Quantitative determination of common urinary odorants and their glucuronide conjugates in human urine

Abstract

Our previous study on the identification of common odorants and their conjugates in human urine demonstrated that this substance fraction is a little-understood but nonetheless a promising medium for analysis and diagnostics in this easily accessible physiological medium. Smell as an indicator for diseases, or volatile excretion in the course of dietary processes bares high potential for a series of physiological insights. Still, little is known today about the quantitative composition of odorous or volatile targets, as well as their non-volatile conjugates, both with regard to their common occurrence in urine of healthy subjects, as well as in that of individuals suffering from diseases or other physiological misbalancing. Accordingly, the aim of our study was to develop a highly sensitive and selective approach to determine the common quantitative composition of selected odorant markers in healthy human subjects, as well as their corresponding glucuronide conjugates. We used one- and two-dimensional high resolution gas chromatography-mass spectrometry in combination with stable isotope dilution assays to quantify commonly occurring and potent odorants in human urine. The studies were carried out on both native urine and on urine that had been treated by glucuronidase assays, with analysis of the liberated odor-active compounds using the same techniques. Analytical data are discussed with regard to their potential translation as future diagnostic tool.

Figure 1

Minimum, median and maximum concentrations of selected odorants in native human urine. Concentrations are given in [µg/mol creatinine] and displayed on a logarithmic scale.

Figure 2

Minimum, median and maximum concentrations of selected odorants in glucuronidase-treated human urine. Concentrations are given in [µg/mol creatinine] and displayed on a logarithmic scale.

Figure 3

(a) Comparison of median concentrations of selected odorants in native and glucuronidase-treated human urine. Concentrations are given in [µg/mol creatinine] and displayed in a logarithmic scale. (b) Comparison of median concentrations of selected odorants in native and glucuronidase-treated human urine. Concentrations are given in percent, the concentration of the compounds in the glucuronidase-treated urine is set 100 percent.

Figure 4

Keto-enol tautomerism of (E)-β-damascenone and resonance stabilization of the enol.