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Quantifying the levels of Queuosine metabolites in the human diet Chandrasekaran S., Dr Pan X., Prof. Woodside J., & Prof. Green B., Institute for Global Food Security, School of Biological Sciences Queen's University Belfast, UK Introduction: The nucleoside queuosine (Q) is a nutritionally important micronutrient. Q is an evolutionally conserved tRNA modification at position 34 of four specific tRNAs important for efficient protein translation. Germ-free mice lacking QtRNA modification and tyrosine exhibit translation errors and higher mortality, but queuine (Q nucleobase) replacement via the diet restored survival. However, the quantities of Q metabolites in a typical human diet are unknown, and human requirements have not yet been established. Purpose: This study assessed the amounts of Q metabolites (queuine (q), queuosine, queuosine monophosphates (QMP) and Q precursor (PreQ1) in a systematically selected list of foods, and then used food diary data to calculate daily Q consumption in a UK diet. Methodology: Data from the UK National Diet and Nutrition Survey (NDNS 5Y) were processed and interrogated to ultimately obtain the most frequently consumed food in each of the 31 food categories. This reflected the consumption of >99.5% of UK consumers. A methanol-based extraction technique was developed to extract free Q metabolites. A tRNA isolation and hydrolysis method was developed and optimised to extract tRNA-bound Q metabolites from different food matrices. A quantitative LC-MS/MS method (SCIEX 5500+) was developed to measure q, Q, QMPs and PreQ1 in food samples. Finally, 4-day food diary data from 93 persons enrolled in the Northern Ireland Dietary Assessment Study (NIDAS) were used to calculate the average daily consumption of Q metabolites. Results: Q metabolite levels varied significantly across the many food types, with dairy products typically containing the highest overall levels. Total Q metabolites levels in foods ranged from 0.05ng/g to 108ng/g, with the mean level being 20ng/g. The calculated Q consumption of participants in NIDAS ranged from nil/day in some individuals to 170μg/day in others. The typical mean intake of Q metabolites was 18μg/day. Conclusion: This is the first study to ascertain human Q exposure from the diet and advances our knowledge of its nutritional importance. Acknowledgement: We thank Prof. V. Kelly (Trinity College Dublin, Ireland) and Prof. V. deCracy Legard (University of Florida, USA) for the provision of Q/q standards. This work was funded by Health and Social Care in Northern Ireland (HSCNI) STL/5460/18 in support of a international research consortium through the US-Ireland programme. Scholar is supported by CITI-GENS, a Horizon2020 funded Marie Skłodowska-Curie doctoral training programme of interdisciplinary PhD students.
Chandrasekaran et al. (Fri,) studied this question.