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

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).

Lack of Effect of Oral Sulforaphane Administration on Nrf2 Expression in COPD: A Randomized, Double-Blind, Placebo Controlled Trial

“…We did quality control testing of gel capsules stored at each of the three clinical centers over the course of the study that demonstrated that the sulforaphane content of the gel capsules was stable. Furthermore, sulforaphane has been shown to be bioavailable from gel caps and, similar to juice preparations, to be metabolized rapidly [20,27–29]. We confirmed that sulforaphane was well absorbed as evident from the levels of its dithiocarbamate metabolites in the plasma of participants.…”

Sulforaphane Augments Glutathione and Influences Brain Metabolites in Human Subjects: A Clinical Pilot Study

“…The extract was standardized to 100 µmol sulforaphane in the form of 2 gel capsules per day over 7 consecutive days, as described previously [45, 53-58]. The dose of 100 μmol sulforaphane and the 7-day treatment duration were determined empirically from previous studies, including a trial demonstrating induction of antioxidant enzymes in nasal lavage cells of human subjects [59] and improved excretion of air pollutants [56].…”

“…The dose of 100 μmol sulforaphane and the 7-day treatment duration were determined empirically from previous studies, including a trial demonstrating induction of antioxidant enzymes in nasal lavage cells of human subjects [59] and improved excretion of air pollutants [56]. Our formulation of sulforaphane is 80% bioavailable [58], reaches peak plasma levels 1 h after oral ingestion, declines with first-order kinetics, and is actively excreted in urine (60% at 8 h) [58, 60]. …”

Natural compounds targeting major cell signaling pathways: a novel paradigm for osteosarcoma therapy

“…This compound is a member of the isothiocyanate family and obtained from cruciferous vegetables including Brussels sprouts, cabbage, and broccoli [62]. Sawai et al evaluated the effect of SFN and radiation treatment on LM8 murine OS cells.…”