Heating decreases epithiospecifier protein activity and increases sulforaphane formation in broccoli

Nathan V. Matusheski, John A. Juvik, Elizabeth H. Jeffery

Research output: Contribution to journalArticlepeer-review

Abstract

Sulforaphane, an isothiocyanate from broccoli, is one of the most potent food-derived anticarcinogens. This compound is not present in the intact vegetable, rather it is formed from its glucosinolate precursor, glucoraphanin, by the action of myrosinase, a thioglucosidase enzyme, when broccoli tissue is crushed or chewed. However, a number of studies have demonstrated that sulforaphane yield from glucoraphanin is low, and that a non-bioactive nitrile analog, sulforaphane nitrile, is the primary hydrolysis product when plant tissue is crushed at room temperature. Recent evidence suggests that in Arabidopsis, nitrile formation from glucosinolates is controlled by a heat-sensitive protein, epithiospecifier protein (ESP), a non-catalytic cofactor of myrosinase. Our objectives were to examine the effects of heating broccoli florets and sprouts on sulforaphane and sulforaphane nitrile formation, to determine if broccoli contains ESP activity, then to correlate heat-dependent changes in ESP activity, sulforaphane content and bioactivity, as measured by induction of the phase II detoxification enzyme quinone reductase (QR) in cell culture. Heating fresh broccoli florets or broccoli sprouts to 60°C prior to homogenization simultaneously increased sulforaphane formation and decreased sulforaphane nitrile formation. A significant loss of ESP activity paralleled the decrease in sulforaphane nitrile formation. Heating to 70°C and above decreased the formation of both products in broccoli florets, but not in broccoli sprouts. The induction of QR in cultured mouse hepatoma Hepa lclc7 cells paralleled increases in sulforaphane formation.

Original languageEnglish (US)
Pages (from-to)1273-1281
Number of pages9
JournalPhytochemistry
Volume65
Issue number9
DOIs
StatePublished - May 2004

Keywords

  • Anticarcinogen
  • Brassica oleracea
  • Broccoli
  • Cancer
  • Cruciferae
  • Epithiospecifier protein
  • Quinone reductase
  • Sulforaphane
  • Sulforaphane nitrile

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Plant Science
  • Horticulture

Fingerprint Dive into the research topics of 'Heating decreases epithiospecifier protein activity and increases sulforaphane formation in broccoli'. Together they form a unique fingerprint.

Cite this