Table 2.
The PCA loading score and variable importance point (VIP) score of PLS-DA.
| No. | Metabolite | Unsupervised Learning | Supervised Learning | |
|---|---|---|---|---|
| PCA Loading Score | PLS-DA | |||
| PC1 | PC2 | VIP Score a | ||
| 1 | Alanine | −0.137 | 0.110 | 0.240 |
| 2 | Glycine | −0.043 | 0.314 | 0.557 |
| 3 | α-Aminobutyric acid | −0.025 | −0.033 | 0.850 |
| 4 | Valine | −0.219 | −0.187 | 0.828 |
| 5 | Leucine | −0.247 | 0.021 | 0.356 |
| 6 | Isoleucine | −0.231 | −0.101 | 0.185 |
| 7 | Proline | 0.048 | −0.203 | 0.734 |
| 8 | Pipecolic acid | 0.197 | −0.036 | 0.705 |
| 9 | Pyroglutamic acid | −0.237 | −0.002 | 2.375 |
| 10 | Methionine | −0.011 | 0.079 | 0.491 |
| 11 | Serine | 0.034 | 0.203 | 0.365 |
| 12 | Threonine | 0.001 | −0.171 | 0.064 |
| 13 | Phenylalanine | −0.112 | 0.265 | 0.323 |
| 14 | Aspartic acid | −0.047 | 0.280 | 0.008 |
| 15 | 4-Hydroxyproline | 0.002 | −0.167 | 0.707 |
| 16 | Pyruvic acid | −0.100 | 0.003 | 0.615 |
| 17 | Acetoacetic acid | −0.056 | 0.092 | 0.660 |
| 18 | Lactic acid | −0.178 | −0.001 | 0.223 |
| 19 | Glycolic acid | −0.107 | −0.034 | 1.438 |
| 20 | 2-Hydroxybutyric acid | −0.142 | −0.037 | 0.471 |
| 21 | 3-Hydroxypropionic acid | −0.183 | 0.020 | 2.384 |
| 22 | 3-Hydroxybutyric acid | −0.194 | 0.124 | 2.391 |
| 23 | Succinic acid | −0.235 | 0.047 | 1.114 |
| 24 | Fumaric acid | −0.193 | 0.115 | 0.147 |
| 25 | Oxaloacetic acid | −0.205 | 0.115 | 0.334 |
| 26 | α-Ketoglutaric acid | −0.216 | 0.058 | 0.233 |
| 27 | 4-Hydroxyphenylacetic acid | 0.014 | 0.049 | 0.080 |
| 28 | Malic acid | −0.174 | 0.160 | 0.572 |
| 29 | 2-Hydroxyglutaric acid | −0.146 | 0.078 | 0.988 |
| 30 | cis-Aconitic acid | −0.051 | 0.093 | 1.083 |
| 31 | Citric acid | −0.092 | 0.164 | 0.650 |
| 32 | Isocitric acid | −0.096 | 0.153 | 0.569 |
| 33 | Dodecanoic acid (C12:0) | −0.016 | −0.064 | 0.463 |
| 34 | Tetradecanoic acid (C14:0) | 0.046 | −0.079 | 0.695 |
| 35 | Palmitoleic acid (C16:1) | 0.080 | −0.184 | 0.143 |
| 36 | Palmitic acid (C16:0) | 0.113 | −0.155 | 1.812 |
| 37 | γ-Linolenic acid (γ-C18:3) | −0.180 | −0.249 | 0.935 |
| 38 | Linoleic acid (C18:2) | −0.061 | −0.135 | 0.514 |
| 39 | Oleic acid (C18:1) | −0.115 | −0.097 | 0.522 |
| 40 | Octadecanoic acid (C18:0) | −0.230 | −0.184 | 2.524 |
| 41 | Arachidonic acid (C20:4) | −0.210 | −0.115 | 1.359 |
| 42 | 11-Eicosenic acid (C20:1) | −0.081 | −0.220 | 0.351 |
| 43 | Eicosadienoic acid (C20:2) | −0.099 | −0.240 | 0.859 |
| 44 | Eicosanoic acid (C20:0) | −0.186 | −0.192 | 0.569 |
| 45 | Docosahexaenoic acid (DHA, C22:6) | −0.180 | 0.007 | 1.974 |
| 46 | Docosatetraenoic acid (C22:4) | −0.145 | −0.131 | 1.129 |
| 47 | Erucic acid (C22:1) | −0.103 | −0.163 | 0.835 |
| 48 | Docosanoic acid (C22:0) | −0.093 | −0.038 | 0.550 |
| 49 | Nervonic acid (C24:1) | −0.083 | 0.042 | 0.620 |
| 50 | Tetracosanoic acid (C24:0) | −0.058 | 0.004 | 0.575 |
| 51 | Hexacosanoic acid(C26:0) | 0.030 | 0.015 | 0.532 |
a Variable importance in projection score.