TABLE 4.
Putative identification of major chemical constituents in A. tinctoria extracts (Experiment 3, negative mode, ESI).
| Code | Retention time (min) | UV | (m/z) | MS major ion(s) | Molecular formula | Δ ppm | Δ mDa | MS/MS fragments (m/z) | Putative identification |
| 1 | 4.60 | 513, 272. | 301.1086 | [M − H]– | C17H18O5 | 3.30 | 1.00 | 286.0847 232.0375 |
Methylshikonin isomer I |
| 11 | 4.78 | 515, 274, 490 | 287.0934 | [M − H] – | C16H16O5 | 5.06 | 1.45 | 218.0227 190.0273 |
Shikonin |
| 12 | 5.26 | n.d. | 797.2762 | [M − H] – | C33H50O22 | 5.83 | 4.65 | 527.1894 | Not identified |
| 13 | 5.85 | 516, 274, 490 | 329.1030 | [M − H] – | C18H18O6 | 1.48 | 0.49 | 269.0829 251.0709 241.0865 |
Acetylshikonin |
| 14 | 7.62 | n.d. | 1,111.3696 | [M − H] – | C47H68O30 | −1.90 | −2.12 | 841.2741 571.1847 1023.3120 |
Not identified |
| 15 | 7.98 | n.d. | 1,147.3676 | [M − H] – | C50H68O30 | −3.59 | −4.12 | 877.2743 607.1854 1047.3101 |
Not identified |
| 6 | 8.00 | 517, 484, 281 | 269.0829 | [M − H] – | C16H14O4 | 5.63 | 1.52 | 251.0712 241.0868 |
Anhydroalkannin |
Δm, mass errors; [M − H] –, m/z of the deprotonated molecular in negative ionization mode; m/z, mass to charge ratio.