Characterization and Interrelations of One-Carbon Metabolites in Tissues, Erythrocytes, and Plasma in Mice with Dietary Induced Folate Deficiency
Chair of Analytical Food Chemistry, Technical University of Munich, Alte Akademie 10, Freising D-85354, Germany
Institute for Food & Health (Z I E L), Technical University of Munich, Weihenstephaner Berg 1, Freising D-85354, Germany
Chair of Nutritional Physiology, Technical University of Munich, Gregor-Mendel-Straße 2, Freising D-85354, Germany
Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation (QAAFI), University of Queensland, Brisbane, QLD 4072, Australia
Author to whom correspondence should be addressed.
Nutrients 2017, 9(5), 462; https://doi.org/10.3390/nu9050462
Received: 2 March 2017 / Revised: 22 April 2017 / Accepted: 1 May 2017 / Published: 5 May 2017
Studies on one-carbon metabolism for the assessment of folate deficiency have focused on either metabolites of folate metabolism or methionine cycle. To bridge the gap between deficiency markers in these pathways we designed a dietary induced folate deficiency study using male C57BL/6N mice. After weaning (3 weeks) mice were fed a defined control diet (1 week) before being fed a folate deficient diet (n = 6 mice) and the control diet (n = 6 mice) for 12 additional weeks. Thereafter, we determined total homocysteine in plasma and folate in erythrocytes as well as S-adenosylmethionine, S-adenosylhomocysteine, and six folate vitamers in tissues including 5-methyltetrahydrofolate, 5-formyltetrahydrofolate, 5,10-methenyltetrahydrofolate, tetrahydrofolate, 10-formylfolic acid, and folic acid by means of stable isotope dilution assays coupled with liquid chromatography tandem mass spectrometry. In all organs, except heart (mainly 5-mehtyltetrahydrofolate), tetrahydrofolate constitutes the main vitamer. Moreover, in liver tetrahydrofolate was most abundant followed by 5-methyltetrahydrofolate (heart: tetrahydrofolate), 5-formyltetrahydrofolate, and 5,10-methenyltetrahydrofolate. Because of the significant decrease (p < 0.05) of folate status and S-adenosylmethionine/S-adenosylhomocysteine ratio accompanied with increasing S-adenosylhomocysteine (p < 0.05), hepatocytes are most susceptible to folate deficiency. To the best of our knowledge, we herein present the first method for simultaneous quantitation of eight metabolites for both folate and methionine cycle in one tissue sample, tHcy in plasma, and erythrocyte folate to shed light on physiological interrelations of one-carbon metabolism.