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. 2022 Jan 17;12(1):88. doi: 10.3390/metabo12010088

Table 2.

Suggested biotransformation of Hac based on phase I and phase II metabolism experiments. Metabolites detected by UHPLC-(+ESI)-QqTOF MS are grouped by similar biotransformation reactions and characterized by their retention time (Rt), elemental formula, measured protonated molecule [M+H]+ and mass deviations (Δm—measured/calculated mass).

No. Metabolite Biotransformation Rt (min) Formula [M+H]+ (m/z) Δm (mDa) a Δm (ppm) a
16 Hac -(GSH)2 GSH conjugation 4.2 C37H54N6O17S2 919.3017 4.3 4.7
17 Hac-(GSH)2 GSH conjugation 4.4 C37H54N6O17S2 919.3043 1.7 1.8
18 Hac-GSH-CysGly GSH conjugation;
cleavage of Glu		 3.9 C32H47N5O14S2 790.2672 3.8 4.8
19 Hac-GSH GSH conjugation 5.0 C27H37N3O11S 612.2245 2.3 3.8
20 Hac-GSH GSH conjugation 5.2 C27H37N3O11S 612.2204 −1.8 −2.9
21 Hac-GSH GSH conjugation 5.4 C27H37N3O11S 612.2231 0.9 1.5
22 Hac-GSH GSH conjugation 5.6 C27H37N3O11S 612.2217 0.5 0.8
23 Hac-GSH-H2O GSH conjugation;
water addition		 4.6 C27H39N3O12S 630.2311 −1.6 −2.5
24 Hac-GSH-H2O-CH3 GSH conjugation;
water addition;
O-methylation		 5.6 C28H41N3O12S 644.2513 2.9 4.5
25 Hac-GSH-H2O-CH3 GSH conjugation;
water addition;
O-methylation		 5.7 C28H41N3O12S 644.2460 −2.4 −3.7
26 Hac-CysGly GSH conjugation,
cleavage of Glu		 5.1 C22H30N2O8S 483.1814 1.8 3.7
27 Hac-CysGly GSH conjugation,
cleavage of Glu		 5.3 C22H30N2O8S 483.1814 1.8 3.7
28 Hac-CysGly-H2O GSH conjugation,
cleavage of Glu		 4.0 C22H32N2O9S 501.1885 −1.6 −3.2
29 Hac-CysGly-H2O GSH conjugation,
cleavage of Glu,
water addition		 4.3 C22H32N2O9S 501.1925 2.4 4.8
30 Hac-CysGly-H2O GSH conjugation,
cleavage of Glu;
water addition		 4.6 C22H32N2O9S 501.1917 1.6 3.2
31 Hac-CysGly-H2O GSH conjugation,
cleavage of Glu;
water addition		 4.8 C22H32N2O9S 501.1881 −2.0 −4.0
32 Hac-Cys Cys conjugation/GSH conjugation, cleavage of Glu and Gly 5.4 C20H27NO7S 426.1599 1.8 4.2
33 Hac-H2O water addition 6.0 C17H22O6 323.1480 −1.0 −3.1
34 Hac-H2O water addition 6.3 C17H22O6 323.1483 −0.7 −2.2
35 Hac-H2O-CH3 water addition;
O-methylation		 7.9 C18H24O6 337.1657 1.1 3.3
36 Hac-OH hydroxylation 5.4 C17H20O6 321.1314 −1.9 −5.9
37 Hac-OH hydroxylation 6.7 C17H20O6 321.1332 −0.1 −0.3
38 Hac-H2O-OH water addition, hydroxylation 5.8 C17H22O7 339.1448 1.0 2.9
39 DHac hydrogenation 6.9 C17H22O5 307.1525 −1.5 −4.9

a Mass accurancy of the used QqTOF MS system (Bruker micrOTOF-Q II) is specified as ±2 mDa (m/z < 400) and ±5 ppm (m/z > 400) for signals with intensity >10,000 counts). The calculated mass deviations are within these specifications.