Fig. 1
Analytical HPLC-DAD-ESI-MS chromatogram (at 278, 257 and 320 nm) of a Moroccan Jujube (Ziziphus lotus) honey (10g) dissolved in doubly distilled water (50.0 mL) I. 4-hydroxyquinoline glucoside, II. 4-hydroxyquinoline, III. p-hydroxybenzoic acid, IV. caffeic acid, V. kynurenic acid, VI. methyl syringate.
Fig. 2
Analytical HPLC-DAD-ESI-MS chromatogram (at 257 and 320 nm) of a SPE (10% methanol) fraction of Moroccan Jujube (Ziziphus lotus) honey (10g) I. 4-hydroxyquinoline glucoside, II. 4-hydroxyquinoline, III. p-hydroxybenzoic acid.
Fig. 3
Analytical HPLC-DAD-ESI-MS chromatogram (at 257 and 320 nm) of a SPE (25% methanol) fraction of Moroccan Jujube (Ziziphus lotus) honey (10 g) II. 4-hydroxyquinoline, III. p-hydroxybenzoic acid, IV. caffeic acid, V. kynurenic acid.
Fig. 4
Analytical HPLC-DAD-ESI-MS chromatogram (at 257 and 320 nm) of a SPE (100% methanol) fraction of Moroccan Jujube (Ziziphus lotus) honey (10 g) VI. methyl syringate.
Table 1
HPLC-ESI-MS data in negative ion mode at a fragmentor voltage (100 V) of polyphenolic, alkaloid and terpenoid compounds detected in Jujube and Chestnut honey extracts
| Number | Phenolic compound | Molecular formula | Rt (min) | Molecular weight (exact) | [M-H]− | [2M-H]− |
|---|---|---|---|---|---|---|
| Jujube honeys (Morocco)* | ||||||
| I | 4-Hydroxyquinoline glucoside | C15H17NO6 | 11.97 | 307.106 | 306.2 | 613.1 |
| II | 4-Hydroxyquinoline | C9H7NO | 17.45 | 145.053 | 144.2 | 289.1 |
| III | p-Hydroxybenzoic acid | C7H6O3 | 19.82 | 138.032 | 137.2 | 275.2 |
| IV | Caffeic acid | C9H8O4 | 22.11 | 180.042 | 179.1 | 359.1 |
| V | Kynurenic acid | C10H7NO3 | 26.03 | 189.043 | 188.1 | 377.1 |
| VI | Methyl syringate | C10H12O5 | 35.69 | 212.068 | 211.1 | 423.0 |
| Chestnut honey (Italy)# | ||||||
| VII | 4-(1′-Hydroxy-1′-dimethyl) cyclohexa-1,3-diene-1 carboxylic acid-1-gentobioside | C22H34O13 | 15.18 | 505.199 | 505.2 | 1011.4 |
| VIII | 3-PKA | C14H14N2O3 | 16.28 | 258.100 | 257.1 | n.d. |
| IX | Caffeic acid | C9H8O4 | 17.99 | 180.042 | 179.1 | 359.1 |
| X | p-Coumaric acid | C9H8O3 | 21.48 | 164.047 | 163.1 | 327.1 |
| XI | 4-(1′-Hydroxy-1′-dimethyl) cyclohexa-1,3-diene-1 carboxylic acid | C10H14O3 | 22.31 | 182.094 | 181.2 | 363.1 |
| XII | Kynurenic acid tautomer | C10H7NO3 | 22.54 | 189.042 | 188.1 | 377.1 |
| XIII | Gamma-Lact-3-PKA | C14H12N2O2 | 24.32 | 240.089 | 239.1 | n.d. |
| XIV | Kynurenic acid | C10H7NO3 | 30.62 | 189.042 | 188.1 | 377.1 |
Table 2
GC-EI-MS of aglycone polyphenolic and alkaloid compound TMS-derivatives detected in Jujube (Ziziphus lotus) honey
| No | Polyphenolic compound | Rt (min.) | M+calc. | Major neutral fragments (m/z %) |
|---|---|---|---|---|
| II | 4-Hydroxyquinoline | 16.38 | 217 | 73(29), 101(13), 172(18), 202(100), 217(49) |
| III | p-Hydroxybenzoic acid | 16.51 | 282 | 73(74), 193(56), 223(71), 267(100), 282(28) |
| IV | trans-Caffeic acid | 29.30 | 396 | 73(100),191(14), 219(7), 307(11), 381(24), 396(99) |
| V | Kynurenic acid | 27.67 | 333 | 73(85), 231(81), 288(21), 304(34), 318(100), 333(10) |
| VI | Methyl syringate | 21.30 | 284 | 73(26), 223(24), 254(100), 269(46), 284(31) |
[i] Base peak = bold
Table 3
Major polyphenolic compounds, alkaloids and terpenoids detected in Jujube honeys and Chestnut honey (Italy)
| Number | Phenolic compound | Jujube honey samples (mg/kg) | |||
| H1 | H2 | H3 | H4 | ||
| Jujube honeys (Morocco) | |||||
| I | 4-Hydroxyquinoline glucoside | 3.58±0.28 | 3.67±0.19 | 2.61±0.10 | 8.11±0.32 |
| II | 4-Hydroxyquinoline | 3.38±0.37 | 3.38±0.09 | 3.38±0.18 | 16.29±0.86 |
| III | p-Hydroxybenzoic acid | 1.55±0.06 | 1.60±0.28 | 1.16±0.11 | 2.43±0 |
| IV | Caffeic acid | 1.41±0.13 | 1.18±0.04 | 0.77±0.07 | 3.44±0 |
| V | Kynurenic acid | 7.08±0.30 | 6.69±0.30 | 3.89±0.30 | 8.58±0.20 |
| VI | Methyl syringate | 12.24±0.18 | 12.98±0.92 | 4.83±0.12 | 3.31±0.09 |
| Total (mg/kg) | 29.24±1.42 | 29.50±1.27 | 16.64±0.67 | 42.16±1.07 | |
| Chestnut honey (Italy) | |||||
| Number | Phenolic compound | H5 | |||
| mg/kg | |||||
| VII | 4-(1′-Hydroxy-1′-dimethyl) cyclohexa-1,3-diene-1 carboxylic acid-1-gentobioside | 305±4 | |||
| VIII | 3-PKA | 187±3 | |||
| IX | Caffeic acid | 13±0.1 | |||
| X | p-Coumaric acid | 7±0.1 | |||
| XI | 4-(1′-Hydroxy-1′-dimethyl) cyclohexa-1,3-diene-1 carboxylic acid | 179±11 | |||
| XII | Kynurenic acid tautomer | 94±2 | |||
| XIII | Gamma-Lact-3-PKA | 43±2 | |||
| XIV | Kynurenic acid | 1246±17 | |||
| Total terpenoids (mg/kg) | 484 | ||||
| Total alkaloids (mg/kg) | 1570 | ||||
| Total polyphenols (mg/kg) | 20 | ||||
| Total (mg/kg) | 2074 | ||||
Fig. 5
Analytical HPLC-DAD-ESI-MS chromatogram (at 320 nm) of an Italian Chestnut (Castania sativa Mill.) honey (10 g) dissolved in doubly distilled water (50.0 mL) VII. 4-(1′-hydroxy-1′-dimethyl)cyclohexa-1,3-diene-1 carboxylic acid-1-gentobioside, VIII. 3-pyrrolinyl-kynurenic acid (3-PKA), IX. caffeic acid, X. p-coumaric acid, XI. 4-(1′-hydroxy-1′-dimethyl)cyclohexa-1,3-diene-1 carboxylic acid-1, XII. kynurenic acid tautomer, XIII. gamma-lact-3-PKA, XIV. kynurenic acid.
Fig. 6
Structures of the phenolic compounds detected and identified in Moroccan Jujube (Ziziphus lotus) honeys I. 4-hydroxyquinoline glucoside, II. 4-hydroxyquinoline, III. p-hydroxybenzoic acid, IV. caffeic acid, V. kynurenic acid, VI. methyl syringate.
Fig. 7
Structures of the major polyphenolic compounds identified in Italien chestnut (Castania sativa Mill.) honey VII. 4-(1′-hydroxy-1′-dimethyl)cyclohexa-1,3-diene-1 carboxylic acid-1-gentobioside, VIII. 3-pyrrolinyl-kynurenic acid (3-PKA), IX. caffeic acid, X. p-coumaric acid, XI. 4-(1′-hydroxy-1′-dimethyl)cyclohexa-1,3-diene-1 carboxylic acid-1, XII. kynurenic acid tautomer, XIII. gamma-lact-3-PKA, XIV. kynurenic acid.