Table 2 Urine potential biomarkers associated with ESCC.

No.	RT(min)	m/z	metabolite identification	P-value^c	VIP^d	trend^e	related pathway	The identification score^f
1	9.43	130.0501	Pyroglutamic acid^b	3.65E-06	6.59	↑	Glutamine metabolism	6
2	7.45	134.0591	Indoxyl^b	0.006	1.52	↑	Tryptophan metabolism	6
3	2.27	139.0507	Urocanic acid^a,b	0.017	1.53	↑	Histidine metabolism	8
4	1.45	162.1097	L-Carnitine^a,b	0.021	2.79	↑	Fatty acid transportation	8
5	2.27	165.0554	L-Fucose^a,b	0.003	1.88	↑	Fructose and mannose degradation	8
6	2.89	169.0378	Uric acid^a,b	4.89E-05	7.12	↑	Purine metabolism	8
7	9.56	181.0719	Paraxanthine^b	0.012	2.31	↓	Caffeine metabolism	6
8	2.07	204.1249	Acetylcarnitine^b	0.025	6.65	↑	Fatty acid β oxidation	6
9	3.41	228.0801	Deoxycytidine^a,b	2.51E-09	4.36	↑	Pyrimidine metabolism	8
10	9.43	265.1169	Phenylacetylglutamine^a,b	7.8E-07	12.91	↑	Phenylalanine metabolism	8
11	11.93	274.2009	Heptanoylcarnitine (carnitine C 7:0)^b	0.031	1.69	↓	Fatty acid β oxidation	6
12	12.3	286.2005	Octenoylcarnitine (carnitine C 8:1)	0.008	2.13	↓	Fatty acid β oxidation	4
13	13.39	300.2163	Nonenoylcarnitine (carnitine C 9:1)	0.025	1.39	↓	Fatty acid β oxidation	4
14	14.03	302.2319	Nonanoylcarnitine (carnitine C 9:0)^b	0.0025	3.39	↓	Fatty acid β oxidation	6
15	14.92	316.2472	Decanoylcarnitine (carnitine C 10:0)^a,b	0.012	1.36	↓	Fatty acid β oxidation	8
16	15.14	328.2473	Undecenoylcarnitine (carnitine C 11:1)	0.019	1.78	↓	Fatty acid β oxidation	4
17	5.08	330.0588	cAMP^a,b	0.016	2.15	↑	Purine metabolism	8
18	11.70	330.2650	Undecanoylcarnitine (carnitine C 11:0)^b	0.019	1.45	↓	Fatty acid β oxidation	6
19	4.94	346.0547	cGMP^a,b	2E-14	3.17	↑	Purine metabolism	8

^aMetabolites confirmed by standard compounds. ^bMetabolites provisionally identified by database searches and MS fragmentation. Others, proposals based on MS fragmentation and exact mass data. ^cP value of independent t-test. ^dVIP is variable importance in the projection obtained from OPLS-DA with a threshold of 1.0. ^eChange trend compared with controls. (↑): up-regulated. (↓): down-regulated. ^fThe identification score is calculated by the scoring metric.

Search