Table 1.
The content of phenolic compounds (results are expressed as mg/kg FM) in aqueous grape pomace seed extract of Prokupac variety, determined using UHPLC-Orbitrap MS; retention time (tR), molecular formula, calculated/exact mass, mean mass accuracy (ppm), and major MS2 fragments.
| Phenolic Compounds | tR, Min | Molecular Formula | Calculated Mass, [M–H]–/M+ |
Exact Mass, [M–H]–/M+ |
ppm | MS2 Fragments (% Base Peak) |
Content (mg/kg FW) |
|---|---|---|---|---|---|---|---|
| Hydroxybenzoic Acids and Derivatives | |||||||
| Gallic acid a | 3.04 | C7H5O5− | 169.01425 | 169.01436 | −0.11 | 125(100) | 286.41 ± 8.28 |
| Gallic acid hexoside isomer 1 b | 4.11 | C13H15O10− | 331.06707 | 331.06723 | −0.16 | 271(40), 241(15), 211(20), 169(100), 125(10) | 8.31 ± 0.26 |
| Dihydroxybenzoic acid hexoside b | 4.30 | C13H15O9− | 315.07216 | 315.07251 | −0.35 | 153(100), 152(50), 109(15), 108(10) | 12.84 ± 0.99 |
| Gallic acid hexoside isomer 2 b | 4.31 | C13H15O10− | 331.06707 | 331.06726 | −0.19 | 294(10), 271(20), 169(100), 125(10) | 66.65 ± 4.79 |
| Protocatechuic acid b | 4.75 | C7H5O4− | 153.01933 | 153.01955 | −0.22 | 109(100), 95(75), 79(20), 59(10) | 27.92 ± 3.39 |
| Gallic acid hexoside isomer 3 b | 4.76 | C13H15O10− | 331.06707 | 331.06592 | 1.15 | 169(100), 125(5) | 222.47 ± 13.83 |
| Digalloyl hexoside b | 5.08 | C20H19O14− | 483.07803 | 483.07764 | 0.39 | 331(20), 313(20), 271(100), 211(10), 169(10) | 4.14 ± 0.30 |
| Methylgallate b | 6.11 | C8H7O5− | 183.02990 | 183.03017 | –0.27 | 168(100), 124(80) | 0.64 ± 0.04 |
| Syringic acid hexoside b | 6.21 | C15H19O10− | 359.09837 | 359.09837 | 0.00 | 197(100) | 18.52 ± 0.35 |
| Ethylgallate b | 7.16 | C9H9O5− | 197.04555 | 197.04530 | 0.25 | 169(100), 125(5) | 225.33 ± 9.35 |
| Ellagic acid b | 7.29 | C14H5O8− | 300.99899 | 300.99918 | −0.19 | 284(40), 271(60), 257(100), 229(85), 185(40) | 1.16 ± 0.09 |
| Σ | 874.39 (50.58) | ||||||
| Hydroxycinnamic Acids and Derivatives | |||||||
| Caffeoyltartaric acid c | 4.87 | C13H11O9− | 311.04031 | 311.04141 | −1.10 | 179(40), 177(15), 149(100) | 193.78 ± 6.42 |
| Caffeic acid a | 5.38 | C9H7O4− | 179.03498 | 179.03545 | −0.47 | 135(100) | 32.82 ± 1.96 |
| Coumaroyltartaric acid c | 5.60 | C13H11O8− | 295.04594 | 295.04623 | −0.29 | 163(100), 149(10), 119(5) | 72.63 ± 2.46 |
| Σ | 299.24 (17.13) | ||||||
| Flavan–3-ols and Procyanidins | |||||||
| B type procyanidin trimer isomer 1 d | 4.69 | C45H37O18- | 865.19854 | 865.20264 | −4.10 | 695(100), 577(60), 425(30), 407(30), 287(30) | 13.07 ± 0.24 |
| B type procyanidin dimer isomer 1 d | 5.47 | C30H25O12− | 577.13515 | 577.13318 | 1.97 | 559(10), 451(30), 425(100), 407(40), 289(20), 287(10) | 61.39 ± 3.31 |
| B type procyanidin dimer isomer 2 d | 5.72 | C30H25O12− | 577.13515 | 577.13531 | −0.16 | 559(5), 451(20), 425(100), 407(35), 289(20), 287(10) | 46.18 ± 2.74 |
| B type procyanidin trimer isomer 2 d | 5.73 | C45H37O18− | 865.19854 | 865.20087 | −2.33 | 695(100), 577(80), 425(30), 407(40), 287(35) | 34.51 ± 1.04 |
| B type procyanidin dimer isomer 3 d | 6.02 | C30H25O12− | 577.13515 | 577.13379 | 1.36 | 559(10), 451(20), 425(100), 407(40), 289(20), 287(10) | 91.54 ± 3.15 |
| Catechin a | 6.17 | C15H13O6− | 289.07176 | 289.07089 | 0.87 | 271(5), 245(100), 205(40), 179(15), 125(5) | 83.45 ± 3.48 |
| B type procyanidin dimer gallate isomer 1 d | 6.23 | C37H29O16− | 729.14611 | 729.14734 | −1.23 | 577(90), 559(80), 425(20), 407(100), 289(20) | 14.82 ± 0.65 |
| B type procyanidin dimer gallate isomer 2 d | 6.44 | C37H29O16− | 729.14611 | 729.14728 | −1.17 | 577(50), 559(60), 425(10), 407(100), 289(20) | 61.99 ± 1.65 |
| Epicatechin d | 6.54 | C15H13O6− | 289.07176 | 289.07068 | 1.08 | 271(5), 245(100), 205(40), 179(15), 125(5) | 90.58 ± 2.51 |
| B type procyanidin dimer digallate d | 6.80 | C44H33O20− | 881.15707 | 881.15723 | −0.16 | 729(100), 711(30), 577(10), 559(20), 407(30) | 0.93 ± 0.07 |
| Catechin gallate d | 7.09 | C22H17O10− | 441.08272 | 441.08218 | 0.54 | 331(10), 289(100), 271(10), 169(25) | 10.10 ± 0.57 |
| Σ | 508.56 (29.42) | ||||||
| Flavonol Aglycones and Glycosides | |||||||
| Dihydro-syringetin–3-O-hexoside e | 5.54 | C23H25O13− | 509.13006 | 509.12967 | 0.39 | 491(10), 461(30), 355(40), 347(65), 329(100) | 0.54 ± 0.06 |
| Quercetin–3-O-glucoside a | 7.06 | C21H19O12− | 463.08820 | 463.08786 | 0.34 | 301(100), 300(30) | 0.37 ± 0.04 |
| Σ | 0.915(0.05) | ||||||
| Anthocyanins | |||||||
| Delphinidin–3-O-glucoside a | 4.85 | C21H21O12+ | 465.10275 | 465.10294 | −0.41 | 304(15), 303(100) | 1.29 ± 0.09 |
| Petunidin–3-O-hexoside f | 5.27 | C22H23O12+ | 479.11840 | 479.11884 | −0.92 | 318(10), 317(100) | 1.48 ± 0.10 |
| Peonidin–3-O-glucoside a | 5.53 | C22H23O11+ | 463.12349 | 463.12366 | −0.37 | 302(10), 301(100) | 2.56 ± 0.22 |
| Malvidin–3-O-glucoside a | 5.59 | C23H25O12+ | 493.13405 | 493.13394 | 0.22 | 332(10), 331(100) | 28.53 ± 3.32 |
| Peonidin–3-O-(6″-acetyl)hexoside f | 6.42 | C24H25O12+ | 505.13405 | 505.13351 | 0.54 | 302(10), 301(100) | 1.32 ± 0.12 |
| Malvidin–3-O-(6″-acetyl)hexoside f | 6.48 | C25H27O13+ | 535.14462 | 535.14398 | 0.64 | 332(10), 331(100) | 6.14 ± 0.55 |
| Peonidin–3-O-(6″-p-coumaroyl)hexoside f | 7.12 | C31H29O13+ | 609.16027 | 609.16077 | −0.50 | 302(10), 301(100) | 1.44 ± 0.16 |
| Malvidin–3-O-(6″-p-coumaroyl)hexoside f | 7.18 | C32H31O14+ | 639.17083 | 639.17163 | −0.80 | 332(10), 331(100) | 2.77 ± 0.42 |
| Σ | 45.54 (2.63) | ||||||
| Σ | 1728.64 | ||||||
Content of phenolics are presented as mean values ± standard deviations (n = 3); Values in parenthesis represent relative amount of phenolic class in seed extract; a Compounds quantified using available standards; Compounds that were quantified and expressed as equivalents of gallic acid b; caffeic acid c; catechin d; quercetin–3-O-glucoside e; malvidin–3-O-glucoside f.