Table 9

Comparison of the proton chemical shifts in the standard carboxylic acid metabolite M-2 and metabolite M-1

Proton on CarbonProton Chemical Shift in Standard Carboxylic Acid Metabolite M-2Proton Chemical Shift in Metabolite M-1
7 and 117.517.51
8 and 107.957.96
21 and 257.417.45
22 and 248.008.10

Glucuronide formation causes significant shifts of the signals of the protons on C-21 and =25 and C-22 and =24.