Estrogens, formation

Several potent anti-estrogens also have a potential to be used as 17/f-HSD inhibitors because some of them have a dual site of inhibitory action they block both the estrogen receptor (anti-estrogen effect) and estrogen formation (inhibitory effect on 17/f-HSD). Despite the complexity of a dually active agent, such inhibitors have interesting properties suitable for their potential use in the treatment of estrogen-sensitive diseases, but their potency and selectivity for 17/1-HSDl have to be improved [98]. 

According to the available returns the average reported dosages were 500-750mg daily to inhibit excessive estrogen formation from AAS aromatization and 1000-2000mg daily for the purpose of cortisol inhibition. Most reported a scaled weekly dosage... 

Aromatase inhibitors constitute an additional antiestrogenic principle that is based upon inhibition of estrogen formation. They are used chiefly in the therapy of advanced breast cancer when the tumor has become insensitive to estrogen and the patient has completed menopause. However, one agent in this class (anastrozole) was recently licensed for use in early breast cancer. 

Stone, N. N., Fair, W. R., and Fishman, J., Estrogen formation in human prostatic tissue from patients with and without benign prostatic hyperplasia. Prostate 9, 311—318 (1986). 

The valve that allows entry of 17-OH pregnenolone into the sex steroid pathway is the 17,20-lyase component of CYP17, the SER enzyme that catalyzes the 17a-hydroxylation of steroids. As noted above, the lyase component of the enzyme is active in certain tissues for reasons that are not currently clear. Both A" and steroids are known to feed into the sex steroid pathways although the absence of 3/6HSD precludes the former. It should be emphasized that the formation of androgenic steroids is necessary before estrogen formation is possible therefore, the initial reaction in the sex steroid pathway invariably produces an androgenic steroid. 

Takayanagi, R., K. Goto, S. Suzuki, S. Tanaka, S. Shimoda, and H. Nawata (2002). Dehy-droepiandrosterone (DHEA) as a possible source for estrogen formation in bone cells Correlation between bone mineral density and serum DHEA-sulfate concentration in postmenopausal women, and the presence of aromatase to be enhanced by 1,25-dihydroxyvitamin Dj in human osteoblasts. Mech. Ageing Dev. 123, 1107-1114. 

Leshin, M., Baron, J., George, F.W. Wilson, J.D. (1981). Increased estrogen formation and aromatase activity in fibroblasts cultured from the skin of chickens with henny feathering trait. ]. Biol. Chem., 256, 4341-4. 

Indirect and direct metabolism of dehydroepiandrosterone sulfate are combined in estrogen formation during pregnancy, since dehydroepiandrosterone sulfate is hydroxylated into 16a-hydroxydehydroepiandrosterone... 

Aromatase inhibitors (aminogluthetimide, formes-tane, trilostane) block the formation of estrogens from precursor steroids and thus lower estrogen levels. They have been used for treating breast cancer. 

Huber MM, TA Ternes, MU von Gunten (2004) Removal of estrogenic activity and formation of oxidation products during ozonation of 17a-ethinylestradiol. Environ Sci Technol 38 5177-5186. 

Tanghe T, W Dhooge, W Verstraete (2000) Formation of the metabolic intermediate 2,4,5-trimethyl-2-pentanol during incubation of a Sphingomonas sp. strain with the xeno-estrogenic octylphenol. Biodegradation 11 11-19. 

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