Estradiol source

Withdrawal from anaboHc steroid treatment is not required before slaughter because residue levels in edible tissues are negligible, and are significantly lower than other sources of estradiol such as the normal endogenous production in humans and the phytoestrogens consumed in plant food sources (1). 

The ceUular source of the various ovarian steroids has been difficult to unravel, but a transfer of substrates between two cell types is involved. Theca cells are the source of androstenedione and testosterone. These are converted by the aromatase enzyme in granulosa cells to estrone and estradiol, respectively. Progesterone, a precursor for all steroid hormones, is produced and secreted by the corpus luteum as an end-product hormone because these cells do not contain the enzymes necessary to convert progesterone ro other steroid hormones (Figure 42-8). 

Estradiol is formed by lithium aluminium hydride reduction of the ketone. We can formulate this simply as hydride acting as the nucleophile, though hydride delivery by LAH is strictly more complex than this. Unless you are specifically asked for details, treat LAH as a source of hydride ion. 

The testis, like the ovary, has both gametogenic and endocrine functions. The onset of gametogenic function of the testes is controlled largely by the secretion of FSH by the pituitary. High concentrations of testosterone locally are also required for continuing sperm production in the seminiferous tubules. The Sertoli cells in the seminiferous tubules may be the source of the estradiol produced in the testes via aromatization of locally produced testosterone. With LH stimulation, testosterone is produced by the interstitial or Leydig cells found in the spaces between the seminiferous tubules. 

The Applied Biosystems Company have demonstrated outstanding estradiol measurement sensitivity at levels down to 0.1 pg on-column on their API 5000 instrument with an APCI source. The linearity was excellent over the range 0.001-10 ng/ml (company demonstration data). Thus, this analyte should not require derivatization if the latest equipment is available. 

Guo and co-workers [24,25] have spearheaded the development of MS/MS serum steroid profiles. Their most recent report describes profiling in 11 min of 12 steroids in 200 pi serum with minimal work-up, comprising acetonitrile protein precipitation. The steroids analyzed were as follows DHEA sulfate, DHEA, aldosterone, cortisol, corticosterone, 11-deoxycortisol, androstenedione, estradiol, testosterone, 17-hy-droxyprogesterone, progesterone, and 25-hydroxyvitamin D3. Stable-isotope-labeled internal standards were incorporated for each steroid. An API-5000 instrument was used with the APPI source in positive-ion mode, with the exception of aldosterone, which had greater sensitivity in negative-ion mode. Separation was carried out on a C8 column, which allowed more rapid separation than the more commonly utilized C18. The MRM transitions utilized are shown in Table 5.3.1. The lower level of sensitivity was between 1.5 and 10 pg/ml, dependent on the steroid. The authors were exhaustive in addressing issues of accuracy, recovery (90-110%) and reproducibility (< 12.2% for same-day and between-day). 

Figure 6.28 Metabolism of diethylstilboestrol via an epoxide intermediate. This potentially reactive intermediate may show an affinity for the estradiol receptor and thereby accumulate in oestrogen target organs. This may facilitate reaction with DNA in these organs. Source. From Ref. 10.

In the early days of organic chemistry, the word aromatic was used to describe certain fragrant substances from fruits, trees, and other natural sources. Chemists soon realized, however, that substances grouped as aromatic behaved in a chemically different manner from most other organic compounds. Today, the term aromatic refers to the class of compounds that can be represented as having a six-membered ring with three double bonds. Benzene is the simplest aromatic compound, but aspirin, the steroid sex hormone estradiol, and many other important compounds also contain aromatic rings. 

Source Bioavailability data abstracted from Ref. 86, except alfentanil (205), cisapride (214), ethinyl estradiol (215), midazolam (49), triazolam (207), saquinavir (216). 

Estradiol levels in follicular fluid correlate significantly with cleavage rate and with pregnancy in some studies (A3, B9, C2, W4), but not all (H5). In pooled follicular fluid, estradiol level is not associated with pregnancy (Fll, Ml2). It seems that the most estrogenic follicles are the major source of fertilizable oocytes. 

Soy is the most widely available source of isoflavones used therapeutically. They are structurally similar to 17p-estradiol, the most important human estrogen, but their relative binding affinity for the main estrogen receptor, receptor-a (ER-a), is only 0.05-l /o of the binding affinity of 17p-estradiol. A novel receptor. 

In most mammals, estrogens (female sex steroid hormones) are synthesized from cholesterol using the parent ring structure, cyclopentanoperhydrophenan-threne of the estrane series. The steroidogenic pathway includes the production of the androgenic precursors dehydroepiandrosterone and androstenedione, the latter of which is converted to testosterone, then to estradiol-17/i. This requires aromatization of these andogenic precursors by an aromatase enzyme complex. The major source of estrogen in postmenopausal women is the conversion of androstenedione to estrone by aromatase activity... 

Relative binding affinities for the estrogen receptor vary considerably based on the source of the estrogen receptor. Generally, if the RBA for estradiol-17/1 is set at 100, that of estrone is 15-60 and that of estriol is 0.2-30. 

The bis-Cp titanium molecules shown in Scheme 765 have been synthesized and used as potential antiestrogenic vectors to the estradiol receptor and a recognized cytotoxic molecule. They also proved to be particularly easy to exchange with Re in order to prepare organometallic radiopharmaceutical compounds with antiestrogenic properties.2020 These processes have been used as a source for Re(CO)3 through thermal ligand-transfer reaction between Cp titanium complexes and Re2(CO)i0. 

Use Emulsifying agent in cosmetic and pharmaceutical products, source of estradiol. 

Use Antirachitic vitamin when irradiated with UV light, it has vitamin D activity source of estradiol. 

The fight against aging should take into account not only the damage caused by the various sources of cell oxidation but also the fall in hormone levels. For menopausal or postmenopausal women, a standard formula is testosterone propionate 100 mg, estrone 5 mg, estradiol benzoate 5 mg, and water in oil excipient ad 100 g. 

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