A major inducer of anticarcinogenic protective enzymes from broccoli: isolation and elucidation of structure.
Level 5 - mechanism / opinion, no new human data
Preclinical bench and rodent bioassay study with no human participants.
OpenAlex W1967077010 · doi:10.1073/pnas.89.6.2399
What was done
Researchers isolated and structurally characterized phase II enzyme inducers from broccoli (Brassica oleracea italica, SAGA cultivar) using a quinone reductase bioassay in cultured murine hepatoma cells. They synthesized racemic sulforaphane and analogues varying in sulfur oxidation state and methylene chain length (CH3-SOm-(CH2)n-NCS; m = 0-2, n = 3-5), then evaluated their phase II enzyme-inducing potency in murine hepatoma cells and in mouse tissues.
What was found
The major active inducer was identified as (-)-1-isothiocyanato-(4R)-(methylsulfinyl)butane (sulforaphane). Sulforaphane acted as a monofunctional inducer, selectively inducing phase II enzymes (quinone reductase and glutathione S-transferases) without inducing aryl hydrocarbon receptor-dependent cytochromes P-450. Among tested analogues, sulforaphane had the highest inducer potency, with oxygen on sulfur increasing activity. Sulforaphane and its sulfide and sulfone analogues induced quinone reductase and glutathione transferase in mouse tissues. The abstract reports no numerical values, concentrations, or fold-induction levels.
Why it matters
This study identified and characterized sulforaphane as a major molecular driver of phase II detoxification enzyme induction in broccoli, establishing a chemical mechanism for the protective effects of cruciferous vegetables.
Limits
The study is restricted to in vitro murine cells and mouse tissues with no human testing. The abstract omits sample sizes, concentrations, statistical variances, and quantitative induction levels.
Cited by
- supports Researchers at Johns Hopkins discovered sulforaphane in 1992.