Plasma tryptophan levels in children with epilepsy before and after antiepileptic treatment

Copper(II) phthalocyanine as an electrocatalytic electrode for cathodic detection of urinary tryptophan

Herein, we introduce a novel method for tryptophan detection via a reduction reaction facilitated by its interaction with a copper(II) phthalocyanine (CuPc) electrocatalytic electrode. This method addresses challenges associated with the susceptibility of the oxidation response to interference from various species when measuring tryptophan in bodily fluids. The reduction currents exhibit a linear increase with tryptophan concentrations in two ranges: 0.0013-0.10 mM and 0.10-1.20 mM, with the sensitivities of 14.7 ± 0.5 μA mM-1 and 3.5 ± 0.1 μA mM-1, respectively. The limit of detection (LOD, 3SB/m) is determined to be 0.39 μM. The sensor exhibits excellent reproducibility, with the relative standard deviation of <5%. Application of the sensor to authentic urine samples yields a % recovery of 101 ± 4%.

Tryptophan in health and disease

Tryptophan (TRP), an essential amino acid in mammals, is involved in several physiological processes including neuronal function, immunity, and gut homeostasis. In humans, TRP is metabolized via the kynurenine and serotonin pathways, leading to the generation of biologically active compounds, such as serotonin, melatonin and niacin. In addition to endogenous TRP metabolism, resident gut microbiota also contributes to the production of specific TRP metabolites and indirectly influences host physiology. The variety of physiologic functions regulated by TRP reflects the complex pattern of diseases associated with altered homeostasis. Indeed, an imbalance in the synthesis of TRP metabolites has been associated with pathophysiologic mechanisms occurring in neurologic and psychiatric disorders, in chronic immune activation and in the immune escape of cancer. In this chapter, the role of TRP metabolism in health and disease is presented. Disorders involving the central nervous system, malignancy, inflammatory bowel and cardiovascular disease are discussed.

Plasma and urinary serotonin and 5-HIAA in children treated with lamotrigine for intractable epilepsy

Alteration of monoamine levels by some antiepileptic drugs (AEDs) was elucidated in this study. Lamotrigine (LTG) is a new AED, acting the sodium-channels. LTG was given as add-on therapy to 16 patients aged 4.5-18 yrs with intractable epilepsy and comedicated with carbamazepine or valproate. An equal group of epileptics with comparable clinical characteristics and treatment served as control. Plasma and urinary (24 h-samples) serotonin and 5-HIAA were determined before onset of LTG therapy and after 2-3 months. HPLC and electrochemical detection was used for the determination of serotonin (5-HT) and 5-hydroxy indoleacetic acid (5-HIAA). No significant effect of LTG on both urinary 5-HT and 5-HIAA levels was found, whereas plasma 5-HT concentrations significantly decreased in comparison with levels before LTG starting and relevant values in controls. This findings was noted in 7/16 children with favourable response to LTG. Increased serotonin catabolism may be result of LTG action.