Table 3.
Qualitative and quantitative characterization of polyphenols in methanol extract of USO 31 and Futura 75 hempseed oil (HSO) and their processing byproducts (hempseed meal, HSM) by LC-DAD-ESI-MS analysis. Data, which are the mean ± standard deviations (SD) of three independent experiments (n = 3), were expressed as µg/100 g of fresh weight (FW).
| Compounds | n | Rt (min) | λmax (nm) | MS (m/z) [M–H]− | USO 31 HSO | USO 31 HSM | Futura 75 HSO | Futura 75 HSM |
|---|---|---|---|---|---|---|---|---|
| Hydroxybenzoic acids | ||||||||
| Gallic acid | 1 | 6.68 | 268 | 169 | 0.58 ± 0.01 a | 1.00 ± 0.03 b | 0.03 ± 0.00 | <LOD |
| Protocatechuic acid | 2 | 13.20 | 258; 293 | 153 | 0.04 ± 0.00 | 1.30 ± 0.02 b | 0.04 ± 0.00 | <LOD |
| 4-Hydroxybenzoic acid | 3 | 23.25 | 253 | 137 | 2.37 ± 0.04 a | 1.66 ± 0.01 b | 0.03 ± 0.00 | 0.03 ± 0.00 |
| Vanillic acid | 5 | 31.19 | 262; 291 | 167 | 1.44 ± 0.01 a | 0.69 ± 0.01 b | 0.02 ± 0.00 | <LOD |
| Hydroxycinnamic acids | ||||||||
| Chlorogenic acid | 6 | 31.756 | 291; 319 | 353 | 0.05 ± 0.00 a | <LOD | 0.04 ± 0.00 | <LOD |
| trans-p-Cumaric acid | 8 | 42.575 | 309 | 163 | 0.12 ± 0.00 a | 2.18 ± 0.05 b | 0.01 ± 0.00 | <LOD |
| Flavanones | ||||||||
| Eriodictyol-7-O-glucoside | 9 | 47.785 | 284; 327 | 449 | 14.87 ± 0.35 a | 1.91 ± 0.02 b | 1.23 ± 0.02 | <LOD |
| Naringenin-7-O-glucoside | 10 | 53.843 | 283; 332 | 433 | 0.21 ± 0.01 a | 6.95 ± 0.03 b | 0.18 ± 0.01 | 5.85 ± 0.04 |
| Eriodictyol | 14 | 60.774 | 287 | 287 | 14.33 ± 0.32 a | 6.98 ± 0.02 b | 3.57 ± 0.02 | 1.68 ± 0.01 |
| Naringenin | 16 | 66.997 | 289 | 271 | 0.05 ± 0.00 | 3.45 ± 0.04 b | 0.05 ± 0.00 | 3.28 ± 0.04 |
| Naringin | 17 | 69.423 | 284; 330 | 579 | 0.06 ± 0.00 a | <LOD | 0.05 ± 0.00 | <LOD |
| Flavonols | ||||||||
| Quercetin-3-O-rutinoside | 11 | 55.292 | 256; 357 | 609 | 77.89 ± 1.55 a | 12.51 ± 0.12 b | 56.93 ± 0. 84 | 16.67 ± 0.88 |
| Quercetin-3-O-glucoside | 12 | 55.596 | 254; 354 | 462 | 0.07 ± 0.00 a | <LOD | 0.11 ± 0.00 | <LOD |
| Kaempferol-3-O-rutinoside | 13 | 60.614 | 266; 350 | 593 | 0.06 ± 0.00 a | <LOD | 0.08 ± 0.00 | <LOD |
| Isoflavones | ||||||||
| Daidzein | 15 | 63.697 | 248; 302 | 253 | 1.96 ± 0.05 a | 0.53 ± 0.02 b | 1.38 ± 0.01 | 0.31 ± 0.01 |
| Genistein | 18 | 69.632 | 261; 332 | 253 | 3.54 ± 0.12 a | 0.84 ± 0.01 b | 0.65 ± 0.02 | 0.25 ± 0.01 |
| Flavones | ||||||||
| Apigenin | 19 | 75.484 | 268; 330 | 269 | 2.54 ± 0.08 a | 0.93 ± 0.03 a | 6.04 ± 0.05 | 2.38 ± 0.04 |
| Flavanols | ||||||||
| Catechin | 4 | 25.277 | 279 | 289 | 4.88 ± 0.15 a | 2.85 ± 0.02 a | 9.43 ± 0.08 | 5.47 ± 0.05 |
| Epicatechin | 7 | 35.944 | 279 | 289 | 0.19 ± 0.00 a | 0.79 ± 0.01 a | 0.60 ± 0.02 | 1.17 ± 0.03 |
| Total | 125.24 | 44.58 | 80.48 | 37.89 |
Rt, retention time; λmax, maximum absorbance peak; a p < 0.05 vs. Futura 75 HSO; b p < 0.05 vs. Futura 75 HSM; LOD ≤ 1 ng/mL.