Sulforaphane Bioavailability from Glucoraphanin-Rich Broccoli: Control by Active Endogenous Myrosinase

PLoS One. 2015 Nov 2;10(11):e0140963. doi: 10.1371/journal.pone.0140963. eCollection 2015.

Abstract

Glucoraphanin from broccoli and its sprouts and seeds is a water soluble and relatively inert precursor of sulforaphane, the reactive isothiocyanate that potently inhibits neoplastic cellular processes and prevents a number of disease states. Sulforaphane is difficult to deliver in an enriched and stable form for purposes of direct human consumption. We have focused upon evaluating the bioavailability of sulforaphane, either by direct administration of glucoraphanin (a glucosinolate, or β-thioglucoside-N-hydroxysulfate), or by co-administering glucoraphanin and the enzyme myrosinase to catalyze its conversion to sulforaphane at economic, reproducible and sustainable yields. We show that following administration of glucoraphanin in a commercially prepared dietary supplement to a small number of human volunteers, the volunteers had equivalent output of sulforaphane metabolites in their urine to that which they produced when given an equimolar dose of glucoraphanin in a simple boiled and lyophilized extract of broccoli sprouts. Furthermore, when either broccoli sprouts or seeds are administered directly to subjects without prior extraction and consequent inactivation of endogenous myrosinase, regardless of the delivery matrix or dose, the sulforaphane in those preparations is 3- to 4-fold more bioavailable than sulforaphane from glucoraphanin delivered without active plant myrosinase. These data expand upon earlier reports of inter- and intra-individual variability, when glucoraphanin was delivered in either teas, juices, or gelatin capsules, and they confirm that a variety of delivery matrices may be equally suitable for glucoraphanin supplementation (e.g. fruit juices, water, or various types of capsules and tablets).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Biological Availability
  • Brassica / chemistry*
  • Dietary Supplements
  • Drug Delivery Systems
  • Female
  • Glucosinolates / administration & dosage*
  • Glucosinolates / pharmacokinetics
  • Glycoside Hydrolases / administration & dosage*
  • Glycoside Hydrolases / metabolism
  • Humans
  • Imidoesters / administration & dosage*
  • Imidoesters / pharmacokinetics
  • Isothiocyanates / pharmacokinetics
  • Isothiocyanates / urine*
  • Male
  • Middle Aged
  • Plant Extracts / analysis
  • Plant Extracts / pharmacokinetics
  • Seedlings / metabolism
  • Seeds / metabolism

Substances

  • Glucosinolates
  • Imidoesters
  • Isothiocyanates
  • Plant Extracts
  • Glycoside Hydrolases
  • thioglucosidase
  • sulforafan
  • glucoraphanin

Grant support

This work was supported by a generous non-restricted donation from the Lewis B. and Dorothy Cullman Foundation. Funding to cover the cost of including a commercial supplement was provided by Brassica Protection Products LLC, and the supplements themselves were provided free of charge by their manufacturer (Xymogen) as detailed in the manuscript. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.