Structure of Equilenin at 100 K: an estrone-related steroid

Abstract

The structure of the estrone-related steroid, Equilenin, C 18 H 18 O 2 (systematic name 3-hydroxy-13-methyl-11,12,13,14,15,16-hexahydrocyclopenta[a]phenanthren-17-one), has been determined at 100 K. The crystals are orthorhombic, P2 1 2 1 2 1 , and the absolute structure of the molecule in the crystal has been determined by resonant scattering [Flack parameter = À0.05 (4)]. The C atoms of the A and B rings are almost coplanar, with an r.m.s. deviation from planarity of 0.0104 Å . The C ring has a sofa conformation, while the D ring has an envelope conformation with the methine C atom as the flap. The keto O atom and the methyl group are translated 0.78 and 0.79 Å , respectively, from the equivalent positions on 17-estrone. In the crystal, molecules are linked by O-HÁ Á ÁO hydrogen bonds, forming chains parallel to the c-axis direction.

Structural and vibrational studies of equilenin, equilin and estrone steroids

“…Structurally, equilenin [13] is different from equilin and estrogen in the B ring, as can be seen in Figure 2. [13], with two aromatic C-H bonds in B. In equilin, due to the presence of a C=C in B only an aromatic C-H bond it is observed in this ring.…”

“…The initial theoretical structure of equilenin was that experimental determined by X-ray diffraction to 100 K by Frampton and MacNicol [13] and, later with this structure were modelled the structures corresponding to equilin and estrone by using the GaussView program [28]. The optimizations of three structures in gas phase were carried out with the Revision A.02 of Gaussian program [29] and by using the hybrid B3LYP/6-31G* method [26,27].…”

“…Here, the calculated geometrical parameters for equilenin, equilin and estrone steroids in gas phase by using the B3LYP/6-31G* method were compared with the experimental values determined for equilenin by Frampton and MacNicol [13]. The root-meansquare deviation (RMSD) values were employed to compare the experimental values with the corresponding theoretical ones.…”

“…Steroid hormones are important compounds found in the human body that are derived from cholesterol and have characteristics lipid-soluble and normally are grouped into two classes: corticosteroids and sex steroids differenced by bonding receptors and biological functions [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Hence, different factors (solubilization, motility, transport, metabolism, and complementarity of fit between hormone and receptor) have influence on the activity of steroid hormones.…”

“…Steroid hormones have multiple functions in the human body being among others, control metabolism, immune functions, inflammation, salt and water balance, development of sexual characteristics, and the ability to resist illness and hurt [18][19][20][21][22]. For instance, estrone, estradiol, estriol, equilenin, equilin and their derivatives are some of species associated with estrogens and, obviously, to steroid hormones [1][2][3][4][5][6][7][8][9]11,13]. Structural studies on these hormones and their quick identifications are very important from medicinal, chemistry, human health, environmental and pharmacological points of view because when these hormones are discharged toward the environmental can affect the systems of all living beings [14,15].…”