Retro-Aldol and Redox Reactions of Amadori Compounds
J. Agric. Food Chem., Vol. 44, No. 3, 1996 673
Ta ble 1. Ma ss Sp ectr om etr ic Da ta
1-(1′-p yr r olid in yl)-2-p r op a n on e (2)
from pyrolysis of Amadori proline: 127 (2), 85 (06), 84 (100), 82 (2), 56 (07), 55 (20), 54 (3), 43 (07), 42 (43), 41 (07)
from acetol/ pyrrolidine reaction mixture: 127 (2), 85 (07), 84 (100), 82 (2), 56 (07), 55 (19), 54 (3), 43 (07), 42 (42), 41 (07)
from pyruvaldehyde/proline/formic acid reaction mixture: 127 (1), 85 (06), 84 (100), 82 (1), 56 (06), 55 (19), 54 (2), 43 (07), 42 (43), 41 (06)
from pyrolysis of 1-(prolino)-1-deoxy-D-glyceraldehyde: 127 (2), 85 (07), 84 (100), 82 (2), 56 (07), 55 (18), 54 (3), 43 (07), 42 (41), 41 (08)
from glycerladehyde/pyrrolidine reaction mixture: 127 (2), 85 (06), 84 (100), 82 (2), 56 (06), 55 (18), 54 (3), 43 (06), 42 (39), 41 (06)
from dihydroxyacetone/pyrrolidine reaction mixture: 127 (2), 85 (06), 84 (100), 82 (2), 56 (06), 55 (18), 54 (3), 43 (06), 42 (39), 41 (06)
literature data:a 127 (2), 85 (06), 84 (100), 82 (2), 56 (06), 55 (18), 54 (3), 43 (07), 42 (31), 41 (04)
2-h yd r oxy-1-(1′-p yr r olid iyl)-1-bu ten -3-on e (3)
from Amadori proline: 155 (72), 138 (10), 137 (12), 126 (8), 112 (96), 84 (100), 83 (27), 70 (74), 57 (14), 56 (30), 55 (41), 43 (66), 42 (50)
literature data:a 155 (67), 138 (09), 137 (11), 126 (7), 112 (97), 84 (100), 83 (26), 70 (64), 57 (11), 56 (24), 55 (36), 43 (52), 42 (55)
2-h yd r oxy-1-(N-m or p h olin o)-1-bu ten -3-on e
from Amadori morpholine: 172 (2), 171 (21), 127 (8), 126 (2), 112 (12), 100 (100), 98 (7), 86 (11), 85 (8), 84 (5), 83 (4), 70 (35), 57 (5), 56
(17), 55 (18), 43 (20), 42 (24), 41 (17)
3-(1′-p yr r olid in yl)-2-bu ta n on e (4)
from 3-hydroxy-2-butanone/proline reaction mixture: 141 (0.4), 99 (8), 98 (100), 70 (4), 69 (7), 68 (2), 56 (27), 55 (9), 54 (4), 42 (7), 41 (8)
from pyrolysis of proline Amadori: 141 (0.2), 99 (8), 98 (100), 70 (4), 69 (8), 68 (2), 56 (30), 55 (9), 54 (4), 42 (7), 41 (9)
1-(N-m or p h olin o)-2-p r op a n on e (6)
from pyrolysis of Amadori morpholine: 143 (2), 115 (4), 101 (6), 100 (100), 86 (2), 85 (2), 70 (11), 57 (6), 56 (33), 55 (2), 54 (2),
43 (11), 42 (22), 41 (1)
from morpholine/acetol reaction mixture: 143 (2), 115 (1), 101 (7), 100 (100), 86 (1), 85 (2), 70 (12), 57 (3), 56 (32), 55 (2),
54 (2), 43 (11), 42 (20), 41 (8)
d i-TMS of 1-(p r olin o)-1-d eoxy-D-glycer a ld eh yd e (7)
from pyrolysis of Amadori proline: 332 (1), 331 (3), 316 (6), 288 (2), 258 (1), 216 (3), 215 (10), 214 (56), 202 (5), 201 (16), 200 (100),
189 (2), 186 (8), 174 (1), 173 (2), 172 (13), 170 (1), 156 (1), 147 (1), 142 (11), 130 (3), 129 (17), 103 (18), 96 (8), 83 (7), 82 (8), 75 (11), 74 (4),
73 (40), 70 (4), 68 (2), 61 (2), 59 (4), 58 (2), 55 (14), 54 (3), 45 (7), 43 (3), 42 (4)
1-(N-m or p h olin o)-1-d eoxy-D-glycer a ld eh yd e
from pyrolysis of Amadori morpholine: 159 (0.5), 129 (0.2), 114 (2), 101 (6), 100 (100), 87 (2), 86 (2), 85 (2), 72 (3), 70 (8), 57 (6), 56 (22),
55 (3), 44 (5), 43 (13), 42 (16)
1, 2-(1′,1′-d ip yr r olid in yl)-1-p r op en e (10)
from pyrolysis of glyceraldehyde/proline mixture: 181 (14), 180 (100), 179 (2), 165 (3), 152 (8), 151 (16), 150 (3), 139 (9), 138 (11), 137
(47), 136 (8), 135 (2), 134 (3), 125 (9), 124 (20), 123 (70), 122 (23), 121 (3), 120 (3), 112 (5), 111 (61), 110 (68), 109 (47), 108 (20), 107 (2),
106 (2), 98 (11), 97 (29), 96 (56), 95 (15), 94 (8), 93 (2), 85 (3), 84 (40), 83 (70), 82 (27), 81 (20), 80 (10), 79 (3), 71 (4), 70 (38), 69 (25), 68
(40), 67 (9), 66 (3), 56 (17), 55 (33), 54 (19), 53 (7), 52 (2), 44 (3), 43 (9), 42 (42), 41 (43)
from acetol/2× pyrrolidin reaction mixture: 181 (13), 180 (100), 179 (7), 165 (4), 152 (7), 151 (15), 150 (4), 139 (8), 138 (9), 137 (42), 136
(7), 135 (2), 134 (2), 125 (8), 124 (18), 123 (63), 122 (22), 121 (2), 120 (3), 112 (5), 111 (61), 110 (64), 109 (46), 108 (20), 107 (2), 106 (2), 98
(10), 97 (27), 96 (54), 95 (15), 94 (9), 93 (2), 85 (3), 84 (43), 83 (72), 82 (26), 81 (20), 80 (10), 79 (3), 71 (5), 70 (39), 69 (25), 68 (40), 67 (9),
66 (3), 56 (17), 55 (35), 54 (21), 53 (8), 52 (3), 44 (3), 43 (10), 42 (47), 41 (48)
1,2-(N,N-d im or p h olin o)-1-p r op en e
from Amadori morpholine: 213 (13), 212 (100), 167 (3), 155 (5), 154 (35), 153 (32), 140 (7), 139 (36), 138 (7), 129 (7), 128 (6), 127 (45), 126
(26), 125 (13), 124 (7), 123 (8), 114 (5), 113 (5), 112 (27), 111 (4), 110 (11), 109 (10), 108 (4), 100 (35), 98 (9), 97 (18), 96 (66), 95 (32), 94 (7),
86 (14), 85 (11), 84 (19), 83 (16), 82 (23), 81 (6), 80 (6), 70 (18), 69 (25), 68 (22), 67 (9), 58 (3), 57 (9), 56 (28), 55 (30), 54 (19), 45 (9), 44 (8),
43 (19), 42 (41), 41 (36)
from acetol/2× morpholine reaction mixture: 213 (13), 212 (100), 167 (2), 155 (5), 154 (36), 153 (33), 140 (8), 139 (38), 138 (6), 129 (7),
128 (6), 127 (48), 126 (27), 125 (13), 124 (6), 123 (8), 114 (7), 113 (5), 112 (29), 111 (4), 110 (11), 109 (10), 108 (4), 100 (38), 98 (11), 97 (20), 96
(70), 95 (33), 94 (8), 86 (15), 85 (11), 84 (21), 83 (17), 82 (26), 81 (6), 80 (6), 70 (19), 69 (27), 68 (24), 67 (9), 58 (4), 57 (10), 56 (32), 55 (33),
54 (19), 45 (10), 44 (12), 43 (20), 42 (47), 41 (40)
a
Tressl et al. (1993).
MATERIALS AND METHODS
bonyl compounds arising from the interaction of R-di-
carbonyls with amino acids through Strecker degrada-
All reagents and chemicals were purchased from Aldrich
Chemical Co. (Milwaukee, WI). [1-13C]-D-Glucose, [2-13C]-D-
glucose, [6-13C]-D-glucose, and [2-13C]-D-ribose were also pur-
chased from Aldrich. [3-13C]-D-Glucose, [4-13C]-D-glucose, and
[5-13C]-D-glucose were purchased from ICON Services Inc.
(Summit, NJ ). Melting points were determined on a Fischer
melting point apparatus and are uncorrected. 13C NMR
spectra were recorded at 125.8 MHz using dioxane as external
standard (δ 67.4) on a Bruker AMX500 instrument. Infrared
spectra were recorded in CaF2 IR cells on a Nicolet 8210
Fourier-transform spectrometer equipped with a deuterated
triglycine sulfate (DTGS) detector. The synthesis of Amadori-
proline was performed according to published procedures
(Vernin et al., 1992).
Syn th esis of 1-(P r olin o)-1-d eoxy-D-glycer a ld eh yd e (7).
D-Glyceraldehyde (2.0 g, 0.02 mol) and l-proline (9.2 g, 0.04
mol) were mixed in methanol (40.0 mL), stirred at room
temperature for 3 h, and stored at 4 °C for 15 h. The resulting
precipitate was filtered and crystallized from water/methanol
(1:1 v/v): yield 17.5% (0.67 g, 0.0035 mol); mp 111-112 °C;
νmax 270, 210 nm; FTIR (methanol) 1743 (CdO), 1622 cm-1
(COO-); 13C NMR (D2O) δ 206.84 (CdO), 176.33 (COO-),
72.87 (C-2′ proline), 68.51 (C-5′ proline), 62.76 (CH2OH), 58.77
(-CH2N), 31.22 (C-3′ proline), 25.69 (C-4′ proline); EIMS, di-
TMS derivative, m/ z (relative intensity) 332 (1), 331 (3), 316
tion (Weenen et al., 1994). These authors proposed a
mechanism consistent with the 13C distribution, accord-
ing to which the sugars first underwent â-elimination
to form various deoxyosones which then, through retro-
aldol cleavages at C3-C4, C2-C3, or C5-C4, formed
pyruvaldehyde and 1-hydroxy-2,3-butanedione. To un-
derstand and confirm the mechanism of formation of
C3 and C4 units in the Maillard reaction and to
circumvent their dimerization to form pyrazines, proline
was used as the model amino acid, which is known to
form volatile short chain pyrrolidine derivatives related
to pyruvaldehyde and 1-hydroxy-2,3-butanedione. Fur-
thermore, D-glucoses 13C-enriched at C1, C2, C3, C4, C5,
and C6 positions were systematically reacted with
proline to confirm the origin of C3 and C4 units and to
monitor the occurrence, if any, of chain lengthening
through aldol condensations that could be detected by
observing the scrambling of labels. However, it should
be recognized that more than one mechanism can be
compatible with the observed distribution patterns of
the labeled products.