Table 2.
Marker metabolites found in the GC/MS chromatograms of any two groups of CK, SK, and NC
| No | Compoundsa | RTb (min) | Fragsc (m/z) |
CK vs. NC |
SK vs. NC |
CK vs. SK |
Biochemical pathwayg | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| VIPd | Pe | FCf | VIPd | Pe | FCf | VIPd | Pe | FCf | |||||
| 1 |
LA |
5.68 |
147 |
1.88 |
2.62E-04 |
−0.79 |
2.13 |
4.90E-04 |
−0.73 |
|
|
|
Glycolysis;gluconeogenesis |
| 2 |
GLCA |
16.56 |
319 |
1.76 |
6.84E-04 |
−0.79 |
2.02 |
1.58E-03 |
−0.66 |
|
|
|
Pentose and glucuronate interconversions |
| 3 |
L-ala |
6.23 |
116 |
2.03 |
8.88E-05 |
−0.75 |
1.18 |
4.86E-02 |
−0.28 |
2.22 |
1.22E-03 |
−0.47 |
Alanine and aspartate metabolism |
| 4 |
GA |
5.87 |
147 |
1.89 |
1.53E-04 |
−0.56 |
2.12 |
5.94E-04 |
−0.48 |
|
|
|
Fatty acid metabolism |
| 5 |
Ribitol |
14.3 |
217 |
1.07 |
3.54E-02 |
−0.48 |
1.19 |
4.77E-02 |
−0.27 |
|
|
|
Glycolysis; Pentose phosphate Pathway |
| 6 |
pGlu |
11.83 |
156 |
1.54 |
2.83E-03 |
−0.43 |
1.34 |
1.77E-02 |
−0.29 |
|
|
|
Glutathione metabolism |
| 7 |
Gal |
16.03 |
73 |
1.83 |
9.86E-04 |
−0.38 |
1.85 |
3.02E-03 |
−0.61 |
|
|
|
Galactose metabolism |
| 8 |
THBA |
12.17 |
292 |
1.46 |
7.32E-04 |
−0.38 |
1.43 |
1.77E-02 |
−0.24 |
|
|
|
Fatty acid metabolism; Butanoate metabolism |
| 9 |
Glc |
16.21 |
319 |
1.66 |
2.98E-04 |
−0.31 |
1.77 |
2.78E-03 |
−0.22 |
2.26 |
2.15E-02 |
−0.14 |
Glycolysis/gluconeogenesis |
| 10 |
Gly |
9.05 |
174 |
1.45 |
1.62E-03 |
0.37 |
2.16 |
4.21E-05 |
0.45 |
|
|
|
Glycine, Serine and Threonine Metabolism |
| 11 |
L-ile |
8.87 |
158 |
1.67 |
1.72E-04 |
0.41 |
2.2 |
1.97E-05 |
0.44 |
|
|
|
Valine, leucine and isoleucine degradation |
| 12 |
AABA |
7.19 |
130 |
1.29 |
8.28E-03 |
0.53 |
1.94 |
1.89E-04 |
0.7 |
|
|
|
Fatty Acid Metabolism; Glycolysis; Glutamate metabolism; |
| 13 |
AMA |
11.19 |
218 |
1.35 |
2.58E-03 |
0.56 |
2.12 |
2.83E-05 |
0.67 |
|
|
|
dicarboxylic acid; malonate; biosynthetic formation of glycine |
| 14 |
αTP |
26.16 |
502 |
1.79 |
6.08E-03 |
0.57 |
1.11 |
5.02E-02 |
0.41 |
|
|
|
Antioxidant |
| 15 |
Sitosterol |
28.57 |
357 |
2.25 |
7.58E-07 |
0.70 |
1.37 |
6.92E-03 |
0.41 |
1.69 |
1.71E-02 |
0.29 |
Steroid biosynthesis;immunity |
| 16 |
HMA |
13.68 |
129 |
1.79 |
2.42E-04 |
0.82 |
1.39 |
6.73E-03 |
0.47 |
|
|
|
cholesterol synthesis and fatty acid mobilization |
| 17 |
3HV |
8.05 |
147 |
1.86 |
9.89E-05 |
0.91 |
1.8 |
7.83E-03 |
0.59 |
2.59 |
1.57E-03 |
0.31 |
Valine, leucine and isoleucine biosynthesis |
| 18 |
PA |
17.26 |
117 |
2.04 |
4.68E-05 |
1.00 |
2.05 |
1.25E-04 |
0.77 |
|
|
|
Fatty acid metabolism |
| 19 |
HA |
18.17 |
327 |
2.08 |
1.18E-05 |
1.09 |
2.24 |
2.94E-05 |
0.75 |
2.08 |
3.68E-02 |
0.34 |
Fatty acid metabolism |
| 20 |
SA |
18.71 |
341 |
2.26 |
5.60E-07 |
1.14 |
2.22 |
4.30E-05 |
0.76 |
2.34 |
8.85E-03 |
0.37 |
Fatty acid metabolism |
| 21 |
BHBA |
7.02 |
147 |
2.58 |
2.83E-10 |
1.33 |
3.06 |
2.43E-10 |
0.81 |
3.32 |
4.49E-05 |
0.53 |
Synthesis and degradation of ketone bodies |
| 22 |
T-9-OA |
18.82 |
339 |
2.09 |
1.76E-06 |
1.39 |
2.45 |
3.75E-07 |
1.06 |
|
|
|
Fatty acid metabolism |
| 23 |
MA |
15.36 |
285 |
1.73 |
7.58E-05 |
1.58 |
2.22 |
4.87E-06 |
1.14 |
|
|
|
Fatty acid metabolism |
| 24 |
C-9-HA |
17.09 |
311 |
1.68 |
9.90E-05 |
1.66 |
2.15 |
6.81E-06 |
1.28 |
|
|
|
Fatty acid metabolism |
| 25 |
2PC |
10.23 |
156 |
2.19 |
4.12E-06 |
1.79 |
2.77 |
1.53E-09 |
1.78 |
|
|
|
Lysine metabolism |
| 26 |
L-ser |
9.77 |
204 |
1.34 |
1.43E-02 |
−0.49 |
|
|
|
2.37 |
3.36E-04 |
−0.43 |
Glycine, serine, and threonine metabolism |
| 27 |
GABA |
11.91 |
84 |
1.73 |
2.91E-04 |
−0.71 |
|
|
|
2.27 |
8.44E-04 |
−0.48 |
Fatty acid metabolism; Glycolysis; Glutamate metabolism; Pyruvate metabolism |
| 28 |
Melibiose |
24.37 |
204 |
1.05 |
2.19E-02 |
−0.66 |
|
|
|
|
|
|
Arginine and proline metabolism |
| 29 |
Erythritol |
11.72 |
147 |
1.1 |
1.75E-02 |
−0.43 |
|
|
|
|
|
|
Galactose metabolism |
| 30 |
3HIV |
7.69 |
75 |
1.05 |
1.24E-02 |
−0.26 |
|
|
|
|
|
|
Pentose phosphate pathway |
| 31 |
2Me3HB |
7.53 |
117 |
1.34 |
5.91E-03 |
0.36 |
|
|
|
|
|
|
Valine, leucine and isoleucine biosynthesis |
| 32 |
Xylitol |
14.11 |
307 |
1.2 |
5.67E-03 |
0.42 |
|
|
|
|
|
|
Fatty acid metabolism; ketogenesis |
| 33 |
4HYP |
11.88 |
230 |
|
|
|
1.61 |
5.97E-03 |
0.47 |
1.3 |
2.90E-02 |
−0.24 |
Glycolysis; Pentose phosphate Pathway |
| 34 |
L-orn |
15.17 |
142 |
|
|
|
1.16 |
6.00E-02 |
−0.68 |
|
|
|
Urea Cycle; D-arginine and D-ornithine metabolism |
| 35 |
MMA |
8.53 |
319 |
|
|
|
1.33 |
1.83E-02 |
−0.39 |
|
|
|
dicarboxylic acid;malonate |
| 36 |
2-KG |
12.47 |
73 |
|
|
|
1.17 |
4.48E-02 |
−0.26 |
|
|
|
TCA Cycle; Glycolysis |
| 37 |
L-leu |
8.57 |
158 |
|
|
|
1.28 |
1.84E-02 |
0.19 |
|
|
|
Valine, leucine, and isoleucine metabolism |
| 38 |
Citrate |
15.24 |
73 |
|
|
|
|
|
|
1.72 |
7.87E-03 |
−0.59 |
TCA Cycle |
| 39 |
DHBA |
10.7 |
73 |
|
|
|
|
|
|
2.28 |
1.75E-02 |
−0.29 |
Fatty acid metabolism; Butanoate metabolism |
| 40 | L-pro | 8.91 | 142 | 1.53 | 1.43E-02 | −0.22 | Arginine and proline metabolism | ||||||
aSignificant changes in the levels of corresponding metabolites between arbitrary two groups by the ANOVA and t-test (P < 0.05).
2PC 2-piperidinecarboxylic acid, C-9-HA cis-9-hexadecenoic acid, MA myristic acid, T-9-OA Trans-9-octadecenoic acid, BHBA 3-hydroxybutyric acid, SA stearic acid, HA heptadecanoic acid, PA palmitic acid, 3HV 3-hydroxyvaleric acid, HMA 3-hydroxy-3-methylglutaric acid, αTP α-tocopherol, AMA aminomalonic acid, AABA α-aminobutyric acid, L-ile l-isoleucine, Gly glycine, Glc Glucose, THBA 2,3,4-trihydroxybutyric acid, Gal galactose, pGlu pyroglutamic acid, GA glycolic acid, L-ala l-alanine, GLCA glucuronic acid, LA lactic acid, GABA 4-aminobutyric acid, L-ser l-serine, 4HYP 4-hydroxyproline, 3-HIV 3-hydroxyisovaleric acid, 2Me3HB 2-methyl-3-hydroxybutyric acid, L-orn l-ornithine, MMA methylmalonic acid, 2-KG 2-ketoglutaric acid, L-leu l-leucine, Cit citrate, DHB 3,4-dihydroxybutyric acid, L-pro, l-proline.
bRetention time.
cPeaks in total ion chromatograms (TICs) are numbered according to their retention time. The identification of a metabolite is based on National Institute of Standards and Technology (NIST08) mass spectra database according to the match of masses (m/z) between the interested peak’s fragmentation pattern and that from the standard database.
dVariable importance in the projection (VIP) was obtained from OPLS-DA model with value higher than 1.0.
eThe p-value calculated from two-tailed student's t test.
fFold change (FC) was calculated as binary logarithm of average mass response ratio between two groups, where the positive value means that the average mass response of the metabolite in the former is larger than that in the latter and vice versa.
gInformation from KEGG database or NuGOwiki database.