51: 3643.
8. Fogliano V, Monti SM, Musella T, Randazzo G, Ritieni A. For-
mation of coloured Maillard reaction products in a gluten-
glucose model system. Food Chemistry 1999; 66: 293.
¨
9. Homoki-Farkas P, Orsi F, Kroh LW. Methylglyoxal determina-
tion from different carbohydrates during heat processing. Food
Chemistry 1996; 59: 157.
10. Huyghues-Despointes A, Yaylayan VA, Keyhani A. Pyroly-
sis/GC/MS analysis of 1-[(20-carboxy)pyrrolidinyl]-l-deoxy-D-
fructose (Proline Amadori compound). Journal of Agricultural
and Food Chemistry 1994; 42: 2519.
11. Hofmann T, Bors W, Stettmaier K. Studies on radical intermedi-
ates in the early stage of the nonenzymatic browning reaction of
carbohydrates and amino acids. Journal of Agricultural and Food
Chemistry 1999; 47: 379.
12. Yaylayan VA, Huyghues-Despointes A. Chemistry of Amadori
rearrangement products: analysis, synthesis, kinetics, reactions
and spectroscopic properties. Critical Reviews in Food Science and
Nutrition 1994; 34: 321.
13. Davidek T, Clety N, Aubin S, Blank I. Degradation of the
Amadori compound N-(1-Deoxy-D-fructos -1-yl)glycine in aque-
ous model systems. Journal of Agricultural and Food Chemistry
2002; 50: 5472.
14. Eichner K, Reutter M, Wittmann R. In The Maillard Reaction
in Food Processing, Human Nutrition and Physiology, Finot PA,
Aeschbacher HU, Hurrel RF, Liardon R (eds). Birkha¨user Ver-
lag: Basel, 1990; 63.
Acknowledgements
This research project was partly supported by Shanghai Postdoctoral
Scientific Program (No. 06R214213).
15. Davidek T, Clety N, Devaud S, Robert F, Blank I. Simultaneous
quantitative analysis of Maillard reaction precursors and
products by high-performance anion exchange chromatography.
Journal of Agricultural and Food Chemistry 2003; 51: 7259.
16. Staempfli AA, Blank I, Fumeaux R, Fay LB. Study on the decom-
position of the Amadori compound N-(1-Deoxy-D-fructos -1-yl)-
glycine in model systems: quantification by fast atom bombard-
ment tandem mass spectrometry. Biological Mass Spectrometry
1994; 23: 642.
Yours,
JUN WANG,1,2Ł YI-MIN LU,2 BAI-ZHAN LIU2 and HE-YONG HE1
1
Department of Chemistry, Fudan University, Shanghai 200433, P. R. China
2
Technical Center, Shanghai Tobacco (Group) Company, Shanghai 200082,
P. R. China
17. Hau J, Devaud S, Blank I. Detection of Amadori compounds by
capillary eletrophoresis coupled to tandem mass spectrometry.
Electrophoresis 2004; 25: 2077.
18. Davidek T, Kraehenbuehl K, Devaud S, Robert F, Blank I. Anal-
ysis of Amadori compounds by high-performance cation
exchange chromatography coupled to tandem mass spectrome-
try. Analytical Chemistry 2005; 77: 170.
References
1. Hodge JE. Chemistry of browning reaction in model systems.
Journal of Agricultural and Food Chemistry 1953; 1: 928.
2. Ledl F, Schleicher E. New aspects of the Maillard reaction in
foods and in the human body. Angewandte Chemie International
Edition sin English 1990; 29: 565.
Copyright  2007 John Wiley & Sons, Ltd.
J. Mass Spectrom. 2008; 43: 262–264
DOI: 10.1002/jms