Characterization of furanocoumarin metabolites in parsnip webworm, Depressaria pastinacella

James K. Nitao, Mark Berhow, Sandra M. Duval, David Weisleder, Steven F. Vaughn, Arthur Zangerl, M. R. Berenbaum

Research output: Contribution to journalArticlepeer-review


Although metabolites of furanocoumarins have been characterized in a wide range of organisms, to date they have been identified in only a single insect species, Papiliopolyxenes. Depressariapastinacella, the parsnip webworm, like P. polyxenes a specialist on Apiaceae, routinely consumes plant tissues higher in furanocoumarin content than does P. polyxenes and is capable of faster cytochrome P-450-mediated detoxification of these compounds. In this study, we characterized metabolites of xanthotoxin, a linear furanocoumarin, and sphondin, an angular furanocoumarin, in midguts and frass of parsnip webworms. Two metabolites were isolated and identified from webworms fed artificial diet containing xanthotoxin. LC-ESI-MS analysis resulted in the determination of a MW of 266 for the compound in the frass and one of the compounds in the midgut; 1H NMR confirmed its structure as 6-(7-hydroxy-8-methoxycoumaryl)hydroxyacetic acid (HCHA). The second compound from the midgut had a MW of 252 and was identified by 1H NMR and 13C NMR analysis as 6-(7-hydroxy-8-methoxycoumaryl)-hydroxyethanol) (HMCH). Whereas HCHA has been found in frass of Papilio polyxenes fed xanthotoxin, HMCH has not been reported previously in insects. Although the first step of metabolism of xanthotoxin in webworms as well as P. polyxenes is likely the formation of an epoxide on the furan ring, angular furanocoumarin metabolism in webworms appears to differ. The principal metabolite of sphondin was identified as demethylated sphondin (6-hydroxy-2H-furo[2,3-h]-1-benzopyran-2-one) by LC-ESI-MS and confirmed by 1H NMR and 13C NMR analyses. That webworms produce metabolites of xanthotoxin in common not only with other Lepidoptera (e.g., HCHA) but with other vertebrates (e.g., HMCH) suggests a remarkable conservatism in the metabolic capabilities of cytochrome P-450s and raises the possibility that insects may share other detoxification reactions with vertebrates with respect to toxins in foodplants.

Original languageEnglish (US)
Pages (from-to)671-682
Number of pages12
JournalJournal of Chemical Ecology
Issue number3
StatePublished - Mar 1 2003


  • Cytochrome P-450
  • Depressaria pastinacella
  • Furanocoumarin metabolites
  • Insect-plant interactions
  • Papilio polyxenes
  • Sphondin
  • Xanthotoxin

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Biochemistry


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