Autoxidation Kinetics of Tetrahydrobiopterin-Giving Quinonoid Dihydrobiopterin the Consideration It Deserves.

In humans, tetrahydrobiopterin (H4Bip) is the cofactor of several essential hydroxylation reactions which dysfunction cause very serious diseases at any age. Hence, the determination of pterins in biological media is of outmost importance in the diagnosis and monitoring of H4Bip deficiency. More than half a century after the discovery of the physiological role of H4Bip and the recent advent of gene therapy for dopamine and serotonin disorders linked to H4Bip deficiency, the quantification of quinonoid dihydrobiopterin (qH2Bip), the transient intermediate of H4Bip, has not been considered yet.

Quantification of Monoamine Neurotransmitter Metabolites and Cofactors in Cerebrospinal Fluid: State-of-the-Art.

Inborn errors of monoamine neurotransmitter metabolism are rare diseases characterized by nonspecific neurological symptoms. These symptoms appear in early childhood and correspond to movement disorders, epilepsy, sleep disorders and/or mental disability. Cerebrospinal fluid biomarkers have been identified and validated to allow specific diagnosis of these diseases.

Quantification of monoamine biomarkers in cerebrospinal fluid: Comparison of a UHPLC-MS/MS method with a UHPLC coupled to fluorescence detection method.

Inborn errors of monoamine neurotransmitter metabolism are rare genetic diseases classified as catecholamine and serotonin metabolism disorders or neurotransmitter transportopathies. To diagnose these orphan diseases, monoamine metabolites have been identified and validated as cerebrospinal fluid (CSF) biomarkers: 5-hydroxy-tryptophane, 5-hydroxy-indol-acetic acid, 3-ortho-methyl-DOPA, homovanillic acid, and 3-methoxy-4-hydroxyphenylglycol. The present work presents a UHPLC-MS/MS method developed for the quantification of these metabolites in CSF and compares it with a previously described UHPLC with fluorescence detection (UHPLC-FD) method.

Multianalytical Approach for Deciphering the Specific MS/MS Transition and Overcoming the Challenge of the Separation of a Transient Intermediate, Quinonoid Dihydrobiopterin.

Despite recent technological developments in analytical chemistry, separation and direct characterization of transient intermediates remain an analytical challenge. Among these, separation and direct characterization of quinonoid dihydrobiopterin (qH2Bip), a transient intermediate of tetrahydrobiopterin (H4Bip)-dependent hydroxylation reactions, essential in living organisms, with important and varied human pathophysiological impacts, are a clear illustration. H4Bip regeneration may be impaired by competitive nonenzymatic autoxidation reactions, such as isomerization of qH2Bip into a more stable 7,8-H2Bip (H2Bip) isomer, and subsequent nonenzymatic oxidation reactions.

A rapid and sensitive method for the quantification of dopamine and serotonin metabolites in cerebrospinal fluid based on UHPLC with fluorescence detection.

Inborn errors of dopamine and serotonin metabolism are diseases caused by deficiencies in enzymes belonging to metabolic pathways. The specific diagnosis of these inborn illnesses is based on the identification and quantification of biomarkers in cerebrospinal fluid (CSF), especially: 5-hydroxy-tryptophane (5-HTP), 5-hydroxy-indol-acetic acid (5-HIAA), 3-ortho-methyl-DOPA (3-OMD), homovanillic acid (HVA) and 3-methoxy-4-hydroxyphenylglycol (MHPG). In the present work, we propose a novel ultrahigh performance liquid chromatography (UHPLC) method coupled to fluorescence detection (FD) to quantify simultaneously the five dopamine and serotonin metabolites.