Glucosinolate and Desulfo-glucosinolate Metabolism by a Selection of Human Gut Bacteria.
Level 5 - mechanism / opinion, no new human data
In vitro laboratory study with no human or animal subjects
PubMed 27301252 · doi:10.1007/s00284-016-1079-8
What was done
The study examined the in vitro metabolism of three dietary glucosinolates—sinigrin (SNG), glucotropaeolin (GTP), and gluconasturtiin (GNT)—along with their desulfo-derivatives (DS-GSLs), using three human gut bacterial isolates: Enterococcus casseliflavus CP1, Lactobacillus agilis R16, and Escherichia coli VL8. Cultures were monitored over 24 hours to track the conversion to isothiocyanates (ITCs) and nitriles (NITs), media pH shifts, and the effects of Fe2+ and Mg2+ ions on metabolite profiles.
What was found
All strains metabolized GNT completely within 24 hours to phenethyl ITC and phenethyl NIT (PNIT), except L. agilis R16 which produced only PNIT. At least 80% of GTP and SNG were metabolized by all three strains within 24 hours. The total percentage of products accounted for 3% to 53% of the initial glucosinolates. ITC production peaked between 4 and 10 hours in most cases and gradually declined, while NIT production increased and remained relatively constant. DS-GSLs yielded NITs. For GNT and its desulfo form, Fe2+ increased NIT production, while Mg2+ stimulated ITC formation.
Why it matters
This study demonstrates that human gut bacteria possess pathways to degrade intact and desulfated glucosinolates into bioactive compounds independently of plant myrosinase, with product distributions modulated by local cation concentrations.
Limits
This was an in vitro monoculture experiment testing only three isolated bacterial strains, which does not reflect the complex community interactions, transport, or degradation rates in the human gut. Measured end products accounted for only 3% to 53% of starting material, leaving most metabolic breakdown products unidentified. No in vivo human data or clinical outcomes were measured.
Cited by
- supports Strains of Enterococcus, Lactobacillus, and Bifidobacterium species possess myrosinase activity.