The Kay Lab in-house phytochemical metabolome database (P-MetDB) informs unique vs common metabolites predictive of diets rich in plant-products, and human and microbial metabolism.  P-MetDB was established by assessing what people eat using a) NHANES self-reported dietary intake data; b) USDA consumer purchase survey; and c) systematic reviews of the literature, capturing compounds reported in these phytochemical rich-dietary sources, and/or metabolites reported in biospecimens as derived from those foods; d) extracting chemical identifiers from online databases, and e) obtaining MS(n) fragmentation voltages and profiles from the optimization of purchased reference standards for the selected compounds. In addition, the Kay-Lab modelled additional metabolites, using known routes of microbial metabolism and human phase II conjugation (e.g., sulfate, glucuronides, or methyl conjugates). 

Literature was assessed for reported metabolites of phytochemical-rich dietary sources, including coffee, black tea, green tea, apple, grape, grapefruit, orange, lemon, berries, banana, cocoa, onion, mango, barley, rye, wheat, rice, corn, oat, buckwheat, radish, Swiss chard, brassica Rapa, malt beverages, and soy. A targeted quantitative MS(n) metabolomic assay was developed in-house based on P-MetDB, and covers over 500 analytes which have been quantitated in over 5,000 biospecimens collected from humans participating in dietary studies rich in coffee, tea, cocoa, grains, soy, and fruits (e.g., berries, banana, mango, citrus etc.)1-10.

The LC-MS(n) spectral features, retention times, and chromatographic quality data were incorporated into P-MetDB. The metabolites detected represent 50 chemical subclasses, including (ethyl)indoles, (phenyl)ethenone, amino acids, aminouracils, benzene derivatives, benzoylglutamic acids, caffeoylquinic acids, catecholamines, cinnamyl derivatives, coumarins, flavonoids, gallates, glutamic acids, hippuric acids, hydroxytoluenes, isoflavones, methylxanthines, nicotinic acids, phenyl amines, phenylacetic acids, (phenyl)propanoic acids, purines, quinic acids, stilbenes, valeric acids, valerolactones, (phenyl)valerolactones, vitamins and xanthonoids1-10. The metabolomics assay developed based on P-MetDB utilizes a SCIEX® QTRAP 6500+ for identification and qualification. A final targeted broad-spectrum quantitative diet quality ADsMRM assay was developed, providing separation for signatures of diets high in phytochemicals, and reflecting gut microbial and human endogenous metabolism. The final analytes were chosen based on frequency, abundance and qualitative and quantitative reproducibility as established in the over 5000 biospecimens analyzed from the nutrition intervention studies described above.

Continued Development

This work is presently being extended to incorporate further Kay Lab database targets which have been curated through systematic review of the literature and database mining. We are now working to annotate signals in HRMS datasets which match to molecular formula and monoisotopic mass within the extended Kay Lab dietary phytochemical metabolome library, which comprises over 5300 reported phytochemicals and phytochemical metabolites from commonly consumed foods. Signals will be matched using the UNC Charlotte ADAP platform and identified targets will be prioritized for expanding reference standard libraries for HRMS identity conformation in study pools (such as HHEAR, CHEAR and NIST).

  1.         Curtis, P. J.; van der Velpen, V.; Berends, L.; Jennings, A.; Feelisch, M.; Umpleby, A. M.; Evans, M.; Fernandez, B. O.; Meiss, M. S.; Minnion, M.; Potter, J.; Minihane, A.-M.; Kay, C. D.; Rimm, E. B.; Cassidy, A., Blueberries improve biomarkers of cardiometabolic function in participants with metabolic syndrome—results from a 6-month, double-blind, randomized controlled trial. The American Journal of Clinical Nutrition 2019, 109 (6), 1535-1545.
  2.          Chandra, P.; Rathore, A. S.; Kay, K. L.; Everhart, J. L.; Curtis, P.; Burton-Freeman, B.; Cassidy, A.; Kay, C. D., Contribution of Berry Polyphenols to the Human Metabolome. Molecules (Basel, Switzerland) 2019, 24 (23), 4220.
  3.          Nieman, D. C.; Kay, C. D.; Rathore, A. S.; Grace, M. H.; Strauch, R. C.; Stephan, E. H.; Sakaguchi, C. A.; Lila, M. A., Increased plasma levels of gut-derived phenolics linked to walking and running following two weeks of flavonoid supplementation. Nutrients 2018, 10 (11), 1718.
  4.          Ahmad, A. F.; Rich, L.; Koch, H.; Croft, K. D.; Ferruzzi, M. G.; Kay, C. D.; Hodgson, J. M.; Ward, N. C., Effect of adding milk to black tea on vascular function in healthy men and women: a randomised controlled crossover trial. Food & function 2018, 9 (12), 6307-6314.
  5.          Nieman, D. C.; Ramamoorthy, S.; Kay, C. D.; Goodman, C. L.; Capps, C. R.; Shue, Z. L.; Heyl, N.; Grace, M. H.; Lila, M. A., Influence of ingesting a flavonoid-rich supplement on the metabolome and concentration of urine phenolics in overweight/obese women. Journal of proteome research 2017, 16 (8), 2924-2935.
  6.          Hazim, S.; Curtis, P. J.; Schär, M. Y.; Ostertag, L. M.; Kay, C. D.; Minihane, A.-M.; Cassidy, A., Acute benefits of the microbial-derived isoflavone metabolite equol on arterial stiffness in men prospectively recruited according to equol producer phenotype: a double-blind randomized controlled trial. The American journal of clinical nutrition 2016, 103 (3), 694-702.
  7.          Schär, M. Y.; Curtis, P. J.; Hazim, S.; Ostertag, L. M.; Kay, C. D.; Potter, J. F.; Cassidy, A., Orange juice–derived flavanone and phenolic metabolites do not acutely affect cardiovascular risk biomarkers: a randomized, placebo-controlled, crossover trial in men at moderate risk of cardiovascular disease. The American journal of clinical nutrition 2015, 101 (5), 931-938.
  8.          De Ferrars, R.; Czank, C.; Zhang, Q.; Botting, N.; Kroon, P.; Cassidy, A.; Kay, C., The pharmacokinetics of anthocyanins and their metabolites in humans. British journal of pharmacology 2014, 171 (13), 3268-3282.
  9.          Nieman, D. C.; Gillitt, N. D.; Chen, G.-Y.; Zhang, Q.; Sha, W.; Kay, C. D.; Chandra, P.; Kay, K. L.; Lila, M. A., Blueberry and/or Banana Consumption Mitigate Arachidonic, Cytochrome P450 Oxylipin Generation During Recovery From 75-Km Cycling: A Randomized Trial. Frontiers in nutrition 2020, 7, 121.
  10.        Czank, C.; Cassidy, A.; Zhang, Q.; Morrison, D. J.; Preston, T.; Kroon, P. A.; Botting, N. P.; Kay, C. D., Human metabolism and elimination of the anthocyanin, cyanidin-3-glucoside: a 13C-tracer study. The American of Clinical Nutrition 2013, 97 (5), 995-1003.