L-Tryptophan-d5 is a deuterated compound of L-tryptophan used as a standard in GC or LC-MS quantification[1]. L-Tryptophan is an essential amino acid and a precursor of serotonin, melatonin, and vitamin B3[2]. L-Tryptophan serves as a substrate for tryptophan hydroxylase (TPH), indoleamine-2,3-dioxygenase (IDO), and tryptophan-2,3-dioxygenase (TDO) for the biosynthesis of serotonin (5-HT) and kynurenine[3]. L-Tryptophan is also metabolized to indole, pyruvate, and ammonia by intestinal bacteria expressing tryptophanase[4].
In vivo, oral administration of L-tryptophan (300mg/kg) to Wistar rats during the day (8:00) increased the levels of 5-HT, 5-hydroxy-L-tryptophan (5-HTP), and 5-hydroxyindole-3-acetic acid (5-HIAA) in the diencephalon of rats. When administered at night (20:00), 5-HT decreased, but the 5-HT/5-HIAA ratio remained unchanged, and melatonin levels and the innate immune response of peritoneal macrophages increased significantly[5].
References:
[1] Kyle J E, Stratton K G, Zink E M, et al. A resource of lipidomics and metabolomics data from individuals with undiagnosed diseases[J]. Scientific data, 2021, 8(1): 114.
[2] Richard D M, Dawes M A, Mathias C W, et al. L-tryptophan: basic metabolic functions, behavioral research and therapeutic indications[J]. International Journal of Tryptophan Research, 2009, 2: IJTR. S2129.
[3] Modoux M, Rolhion N, Mani S, et al. Tryptophan metabolism as a pharmacological target[J]. Trends in pharmacological sciences, 2021, 42(1): 60-73.
[4] Bosi A, Banfi D, Bistoletti M, et al. Tryptophan metabolites along the microbiota-gut-brain axis: an interkingdom communication system influencing the gut in health and disease[J]. International Journal of Tryptophan Research, 2020.
[5]Esteban S, Nicolaus C, Garmundi A, et al. Effect of orally administered L-tryptophan on serotonin, melatonin, and the innate immune response in the rat[J]. Molecular and cellular biochemistry, 2004, 267: 39-46.
L-色氨酸-d5（L-Tryptophan-d5）是L-色氨酸的氘代化合物，用作GC或LC-MS定量中的标准品[1]。L-色氨酸是一种必需氨基酸，是血清素、褪黑素和维生素 B3的前体[2]。L-色氨酸作为色氨酸羟化酶（TPH）、吲哚胺-2,3-双加氧酶（IDO）和色氨酸-2,3-双加氧酶（TDO）的底物，用于生物合成血清素（5-HT）和犬尿氨酸[3]。L-色氨酸也被表达色氨酸酶的肠道细菌代谢为吲哚、丙酮酸和氨[4]。
在体内，L-色氨酸（300mg/kg）通过口服给药处理Wistar大鼠，在白天（8：00）给药可增加大鼠间脑5-HT、5-羟基-L-色氨酸（5-HTP）和 5-羟基吲哚-3-乙酸（5-HIAA） 水平。在夜间（20：00）给药，5-HT下降，但5-HT/5-HIAA 比率保持不变，褪黑激素水平和腹膜巨噬细胞的先天免疫反应显著增加[5]。