17α-Epiestriol, or simply 17-epiestriol, also known as 16α-hydroxy-17α-estradiol or estra-1,3,5(10)-triene-3,16α,17α-triol, is a minor and weak
endogenousestrogen, and the 17α-
epimer of
estriol (which is 16α-hydroxy-17β-estradiol).[1][2][3] It is formed from
16α-hydroxyestrone.[4][5] In contrast to other endogenous estrogens like
estradiol, 17α-epiestriol is a selective
agonist of the
ERβ.[6] It is described as a relatively weak estrogen, which is in accordance with its relatively low
affinity for the
ERα.[7] 17α-Epiestriol has been found to be approximately 400-fold more potent than estradiol in inhibiting
tumor necrosis factor α (TNFα)-induced
vascular cell adhesion molecule 1 (VCAM-1)
expressionin vitro.[8]
Relative affinities (%) of 17α-epiestriol and related steroids[9][10][11][12]
Values are percentages (%). Reference
ligands (100%) were
progesterone for the
PRTooltip progesterone receptor,
testosterone for the
ARTooltip androgen receptor,
E2 for the
ERTooltip estrogen receptor,
DEXATooltip dexamethasone for the
GRTooltip glucocorticoid receptor,
aldosterone for the
MRTooltip mineralocorticoid receptor,
DHTTooltip dihydrotestosterone for
SHBGTooltip sex hormone-binding globulin, and
cortisol for
CBGTooltip Corticosteroid-binding globulin.
17α-Epiestriol, or simply 17-epiestriol, also known as 16α-hydroxy-17α-estradiol or estra-1,3,5(10)-triene-3,16α,17α-triol, is a minor and weak
endogenousestrogen, and the 17α-
epimer of
estriol (which is 16α-hydroxy-17β-estradiol).[1][2][3] It is formed from
16α-hydroxyestrone.[4][5] In contrast to other endogenous estrogens like
estradiol, 17α-epiestriol is a selective
agonist of the
ERβ.[6] It is described as a relatively weak estrogen, which is in accordance with its relatively low
affinity for the
ERα.[7] 17α-Epiestriol has been found to be approximately 400-fold more potent than estradiol in inhibiting
tumor necrosis factor α (TNFα)-induced
vascular cell adhesion molecule 1 (VCAM-1)
expressionin vitro.[8]
Relative affinities (%) of 17α-epiestriol and related steroids[9][10][11][12]
Values are percentages (%). Reference
ligands (100%) were
progesterone for the
PRTooltip progesterone receptor,
testosterone for the
ARTooltip androgen receptor,
E2 for the
ERTooltip estrogen receptor,
DEXATooltip dexamethasone for the
GRTooltip glucocorticoid receptor,
aldosterone for the
MRTooltip mineralocorticoid receptor,
DHTTooltip dihydrotestosterone for
SHBGTooltip sex hormone-binding globulin, and
cortisol for
CBGTooltip Corticosteroid-binding globulin.