Article Figures & Data
Figures
- Fig. 1.
Chemical structures of VG, its major metabolite M20.7, and the cysteine-conjugated metabolite M407.
- Fig. 2.
Plasma concentration-time profile and urinary and fecal excretions after a single oral dose of 30 mg/kg VG to male Sprague-Dawley rats. (A) Blood was drawn at 1, 2, 4, 8, 24, and 48 hours postdosing to measure plasma concentrations of VG and its metabolites M20.7 and M407. Urinary (B) and fecal (C) excretions were measured up to 48 hours postdosing. Data are shown as the mean ± S.D. of three rats.
- Fig. 3.
Urinary, fecal, and biliary excretions of VG and its metabolites M20.7 and M407 after a single oral administration of 30 mg/kg VG to bile duct–cannulated rats. Urine (A), feces (B), and bile (C) were collected up to 48 hours postdosing to measure the excretion of VG, M20.7, and M407. Data are shown as the mean ± S.D. of three rats.
- Fig. 4.
Proposed metabolic pathways of VG in rats. *Derived from He et al. (2009b).
- Fig. 5.
Product-ion spectra and proposed structures of the newly identified metabolites M583 and M464. (A and C) Fecal homogenate (0–24 hours) and biliary (0–4 hours) samples collected from three rats were pooled and analyzed by high-resolution LC-MS to obtain product-ion spectra of the ion ([M+H]+) or ([M−H]−) of M583 and M464. Proposed structures and fragmentations of M583 (B) and M464 (D). *Nonspecific interference peak.
- Fig. 6.
Formation of M464 and M611 by in vitro incubation of VG with GSH. (A) VG (100 μM) was incubated with or without GSH (100 mM) at 37°C for 24 hours to obtain UV light chromatograms at 207 nm. (B) Product-ion spectra of the ion at m/z 612 ([M+H]+) or m/z 610 ([M−H]−) obtained from M611. (C) Proposed structure and fragmentation of M611.
- Fig. 7.
Effects of human GST on M464 production from VG. (A) VG (100 μM) was incubated with HLC (1 mg/ml), GSH (5 mM), and EA (100 μM) at 25°C for 30 minutes. (B) CDNB (200 μM) was incubated with HLC (0.01 mg/ml), GSH (5 mM), and EA (100 μM) at 25°C for 5 minutes. Data are shown as the mean ± S.D. of triplicate determinations. ***P < 0.001 (Tukey’s test). NS, not significant.
- Fig. 8.
Proposed mechanisms for irreversible covalent binding of GSH to VG.
Tables
- TABLE 1
Plasma pharmacokinetics parameters after a single oral administration of 30 mg/kg VG to male Sprague-Dawley rats
Data are shown as the mean ± S.D. of three rats.
Compound Cmax (μM) tmax (h) AUCinf (μM h) t1/2,z (h) VG 2.919 ± 0.144 1.00 ± 0 17.28 ± 4.65 4.535 ± 1.099 M20.7 3.710 ± 0.534 1.33 ± 0.58 44.19 ± 7.54 6.040 ± 0.490 M407 0.001847 ± 0.00017 1.00 ± 0 0.1514 ± 0.0946 6.895 ± 3.817 AUCinf, area under the plasma concentration-time curve from time zero to infinity; t1/2,z, terminal-phase elimination half-life; tmax, time to reach Cmax.
Peak Retention Time (min) Normal Rats Bile Duct–Cannulated Rats Polarity, Accurate Masses and Δ of [M+H]+ and [M−H]− Estimated Formula Identified or Estimated Structure Da (mDa) M15.3 2.06–2.12 U, F U, F, B Pos: 226.1432-9 (−0.6 to 0.1)Neg: not detectable C12H19NO3 Carboxylic acid metabolite of VG M583 2.0–2.9 (broad) B Pos: 584.2267 (−0.5)Neg: 582.2117 (−1.0) C26H37N3O10S O-Glucuronide of M407 M20.7 2.0–3.0 (broad) P, U, F U, F, B Pos: 323.1958-66 (−0.7 to 0.1)Neg: 321.1805-20 (−1.5 to 0) C17H26N2O4 Carboxylic acid metabolite of VG M20.2 2.8–3.5 (broad) P, U U, B Pos: 480.2335-45 (−0.5 to 0.5)Neg: 478.2193-5 (−0.2 to 0) C23H33N3O8 O-Glucuronide of VG Mono-hydroxyl VG-1 3.45–3.58 P, U, F U, F, B Pos: 320.1963-70 (−0.6 to 0.1)Neg: not detectable C17H25N3O3 Mono-hydroxyl VG M18.6 3.55–3.68 P, U, F U, F, B Pos: 322.2117-26 (−0.8 to 0.1)Neg: not detectable C17H27N3O3 Amide metabolite of VG Mono-hydroxyl VG-2 3.83–3.98 P, U, F U, F, B Pos: 320.1961-8 (−0.8 to −0.1)Neg: not detectable C17H25N3O3 Mono-hydroxyl VG M407 3.86–3.96 P, U, F U, F, B Pos: 408.1942-54 (−1.0 to 0.2)Neg: 406.1796-811 (−1.0 to 0.5) C20H29N3O4S Cysteine conjugate of VG M464 4.01–4.09 U, F U, F, B Pos: 465.2156-65 (−1.0 to −0.1)Neg: 463.2021 (0) C22H32N4O5S Cysteinylglycine conjugate of VG VG 4.38–4.45 P, U, F U, F, B Pos: 304.2012-9 (−0.8 to −0.1)Neg: not detectable C17H25N3O2 VG B, bile sample at 0–4, 4–8, and 8–24 h; F, feces sample at 0–24 h; Neg, negative ionization mode; P, plasma sample 1, 2, and 4 h postdosing; Pos, positive ionization mode; U, urine sample at 0–24 h; Δ, the difference between measured accurate mass and calculated exact mass.
- TABLE 3
Biliary excretions of the metabolites M583 and M20.2 in bile duct–cannulated rats
Biliary samples obtained from VG-treated bile duct–cannulated rats were deconjugated using β-glucuronidase to calculate the biliary excretion of glucuronides. Data are shown as the mean ± S.D. of three rats. Biliary excretion differed significantly (P < 0.01) between incubations with and without β-glucuronidase (unpaired t test).
Analyte Biliary excretion (% of dose) (analyzed compounds) β-Glucuronidase(−) β-Glucuronidase(+) Δ M407 0.0521 ± 0.0084 (M407) 0.151 ± 0.024 (M407 + M583) 0.0984 ± 0.0174 (M583) VG 0.225 ± 0.048 (VG) 33.1 ± 5.7 (VG + M20.2) 32.9 ± 5.7 (M20.2) Δ, the difference between incubation with and without β-glucuronidase.
Data Supplement
- Supplemental Figure -
1. Typical ion chromatograms obtained from rat plasma, urine, feces, and bile following a single oral dose of VG.
- Supplemental Figure -
