| dbo:abstract
|
- A catechol estrogen is a steroidal estrogen that contains catechol (1,2-dihydroxybenzene) within its structure. The catechol estrogens are endogenous metabolites of estradiol and estrone and include the following compounds:
* 2-Hydroxylated:
* 2-Hydroxyestradiol
* 2-Hydroxyestrone
* 2-Hydroxyestriol
* 4-Hydroxylated:
* 4-Hydroxyestradiol
* 4-Hydroxyestrone
* 4-Hydroxyestriol The most abundant catechol estrogen in serum and urine is 2-hydroxyestrone, with 2-hydroxyestradiol and 2-hydroxyestriol also being formed, while the principal 4-hydroxy catechol estrogen, 4-hydroxyestrone, is present in only small amounts in urine. 4-Hydroxyestriol has been detected in the urine of pregnant women. The catechol estrogens are formed from estradiol and estrone by cytochrome P450 enzymes predominantly in the liver but also in extrahepatic tissues, and are metabolized by catechol O-methyltransferase (COMT) into methoxylated estrogens such as 2-methoxyestradiol and 4-methoxyestrone as well as by conjugation via other phase II enzymes. Under poor conditions of inactivation by phase II enzymes, catechol estrogens can undergo oxidation to reactive quinones and semiquinones, and this has been hypothesized to contribute to estrogen-induced carcinogenesis. Similarly to estradiol and estrone, catechol estrogens possess estrogenic activity. 2-Hydroxylated catechol estrogens are weak and possibly antiestrogenic estrogens, whereas their 4-hydroxylated counterparts are more potent in their estrogenic activity. For instance, 2-hydroxyestrone reportedly shows negligible uterotrophic effect in animals, whereas 4-hydroxy catechol estrogens show moderate changes in stimulating uterine weight. In addition to being substrates for COMT similarly to catecholamines like dopamine, norepinephrine, and epinephrine, catechol estrogens are potent competitive inhibitors of COMT as well as of tyrosine hydroxylase, and may affect both catecholamine biosynthesis and metabolism. (en)
- 儿茶酚雌激素（英語：catechol estrogen）是指带有儿茶酚（1,2-二羟基苯，邻苯二酚）结构的甾体雌激素。儿茶酚雌激素通常是雌二醇和雌酮的内源性代謝產物，包括以下产物：
* 2-羟基化：
* 2-羟基雌酮
* 2-羟基雌二醇
* 2-羟基雌三醇
* 4-羟基化：
* 4-羟基雌酮
* 4-羟基雌二醇
* 4-羟基雌三醇 儿茶酚雌激素可被儿茶酚-O-甲基转移酶（COMT）甲基化形成以下代谢产物：
* 2-甲氧基化：
* 2-甲氧基雌酮
* 2-甲氧基雌二醇
* 2-甲氧基雌三醇
* 4-甲氧基化：
* 4-甲氧基雌酮
* 4-甲氧基雌二醇
* 4-甲氧基雌三醇 (zh)
|
