Tryptophan and Neurotransmitters:

Tryptophan is an essential amino acid that plays a crucial role in the synthesis of various neurotransmitters in the brain. It is obtained from the diet and serves as a precursor for the synthesis of several important neurotransmitters, including serotonin, melatonin, and niacin.

Neurotransmitters derived from Tryptophan:

Among the given options, the neurotransmitter derived from tryptophan is serotonin (option B).

Explanation:

1. Tryptophan Metabolism:
Tryptophan is an essential amino acid that cannot be synthesized by the body and must be obtained from the diet. It is primarily found in protein-rich foods such as meat, dairy products, eggs, and certain plant-based sources like seeds and nuts. Once ingested, tryptophan is metabolized through various pathways.

2. Tryptophan Hydroxylase:
Tryptophan hydroxylase is the enzyme responsible for the initial step in the synthesis of serotonin. It catalyzes the conversion of tryptophan into 5-hydroxytryptophan (5-HTP). This reaction requires the cofactor tetrahydrobiopterin (BH4) and oxygen.

3. Aromatic L-amino Acid Decarboxylase:
Following the conversion of tryptophan to 5-HTP, the enzyme aromatic L-amino acid decarboxylase converts 5-HTP into serotonin. This enzyme removes a carboxyl group from 5-HTP, resulting in the formation of serotonin.

4. Serotonin as a Neurotransmitter:
Serotonin, also known as 5-hydroxytryptamine (5-HT), is a neurotransmitter that plays a crucial role in regulating mood, sleep, appetite, and various other physiological processes. It is involved in the modulation of emotions, cognition, and behavior.

Conclusion:
In summary, tryptophan serves as a precursor for the synthesis of serotonin. The conversion of tryptophan to serotonin involves the enzymes tryptophan hydroxylase and aromatic L-amino acid decarboxylase. Serotonin functions as a neurotransmitter and is involved in various physiological processes in the brain and body.