Estrogens synthetic

NaturaHy occurring and synthetic estrogens and androgens have been extensively and safely used to improve efficiency and carcass composition ia growing beef catde in the United States since the early 1950s. Several anaboHc steroid implants have been approved for use in beef catde in the United States, but only one, zeranol [55331-29-8] is approved for use in lambs. Anabolic steroids are not used for growth regulation in swine or poultry (see Steroids). 

Synthetic Estrogens" under "Hormones" in ECT 1st ed., Vol. 7, pp. 536—547, by P. E. Dreisbach, Calco Chemical Division, American Cyanamid Company "Nonsteroidal Estrogens" under "Hormones" in ECT 2nd ed., VoL 11, pp. 127—141, by R. 1. Dorfman, Syntex Research Division of Syntex Corporation "Nonsteroidal Estrogens" under "Hormones" in ECT 3rd ed., Vol. 12, pp. 658—691, by G. C. Crawley, Imperial Chemical Industries Limited. 

Female sexual development and behaviour in mammals occurs by default and requires no ovarian secretion, and it is only in genetic males that the testis can secrete hormones which destroy this female pattern and superimpose that of the male. Sexual differentiation is not so well defined in fish, and larval exposure to both synthetic estrogens and androgens is widely used in aquaculture to produce monosex cultures. Endocrine disruption of sexual differentiation in fish may therefore reflect both the complexity and diversity of such processes between different species. Some care is required in use of the terms hermaphrodite and sex-reversal since a true hermaphrodite has both functional testes and ovaries and a sex-reversed fish is fully functional as its final sex—both produce the appropriate viable gametes. Such functional sex-reversal is not possible in mammals, but in some species of fish it is the normal developmental pattern. In most of the cases of hermaphroditism or sex-reversal reported in the non-scientific press, there is evidence only for a few ovarian follicles within a functional testis. This may be considered as feminisation or a form of intersex, and is very clearly endocrine disruption, but it is certainly neither sex-reversal nor hermaphroditism. In some cases the terms have even been used to infer induction of a single female characteristic such as production of yolk-protein by males. 

Heterocycles as synthetic estrogens in emerging therapies for the prevention or treatment of postmenopausal osteoporosis 99JMC1. 

Self-condensation of the substituted propiophenone, 15, by the pinacol reaction proceeds to give the glycol, 16, as the meso isomer. (If it is assumed that the transition state for this reaction resembles product, this stereoselectivity can be rationalized on the grounds of steric interaction compare A, which leads to the observed product, with B.) Dehydration under very specialized conditions (acetyl chloride, acetic anhydride) affords the bisstyrene-type diene (17). Removal of the acyl groups by means of base affords the synthetic estrogen, dien-... 

Kidd, K.A., Blanchfield, P.J., and Mills, K.H. et al. (2007). Collapse of a fish population after exposure to a synthetic estrogen. Proceedings of the National Academy of Sciences of the United States of America 104, 8897-8901. 

In some animals, consumption of a phytoestrogen-rich diet can cause temporary infertility and reproductive system disorders (Irvine, 1999). In humans, lower testosterone levels and a decline in human semen quality over the past century have been luiked to increased exposure to environmental endocrine disrupters (EDCs) (Sharpe and Skakkebaek, 1993). Furthermore, cases of sexual impotence have been reported in males exposed to synthetic estrogens in the pharmaceutical industry (Mattison et al., 1990). If this might be the case, the fetal-prepubertal period and Sertoli cell development would be of critical importance (Sharpe and Skakkebaek, 1993). However, an adverse effect of phytoestrogens on male fertility has yet to be proven. Recent work (Mitchell et al., 2001) addressing this point led to the conclusion that up to 40 mg/day of isoflavones over a two-month period had no effects on gonadotrophin and... 

Combined oral contraceptives contain a combination of a synthetic estrogen and one of several steroids with progestational activity. Most oral contraceptives contain one of two types of estrogen ethinyl estradiol, which is pharmacologically... 

The natural estrogens E1-E3, as well as the synthetic estrogen EE2, have received considerable attention in the last decade as they are able to induce strong... 

Baronti C, Curini R, D Ascenzo G, Di Corcia A, Gentili A, Samperi R (2000) Monitoring natural and synthetic estrogens at activated sludge sewage treatment plants and in a receiving river water. Environ Sci Technol 34 5059-5066... 

Hormonal contraceptives contain either a combination of synthetic estrogen and synthetic progestin or a progestin alone. 

Two synthetic estrogens are used in hormonal contraceptives in the United States, ethinyl estradiol (EE) and mestranol. Mestranol must be converted to EE in the liver to be active. It is approximately 50% less potent than EE. Most combined oral contraceptives (OCs) contain estrogen at doses of 20 to 50 meg of EE daily. The contraceptive ring produces one-half the serum concentration of EE derived from a 30-mcg OC. 

The three main classes of phytoestrogens (and common food sources) are isoflavones (soybeans), lignans (cereals and oilseeds such as flaxseed), and coumestans (alfalfa sprouts). The biologic potency of phytoestrogens varies and is less than that of synthetic estrogen. 

In activated sludge, the synthetic estrogens ethynylestradiol and mestranol have been shown to remain stable and intact over 5 days, while progestogens are already up to more than 50% disintegrated after 48 h [32]. 

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