Isotope tracing reveals water-mediated deuterium loss from hydroxycoumarins in cassava roots, indicating a Michael-type addition mechanism during postharvest deterioration.
Key Points
To investigate the mechanism responsible for unexpected deuterium loss from carbon-2 of hydroxycoumarins during postharvest physiological deterioration in cassava roots.
Conducted stable isotope feeding experiments in cassava root tissues using E-cinnamic-d7 acid alongside deuterium oxide (D2O).
Analyzed metabolic extracts using liquid chromatography-mass spectrometry (LC-MS) to monitor deuterium retention and substitution patterns.
Supplementation with deuterium oxide during labelled substrate feeding promoted the formation of d4-labelled hydroxycoumarin products while diminishing d3-labelled species.
LC-MS tracing confirmed a Michael-type nucleophilic addition of endogenous water across the carbon-2 to carbon-3 alkene bond, driving selective deuterium loss at carbon-2.