4-Methoxyestrone
# 4-Methoxyestrone

4-Methoxyestrone (4-ME1) is an endogenous, naturally occurring methoxylated catechol estrogen and metabolite of estrone that is formed by catechol O-methyltransferase via the intermediate 4-hydroxyestrone. It has estrogenic activity similarly to estrone and 4-hydroxyestrone.

vte Selected biological properties of endogenous estrogens in rats :

| Estrogen | ER RBA (%) | Uterine weight (%) | Uterotrophy | LH levels (%) | SHBG RBA (%) |
| - | - | - | - | - | - |
| Control | – | 100 | – | 100 | – |
| Estradiol (E2) | 100 | 506 ± 20 | +++ | 12–19 | 100 |
| Estrone (E1) | 11 ± 8 | 490 ± 22 | +++ | ? | 20 |
| Estriol (E3) | 10 ± 4 | 468 ± 30 | +++ | 8–18 | 3 |
| Estetrol (E4) | 0.5 ± 0.2 | ? | Inactive | ? | 1 |
| 17α-Estradiol | 4.2 ± 0.8 | ? | ? | ? | ? |
| 2-Hydroxyestradiol | 24 ± 7 | 285 ± 8 | $+^b$ | 31–61 | 28 |
| 2-Methoxyestradiol | 0.05 ± 0.04 | 101 | Inactive | ? | 130 |
| 4-Hydroxyestradiol | 45 ± 12 | ? | ? | ? | ? |
| 4-Methoxyestradiol | 1.3 ± 0.2 | 260 | ++ | ? | 9 |
| $4-Fluoroestradiol^a$ | 180 ± 43 | ? | +++ | ? | ? |
| 2-Hydroxyestrone | 1.9 ± 0.8 | 130 ± 9 | Inactive | 110–142 | 8 |
| 2-Methoxyestrone | 0.01 ± 0.00 | 103 ± 7 | Inactive | 95–100 | 120 |
| 4-Hydroxyestrone | 11 ± 4 | 351 | ++ | 21–50 | 35 |
| 4-Methoxyestrone | 0.13 ± 0.04 | 338 | ++ | 65–92 | 12 |
| 16α-Hydroxyestrone | 2.8 ± 1.0 | 552 ± 42 | +++ | 7–24 | <0.5 |
| 2-Hydroxyestriol | 0.9 ± 0.3 | 302 | $+^b$ | ? | ? |
| 2-Methoxyestriol | 0.01 ± 0.00 | ? | Inactive | ? | 4 |
| Notes: Values are mean ± SD or range. ER RBA = Relative binding affinity to estrogen receptors of rat uterine cytosol. Uterine weight = Percentage change in uterine wet weight of ovariectomized rats after 72 hours with continuous administration of 1 μg/hour via subcutaneously implanted osmotic pumps. LH levels = Luteinizing hormone levels relative to baseline of ovariectomized rats after 24 to 72 hours of continuous administration via subcutaneous implant. Footnotes: $^a$ = Synthetic (i.e., not endogenous). $^b$ = Atypical uterotrophic effect which plateaus within 48 hours (estradiol's uterotrophy continues linearly up to 72 hours). Sources: See template. ||||||
