title: Isothiocyanate concentrations and interconversion of sulforaphane to erucin in human subjects after consumption of commercial frozen broccoli compared to fresh broccoli.
abstract: METHODS
  Sulforaphane (a potent anticarcinogenic isothiocyanate derived from glucoraphanin) is widely considered responsible for the protective effects of broccoli consumption. Broccoli is typically purchased fresh or frozen and cooked before consumption. We compared the bioavailability and metabolism of sulforaphane from portions of lightly cooked fresh or frozen broccoli, and investigated the bioconversion of sulforaphane to erucin.
  
  
  RESULTS
  Eighteen healthy volunteers consumed broccoli soups produced from fresh or frozen broccoli florets that had been lightly cooked and sulforaphane thio-conjugates quantified in plasma and urine. Sulforaphane bioavailability was about tenfold higher for the soups made from fresh compared to frozen broccoli, and the reduction was shown to be due to destruction of myrosinase activity by the commercial blanching-freezing process. Sulforaphane appeared in plasma and urine in its free form and as several thio-conjugates forms. Erucin N-acetyl-cysteine conjugate was a significant urinary metabolite, and it was shown that human gut microflora can produce sulforaphane, erucin, and their nitriles from glucoraphanin.
  
  
  CONCLUSIONS
  The short period of blanching used to produce commercial frozen broccoli destroys myrosinase and substantially reduces sulforaphane bioavailability. Sulforaphane was converted to erucin and excreted in urine, and it was shown that human colonic flora were capable of this conversion.
authors.affiliation: Institute of Food Research, Norwich Research Park, Norwich, UK.
authors.forename: Shikha
authors.initials: S
authors.lastname: Saha
authors.forename: Wendy
authors.initials: W
authors.lastname: Hollands
authors.forename: Birgit
authors.initials: B
authors.lastname: Teucher
authors.forename: Paul W
authors.initials: PW
authors.lastname: Needs
authors.forename: Arjan
authors.initials: A
authors.lastname: Narbad
authors.forename: Catharine A
authors.initials: CA
authors.lastname: Ortori
authors.forename: David A
authors.initials: DA
authors.lastname: Barrett
authors.forename: John T
authors.initials: JT
authors.lastname: Rossiter
authors.forename: Richard F
authors.initials: RF
authors.lastname: Mithen
authors.forename: Paul A
authors.initials: PA
authors.lastname: Kroon
mesh_terms: D000328:Adult; D000368:Aged; D016588:Anticarcinogenic Agents / Q000493:pharmacokinetics; D001682:Biological Availability; D001937:Brassica / Q000737:chemistry*; D018592:Cross-Over Studies; D005260:Female; D005511:Food Handling; D005615:Freezing; D041981:Gastrointestinal Tract / Q000187:drug effects / Q000378:metabolism / Q000382:microbiology; D005961:Glucosinolates / Q000493:pharmacokinetics; D006026:Glycoside Hydrolases / Q000378:metabolism; D006801:Humans; D007096:Imidoesters / Q000493:pharmacokinetics; D017879:Isothiocyanates / Q000032:analysis / Q000493:pharmacokinetics*; D007700:Kinetics; D008297:Male; D054892:Metagenome; D008875:Middle Aged; D010091:Oximes; D013440:Sulfides / Q000493:pharmacokinetics* / Q000652:urine; D013454:Sulfoxides; D013861:Thiocyanates / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D055815:Young Adult
chemical_list: D016588:Anticarcinogenic Agents; D005961:Glucosinolates; D007096:Imidoesters; D017879:Isothiocyanates; D010091:Oximes; D013440:Sulfides; D013454:Sulfoxides; D013861:Thiocyanates; C037152:isothiocyanic acid; C073539:erucin; D006026:Glycoside Hydrolases; C022739:thioglucosidase; C016766:sulforaphane; C119494:glucoraphanin