5-hydroxy-L-Tryptophan (5-HTP) is an intermediate in the biosynthesis of serotonin from tryptophan.1 When injected systemically in animals, 5-HTP is converted to serotonin and has both peripheral and central nervous system effects.2,3,4 In ex vivo studies, 5-HTP can be metabolized to melatonin with circadian rhythmicity, using serotonin as an intermediate.5 5-HTP can also be synthesized by gut microbiota and acts as an activator of the aryl hydrocarbon receptor.6
1.Martinez, A., Knappskog, P.M., and Haavik, J.A structural approach into human tryptophan hydroxylase and its implications for the regulation of serotonin biosyntheisCurr. Med. Chem.8(9)1077-1091(2001) 2.Haberzettl, R., Fink, H., and Bert, B.The murine serotonin syndrome - evaluation of responses to 5-HT-enhancing drugs in NMRI miceBehav. Brain Res.277204-210(2015) 3.Laporta, J., Moore, S.A.E., Weaver, S.R., et al.Increasing serotonin concentrations alter calcium and energy metabolism in dairy cowsJ. Endocrinol.226(1)43-55(2015) 4.Schmid, C.L., and Bohn, L.M.Serotonin, but not N-methyltryptamines, activates the serotonin 2A receptor via a β-arrestin2/Src/Akt signaling complex in vivoJ. Neurosci.30(40)13513-13524(2010) 5.Cahill, G.M., and Besharse, J.C.Circadian regulation of melatonin in the retina of Xenopus laevis: imitation by serotonin availabilityJ. Neurochem.54(2)716-719(1990) 6.Sridharan, G.V., Choi, K., Klemashevich, C., et al.Prediction and quantification of bioactive microbiota metabolites in the mouse gutNat. Commun.55492(2014)