TABLE 2.
Polyphenol contents (%) in dried aqueous extracts from sweet marjoram (ExOm), common thyme (ExTv), wild thyme (ExTs), and peppermint (ExMp) (as heatmap).
| Compound | Symbol | HPLC-PDA | ExOm | ExTv | ExTs | ExMp | |
|---|---|---|---|---|---|---|---|
| λ (nm) | tR (min) | % ± SD in dry aqueous extract (m/m) | |||||
| Arbutin | Ab | 280 | 3.7 | 2.1 ± 0.03 | 0.5 ± 0.01 | 0 | 0 |
| Caffeic acid | CA | 320 | 8.3 | 1.1 ± 0.04 | 0.4 ± 0.02 | 0.3 ± 0.01 | 0.1 ± 0 |
| Rosmarinic acid | RA | 320 | 16.8 | 7.9 ± 0.31 | 15.1 ± 0.57 | 19.3 ± 0.8 | 5.9 ± 0.36 |
| Lithospermic acid | LA | 320 | 16.5 | 0 | 0 | 6.3 ± 0.12 | 2.5 ± 0.06 |
| Eriodictyol-7-O-rutinoside | Er | 280 | 12.1 | 0.3 ± 0.01 | 0.6 ± 0.01 | 0.3 ± 0.01 | 26.9 ± 0.6 |
| Luteolin-7-O-rutinoside | Lr | 360 | 12.4 | < LQ | 0.3 ± 0.02 | 0.2 ± 0.01 | 8.9 ± 0.31 |
| Luteolin-7-O-β-glucuronide | Lgr | 360 | 13.2 | 4 ± 0.13 | 6.6 ± 0.24 | 10.1 ± 0.27 | 2.8 ± 0.14 |
| Apigenin-7-O-β-glucuronide | Agr a | 360 | 15.8 | 1.5 ± 0.04 | 0.5 ± 0.01 | 0.4 ± 0.01 | 0.1 ± 0 |
| Vicenin-2 | V2 a | 360 | 6.9 | 1.2 ± 0.07 | 0 | 0 | 0 |
| Sum of phenolic acids | PAs | Calculated | 9 ± 0.35 | 15.5 ± 0.49 | 25.9 ± 0.51 | 8.4 ± 0.28 | |
| Sum of flavonoids | Fs | 6.9 ± 0.26 | 7.9 ± 0.33 | 11 ± 0.27 | 38.7 ± 0.64 | ||
| Sum of polyphenols | PPs | 18 ± 0.53 | 24 ± 0.51 | 36.9 ± 0.42 | 47.1 ± 0. 7 | ||
a
Calculated as Lgr.
LQ, limit of quantification; Ex, an extract of; Om, Origanum majorana; Tv, Thymus vulgaris; Ts, Thymus serpyllum; Mp, Mentha × piperita; n = 6.