Bioavailable Sulforaphane Quantitation in Plasma by LC-MS/MS Is Enhanced by Blocking Thiols

Area of Science:

• Analytical Chemistry
• Biochemistry
• Pharmacology

Background:

• Sulforaphane (SFN) quantification in biological matrices is difficult due to its electrophilic nature and metabolite instability.
• Loss of SFN occurs during sample preparation via conjugation with protein thiols, leading to underestimation.

Purpose of the Study:

• To develop a reliable method for quantifying sulforaphane (SFN) and its thiol metabolites in biological samples.
• To overcome challenges associated with SFN's reactivity and metabolite dissociation during analysis.

Main Methods:

• Utilized liquid chromatography-tandem mass spectrometry (LC-MS/MS) for SFN and metabolite quantification.
• Employed iodoacetamide (IAA) as an alkylating agent to block thiols, releasing SFN from proteins and stabilizing metabolites.

Main Results:

• The IAA thiol-blocking method increased SFN recovery in serum from 32% to 94%.
• Achieved a method limit of quantitation of 4.7 nM for SFN.
• Analysis of clinical samples showed 6-fold higher SFN concentrations with the IAA method compared to its omission.

Conclusions:

• The IAA thiol-blocking strategy effectively enhances the accurate quantification of bioavailable sulforaphane (SFN) in biological samples.
• This streamlined method improves SFN analysis in plasma, overcoming previous limitations in sample preparation and metabolite stability.