| Abstract
| - Consumption of Brassica vegetables is associated with a reduced risk of cancer of the alimentarytract in animal models and human populations. We used raw juice extracted from Brussels sproutsrich in the glucosinolate sinigrin to explore the effect of naturally occurring glucosinolate breakdownproducts on cell cycle progression and apoptosis in human colorectal carcinoma cells (HT29). Juicewas prepared from sprout tissue immediately before use, and the glucosinolate breakdown productswere determined by gas chromatography mass spectrometry and liquid chromatography massspectrometry. The cell cycle was analyzed by flow cytometry on detached and adherent cells, andapoptosis was measured in the detached population by annexin V staining. Twenty-four hours afterchallenge with juice (10 μL/mL), 7−13% of adherent cells had detached from the substratum but themajority (82%) of these cells had not entered apoptosis, whereas only 33% of detached control cellswere not apoptotic (p< 0.05). The main glucosinolate breakdown products were as follows: thesinigrin breakdown product, 1-cyano-2,3-epithiopropane (ca. 38 mM); the gluconapin hydrolysisproduct, 3-butenyl isothiocyanate (ca. 2.2.mM); the glucobrassicin metabolite, ascorbigen (ca. 8 mM);and low concentrations of other indole glucosinolate-derived hydrolysis products such as neoascorbigen and 3,3‘-diindolylmethane. A variety of biologically active glucosinolate breakdown productsare released by mechanical disruption of raw Brussels sprout tissue, but contrary to previousassumptions, allyl isothiocyanate is not the main compound responsible for the inhibition of cellproliferation. Keywords: Brussels sprouts; glucosinolate metabolites; isothiocyanates; cell cycle; cyano-epithioalkanes; adhesion; apoptosis
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