Effect of cooking brassica vegetables on the subsequent hydrolysis and metabolic fate of glucosinolates (original) (raw)
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Journal of Agricultural and Food Chemistry, 2006
In cabbage, glucosinolates such as sinigrin are hydrolyzed by plant myrosinase to allyl isothiocyanate (AITC), allyl cyanide, and, in the presence of an epithiospecifier protein, 1-cyano-2,3-epithiopropane (CEP). Isothiocyanates have been implicated in the cancer-protective effects of Brassica vegetables. The effect of processing on the hydrolysis of glucosinolates was investigated in cabbage. Cabbage was steamed or microwaved for six time durations over 7 min. Glucosinolate concentrations were slightly reduced after microwave cooking (P < 0.001) but were not influenced after steaming (P < 0.05). Myrosinase activity was effectively lost after 2 min of microwave cooking and after 7 min of steaming. Hydrolysis of residual glucosinolates following cooking yielded predominantly CEP at short cooking durations and AITC at longer durations until myrosinase activity was lost. Lightly cooked cabbage produced the highest yield of AITC on hydrolysis in vitro, suggesting that cooking Brassica vegetables for a relatively short duration may be desirable from a health perspective.
Molecular Nutrition & Food Research, 2008
Glucosinolates (GLSs) are found in Brassica vegetables. Examples of these sources include cabbage, Brussels sprouts, broccoli, cauliflower and various root vegetables (e.g. radish and turnip). A number of epidemiological studies have identified an inverse association between consumption of these vegetables and the risk of colon and rectal cancer. Animal studies have shown changes in enzyme activities and DNA damage resulting from consumption of Brassica vegetables or isothiocyanates, the breakdown products (BDP) of GLSs in the body. Mechanistic studies have begun to identify the ways in which the compounds may exert their protective action but the relevance of these studies to protective effects in the human alimentary tract is as yet unproven. In vitro studies with a number of specific isothiocyanates have suggested mechanisms that might be the basis of their chemoprotective effects. The concentration and composition of the GLSs in different plants, but also within a plant (e.g. in the seeds, roots or leaves), can vary greatly and also changes during plant development. Furthermore, the effects of various factors in the supply chain of Brassica vegetables including breeding, cultivation, storage and processing on intake and bioavailability of GLSs are extensively discussed in this paper.
Glucosinolates in the human diet. Bioavailability and implications for health
The glucosinolates are a large group of sulphur-containing glucosides found in brassica vegetables. After physical damage to the plant tissue, glucosinolates are broken down, by the endogenous enzyme myrosinase, releasing glucose and a complex variety of biologically active products. The most important and extensively studied of these compounds are the isothiocyanates. Glucosinolates can be degraded or leached from vegetable tissue during food processing, but thermal inactivation of myrosinase preserves some intact glucosinolates in cooked vegetables. Once ingested, any remaining intact glucosinolates may be broken down by plant myrosinase in the small intestine, or by bacterial myrosinase in the colon. Isothiocyanates are absorbed from the small bowel and colon, and the metabolites are detectable in human urine 2–3 h after consumption of brassica vegetables. Isothiocyanates are potent inducers of Phase II enzymes in vitro, and they have been shown to increase the metabolism and detoxification of chemical carcinogens in vitro and in animal models. Some of these compounds also inhibit mitosis and stimulate apoptosis in human tumour cells, in vitro and in vivo. This second effect raises the possibility that in addition to blocking DNA damage, isothiocyanates may selectively inhibit the growth of tumour cells even after initiation by chemical carcinogens. Epidemiological evidence supports the possibility that glucosinolate breakdown products derived from brassica vegetables may protect against human cancers, especially those of the gastrointestinal tract and lung. To define and exploit these potentially anticarcinogenic effects it is important to understand and manipulate glucosinolate chemistry and metabolism across the whole food-chain, from production and processing to consumption.
Journal of Food Processing and Preservation, 2012
The aim of this study is to evaluate the effect of postharvest conditions and food processing on beneficial glucosinolates (GLs) present in Brassicacea plants. Also, we evaluate the role of endogenous enzyme, the myrosinase, on natural GL degradation. The myrosinase activity (MA) was measured either by spectrophotometric and high-performance liquid chromatography (HPLC) methods and the GLs were identified and quantified by HPLC. The samples were submitted to a different temperature regime for 72 h, and to three different cooking methods. The results showed a different MA between cultivars, however not significantly different. The GLs were affected by temperature and by cooking method, depending however on cultivar (P < 0.05). The highest total GLs were obtained under refrigerator (1,784.7 mmoles·100/G dry weight [DW]). The steam method contributed to the higher GL preservation and in opposition the classic method (boiling water) led to higher losses in GL content (57% in Brassica oleracea and 81% in Brassica rapa cultivars).
Myrosinase Hydrolysates of Brassica oleraceae L. Var. italica Reduce the Risk of Colon Cancer
Phytotherapy Research, 2011
By means of liquid chromatography-electrospray ionization (LC-ESI) mass spectrometry two glucosinolates, glucoiberin and 3-hydroxy,4(α-L-rhamnopyranosyloxy) benzyl glucosinolate, were identified in the aqueous extract of Brassica oleraceae L var. italica. Further, two compounds were isolated after enzymatic hydrolysis of the aqueous extract by myrosinase, one of them was identified as 4-vinyl-3-pyrazolidinone. The second compound (sulphoraphane) 1-isothiocyanate-4-methyl-sulphinyl butane, converted to the most stable form of thiourea (sulphoraphane thiourea). The crude extract (80% alcohol extract) of broccoli florets was examined for cytotoxic activity against different human cancer cell lines, it showed good inhibition of colon cancer (IC 50 3.88 µg/mL). On the other hand each of the successive extracts (petroleum ether, chloroform, ethyl acetate and ethanol) showed no significant cytotoxic activity. When myrosinase hydrolysate was tested for cytotoxic activity on the colon cancer cell line it showed very high activity -95% lethality up to 0.78 µg/mL.
Distribution of glucosinolates in some raw and processed Brassica vegetables grown in Croatia
Acta Alimentaria, 2007
The interest in food with chemoprotective properties has been steadily increasing due to many epidemiological studies indicating the lower probability of acquiring some kinds of cancer (e.g. colon, prostate, breast, cervical) in populations, whose diet includes large quantities of Brassica vegetables. The biologically active compounds in Brassica vegetables are the breakdown products of glucosinolates, including isothiocyanates, nitriles, thiocyanates, indoles and oxazolidinethiones from which indoles and isothiocyanates in particular have been implicated to have anticarcinogenic properties. The object of the present study was to investigate glucosinolates distribution as well as their losses during blanching and cooking in edible parts of white cabbage, cauliflower, kohlrabi and collard. In all vegetable, only indole glucosinolates as precursors of anticarcinogenic compounds were identified, while glucoraphane was not detected. In cauliflower and collard, proportion of indole glucosinolates was more then 90%, followed by kohlrabi (>70%) and white cabbage (>50%). Analysis of glucosinolates losses during blanching and cooking showed substantial decrease in all vegetables. The major losses were observed for cauliflower, around 60%, for cooked vegetable, followed by white cabbage (55%), kohlrabi (53%), and collard (44%). The losses after blanching were approximately 15% less then in cooked vegetables. Current nutritional recommendations suggest an increase in the total consumption of Brassica vegetables such as cabbage, cauliflower, kale, kale sprouts, collard, broccoli, and kohlrabi (DAS et al.
British Journal of Nutrition, 2007
Glucosinolate consumption from brassica vegetables has been implicated in reduction of cancer risk. The isothiocyanate breakdown products of glucosinolates appear to be particularly important as chemoprotective agents. Before consumption, brassica vegetables are generally cooked, causing the plant enzyme, myrosinase, to be denatured, influencing the profile of glucosinolate breakdown products produced. Some human intestinal microflora species show myrosinase-like activity (e.g. bifidobacteria). We aimed to increase bifidobacteria by offering a prebiotic (inulin) in a randomised crossover study. Six volunteers consumed inulin (10 g/d) for 21 d followed by a 21 d control period (no inulin). Treatment periods were reversed for the remaining six volunteers. During the last 5 d of each period two cabbage-containing meals were consumed. Total urine output was collected for 24 h following each meal. Cabbage was microwaved for 2 min (lightly cooked) or 5·5 min (fully cooked). Faecal samples...
Frontiers in plant science, 2015
Brassicales contain a myrosinase enzyme that hydrolyzes glucosinolates to form toxic isothiocyanates (ITC), as a defense against bacteria, fungi, insects and herbivores including man. Low levels of ITC trigger a host defense system in mammals that protects them against chronic diseases. Because humans typically cook their brassica vegetables, destroying myrosinase, there is a great interest in determining how human microbiota can hydrolyze glucosinolates and release them, to provide the health benefits of ITC. ITC are highly reactive electrophiles, binding reversibly to thiols, but accumulating and causing damage when free thiols are not available. We found that addition of excess thiols released protein-thiol-bound ITC, but that the microbiome supports only poor hydrolysis unless exposed to dietary glucosinolates for a period of days. These findings explain why 3-5 servings a week of brassica vegetables may provide health effects, even if they are cooked.
Journal of Applied Pharmaceutical Science, 2013
The family Brassicaceae has been very studied due to the pharmacologic properties of the glucosinolates (GLS) and their hydrolysis products, which are associated with the action of an endogenous thioglucosidase myrosinase. Factors such as climate, soil, genotype, seasonal variation, processing, extraction quantification can affect the enzyme activity and stability, leading to increase or decrease the hydrolysis of GLS. Based on this aspect, the main objective of this work is present a review concerning the glucosinolate-myrosinase system, influence of climate and genotype to seasonal variation in the glucosinolate-myrosinase system, effect of thermal and high hydrostatic pressure treatments on the GLS content, as well as, the isolation and quantification of GLS from Brassica.
Glucosinolates are secondary metabolites mostly found in the family Brassicaceae. These compounds are extensively associated with economically important plants, and may provide protective capacity against cellular oxidative stresses. Although known to be present in plants for over 100 years, interest and research about glucosinolate formation, function, and potential benefits to human health has taken place in recent times. Glucosinolates are simple organic compounds consisting of a core molecule combined with different side chains, which contribute to their diversity and subsequently determine the nature of hydrolysis products. Injured or affected plant tissue brings the compartmentalised enzyme myrosinase into contact with the localised glucosinolate, which separates the glucose group from the parent glucosinolate. These compounds have been shown to have the potential to contribute to human nutritional wellbeing, as plants high in glucosinolates are known to possess anti-carcinoge...