To solve the problem, we need to identify which alkaloid among the given options is used as a sedative.
1. Understanding Alkaloids:
Alkaloids are naturally occurring chemical compounds that mostly contain basic nitrogen atoms. Many alkaloids have pharmacological effects.
2. Sedative Properties:
A sedative is a substance that induces sedation by reducing irritability or excitement. It is used to calm the nervous system.
3. Option Analysis:
- Nimbin: Found in neem; has antibacterial and antifungal properties, not sedative.
- Quinine: Used to treat malaria, not a sedative.
- Nicotine: A stimulant, not a sedative.
- Scopolamine: Used as a sedative and to treat motion sickness; has calming effects on the central nervous system.
Final Answer:
The alkaloid used as a sedative is Scopolamine.