estriol and its Impurities
A natural steroidal estrogen, Estriol is also known as 16α-hydroxyestradiol. It is used as a hormone replacement therapy in menopausal symptoms. It is produced by the ovaries during pregnancy. It is an agonist of both of the estrogen receptors (ER), ERα and ERβ. Reference standards of Estriol API, and its pharmacopeial, non pharmacopeial impurities, and stable isotopes are listed below.

![(17β)-3,17-Bis[(tetrahydro-2H-pyran-2-yl)oxy]-est PA 05 0211011](https://www.pharmaffiliates.com/pimages/PA050211011.jpg)
(17β)-3,17-Bis[(tetrahydro-2H-pyran-2-yl)oxy]-estra-1,3,5(10)-trien-6-ol (Mixture of Diasteromers)
(17β)-3,17-Bis[(tetrahydro-2H-pyran-2-yl)oxy]-estra-1,3,5(10)-trien-6-ol (Mixture of Diasteromers)
Catalogue No.:PA 05 0211011
CAS :
122566-22-7
Molecular Formula : C28H40O5
Molecular Weight : 456.62


(8R,9S,13S,14S,15R,16R,17R)-2,4-Dibromo-3,15,16-trihydroxy-13-methyl-7,8,9,11,12,13,14,15,16,17-decahydro-6H-cyclopenta[a]phenanthren-17-yl acetate
(8R,9S,13S,14S,15R,16R,17R)-2,4-Dibromo-3,15,16-trihydroxy-13-methyl-7,8,9,11,12,13,14,15,16,17-decahydro-6H-cyclopenta[a]phenanthren-17-yl acetate
Catalogue No.:PA 05 0211019
CAS :
NA
Molecular Formula : C20H24Br2O5
Molecular Weight : 504.22


(8R,9S,13S,14S,15R,16R,17R)-3-(Benzyloxy)-13-methyl-7,8,9,11,12,13,14,15,16,17-decahydro-6H-cyclopenta[a]phenanthrene-15,16,17-triol
(8R,9S,13S,14S,15R,16R,17R)-3-(Benzyloxy)-13-methyl-7,8,9,11,12,13,14,15,16,17-decahydro-6H-cyclopenta[a]phenanthrene-15,16,17-triol
Catalogue No.:PA 05 0211021
CAS :
1426679-35-7
Molecular Formula : C25H30O4
Molecular Weight : 394.51


(8R,9S,13S,14S,15S,16S,17R)-13-Methyl-7,8,9,11,12,13,14,15,16,17-decahydro-6H-cyclopenta[a]phenanthrene-3,15,16,17-tetraol
(8R,9S,13S,14S,15S,16S,17R)-13-Methyl-7,8,9,11,12,13,14,15,16,17-decahydro-6H-cyclopenta[a]phenanthrene-3,15,16,17-tetraol
Catalogue No.:PA 05 0211023
CAS :
58001-91-5
Molecular Formula : C18H24O4
Molecular Weight : 304.39


(8R,9S,13S,17R)-3,15,17-Trihydroxy-13-methyl-6,7,8,9,11,12,13,17-octahydro-16H-cyclopenta[a]phenanthren-16-one
(8R,9S,13S,17R)-3,15,17-Trihydroxy-13-methyl-6,7,8,9,11,12,13,17-octahydro-16H-cyclopenta[a]phenanthren-16-one
Catalogue No.:PA 05 0211024
CAS :
NA
Molecular Formula : C18H20O4
Molecular Weight : 300.35


(8R,9S,13R)-3,15-Dihydroxy-13-methyl-6,7,8,9,11,12,13,17-octahydro-16H-cyclopenta[a]phenanthren-16-one
(8R,9S,13R)-3,15-Dihydroxy-13-methyl-6,7,8,9,11,12,13,17-octahydro-16H-cyclopenta[a]phenanthren-16-one
Catalogue No.:PA 05 0211025
CAS :
NA
Molecular Formula : C18H20O3
Molecular Weight : 284.36