N-Acetyl-L-phenylalanine is a metabolite of L-phenylalanine .1 It is formed from L-phenylalanine by gut microbiota. Serum levels of N-acetyl-L-phenylalanine are increased in male COVID-19 patients compared with female COVID-19 patients and individuals without COVID-19, and hippocampal levels of N-acetyl-L-phenylalanine are increased in postmortem brain tissue isolated from patients with Alzheimer's disease.1,2 Urinary levels of N-acetyl-L-phenylalanine are negatively correlated with phthalate exposure in normal weight, but not overweight, children.3
1.Escarcega, R.D., Honarpisheh, P., Colpo, G.D., et al.Sex differences in global metabolomic profiles of COVID-19 patientsCell Death Dis.13(5)461(2022) 2.Liu, P., Yang, Q., Yu, N., et al.Phenylalanine metabolism is dysregulated in human hippocampus with Alzheimer's disease related pathological changesJ. Alzheimers Dis.83(2)609-622(2021) 3.Xia, B., Zhu, Q., Zhao, Y., et al.Phthalate exposure and childhood overweight and obesity: Urinary metabolomic evidenceEnviron. Int.121(Pt 1)159-168(2018)