Tryptophan
Tryptophan, an amino acid. Serotonin + melatonin pathway: Trp → 5 htp (tryptophan hydroxylase) → serotonin (see serotonin melatonin axis) (AADC) → melatonin. Parallel…
Serotonin + melatonin pathway: Trp → 5-HTP (tryptophan hydroxylase) → Serotonin (see Tryptophan → serotonin → melatonin) (AADC) → Melatonin. Parallel Kynurenine pathway (>95% of Trp flux; inflammation shifts toward quinolinate / NAD⁺ at the expense of serotonin). NAD⁺ de-novo biosynthesis from kynurenine.
The cited tolerance study (PMID:6805013) dosed 100 mg/kg, roughly 10x this record's range, and tryptophan elimination is demonstrably dose-saturable, so even a value extracted from it would not describe a supplemental dose. Brain uptake depends on the ratio to competing large neutral amino acids at the LAT1 transporter, which a single-compound curve cannot express.
Related compounds
Sources: PMID:10837313, PMID:6805013, PMID:6210561, PMID:6750316