Influence of temperature and ontogeny on the levels of glucosinolates in broccoli (Brassica oleracea Var. italica) sprouts and their effect on the induction of mammalian phase 2 enzymes.
Level 5 - mechanism / opinion, no new human data
Bench laboratory study evaluating plant biochemistry and in vitro enzyme induction with no human subjects.
PubMed 12358509 · doi:10.1021/jf020309x
What was done
The authors investigated how growing temperature and developmental stage (ontogeny over an 11-day period) affect glucosinolate levels (specifically glucoraphanin) in broccoli (Brassica oleracea Var. italica) sprouts, and evaluated their capacity to induce mammalian phase 2 detoxification enzymes. Seedlings were cultivated across day/night temperature regimes (30/15 degrees C, 22/15 degrees C, and 18/12 degrees C) and constant temperatures (11.3 degrees C and 33.1 degrees C), and anatomical distribution between cotyledons and roots was measured.
What was found
Sprouts grown under a 30/15 degrees C day/night regime had significantly higher glucosinolate levels across six consecutive days postemergence compared to 22/15 degrees C and 18/12 degrees C regimes (p < 0.001). Both higher (33.1 degrees C) and lower (11.3 degrees C) constant temperatures induced higher glucosinolate levels in sprouts grown to uniform size. Glucosinolates were highest in cotyledons and lowest in roots. Nongerminated seeds had the highest glucosinolate content and concordantly greater induction of mammalian phase 2 detoxication enzymes, with levels declining as sprouts matured. Specific numerical concentrations and fold-induction values were not reported in the abstract.
Why it matters
This study identifies temperature stress and early developmental timing as key factors maximizing glucoraphanin content in broccoli sprouts. It highlights nongerminated seeds and younger sprouts as having the highest potency for phase 2 enzyme induction.
Limits
This was an in vitro plant cultivation and bench biochemical study without animal or human in vivo feeding trials. The abstract omits sample sizes, experimental replicate numbers, quantitative concentration metrics, and the specific mammalian enzyme assay model used.
Cited by
- supports Glucoraphanin concentration is highest in broccoli seeds, declines on a fresh weight basis during germination and sprouting, plateaus at a low level, and increases again when the plant flowers and sets seed.