Estrone glucuronide

Homogeneous TR-FIAs have been reported in which proprietary lanthanide chelates are used. In a homogeneous immunoassay for T4, a fluorescent europium chelate coupled to thyroxine is quenched by antibody binding. 90 A similar approach is used for estrone-3-glucuronide. 91 TRFIAs based on homogeneous methods have not yet become widely used. 

G Barnard, F. Kohen, H. Mikola, and T. Lovgren, Measurement of estrone-3-glucuronide in urine by rapid, homogeneous time-resolved fluoroimmunoassay, Clin. Chem. 35, 555-559 (1989). 

The enzyme activity is inversely proportional to the concentration of sample Ag. Human IgG at the pico-mole level has been quantified in less than 1.5 h with this method. Estrone-3-glucuronide at the femto-mole level has been quantified with this method. 

Caution should also be exercised when assaying samples from subjects who are receiving oral contraceptives or estrogen replacement therapy because cross-reacting steroids may cause elevated results. Most notably, cross-reactivity with estrone is as high as 10% for some assays, but much lower (<1%) in others. This is likely due to a difference in the specificity of the antibody used for estradiol. Similar effects have been observed for metabolites conjugated at the 3 position, like estrone-3-sulfate and estrone-3-glucuronide. ... 

A novel homogeneous assay for urinary estrone-3-glucuronide has been reported by Kim et al (K8) using an A-aminoethyl-A-ethyl isoluminol derivative (see Table 3, n = 2). In contrast to antibody enhancement, this assay exploits the fact that 2N NaOH enhances free label chemiluminescence, and this is reduced in the presence of specific antibodies. Unlabeled estrone-3-glucuronide reverses the inhibition in a concentration-dependent manner and 8 pg per tube can be minimally detected (K8). 

K8. Kim, J. B., Kwon, O. J., and Barnard, G., A novel homogeneous immunoassay for estrone-3-glucuronide based on antibody protected effects on the enhancement of chemiluminescence by NaOH. In Bioluminescence and Chemiluminescence Current Status (P. E. Stanley and... 

Similar results were obtained by Koy and Slaunwhite (1970) upon injection of doubly labeled estrone glucuronide to a T-tube patient. 

Estrone glucuronide perfused into the fetoplacental unit through the umbilical vein was metabolized to estradiol glucuronide and to estriol glucuronide ivithout previous hydrolysis. This reaction took place principally in fetal liver (Zucconi et al., 1967a). 

Fig. 19. Principal pathways in tbe transfer of androgen and eatri on conji tes between the amniotic cavity, fetus, placenta, and mother. (1) Possible alternatives (2) suggested glucuronidase activity- Ei estrone Kt estradiol estriol Ei S estrone sulfate Et-S estradiol sulfate Kj-S estriol sulfate Ei-Glu estrone glucuronide Ei-Glu estradiol glucuronide Ej-Glu estriol glucuronide Ej-S,Glu estriol-3-sulfale, IbiF ucuronide DIIA dehydroepiandrosterone I60-IIO-DHA l6a-hydroxydehydro-epiandrosterone DlIA-5 dehydroepiandrosterone sulfate I6a-I10-D1IA-S 16a-hy-droxydehydroepiandrasterone sulfate.

Polyphenols and flavanoids in rat liver microsomal fractions have been demonstrated to inhibit glucuronidation of estrone and estradiol in vitro (Zhu et al, 1998). In addition, flavonoids have also been found to induce phase I and II enzymes in rats including UDP-glucuronosyl transferase (Seiss et al, 1996). However, the effects of phytoestrogens have not been evaluated for either their inhibition or induction of glucuronosyl transferase activity. 

After administration of estradiol benzoate to calves, the major metabolites found in muscle were estradiol-17 and estrone. The pattern of metabolites occurring in fat was similar to that in muscle. Highest residue concentrations were found in kidney and liver, the major metabolites being identified in kidney including estradiol-17, estradiol-17 -glucuronide, estradiol-17, and estrone. In liver, major metabolites could not be identified but estradiol-17, estrone, estriol, and glucuronides accounted for the remaining radioactivity (2). 

There are two main types of internal standards. The first ones are stable isotope labeled (SIL) internal standards. They are compounds in which several atoms in the analytes are replaced by their respective stable isotopes, such as deuterium (2H, D or d), 13C, 15N, or 170. Labeling with the first three isotopes are most common, particularly labeling with deuterium (due to less difficulty in synthesis and therefore less expensive). For examples, raloxifene-d4-6-glucuronide was used as the internal standard for the determination of raloxifene-6-glucuronide [5] and 1, 2, 3, 4-13C4 estrone (PCJEl) was used as the internal standard for estrone (El) [6], The usage of stable isotope labeled internal standards in quantitative LC-MS or GC-MS analysis is often termed as isotope dilution mass spectrometry (IDMS) [7],... 

CRITICAL ASSESSMENT OF THE METHOD Using primary cultures of hepatocytes the retention of transporter expression and activity needs to be guaranteed strictly speaking after each preparation. Cryopreserved hepatocytes from one preparation could be a powerful alternative for industrial applications in the future, because transporter expression and activity could only be characterized once. Houle et al. (2003) compared the transporter activities in cropreserved and freshly isolated hepatocytes and found no significant difference in the transport rates of 14C-taurocholate, 3H-estrone sulfate and 3H-estradiol-17 3-D-glucuronide. 

Approx 30 2-hydroxylation (CYP3A4) and sulphate and glucuronide conjugation and up to 30% is excreted unoxidized. Excretion is 60% renal and 40% in faeces. High first pass metabolism Estrone (small amounts)... 

Koenigs-Knorr synthesis of aryl glucuronides. Steroid glucuronides of estrone, 17 /)-estradiol, estriol, and equilenin can be prepared in excellent yield by the reaction of the phenolic steroid with the bromo sugar (I) in toluene using cadmium carbonate as... 

The primary estrogen in premenopausal women is 17-P-estradiol (E2), which is synthesized by developing ovarian follicles. Estradiol is oxidized to estrone (El) and then to estriol (E3). Estrone is also produced in peripheral tissues by aromatization of androstenedione, an androgen precursor that is produced by both the ovaries and the adrenal glands after the menopause, estrone produced in this way becomes the predominant estrogen. All of the estrogens are sulfated and glucuronidated before excretion. 

Isobe et al. [20] extended the seope by analysing both estrogens like estradiol, estrone, and estriol, and their sulfate and glucuronide eonjugates in river water, lake water, and STP samples. SPE in eombination with negative-ion LC-ESl-MS-MS in SRM mode was used. Method deteetion limits between 0.1 and 3.1 ng/1 were reported. While the free steroids and some of the sulfates were deteeted in environmental samples, most of the eonjugates were below the deteetion hmit. 

Representative Chemicals 17/l-Estradiol-3-glu-curonide 17)S-Estradiol-17-glucuronide Estradiol-3,17-disulfate Estradiol-3,17-diglucuronide Estrone-3-sulfate... 

Studies with female CD-I mice with 2% rosemary methanol extract diet increased liver microsomal oxidation and glucuronidation of estradiol and estrone and inhibited uterotropic action (Zhu et al 1998). It is suggested that stimulating certain pathways of estrogen metabolism may be beneficial for the prevention of estrogen-dependent tumors in the target organs of humans and animals. 

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