There is growing awareness that phytochemicals can have profound effects on the cellular
mechanisms that influence upstream endogenous defence processes. This has led to intensified
research into their potential relevance in the prevention and treatment of both acute and chronic
disease. Whereas pharmaceutical medicine has historically looked to plants as sources of the starting
materials for drug development, the focus of nutraceutical medicine is to retain the plant bioactive in
as close to its native state as possible. As a consequence, the potency of some nutraceutical
concentrates or extracts may be lower than required for significant gene expression. The molecular
structure of bioactive phytochemicals to a large extent, determines the molecule’s bioavailability.
Polyphenols are abundant dietary phytochemicals and extensive in vitro research has established
many of the signalling mechanisms involved in favourably modulating human biochemical pathways.
Such pathways are associated with core processes such as redox modulation, activation of
detoxification pathways, immune modulation for infection control and the downregulation of the
synthesis of inflammatory cytokines. Although the relationship between oxidative stress and chronic
disease continues to be affirmed, direct-acting antioxidants such as vitamins A, C, E, beta-carotene
and others have not yielded the expected preventive or therapeutic responses, even though several
large meta-analyses have sought to evaluate the potential benefit of such supplements. Because
polyphenols exhibit poor bioavailability, few of their impressive in vitro findings have been replicated
in vivo. SFN, an aliphatic isothiocyanate, emerges as a phytochemical with comparatively high
potency and high bioavailability. A number of clinical trials have demonstrated its ability to produce
favourable outcomes in conditions for which there are few satisfactory pharmaceutical solutions,
foreshadowing the potential for SFN as a clinically-relevant nutraceutical. Although myrosinase-inert
broccoli sprout extracts are widely available in supplement form, there now exist myrosinase-active
broccoli sprout supplements that yield sufficient SFN to match the doses used in clinical trials. As
such, the clinical application of SFN woluld appear to be much broader than the more readilyavailable polyphenol-based phytochemicals.
Author(s) Details
Christine A. Houghton
University of Queensland, St Lucia Queensland, Australia and Cell-Logic, Australia
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