Question

Total Number of Carbon atoms in pregnane is

• A. 18
• B. 19
• C. 21
• D. 27

Hint:

Remember: Pregnane = 21-carbon steroid backbone; Androstane = 19-carbon; Estrane = 18-carbon.

Answer 1

The Correct Option is C

- Pregnane is a C-21 steroid nucleus. It consists of the basic steroid four-ring structure (cyclopentanoperhydrophenanthrene nucleus) with two additional carbon atoms in the side chain.
- The core steroid structure has 17 carbon atoms: 3 six-membered rings (A, B, and C) and 1 five-membered ring (D).
- In pregnane, a two-carbon side chain is attached at C-17, making the total carbon count: 17 (rings) + 2 (side chain) + 2 (additional substituents) = 21 carbon atoms.
- Pregnane serves as the parent structure for important hormones like progesterone and corticosteroids.