**Question:** Vitamin which formed from amino acid -

A. Vitamin B1 (Thiamine)
B. Vitamin B2 (Riboflavin)
C. Vitamin B3 (Nicotinamide)
D. Vitamin B6 (Pyridoxine)

**Core Concept:** Vitamins are essential micronutrients required for maintaining proper physiological processes in the body. Many vitamins are formed from amino acids, which are building blocks of proteins.

**Why the Correct Answer is Right:** Vitamin B1 is formed from the amino acid threonine. Thiamine plays a crucial role in carbohydrate and lipid oxidation, as well as energy production in the Krebs cycle. It is essential for maintaining proper functioning of the cardiovascular, digestive, and nervous systems.

**Why Each Wrong Option is Incorrect:**

A. Vitamin B2 (Riboflavin) is not formed from an amino acid. It is a coenzyme involved in the electron transport chain and is essential for maintaining proper vision, skin health, and immune system function.

B. Vitamin B3 (Nicotinamide) is not formed from an amino acid. Nicotinamide is involved in the synthesis of NAD+ and NADP+, which are essential coenzymes in cellular respiration and redox reactions.

C. Vitamin B6 (Pyridoxine) is not formed from an amino acid. Pyridoxine is a coenzyme involved in amino acid and neurotransmitter synthesis, as well as red blood cell formation.

**Clinical Pearl:** Understanding the relationship between vitamins and amino acids emphasizes the importance of a balanced diet to ensure adequate micronutrient intake for optimal health and disease prevention.

**Correct Answer:** D. Vitamin B6 (Pyridoxine) is formed from the amino acid glutamine and is essential for maintaining proper neurological function, amino acid and purine nucleotide synthesis, and red blood cell formation.