Untargeted metabolomics analysis of metabolite changes in gastric cancer patients from plateau regions

Table 1 Stability of internal standard responses in quality control samples

Internal standard	Retention time	Mass-to-charge ratio (mz)	RSD
IS1	222.6	121.0439	0.0374
IS2	159.2	133.1057	0.0262
IS3	231.2	152.0591	0.0662
IS4	28.5	127.0805	0.0444
IS5	160.4	127.1428	0.0466
IS6	157.5	135.1208	0.029

RSD: Relative standard deviation.

Table 2 Basic demographic characteristics in the gastric cancer and control groups

Group	Cases	Age (years)	Sex (male/female)
Gastric cancer group	30	60.40 ± 9.902	19/11
Healthy group	30	57.93 ± 11.447	16/14
t/χ2		29.553	0.617
P value		0.386	0.432

Table 3 principal component analysis model parameters

Model	Type	A	n	R2X (cum)	Title
Model 1	PCA	4	67	0.559	Total with QC
Model 2	PCA	4	60	0.559	Total
Model 3	PCA	4	60	0.559	CK vs DG

QC: Quality control; PCA: Principal component analysis; CK: Healthy group; DG: Gastric cancer group.

Table 4 Top 10 differential fecal metabolites between the gastric cancer and control groups

Name	VIP value	P value	Fold change	Trend
Dethiobiotin	2.148	0.000	9.229	Up
Glycylproline	1.269	0.000	3.538	Up
Glycine	1.568	0.001	5.981	Up
Hydroxyisocaproic acid	1.301	0.001	3.609	Up
Tyramine	1.640	0.002	14.039	Up
Methionine sulfoxide	1.263	0.002	2.579	Up
5-Aminopentanoic acid	1.156	0.002	3.367	Up
Citrulline	1.071	0.002	2.692	Up
Betonicine	1.131	0.004	2.286	Up
Formiminoglutamic acid	1.705	0.006	10.948	Up
Cytidine	2.080	0.000	0.154	Down
5'-methylthioadenosine	2.032	0.000	0.207	Down
Trehalose	1.203	0.001	0.205	Down
Melibiose	1.203	0.001	0.205	Down
Lotaustralin	1.591	0.001	0.270	Down
Adenosine	1.043	0.003	0.188	Down
Inosine	1.367	0.003	0.205	Down
Ribothymidine	1.454	0.004	0.218	Down
Raffinose	1.409	0.005	0.179	Down
Galactinol	1.356	0.008	0.108	Down

Table 5 Pathway analysis of differential fecal metabolites between the gastric cancer and control groups

Pathway name	Total	Hits	Raw P value	Impact
Purine metabolism	92	4	0.0072593	0.01303
Cysteine and methionine metabolism	56	3	0.011789	0.08586
Galactose metabolism	41	2	0.048471	0.06586
Lysine degradation	47	2	0.061937	0.07943
Glycine, serine, and threonine metabolism	48	2	0.064295	0.22194
Biotin metabolism	11	1	0.092074	0.19512
Pyrimidine metabolism	60	2	0.094814	0.02789
Arginine and proline metabolism	77	2	0.14362	0.01997
Histidine metabolism	44	1	0.32231	0.01609
Primary bile acid biosynthesis	47	1	0.34023	0.00822
Starch and sucrose metabolism	50	1	0.35769	0.00944
Tyrosine metabolism	76	1	0.49167	0.01424

"Total" represents the total number of metabolites in the pathway; "Hits" refers to the number of differential metabolites involved in the pathway; "Raw P value" is the P value from pathway analysis; "Impact" is the impact value from topology analysis.