Simultaneous determination of tyrosine, tryptophan and 5-hydroxytryptamine in serum of MDD patients by high performance liquid chromatography with fluorescence detection

Abstract

Background: Tyrosine (Tyr), Tryptophan (Trp) and 5-hydroxytryptamine (5-HT) are important amino acids in vivo and have been hypothesized to be involved in many mental disorders. We developed a rapid and sensitive HPLC method for simultaneous measurement of serum Tyr, Trp and 5-HT and explored the clinical significances of Tyr, Trp and 5-HT and the 5-HT/Trp ratio for patients with major depressive disorder (MDD) disease.

Methods: Serum samples were deproteinized by 5% perchloric acid and separated on an Atlantis C18 column (4.6 × 150 mm, 5 μm) with the mobile phase consisting of 0.1 mol/l KH(2)PO(4) and methanol (85:15, V/V).The eluates were monitored by the fluorescence detection with programmed wavelength.

Results: Analysis was achieved in <12.0 min. The limits of quantification were 0.014, 0.005, and 0.024 μmol/l for Tyr, Trp and 5-HT, respectively. Reproducibility and recovery were satisfactory. Tyr, Trp and 5-HT and the 5-HT/Trp ratio were significantly decreased in patients with MDD.

Conclusions: In diseases, like MDD, Tyr, Trp and 5-HT play an important role. This method can potentially be applied as prognostic or diagnostic tool or even to follow the evolution of the illness or of the treatment.