Aims: Cruciferous vegetables such as broccoli accumulate glucoraphanin, hydrolysed to sulforaphane, which activates antioxidant genes via nuclear factor erythroid 2-related factor 2 (nrf2), alleviating age-related diseases. However, sulforaphane’s rapid absorption and excretion raise questions about its impact on peripheral tissues. This study hypothesised that sulforaphane exerts protective effects via extracellular vesicles (EVs) and examined nrf2-induced antioxidant genes within plasma-derived EVs following consumption of glucoraphanin-rich broccoli soup.
Methods: Blood and urine samples were collected from 9 adults, participating in a two-arm, single-blinded, randomised crossover trial consuming glucoraphanin-rich broccoli soup (Intervention) and glucoraphanin-free vegetable soup (Control). Plasma-EVs (n=72; 9 participants × 2 conditions × 4 timepoints) were isolated by size exclusion chromatography, characterised by nanoparticle tracking analysis, transmission electron microscopy, and western blotting. EV mRNA was quantified via quantitative PCR; urine samples (n=126; 9 participants × 2 conditions × 7 timepoints) were analysed for sulforaphane pharmacokinetics using Liquid Chromatography-Mass Spectrometry.
Results: Mean EV particle concentration was 3.12E+11 ± 6.36E+10 (Intervention) and 3.23E+11 ± 7.66E+10 particles/mL (Control); EV protein concentration was 0.10 ± 0.01 µg/µL in both groups. Western blotting confirmed enrichment of EV marker CD9. Mean RNA concentration was 36.10 ng/µL (Intervention) and 33.49 ng/µL (Control). While sulforaphane was detected in urine following Intervention (p<0.001), there were no differences in mRNA abundance within EVs, for the quantifiable genes (AKR1C3, SOD1, GSTP1, GPX1, CD36).
Conclusion: Urinary sulforaphane profiling confirmed the Intervention’s efficacy; however, the genes examined were unaltered within EVs. Further work is needed to understand how dietary sulforaphane mediates its ascribed health benefits.