1st product of tryptophan Catabolism: (A) Kynurenine, (B) Xantheurenic acid, (C) Bradykinin, (D) Melatonin
Answer is A. Kynurenine is formed from tryptophan in presence of enzyme tryptophan pyrrolaseRef: DM Vasudevan - Textbook of Biochemistry, 7th edition, page no: 239, fig 18.8