Biological Properties of Estrogen Sulfates

Possible health impact of animal oestrogens in food

“…In man, it is partly metabolized like oestradiol-17P (Breuer and Scott, 1966), and the affinity of oestradiol-17a to the human oestradiol receptor is identical for oestradiol-17a and oestrone (Hiihnel et al, 1973). By oral uptake in humans, oestrone (whether conjugated as sulphate or not) still showed almost half the biological activity of oestradiol-17P (Herr et al, 1970). Hydrolysis of conjugates before absorption (Diczfaluzy and Levitz, 1970) and oxidation of oestradiol-17P to oestrone by the hepatic first pass (Rubens and Vermeulen, 1983) probably results in similar oral activity.…”

“…The oral uterotrophic activity of zeranol in rats and mice is 0.25 and 0.5% that of diethylstilboestrol (DES) (Baldwin et al, 1983). In women, DES is 4.5-fold more active in inducing withdrawal bleeding than oestradiol-17p after oral application (Herr et al, 1970). Thus, the relative oral activity of zeranol when compared with oestradiol-17P (100%) should amount to 1-2%.…”

“…In the first step of metabolic inactivation, the 17P hydroxyl group is either oxidized to its keto function (oestrone) or epimerized to a hydroxyl group in 17a-position (oestradiol-17a). Although oestrone (El) is about two-fold and oestradiol-17a (E2-17a) about 10-fold less orally active than the parent compound oestradiol-17P (Herr et al, 1970), they contribute to the total oestrogen activity in animals. In cattle fattening, additional application of oestrogens in anabolic preparations to increase live weight gain is licensed in several countries except the EU (e.g.…”

Oestrogen and Endometrial Cancer: A Reappraisal

“…Although oestradiol is a polycyclic hydrocarbon with a single aromatic ring, oestradiol and the products of its metabolism are not characterized by aromatic inner rings. No known pharmacologic oestrogen products resemble the aromatic hydrocarbon carcinogens, although two minor conjugated oestrogens (equilen and equilenin) have one and two double bonds respectively in the B ring (Herr et al 1970). The possibility that oestradiol or oestrogen-like compounds may be involved in the initiation of endometrial cancer cannot be excluded on grounds of chemical structure, but is diminished by current knowledge of structural correlations with carcinogenicity.…”