Question

Most active form of estrogen is --

• A. Estrone
• B. Estriol
• C. \(\beta\)-estradiol
• D. Estetrol

Hint:

Potency ranking of major estrogens:
\[ \text{Estradiol (E2)} > \text{Estrone (E1)} > \text{Estriol (E3)} \] Estradiol has approximately 10-fold higher potency than estrone and 80-fold higher potency than estriol.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Estrogens are a group of steroid hormones that regulate female reproductive development and secondary sex characteristics.
The mammalian body synthesizes multiple forms of estrogen with varying biological potencies.

Step 2: Detailed Explanation:
The three major naturally occurring estrogens in females are:
- Estrone (E1) (A): A weak estrogen dominant post-menopause.
- Estradiol 17\(\beta\)-estradiol (E2) (C): The most abundant and highly potent estrogen during reproductive years. It binds with the highest affinity to estrogen receptors, exhibiting the strongest biological activity.
- Estriol (E3) (B): A weak estrogen produced primarily by the placenta during pregnancy.
- Estetrol (E4) (D): Produced only during pregnancy by the fetal liver, possessing very low potency.

Step 3: Final Answer:
The most active form of estrogen is \(\beta\)-estradiol, corresponding to option (C).