In vitro digestion of sinigrin and glucotropaeolin by single strains of Bifidobacterium and identification of the digestive products.
Level 5 - mechanism / opinion, no new human data
In vitro laboratory study with no human or animal subjects
PubMed 14871576 · doi:10.1016/j.fct.2003.09.008
What was done
Three strains of Bifidobacterium (B. pseudocatenulatum, B. adolescentis, and B. longum) were tested in vitro for degradation of the glucosinolates sinigrin (SNG) and glucotropaeolin (GTL) during 24-48 h cultivation. A cell-free extract from sonicated B. adolescentis was incubated with 0.25 mM SNG at pH 7.0 with or without 0.5 mM L-ascorbic acid, and reaction products in cultured broth were identified using GC-MS.
What was found
All three strains degraded both glucosinolates within 24-48 h, accompanied by a pH decrease from 7.1 to 5.2. SNG digestion by B. adolescentis cell-free extract increased in the presence of 0.5 mM L-ascorbic acid and formed allyl isothiocyanate (AITC) over 120 min at pH 7.0. In cultured broth, GC-MS identified 3-butenenitrile from SNG and phenylacetonitrile from GTL as the major products, while AITC and benzyl isothiocyanate were barely detectable.
Why it matters
This study demonstrates that human intestinal Bifidobacteria harbor myrosinase-like enzymatic activity capable of metabolizing dietary glucosinolates, though medium acidification directs degradation toward nitriles.
Limits
This is an in vitro experiment using single-strain liquid cultures and cell-free extracts, without testing in vivo human physiology, complex gut microbial interactions, or systemic absorption. Exact quantitative degradation rates and product yields were not reported in the abstract.
Cited by
- supports Strains of Enterococcus, Lactobacillus, and Bifidobacterium species possess myrosinase activity.