Table 2.
Discriminatory metabolic features with confirmed molecular identities.
| m/z | RT (sec) | Verified Metabolite or Metabolite Class | Metabolite Identification Level |
AMD/ Controls Fold Change |
IAMD/ Controls Fold Change |
NVAMD/ IAMD Fold Change |
|---|---|---|---|---|---|---|
| Acylcarnitines | ||||||
| 414.3568 | 377.7 | Heptadecanoyl carnitine | 2 | - | - | 2.08 |
| 426.3568 | 366.5 | 11Z-Octadecenylcarnitine | 2 | - | - | 1.74 |
| 424.3419 | 345.9 | Linoleyl carnitine | 2 | - | - | 1.75 |
| 422.3270 | 330.5 | Linolenyl carnitine * | 2 | 1.63 | - | - |
| 274.1263 | 373.8 | Glutaconylcarnitine | 2 | 1.49 | - | - |
| 428.3721 | 392.6 | Stearoylcarnitine | 2 | - | - | 1.83 |
| Lipid metabolites | ||||||
| 466.3518 | 332.9 | LysoSM (d18:1) * | 2 | - | - | 2.34 |
| 516.3057 | 376.2 | LysoPC (18:4) * | 2 | 1.47 | - | - |
| 324.2893 | 471.0 | Linoleoyl ethanolamide | 2 | 1.32 | - | - |
| 326.3045 | 526.9 | N-Oleoylethanolamine | 2 | 1.37 | - | - |
| Steroids and steroid derivatives | ||||||
| 413.3451 | 351.0 | 25-Hydroxyvitamin D2 | 2 | - | - | 2.16 |
| 347.2213 | 271.9 | Cortexolone | 2 | 3.12 | - | - |
| Amino acid-related metabolites | ||||||
| 130.0499 | 51.9 | Pyroglutamic acid | 1 | 1.52 | - | - |
| 209.0910 | 234.1 | Kynurenine | 1 | - | - | 0.72 |
Discriminatory metabolic features were identified by PLS-DA (VIP ≥ 2.0) and linear regression analysis (FDR < 0.1 and p < 0.05). To verify their molecular identities, features were compared with an in-house library of metabolic features whose molecular identities had previously been confirmed. A subset of previously unconfirmed metabolites was evaluated by LC–MS/MS. * molecular identity newly confirmed in this study; m/z: mass-to-charge ratio; RT (sec): retention time (seconds).