Structure elucidation of urinary metabolites of fentanyl and five fentanyl analogues using LC-QTOF-MS, hepatocyte incubations and synthesized reference standards

• Fentanyl analogues constitute a particularly dangerous group of new psychoactive compounds responsible for many deaths around the world. Little is known about their metabolism and studies utilizing LC-QTOF-MS analysis of hepatocyte incubations and/or authentic urine samples does not allow for determination of the exact metabolite structures, especially when it comes to hydroxylated metabolites. In this study seven motifs (2-, 3-, 4- and β-OH as well as 3,4-diOH, 4-OH-3-OMe and 3-OH-4-OMe) of fentanyl and five fentanyl analogues, acetylfentanyl, acrylfentanyl, cyclopropylfentanyl, isobutyrylfentanyl and 4F-isobutyrylfentanyl were synthesized. The reference standards were analyzed by LC-QTOF-MS, which enabled identification of the major metabolites formed in hepatocyte incubations of the studied fentanyls. By comparison with our previous data sets, major urinary metabolites could tentatively be identified. For all analogues, β-OH, 4-OH and 4-OH-3-OMe were identified after hepatocyte incubation. β-OH was the major hydroxylated metabolite for all studied fentanyls, except for acetylfentanyl where 4-OH was more abundant. However, the ratio 4-OH/β-OH was higher in urine samples than in hepatocyte incubations for all studied fentanyls. Also, 3-OH-4-OMe was not detected in any hepatocyte samples, indicating a clear preference for the 4-OH-3-OMe, which was also found to be more abundant in urine compared to hepatocytes. The patterns appear to be consistent across all studied fentanyls and could serve as a starting point in the development of methods and synthesis of reference standards of novel fentanyl analogues where nothing is known about the metabolism.

Ämnesord

NATURVETENSKAP  -- Kemi -- Analytisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Analytical Chemistry (hsv//eng)

Nyckelord

Fentanyl analogue

human hepatocytes

metabolism

new psychoactive substances

reference standards

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)