TABLE 1

Kinetic parameter estimates for the glucuronidation of trans-resveratrol by human liver and intestinal microsomes and recombinant UGT1A isoforms

Data are expressed as estimate ± S.E., n = 6. Estimate units are as follows: Vmax, V2 = nanomoles per minute per milligram; Km, Ki = micromolar.

Conjugation Product
Protein Source
Vmax
Km
Ki
Type of Fit
Goodness of Fit (r2)
R3G HLM 7.4 ± 0.25 280.4 ± 21.6 1022 ± 71.5 PSI 0.91
HIM 12.2 ± 0.34 505.4 ± 29.4a 600.8 ± 20.5a PSI 0.95
UGT1A1 4.4 ± 0.22 279 ± 20.53 383 ± 5.4 PSI 0.93
UGT1A9 5.4 ± 0.13 109.5 ± 5.9b 613.5 ± 18.9bc PSI 0.94
R4′G HLM Vmax1 = 0.45 ± 0.01 Km1 = 65.2 ± 29 N.A. BPM 0.96
Vmax2 = 1.3 ± 0.03 Km2 = 1685 ± 106.8
HIM 8.9 ± 0.14 454.5 ± 21.8 564.3 ± 38.1 PSI 0.95
UGT1A1 0.86 ± 0.02 50.7 ± 1.9 129.7 ± 2.8 PSI 0.97
UGT1A9
2.2 ± 0.05
750
N.A.
Hill (n = 1.6)
0.95

  • PSI, partial substrate inhibition; BPM, biphasic metabolism; N.A., not applicable.

  • ↵ a HLM versus HIM estimate significantly different, p < 0.01.

  • ↵ b UGT1A1 versus UGT1A9 estimate significantly different, p < 0.01.

  • ↵ c Ki was significantly greater than the Km for R3G formation in UGT1A9, p < 0.01.