Table S1.

List of 126 identified blood metabolites

Category/compoundRBC-enrichedReported concentration in plasma or blood, μMAbundanceCVssCV30CV reportedP value between age groups
Nucleotides (7/11)
 ADPX48 ± 13H-M0.050.27X0.64
 AMPX6.2 ± 3.1H-M0.070.33X0.71
 ATPX433 ± 73H-M0.070.17X0.31
 CTPL0.10.330.078
 GDPX15 ± 2L0.090.380.075
 GTPX25 ± 6H-M0.050.32X0.58
 GMPX0L0.240.570.95
 IMPX14–100L0.060.380.55
 UDPX0L0.110.310.79
 UMPX0L0.580.880.86
 UTPL0.250.440.46
Nucleosides, nucleobases and derivatives (1/12)
 1-Methyl-adenosine0.06 ± 0.006H-M0.450.29X0.63
 1-Methyl-guanosine**0.046 ± 0.019L0.230.25X0.25
 AdenineX0.3 ± 0.28L0.20.53X0.71
 Adenosine0.5 ± 0.1L0.380.49X0.052
 Caffeine0–35H-M0.290.92X0.43
 Cytidine0.25 ± 0.19L0.080.33X0.079
 Dimethyl-guanosine0.029 ± 0.005L0.260.46X0.0081
 Dimethyl-xanthine0–8H-M0.250.610.078
 Hypoxanthine**0.38 ± 0.18H-M0.320.35X0.98
 UrateX336 ± 94H-M0.070.28X0.15
 Uridine*3.12 ± 1.31H-M0.140.34X0.84
 Xanthine*1.27 ± 0.78L0.030.56X0.87
Vitamins, coenzymes (2/5)
 4-Aminobenzoate<1 ng/mLL0.032.180.32
 NAD+X23.3 ± 6.9H-M0.080.3X0.046
 NADP+X19.6 ± 6.6H-M0.110.36X0.022
 NicotinamideX0.45H-M0.470.560.38
 PantothenateX2.2 ± 1.02H-M0.20.82X0.022
Nucleotide-sugar derivatives (4/4)
 GDP-glucoseXL0.090.530.26
 UDP-acetyl-glucosamineXL0.140.640.0073
 UDP-glucoseXH-M0.180.240.088
 UDP-glucuronateXL0.240.630.12
Sugar phosphates (8/9)
 6-PhosphogluconateXL0.250.30.49
 Diphospho-glycerateX4,500H-M0.170.240.77
 Fructose-6-phosphateX16L0.210.240.61
 Glucose-6-phosphateX38H-M0.190.290.94
 Glyceraldehyde-3-phosphate**X6.7 ± 1.0L0.490.990.86
 Glycerol-2-phosphate**XL0.160.310.32
 Pentose-phosphateX13.2 ± 4.8L0.280.340.049
 PhosphoglycerateX58 ± 14H-M0.240.290.12
 Sedoheptulose-7-phosphateX0.89 ± 0.41L0.280.52X0.82
Sugars and derivatives (3/6)
 1,5-Anhydroglucitol120 ± 39H-M0.080.46X0.0004
 GluconateX<5H-M0.160.330.32
 Glucosamine0.23–0.68H-M0.190.470.21
 Glucose4700–6100H-M0.150.4X0.54
myo-Inositol*21–49L0.270.24X0.31
N-acetyl-d-glucosamineXH-M0.090.260.82
Organic acids (6/10)
 2-Oxoglutarate8.6 ± 2.6L0.190.54X0.63
 Chenodeoxycholate0.85 ± 0.88H-M0.051.33X0.77
 Glycochenodeoxycholate0.06 ± 0.01H-M0.041.2X0.93
cis-AconitateL0.140.350.11
 CitramalateXL0.150.360.82
 Citrate79 ± 27H-M0.080.31X0.59
 Glutarate0.0–1.8L0.160.290.65
 Glycerate0–24L0.020.430.39
 MalateX0–21H-M0.170.20.76
 SuccinateX8.8 ± 2.7L0.250.60.49
Standard amino acids (0/17)
 Arginine80 ± 20H-M0.040.29X0.64
 Asparagine41 ± 10L0.170.23X0.11
 AspartateX3 ± 1, 400 ± 120H-M0.270.5X0.62
 Glutamate**X25 ± 15, 1,110 ± 360H-M0.440.28X0.29
 Glutamine586 ± 84H-M0.160.2X0.14
 Histidine82 ± 10H-M0.120.19X0.06
 Isoleucine62 ± 14H-M0.180.32X0.012
 Leucine123 ± 25H-M0.130.31X0.002
 Lysine188 ± 32H-M0.240.39X0.87
 Methionine25 ± 4H-M0.190.28X0.17
 Phenylalanine57 ± 9H-M0.010.17X0.041
 Proline168 ± 60L0.190.42X0.47
 Serine114 ± 19L0.270.33X0.2
 Threonine140 ± 33L0.170.42X0.63
 Tryptophan44 ± 7H-M0.080.24X0.22
 Tyrosine59 ± 12H-M0.060.27X0.051
 Valine233 ± 43L0.20.48X0.95
Methylated amino acids (8/13)
 Betaine47 ± 18H-M0.060.51X0.26
 Butyro-betaineX0.76H-M0.120.350.19
 Dimethyl-arginine0.66 ± 0.19H-M0.050.31X0.079
 Dimethyl-lysineL0.040.440.078
 Dimethyl-proline (stachydrine)X7 ± 10.8H-M0.030.79X0.68
 Methyl-histidine16.5 ± 10.1H-M0.040.3X0.45
 Methyl-lysine7 ± 6H-M0.030.730.66
S-methyl-ergothioneineXH-M0.050.630.36
 Trimethyl-histidine (hercynine)XL0.170.570.21
 Trimethyl-lysineX0.56 ± 0.17H-M0.090.38X0.38
 Trimethyl-phenylalanineXL0.111.180.9
 Trimethyl-tryptophan (hypaphorine)XH-M0.031.670.96
 Trimethyl-tyrosine**XL0.252.50.21
Acetylated amino acids (5/7)
N-acetyl-(iso)leucineL0.360.630.056
N-acetyl-arginine1.25 ± 0.28L0.130.62X0.0004
N-acetyl-aspartate<0.35L0.110.580.18
N-acetyl-glutamateXL0.070.570.16
N-acetyl-ornithine*1.1 ± 0.4L0.051.17X0.98
N2-acetyl-lysineL0.070.50.033
N6-acetyl-lysine*L0.130.430.012
Other amino acid derivatives (4/16)
 4-Guanidinobutanoate*<0.013–0.055L0.112.050.19
 Acetyl-carnosineL0.091.070.001
 Arginino-succinate**L0.270.40.61
 Carnosine*X6.5 ± 2.8L0.190.79X0.003
 Citrulline40 ± 10H-M0.060.3X0.001
 CreatineX30.1 ± 12.3H-M0.120.29X0.58
 Creatinine82.6 ± 26.2H-M0.10.35X0.23
 Hippurate4.28 ± 2.61H-M0.421.01X0.28
 Indoxyl-sulfate2.5 ± 1.4H-M0.150.59X0.071
 Kynurenine1.35 ± 0.26L0.060.48X0.91
 Ornithine55 ± 16L0.260.48X0.32
 PhosphocreatineXL0.070.480.65
 Quinolinic acid0.47 ± 0.22L0.31.18X0.23
S-adenosyl-homocysteine*X0.46 ± 0.02L0.080.83X0.044
S-adenosyl-methionine**X0.68 ± 0.03L0.150.88X0.085
 Taurine55 ± 13H-M0.10.37X0.79
Carnitines (0/10)
 Acetyl-carnitineX10.2 ± 2.2H-M0.050.41X0.78
 Butyryl-carnitine0.267 ± 0.077H-M0.020.37X0.19
 Carnitine30 ± 11H-M0.070.2X0.41
 Decanoyl-carnitine0.141 ± 0.053H-M0.121.11X0.47
 Dodecanoyl-carnitine0.052 ± 0.024H-M0.141.11X0.49
 Hexanoyl-carnitine0.080 ± 0.035H-M0.040.76X0.8
 Isovaleryl-carnitine0.138 ± 0.059H-M0.081.98X0.25
 Octanoyl-carnitine0.121 ± 0.053H-M0.251.02X0.61
 Propionyl-carnitineX0.400 ± 0.124H-M0.020.41X0.68
 Tetradecanoyl-carnitine**X0.024 ± 0.006L0.450.47X0.15
Choline derivatives (2/3)
 CDP-choline<3 μMH-M0.070.410.088
 CDP-ethanolamine*<3 μML0.180.430.077
 Glycerophosphocholine32 ± 3H-M0.080.47X0.66
Antioxidant (1/3)
 ErgothioneineX56 ± 47H-M0.120.63X0.2
 Glutathione disulfide (GSSG)X1.69 ± 0.38, 3,210 ± 1,500H-M0.190.18X0.21
 Ophthalmic acid*X0.01–0.03, 11.8–16.4H-M0.120.430.0087
Standards
 Hepes [M+H]+H-M0.060.290.761
 Hepes [M-H]H-M0.080.210.02
 PIPES [M+H]+H-M0.040.140.061
 PIPES [M-H]H-M0.080.230.113
  • The list of 126 compounds and two standards (Hepes, PIPES) detected by LC-MS are shown. Compounds with a single asterisk displayed within-sample variation (CVwi) equal to 0.1–0.2 whereas no asterisk indicates a CVwi less than 0.1. Those compounds with two asterisks had CVwi greater than 0.2. Compounds specifically enriched in RBCs, as opposed to plasma, are indicated (X). Compound concentrations previously reported in the literature (X) are shown (references in Dataset S1). Compound abundance (peak area) is indicated (H-M, high-medium; L, low). Coefficients of variation among three preparations from the same blood sample are denominated (CVss). Ten compounds had CVss values of >0.3, and 23 compounds had CVss values of >0.2 (highlighted in bold). Coefficients of variation for each compound among 30 subjects (CV30) are summarized in Fig. 1 and correspond roughly to other values in the literature. Compounds for which CVs have been reported previously are indicated (X). CV30 values of >0.4 are highlighted in bold. Levels of compounds between young and elderly subjects were considered to differ significantly at P < 0.05. Raw data are deposited in the MetaboLights database (see Data Availability).