X-Ray crystal structure analysis and 13C NMR investigation of estriol 16- and 17-monoglucuronide derivatives

Abstract

The crystal structure of methyl-1-O-[3,16α-dihydroxy-estra-1,3,5(10)-trien-17β-yl]-2,3,4-tri-O-acetyl-β-Dglucopyranosiduronate, 1, clearly shows the β-linkage of the carbohydrate moiety with estriol and unambiguously shows the traps relationship of the 17α- and 16β-protons. ¹³C NMR studies on 1 and on other estriol 16α- and 17β-glucuronide derivatives show differences between the two types of isomer based on the chemical shift values for C-16 and C-17 which are diagnostic. For C-17 derivatives with the β configuration, the chemical shift difference between the C-16 and C-17 signals was about 20 ppm, whereas the difference between the resonances for the 16α-derivatives was only about 5 ppm. The correlation of the 17α-proton with the anomeric proton (H-1′) from estriol 17β-glucuronide derivatives, based on 2D-NOESY spectra, was also useful in distinguishing the estriol 17β-derivatives from the 16α-isomers.