Table 2.
Contents of target phenolic compounds in the extracts obtained from PHWE at different temperatures and from conventional extractions.
| Compounds | Maceration (µg/g RM) |
Reflux (µg/g RM) |
PHWE (µg/g RM) | ||||
|---|---|---|---|---|---|---|---|
| 100 °C | 120 °C | 140 °C | 160 °C | 180 °C | |||
| Quinic acid | 11.32 ± 0.25 b | 18.4 ± 1.1 c | 17.48 ± 0.29 c | 19.4 ± 0.7 cd | 20.8 ± 1.3 d | 20.6 ± 0.6 d | 23.8 ± 1.7 e |
| Arbutin | ND | ND | 7.5 ± 1.2 a | 14.4 ± 0.8 c | ND | ND | ND |
| Adenosine | 3.6 ± 0.7 a | 9.0 ± 0.5 b | 46 ± 6 f | 31.9 ± 1.6 e | 25.8 ± 1.0 d | 25.61 ± 0.15 d | 12.2 ± 0.3 c |
| Tachioside | ND | ND | ND | 10.8 ± 0.3 a | ND | ND | ND |
| Vanillic alcohol | ND | ND | 4.39 ± 0.20 a | 11.0 ± 1.3 b | 23.1 ± 1.5 c | ND | ND |
| p-Hydroxybenzoic acid | 6.99 ± 0.13 a | 12.0 ± 0.4 b | 5.9 ± 0.9 a | 13.7 ± 0.8 c | 16.0 ± 0.7 d | 27.8 ± 0.6 f | 35.6 ± 1.9 g |
| Vanillic acid | 39.6 ± 1.0 c | 66.4 ± 0.5 e | 29.5 ± 2.1 a | 29.0 ± 1.1 a | 36.7 ± 1.8 b | 54.3 ± 2.0 d | 85.7 ± 1.2 f |
| p-Hydroxybenzaldehyde | 9.5 ± 0.4 ab | 29.6 ± 1.0 ab | ND | 35 ± 4 b | 192 ± 4 c | 318 ± 38 d | 384 ± 12 e |
| Caffeic acid | ND | ND | ND | 13.5 ± 1.3 c | 9.7 ± 0.4 b | 7.0 ± 0.6 a | 6.5 ± 0.6 a |
| Syringic acid | 9.5 ± 0.4 ab | 10.3 ± 0.4 ab | 11.76 ± 0.23 ab | 13.6 ± 1.8 b | 21.6 ± 2.4 c | 56.6 ± 2.8 d | 111 ± 9 e |
| Vanillin | ND | 5.3 ± 0.4 a | ND | 6.7 ± 0.6 a | 27.6 ± 2.7 b | 113 ± 6 c | 181 ± 6 d |
| p-Coumaric acid | 7.7 ± 0.4 a | 237.0 ± 2.0 b | 51 ± 5 a | 254 ± 21 b | 896 ± 58 c | 1145 ± 39 e | 1081 ± 49 d |
| Coniferol | ND | 39.4 ± 0.6 b | 10.7 ± 1.5 ab | 76 ± 7 c | 736 ± 21 d | 942 ± 38 e | 49.5 ± 2.7 bc |
| Syringaldehyde | ND | 7.4 ± 0.5 b | 5.10 ± 0.23 ab | 7.42 ± 0.27 b | 22.2 ± 2.8 c | 81.3 ± 2.0 d | 170 ± 5 e |
| Ferulic acid | ND | 4.6 ± 0.4 a | 3.29 ± 0.18 a | 5.4 ± 0.4 a | 22 ± 4 b | 39 ± 4 c | 85 ± 4 d |
| Coniferylaldehyde | ND | ND | ND | ND | 25.7 ± 2.0 a | 60.80 ± 0.27 b | 111 ± 11 c |
| Sinapaldehyde | ND | 8.0 ± 0.7 b | ND | 3.2 ± 0.6 a | 26 ± 3 c | 57.3 ± 0.8 d | 98 ± 5 e |
| Syringaresinol | 8.5 ± 1.1 a | 35.8 ± 1.5 b | 10.8 ± 0.7 a | 63.8 ± 0.6 c | 276 ± 7 e | 519.4 ± 1.2 f | 210 ± 16 d |
| Balanophonin | ND | 3.3 ± 0.3 a | ND | 5.3 ± 0.4 b | 5.50 ± 0.19 b | 7.7 ± 1.1 c | 12.4 ± 1.9 d |
| Total yield | 96.9 ± 2.3 a | 486 ± 4 b | 202.8 ± 1.7 a | 614 ± 25 c | 2391 ± 72 d | 3470 ± 112 f | 2644 ± 22 e |
Results are expressed as mean ± SD (n = 3). Values represented with different lowercase letters are statistically significant differences (p < 0.05). ND: Not detected.