5-hydroxytryptophan (5-HTP) (5-HTP)

5-hydroxytryptophan (5-HTP) is a naturally occurring amino acid and the immediate chemical precursor in the biosynthesis of the neurotransmitter serotonin (5-hydroxytryptamine) [2, 3]. It is synthesized from the essential amino acid L-tryptophan via the enzyme tryptophan hydroxylase and is subsequently converted into serotonin by aromatic L-amino acid decarboxylase [3, 8]. Unlike its precursor tryptophan, 5-HTP readily crosses the blood-brain barrier and bypasses the rate-limiting step of serotonin synthesis, making it a potent agent for elevating central serotonin levels [2, 8, 11]. Clinically, 5-HTP (also known as oxitriptan) is utilized as a dietary supplement or adjunctive therapy for various conditions linked to serotonin deficiency, including major depressive disorder, anxiety, insomnia, and fibromyalgia [1, 5, 12]. While it is effective in modulating mood, sleep, and appetite, its administration carries a significant risk of serotonin syndrome, particularly when combined with other serotonergic drugs like SSRIs or MAOIs [1, 15]. Additionally, historical concerns regarding eosinophilia-myalgia syndrome (EMS) have led to rigorous monitoring of its purity and safety profile [3, 10]. In some clinical settings, it is co-administered with peripheral decarboxylase inhibitors like carbidopa to maximize its central nervous system effects and minimize peripheral side effects [2, 8].

Other names

OxitriptanL-5-hydroxytryptophan5-hydroxy-L-tryptophan5-HTPalpha-Carboxy-5-hydroxytryptamine

Acts as a direct metabolic precursor to serotonin (5-HT); it is decarboxylated by the enzyme aromatic L-amino acid decarboxylase (AADC) to increase serotonin levels in the central nervous system and periphery [2, 3, 8].