17p-oestradiol

ZEA resembles the human 17P-oestradiol hormone produced by theovaries. Although almost non-toxic, in very small doses it has oestrogenic effects that can disrupt the human endocrine system (Benbrook, 2005). It is important to note that transformation products of ZEA can have three to four times higher endocrine disrupting activity than ZEA. 

P-Estradiol (=17p-Oestradiol 17 p-Estradiol) (sterol) isolated by Edward Doisy (USA) (Nobel Prize, Medicine, 1943, with Henrik Dam, Vitamin K)... 

NO, through generation of cyclic GMP and activation of G kinase, modifies profoundly 17P-oestradiol early signalling and contributes to regulate long-term actions of the steroid (Falcone et al. 2002). 

Yen et al. (2001) utilized the fluorescent dye 2 ,7 -dichlorofluorescin diacetate to measure the generation of reactive oxygen species in human umbilical vein endothelial cells. 17P-Oestradiol (54 /jM) pretreatment for 18 h or direct co-incubation significantly suppressed both ferf-butylhydroperoxide-and oxidised LDL-induced stimulation of the generation of reactive oxygen species. 

P-Oestradiol afforded protection against oxidative nerve cell apoptosis. 17P-Oestradiol is indeed a potent antioxidant comparable to other phenolic compound such as a-tocopherol (Behl 1999, Moosmann and Behl 1999). 

Chvapil et al. (1974) studied the effect of both Fe and Fe chelating agents in tissues with a relatively high rate of collagen synthesis such as foetal skin and skin of newborn rats, 17P-oestradiol-stimulated uterus of immature rats, and carrageenan granuloma tissue. Neither systemic nor local injections of... 

Tamoxifen, 4-hydroxytamoxifen, nafoxidine, 1 P-oestradiol and ICI 164,384 were all found to protect rat liver nuclei against Fe(III)-ascorbate-dependent lipid peroxidation (Wiseman and Halliwell 1994). The order of effectiveness of these compounds was 4-hydroxytamoxifen >17P-oestradiol > nafoxidine > tamoxifen > ICI 164,384. The idea of a protection by tamoxifen against the formation of the genotoxic reactive intermediates and products of lipid peroxidation in the nuclear membrane and thus of an anticarcinogenic benefit was later questioned Carthew etal. (2001) found a clear dose-response relationship of tamoxifen-induced DNA adducts in the rat liver and the subsequent increase in the development of liver cancer, with and without phenobarbital promotion. In the absence of phenobarbital promotion there was a threshold value for of tamoxifen-induced DNA adducts (180 adducts/10 nucleotides) and the subsequent induction of liver cancer. 

In vitro, low concentrations of 17P-oestradiol (10 nM) reduced oxidative modification of normal health men volunteers (with total cholesterol < 5.5 mM) blood LDL in the presence of either ascorbic acid or tocopherol (Huang etal. 1999). Introduction of small amounts of esterified 17 -estradiol into lipoproteins by means of incubation of free 17P-cestradiol 17-stearate in plasma did not result in any antioxidant effect (Meng et al. 1999). Using an artificial transfer system (Celite dispersion), larger amounts of 17P-oestradiol esters could be incorporated into lipoproteins. Concentrations ranging between 0.27 and 1.38 molecules/LDL particle for 17P-oestradiol 17-stearate and between 0.36 and 1.93 molecules/LDL particle for 17P-oestradiol 17-oleate resulted in increased Cu -induced oxidation resistance of LDL, as indicated by statistically significant lag time prolongations. 

The most active women s oestrogen derived from hydrocarbon Sp-oestrane (10-92) is 3,17P-oestradiol (abbreviated E2, 10-93), which is supplied to the tissues by blood circulation, where it binds to specific receptors (proteins). In the body, it is transformed into oestrone (10-94) and oestriol (10-93). 

General information Oestradiol valerate is a novel oestrogen, whose structure is similar to that of 17p-oestradiol and is rapidly metabolised to 17p-oestradiol and valeric acid. It has a shorter half-life than ethinylestradiol (EE) and fewer effects. Oestradiol valerate Img is equal to oestradiol 0.76 mg. Oestradiol valerate has been used to create a... 

In another one-year, double-blind, randomised study to evaluate the endometrial safety and bleeding pattern, a low-dose combination of 0.25 mg DRSP/0.5mg 17p-oestradiol demonstrated a favourable risk/benefit profile in postmenopausal women [53 ]. 

Figure 13.20 Chemical formulae of 17P-oestradiol, testosterone, progesterone, trenbolone acetate and melengestrol acetate.

In 2002, the Scientific Committee on Veterinary Measures Relating to Public Health in the EU issued a report which provided evidence from 17 studies of the various hormones. This looked at a number of issues including exposure, alteration of gene expression, oestrogenic potencies, and the genotoxicity of 17P-oestradiol. Needless to say, most of the conclusions were not supportive of... 

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