Table 2.
Summary of cluster analysis representative metabolites
| Cluster representative | ESI mode | Formula | m/z | Metabolite class | Function | Disease associations |
|---|---|---|---|---|---|---|
| Sphingosine 1-phosphate | + | C18H38NO5P | 380.2533 | Phosphosphingolipid | Cell survival, inflammatory response, lipid metabolism | Hepatocellular carcinoma [25], other cancers [26] |
| Pyridoxamine 5′-phosphate (vitamin B6) | + | C8H13N2O5P | 249.0618 | Pyridoxamines | Amino acid metabolism neurotransmitter biosynthesis, lipid metabolism | Ovarian cancer [27] |
| Sphinganine 1-phosphate | + | C18H40NO5P | 382.2718 | Phosphosphingolipid | Membrane stabilization | - |
| Calcidiol (25-hydroxyvitamin D) | + | C27H44O2 | 401.3432 | Vitamin D and derivatives | Vitamin D precursor | Prostate, breast, and colorectal cancer survival [28]; conflicting data for lung cancer incidence [29, 30] |
| 3-Methoxybenzenepropanoic acid | + | C10H12O3 | 181.0858 | Phenylpropanoic acids | - | - |
| 8-Hydroxyguanine | + | C10H13N5O6 | 168.0559 | Purine derivative | Mutagenic base, marker of DNA damage | Lung and stomach cancer [31] |
| 1b,3a,12a-Trihydroxy-5b-cholanoic acid | + | C24H40O5 | 409.3037 | Steroids | Fat absorption and transport | - |
| Glycocholic acid | + | C26H43NO6 | 466.3250 | Steroids | Fat emulsification, bile acid | Hepatocellular carcinoma [32], cholangiocarcinoma [33, 34], prostate cancer [35] |
| MG(0:0/18:1/0:0) | + | C21H40O4 | 357.2989 | Glycerolipids | Lipid metabolism, lipid transport | - |
| 2-Hydroxydecanedioic acid | + | C10H18O5 | 219.1263 | Hydroxy acids | Cell membrane stabilizer, energy storage | Zellweger syndrome [36] |
| Gamma-carboxyethyl hydroxychroman (gamma-CEHC) | + | C15H20O4 | 249.1541 | Benzopyrans | Vitamin E metabolism | Colorectal cancer [37] |
| Cholic acid glucuronide | − | C30H48O11 | 583.3146 | Steroids | Cholesterol metabolism | - |
| Formaldehyde | − | CH2O | 59.0137 | Carbonyl compounds | Protein and nucleic acid metabolism | Leukemia [38], nasopharyngeal cancer [38] |
| 17-Hydroxypregnenolone sulfate | − | C21H32O6S | 411.1838 | Steroids | Lipid metabolism, cell signaling | - |
| N1-Aceytylspermine | − | C9H21N3O | 303.2322 | Carboxylic acids | Cellular metabolism | - |
| Isodesmosine | − | C24H40N5O8 | 525.2811 | Carboxylic acids | Elastin degradation | Liver cirrhosis [34, 39], cystic fibrosis [40, 41] |
| 11-Beta-hydroxyandrosterone-3-glucuronide | − | C25H38O9 | 481.2450 | Hydroxyindoles | Lipid metabolism | - |
| Lithocholic acid glycine conjugate | − | C26H43NO4 | 432.3120 | Steroids | Fat excretion, absorption, and transport | - |
| 3-Methyl-2-oxovaleric acid | − | C6H10O3 | 129.0549 | Ketoacids | Amino acid metabolism | Maple syrup urine disease [42, 43]; colorectal cancer [44, 45] |
| 18-Hydroxycortisol | − | C21H30O6 | 377.1993 | Steroids | - | Primary aldosteronism [46, 47] |
| N(6)-Methyllysine | − | C7H16N2O2 | 159.1177 | Carboxylic acid | Amino acid metabolism | - |
| Deoxycholic acid 3-glucuronide | − | C30H48O10 | 567.3370 | Steroids | Fat emulsification | - |
| 20-Carboxy-leukotriene B4 | − | C20H30O6 | 411.1899 | Fatty acyls | Lipid and drug metabolism | - |
| Pyroglutamic acid | − | C5H7NO3 | 128.0347 | Carboxylic acid | Amino acid metabolism | NSCLC [48] |
Abbreviations: m/z mass-to-charge ratio