COMT, CYP1A1, 2.8.2.15, 17 beta-estradiol, Estradiol 3-glucuronide, SULT1A3, 1.14.14.1, 2.4.1.17, 17beta-estra-1,3,5-trien-3,17-diol 3-sulfate, 1.14.14.1, UGT2B11, UGT1A10, methoxyestradiol, 2.1.1.6, 4-hydroxy- estradiol, CYP2C9, UGT2B28, SULT1E1, CYP3A4, CYP1B1, 2-hydroxy-Estradiol, SULT1A1, CYP2D6, 17beta-estra-1,3,5-trien-3,4,17-triol 4-methyl ether, 1.14.14.1, 16alpha,17beta-estra-1,3,5-trien-3,16,17-triol 16-D-glucuronoside, CYP2C8, 2.1.1.6, estriol, SULT2A1, CYP3A5, CYP2C19, 2.4.1.17, UGT1A1, CYP1A2
Estradiol metabolism.
Endogenous and exogenous estrogens undergo oxidative metabolism by hepatic microsomal cytochrome P-450. Aromatic hydroxylation at either the C2 or C4 position is a major route of Estradiol metabolism in humans and other mammals, although there is less 4-hydroxylation than 2-hydroxylation.
Several cytochrome P450 isoforms including Cytochrome P450, family 2, subfamily C, polypeptides 8 ( CYP2C8 ) [1] and 9 ( CYP2C9 ) [1], Cytochrome P450, family 3, subfamily A, polypeptides 4 ( CYP3A4 ) [2] and 5 ( CYP3A5 ) [1], Cytochrome P450, family 2, subfamily D, polypeptide 6 ( CYP2D6 ) [1], Cytochrome P450, family 1, subfamily A, polypeptides 1 ( CYP1A1 ) [2] and 2 ( CYP1A2 ) [2], Cytochrome P450, family 1, subfamily B, polypeptide 1 ( CYP1B1 ) [3] and Cytochrome P450, family 2, subfamily C, polypeptide 19 ( CYP2C19 ) [1] were shown to catalyze hydroxylation of Estradiol to 2-Hydroxyestradiol or/and 4-Hydroxyestradiol. Furthermore, Catechol-O-methyltransferase ( COMT ) catalyzes the methylation of 2-Hydroxyestradiol and 4-Hydroxyestradiol to 2-Methoxyestradiol and 4-Metoxyestradiol, respectively [4].
Cytochrome 450 isoforms CYP1A2 and CYP3A4 catalyzes the 16alpha-hydroxylation of Estradiol forming Estriol [2]. Estriol is glucuronidated to Estriol 16-D-glucuronoside by UDP glucuronosyltransferase 2 family, polypeptide B11 ( UGT2B11 ) [5].
Other pathways of Estradiol metabolism include formation of glucuronide conjugates and sulfation. UDP glucuronosyltransferase 1 family, polypeptides A1 ( UGT1A1 ) [6] and A10 ( UGT1A10 ) [6], and UDP glucuronosyltransferase 2 family, polypeptide B28 ( UGT2B28 ) [7] convert Estradiol to Estradiol 3-glucuronide.
Several sulfotransferases including Sulfotransferase family, cytosolic, 1A, phenol-preferring, members 1 ( SULT1A1 ) [8] and 3 ( SULT1A3 ) [9], Sulfotransferase family 1E, estrogen-preferring, member 1 ( SULT1E1 ) [10] and Sulfotransferase family, cytosolic, 2A, dehydroepiandrosterone (DHEA)-preferring, member 1 ( SULT2A1 ) [11] catalyze sulfation of Estradiol to 17beta-Estra-1,3,5-trien-3,17-diol 3-sulfate.