Sulforaphane-rich broccoli sprout extract attenuates nasal allergic response to diesel exhaust particles

Abstract

The generation of oxidative stress by ambient air pollution particles contributes to the development of allergic sensitization and asthma, as demonstrated by intranasal challenge with well-characterized diesel exhaust particle (DEP) suspensions in humans. This effect is due to the presence of redox active organic chemicals in DEP, and can be suppressed by antioxidants and inducers of phase II enzymes in animals. In this communication, we determined whether the administration of a standardized broccoli sprout extract (BSE), which contains a reproducible amount of the sulforaphane (SFN) precursor, glucoraphanin, could be used to suppress the nasal inflammatory response in human subjects challenged with 300 μg of an aqueous DEP suspension (equivalent to daily PM exposure levels on a Los Angeles freeway). SFN is capable of inducing an antioxidant and phase II response via activation of the nuclear transcription factor (erythroid-derived 2)-like 2 (Nrf2). Previous studies have shown that 70-90% SFN delivered by BSE is absorbed, metabolized, and excreted in humans. An initial intranasal challenge with DEP in 29 human subjects was used to characterize the magnitude of the inflammatory response. Following a 4 week washout, a BSE that delivers a reproducible and standardized dose of 100 μmol SFN in mango juice was administered daily for four days. The nasal DEP challenge was repeated and lavage fluid collected to perform white blood cell (WBC) counts. The average nasal WBC increased by 66% over the initial screening levels and by 85% over the control levels 24 hours after DEP exposure. However, total cell counts decreased by 54% when DEP challenge was preceded by daily BSE administration for 4 days (p < 0.001). Since the SFN dose in these studies is equivalent to the consumption of 100-200 g broccoli, our study demonstrates the potential preventive and therapeutic potential of broccoli or broccoli sprouts rich in glucoraphanin for reducing the impact of particulate pollution on allergic disease and asthma.

Effect of Broccoli Sprouts on Nasal Response to Live Attenuated Influenza Virus in Smokers: A Randomized, Double-Blind Study

“…Riedl et al[16] reported that ingestion of broccoli sprout homogenates resulted in dose-dependent increased expression of Phase II enzymes over baseline, including HMOX1 and NQO1, in NLF cells from human volunteers, an effect not seen with alfalfa sprouts; the BSH and control preparations and “doses” we used in the present study were modeled after this. It was also recently reported by Heber et al[18] that broccoli sprout extracts at a similar dose, given for 4 days, had a suppressive effect on diesel particle-induced allergic inflammation in volunteers with allergic rhinitis. Hence, SFN-containing broccoli sprout extracts have been examined in relation tochronic inflammatory lung diseases and additional clinical trials are underway assessing the potential of this “nutraceutical” in this context.…”

Phytonutrients Differentially Stimulate NAD(P)H:Quinone Oxidoreductase, Inhibit Proliferation, and Trigger Mitotic Catastrophe in Hepa1c1c7 Cells

“…39 Moreover, the extensive range of efficacious sulforaphane concentrations allowed for the widest window of safety between the minimum effective concentration and the lowest concentration triggering mitotic disruption (Table 1). Our findings, coupled with results from recent clinical trials, 41,42 strongly suggest that sulforaphanecontaining foods may offer exceptional promise as modalities for safely protecting populations exposed to environmental carcinogens. Future studies should focus on specific high-risk groups, with an eye toward identifying stable nutrient delivery platforms affording optimal sulforaphane bioavailability.…”

Environmental effects on immune responses in patients with atopy and asthma

“…86 Sulforaphane, an upregulator of NRF2 that activates antioxidant and phase II enzymes, increased expression of airway epithelial cell antioxidant enzymes, and inhibited diesel exhaust augmentation of allergic inflammation in the nasal airway. 87-89 Omega-3 fatty acid supplementation has been shown to decrease cardiovascular risks associated with experimental PM exposure, and it is likely that this treatment may also be useful in PM-induced asthma. 90 These observations should be tempered against meta-analyses that suggest there are inadequate data to support the efficacy of antioxidants in asthma, 91,92 especially as many studies are underpowered.…”