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Consumption of Brassica vegetables is associated with a reduced risk of cancer of the alimentary tract in animal models and human populations. We used raw juice extracted from Brussels sprouts rich in the glucosinolate sinigrin to explore the effect of naturally occurring glucosinolate breakdown products on cell cycle progression and apoptosis in human colorectal carcinoma cells (HT29). Juice was prepared from sprout tissue immediately before use, and the glucosinolate breakdown products were determined by gas chromatography mass spectrometry and liquid chromatography mass spectrometry. The cell cycle was analyzed by flow cytometry on detached and adherent cells, and apoptosis was measured in the detached population by annexin V staining. Twenty-four hours after challenge with juice (10 microL/mL), 7-13% of adherent cells had detached from the substratum but the majority (82%) of these cells had not entered apoptosis, whereas only 33% of detached control cells were not apoptotic (p < 0.05). The main glucosinolate breakdown products were as follows: the sinigrin breakdown product, 1-cyano-2,3-epithiopropane (ca. 38 mM); the gluconapin hydrolysis product, 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 products are released by mechanical disruption of raw Brussels sprout tissue, but contrary to previous assumptions, allyl isothiocyanate is not the main compound responsible for the inhibition of cell proliferation.

Three sulfur (S) treatements were imposed by applying gypsum to three broccoli cultivars (Claudia, Marathon, and TB-234) known to differ in glucoraphanin content of mature seeds. The S treatments were control (very low added S), low S (23 kg S ha(-)(1)), and high S (92 kg S ha(-)(1)). The gypsum applications during the early vegetative phase of the three broccoli cultivars increased S uptake and the glucoraphanin content in each plant organ. There were significant genotypic differences for the content of both S and glucoraphanin in all plant organs at different growth stages with gypsum applications. A large increase in S and glucoraphanin content was found in the green heads of broccoli and mature seeds. S present in glucoraphanin accounted for only 4-10% of total S content in broccoli heads. However, S present in glucoraphanin in mature seeds accounted for 40-46% of the total S in the seeds of moderate and high glucoraphanin cultivars (Marathon and TB-234). The partitioning of S into glucoraphanin also increased with gypsum applications. Differences in S uptake, S distribution between organs, and partitioning of S into glucoraphanin largely explained the differences in glucoraphanin content in the green heads and mature seeds for the three broccoli cultivars and three S treatments.

The effects of post-harvest and packaging treatments on glucoraphanin (4-methylsulfinylbutyl glucosinolate), the glucosinolate precursor of anticancer isothiocyanate sulforaphane [4-methylsulfinylbutyl isothiocyanate], were examined in broccoli (Brassica oleracea var. italica) during storage times. The results showed that at 20 degrees C, 55% loss of glucoraphanin concentration occurred in broccoli stored in open boxes during the first 3 days of the treatment and 56% loss was found in broccoli stored in plastic bags by day 7. Under both air and controlled atmosphere (CA) storage, glucoraphanin concentration appeared to fluctuate slightly during 25 days of storage and the concentrations under CA was significantly higher than those stored under air treatment. In modified atmosphere packaging (MAP) treatments, glucoraphanin concentration in air control packaging decreased significantly whereas there were no significant changes in glucoraphanin concentration in MAP with no holes at 4 degrees C and two microholes at 20 degrees C for up to 10 days. Decreases in glucoraphanin concentration occurred when the broccoli heads deteriorated. In the present study, the best method for preserving glucoraphanin concentration in broccoli heads after harvest was storage of broccoli in MAP and refrigeration at 4 degrees C. This condition maintained the glucoraphanin concentration for at least 10 days and also maintained the visual quality of the broccoli heads.

Research on natural and bioactive compounds is increasingly focused on their effects on human health, but there are unexpectedly few studies evaluating the relationship between climate and natural antioxidants. The aim of this study was analyze the biological role of six different Brassica vegetables (Brassica oleracea L. and Brassica rapa L.) as a natural source of antioxidant compounds. The antioxidant activity may be assigned to high levels of L-ascorbic acid, total phenolics and total flavonoids of each sample. The climate seasons affected directly the concentration of bioactive components and the antioxidant activity. Broccoli inflorescences and Portuguese kale showed high antioxidant activity in Spring-Summer whilst turnip leaves did so in Summer-Winter. The Brassica vegetables can provide considerable amounts of bioactive compounds and thus may constitute an important natural source of dietary antioxidants. [ABSTRACT FROM AUTHOR]

Distribution of sinigrin (2-propenylglucosinolate) and glucoraphanin (4-methylsulphinylbutylglucosinolate) concentration was determined in seeds and seedlings of Brassica species: B. oleracea, B. nigra, B. juncea, B. rapa and B. napus using a simple and reliable extraction method. Glucosinolates were extracted from seeds and seedlings using boiling water and were analysed by reverse phase ion-pair chromatography with UV detection. High concentrations of sinigrin were found in B. nigra, B. juncea var. rugosa (mustard greens) and B. oleracea (Brussels sprouts, cabbage, cauliflower, and Chinese broccoli). Sinigrin was absent from B. rapa and B. napus and was present in negligible concentrations in B. oleracea var. italica (broccoli). The concentration of sinigrin in the seed was similar to that in the cotyledon and hypocotyl tissues (7-day-old seedling) in most Brassica species tested. Glucoraphanin was found at high concentrations in B. oleracea var. italica and moderate concentrations in B. oleracea var. capitata (cabbage), whilst was absent in B. nigra, B. juncea, B. rapa and B. napus. Glucoraphanin concentration was between 44.2 and 274.1 μmol g−1 DW among broccoli genotypes. Kalibrini®, a new hybrid line between broccoli and Chinese broccoli (kailan) contained a moderate concentration of glucoraphanin (145.3 μmol g−1 DW) compared to its parent lines (274.1 μmol g−1 DW in broccoli but only 1.2 μmol g−1 DW in kailan). Glucoraphanin concentration in seedlings was significantly lower than that in the seed of broccoli while there was no significant difference in sinigrin concentration in seedlings of most Brassica species tested. The study has shown the extensive variability in sinigrin and glucoraphanin concentrations among Brassica species and genotypes that is available for selection and breeding. New elite lines can be produced for use as commercial crops in the health food or nutraceutical industries. [Copyright &y& Elsevier]