Urease from Helicobacter pylori is inactivated by sulforaphane and other isothiocyanates.
Level 5 - mechanism / opinion, no new human data
In vitro biochemical and microbiological mechanistic study
PubMed 23583386 · doi:10.1016/j.bbrc.2013.03.126
What was done
The authors investigated the kinetics and mechanism of Helicobacter pylori and jack bean urease inactivation by sulforaphane (SF) and structurally related isothiocyanates (ITCs). They used UV spectroscopy (260-320 nm) on partially purified H. pylori urease to detect dithiocarbamate bond formation with cysteine thiols. They also compared urease inhibition profiles across multiple natural and synthetic ITCs (including berteroin, hirsutin, phenethyl isothiocyanate, alyssin, erucin, and benzoyl-ITC) and evaluated SF bactericidal activity against both urease-positive and urease-negative H. pylori strains.
What was found
The abstract reports no exact numerical values or kinetic constants. Urease inactivation by SF exhibited first-order kinetics dependent on enzyme and SF concentration. Spectroscopic analysis confirmed time-dependent increases in 260-320 nm absorbance, indicating dithiocarbamate formation between SF isothiocyanate groups and urease cysteine thiols. Structurally related natural ITCs known to be bactericidal (berteroin, hirsutin, phenethyl isothiocyanate, alyssin, erucin) did not inactivate urease. SF remained bactericidal against both urease-positive and urease-negative strains, while benzoyl-ITC strongly inactivated urease without exhibiting bactericidal effects, demonstrating that urease inactivation and bactericidal activity are functionally uncoupled.
Why it matters
These findings define the chemical mechanism of urease inhibition by sulforaphane while demonstrating that its direct antimicrobial effect against H. pylori is not dependent on urease disruption. Inactivating urease may provide a distinct benefit by reducing ammonia generation and downstream gastric inflammation.
Limits
This is entirely an in vitro biochemical and culture study without animal or human clinical data. The abstract does not report specific IC50 values, kinetic rate constants, or quantitative bactericidal concentrations. In vivo bioavailability, gastric mucosal stability, and actual impact on gastric pH and colonization remain unmeasured.
Cited by
- supports Sulforaphane acts as an effective inhibitor of the bacterial urease enzyme, but urease inhibition is not the mechanism by which sulforaphane kills Helicobacter pylori.