Ester, estrogen structure

Therapeutic Function Estrogen Chemical Name Estradiol phosphate polymer Common Name Polymeric ester of phosphoric acid and estradiol Structural Formula r... 

Figure 1.4 The core structure and representatives of sterol lipids, (a) The core structure of the majority of the sterol species or from which the sterol species are resulted, (b) The representative structures of cholesterol (R = H) and cholesteryl esters (R = a fatty acyl), (c) A representative structure of the steroid subgroup species (i.e., estrogen), (d) A representative structure of the secosteroid subgroup (i.e., vitamin Dj). (e) A representative structure of the species among the bile acid subgroup of sterol (i.e., cholic acid).

Sterols are a class of lipids that consist of a steroid and an alcohol. The most physiologically abundant sterol in humans is cholesterol, which is an integral part of the plasma membranes, confaring the fluidity of the lipid bilayer. Due to its amphipathic nature, cholesterol is an important structural component of cell membranes and the outer layer of plasma lipoproteins. Cholesterol plays an essential role both in the structure of cells and as a precursor to corticosteroids, mineral corticoids, bUe acids, vitamin D, and sex hormones such as testosterone, estrogen, and progesterone. As excess free cholesterol has cytotoxicity in cells, it is estrailied to a fatty acid to become a cholesteryl ester, a neutral form of cholesterol. Cholesteryl esters can be stored in the hpid droplets of cells without cytotoxicity, and therefore cholesterol esterification is increased whrai free cholesterol content in cells becomes excessive. 

Testosterone produced by the placenta is transferred to the fetus and is conjugated mainly with sulfuric acid, but in contrast to a high sulfatase activity by the placental tissues for ester sulfates of 3/J-hydroxy-As steroids and for estrogen sulfates, the testosterone sulfate is poorly hydrolyzed by placental tissues (French and Warren, 1966). These results confirm that the sulfatase activity in the placental compartment is conditioned by the structure of the sulfate. In addition, the incubation of testosterone sulfate with a placental microsomal preparation failed to show any formation of estrogens (Cheatum et at., 1968). These last results also agree with the absence of aromatization of testosterone sulfate during pregnancy (Baulieu ef al., 1965). 

---