Stabilized sulforaphane for clinical use: Phytochemical delivery efficiency

Scope: The isothiocyanate sulforaphane (SF) from broccoli is one of the most potent known inducers of the cytoprotective phase 2 response. Its role in a host of biochemical pathways makes it a major component of plant-based protective strategies for enhancing healthspan. Many nutritional supplements are now marketed that purport to contain SF, which in plants exists as a stable precursor, a thioglucoside hydroxysulfate. However, SF in pure form must be stabilized for use in supplements. Methods and results: We evaluated the stability and bioavailability of two stabilized SF preparations-an alpha-cyclodextrin inclusion (SF-alpha CD), and an SF-rich, commercial nutritional supplement. SF-alpha CD area-under-the-curve peak serum concentrations occurred at 2 h, but six of ten volunteers complained of mild stomach upset. After topical application it was not effective in upregulating cytoprotective enzymes in the skin of SKH1 mice whereas pure SF was effective in doing so. Both of these stabilized SF preparations were as potent as pure SF in inducing the cytoprotective response in cultured cells, and they were more stable and as bioavailable. Conclusion: Our studies of a stabilized phytochemical component of foods should encourage further examination of similar products for their utility in chronic disease prevention and therapy.