Quantification of α-Thujone and Its Metabolites in Human Urine after Consumption of a Sage Infusion Using Stable Isotope Dilution Assays

• Main Authors: Irene Thamm, Konrad Tiefenbacher, Michael Rychlik
• Format: Article
• Language: English
• Published: MDPI AG 2018-12-01
• Series: Toxins
• Subjects: thujone; 4-hydroxythujone; 7-hydroxythujone; hydroxythujone conjugates; human study
• Online Access: https://www.mdpi.com/2072-6651/10/12/511

The metabolism of the monoterpene &#945;-thujone was investigated in humans after consumption of sage tea, by analyses of its metabolites 2-hydroxythujone, 4-hydroxythujone, and 7-hydroxythujone in urine. For the quantitation of &#945;-thujone and its metabolites, stable isotope dilution assays were developed. Using <i>d</i>₆-&#945;-thujone as internal standard, we quantified &#945;-thujone by solid phase microextraction GC-MS and the hydroxythujones with <i>d</i>₆-2-hydroxythujone, <i>d</i>₆-4-hydroxythujone, and <i>d</i>₆-7-hydroxythujone after glucuronide/sulfate deconjugation by LC-MS/MS in urine. After the consumption of 575.0 &#181;g &#945;-thujone, the 4-hydroxythujone and 7-hydroxythujone were detectable in the urine of the volunteers under study, after liberation from their glucuronides/sulfates. The 2-Hydroxythujone was not present in any of the volunteer samples above its detection limit. &#945;-Thujone was detectable in a low amount, with a maximum concentration of 94 ng/L for the volunteer with the highest dose of 14.3 &#181;g/kg bw.