Improved method for the determination of the total glucosinolate content of rapeseed by determination of enzymically released glucose

The Effect of Hydrothermally Processed Soybean- and Rapeseed-Based Diets on Performance, Meat and Carcass Quality Characteristics in Growing-Finishing Pigs

The experiment was performed on 60 crossbred weaners with average initial body weight (BW) of 22 kg. The animals were divided into 4 groups, with 15 animals (10 males and 5 females) per group, based on the percentage content of the following components in complete diets: soybean meal, toasted full-fat soybeans, cold-pressed rapeseed cake with increased oil content, extruded rapeseed cake with increased oil content. The growth performance of pigs, carcass characteristics, meat quality and the fatty acid profile of depot fat were determined. The pigs fed complete diets containing toasted soybeans had higher average daily gain (ADG). The animals receiving cold-pressed rapeseed cake were characterised by lower ADG and higher FCR. The carcasses of pigs fed diets containing cold-pressed rapeseed cake and extruded rapeseed cake had lower lean content than the carcasses of pigs administered toasted soybeans. The analysed feedstuffs had no effect on back-fat thickness or meat quality. Cold-pressed and extruded rapeseed cake contributed to changes in the fatty acid profile of backfat, including an increase in the concentrations of monounsaturated fatty acids (MUFAs) and a more desirable n-6/n-3 PUFA ratio. The extrusion processing of rapeseed cake decreased the content of lysine and methionine with cystine by approximately 4%, and reduced total glucosinolate content by approximately 17%. The inclusion of toasted soybeans in pig diets contributed to higher BW gain and carcass dressing percentage. Rapeseed cake with increased oil content led to desirable changes in the fatty acid profile of backfat.

Melatonin treatment affects the glucoraphanin-sulforaphane system in postharvest fresh-cut broccoli (Brassica oleracea L.)

The effect of postharvest melatonin treatment on sulforaphane production of fresh-cut broccoli at 4℃ during storage was investigated in this study. Florets treated with 100 μM melatonin exhibited higher contents of total glucosinolates and sulforaphane. Glucoraphanin content was significantly increased after melatonin treatment, and which was explained by gene analysis. Expressions of glucoraphanin biosynthesis genes including Elong, CYP83A1, MYB28, UGT74B1 and FMOGS-OX1 were up-regulated while AOP2 was obviously decreased by melatonin treatment, leading to a higher glucoraphanin accumulation. In addition, application of melatonin enhanced the myrosinase activity and the expression level of MYO, benefiting the formation of sulforaphane. This study demonstrates that melatonin treatment positively affected the glucoraphanin-sulforaphane system in postharvest fresh-cut broccoli.

Effect of zinc and glucosinolates on nutritional quality of Noccaea caerulescens and infestation by Aleyrodes proletella

The Zn hyperaccumulating plant, Noccaea caerulescens, was grown under controlled conditions at a range of Zn concentrations (0-1000 mg kg(-1) dwt. soil) to determine the effectiveness of hyperaccumulation in deterring the cabbage whitefly, Aleyrodes proletella, and to establish the relationship between levels of foliar Zn and glucosinolates (organic defence compounds). Two weeks after introducing A. proletella adults to the plants, next generation nymphs were quantified. This sucking insect caused minimal damage to plant tissue and did not affect foliar glucosinolate levels. Foliar Zn concentrations increased with increasing soil Zn application and reached a maximum of ~7000 mg kg(-1). More whitefly nymphs were observed on plants as the foliar Zn concentration increased (up to ~3000 mg kg(-1)) after which numbers declined. Zn was an explanatory variable in accumulated generalised linear regression after the variation in the data due to C/N ratio had been accounted for. Nymph numbers declined with increasing C/N ratio and increased with increasing N concentration. The highest glucosinolate concentrations were in shoots with the lowest Zn concentrations; this is consistent with the 'trade-off' hypothesis which states that elemental defence mechanisms allow for lowered organic defences.

Effect of light on quality and bioactive compounds in postharvest broccoli florets

The effect of light treatment (fluorescent and light-emitting diode (LED) green light) on shelf life, visual quality and bioactive compounds in broccoli florets was investigated. The results showed that light treatment extended shelf life and inhibited the decrease of H value and chlorophyll contents in broccoli florets stored at 25 °C. The content of total phenols and glucosinolates were markedly increased by LED green light, but no effect on sulforaphane. Fluorescent and LED green light treatment significantly increased DPPH radical scavenging activity in broccoli, but little effect was found between the two light treatments. These results indicated that LED green light could be a useful technique for extending shelf life, maintaining visual quality and preventing decrease of bioactive compounds in broccoli florets.

A derivatization method for the simultaneous detection of glucosinolates and isothiocyanates in biological samples

Various analytical methods have been established to quantify isothiocyanates (ITCs) that derive from glucosinolate hydrolysis. However, to date there is no valid method applicable to pharmacokinetic studies that detects both glucosinolates and ITCs. A specific derivatization procedure was developed for the determination of ITCs based on the formation of a stable N-(tert-butoxycarbonyl)-L-cysteine methyl ester derivative, which can be measured by high-performance liquid chromatography with ultraviolet detection after extraction with ethylacetate. The novel method, which is also applicable to the indirect determination of glucosinolates after their hydrolysis by myrosinase, was established for the simultaneous determination of glucoraphanin and sulforaphane. By derivatization, the sensitivity of ITC detection was increased 2.5-fold. Analytical recoveries from urine and plasma were greater than 75% and from feces were approximately 50%. The method showed intra- and interday variations of less than 11 and 13%, respectively. Applicability of the method was demonstrated in mice that received various doses of glucoraphanin or that were fed a glucoraphanin-rich diet. Besides glucoraphanin and sulforaphane, glucoerucin and erucin were detected in urine and feces of mice. The novel method provides an essential tool for the analysis of bioactive glucosinolates and their hydrolysis products and, thus, will contribute to the elucidation of their bioavailability.

Maintaining quality and bioactive compounds of broccoli by combined treatment with 1-methylcyclopropene and 6-benzylaminopurine

BACKGROUND

Broccoli deteriorates very quickly after harvest at ambient temperature due to the loss of green colour and the consequent yellowing of florets. To search for an effective method to control quality deterioration, the effect of 1-methylcyclopropene (1-MCP) combined with 6-benzylaminopurine (6-BA) treatment on visual quality, antioxidant enzymes and bioactive compounds in broccoli florets were investigated.

RESULTS

A combined treatment of 2.5 µL L⁻¹ 1-MCP and 200 mg L⁻¹ 6-BA significantly reduced the increase of lightness (L*) value, and retained a high level for the hue value (H) and chlorophyll content. Superoxide dismutase, ascobate peroxidase and catalase activities increased while the activity of peroxidase decreased during storage in treated samples in comparison with the controls. The combined treatment enhanced the biosynthesis of glucosinolate and the formation of the anticarcinogen sulforaphane, which improved the health benefit of broccoli.

CONCLUSION

These results indicate that a combined treatment of 1-MCP and 6-BA could be a good candidate for maintaining the visual quality and enhancing the nutritional value in broccoli during storage at 15 °C.

6-Benzylaminopurine delays senescence and enhances health-promoting compounds of harvested broccoli

The effect of 6-benzylaminopurine (6-BA) on the color, antioxidant activity, and contents of total phenols, glucosinolate, and sulforaphane in broccoli florets was investigated. The results showed that 6-BA treatment markedly inhibited the increase of the L* value and malondialdehyde (MDA) content and retarded the decrease of the H value. 6-BA treatment reduced the rate of chlorophyll degradation by regulating the activities of chlorophyllase and Mg-dechelatase. When compared to control florets, the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity and the activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT) were enhanced in florets treated with 6-BA, whereas the activity of peroxidase (POD) was significantly reduced. The contents of total phenols, glucosinolate, and sulforaphane in broccoli florets were also profoundly increased after treatment with 6-BA. These results indicated that 6-BA could maintain the quality, delay senescence, and improve the nutritional value of broccoli.

Chemical and biological characterisation of nutraceutical compounds of broccoli

People's diet offers a greater and more diverse group of plant bioactives than do drugs, and they often do not realise that many drugs are derived from the compounds originally discovered in plant foods. Numerous epidemiological studies indicate that Brassica vegetables in general, and broccoli in particular, protect humans against cancer since they are rich sources of glucosinolates as well as possessing a high content of flavonoids, vitamins and mineral nutrients. One unusual phytotherapeutic role of broccoli is for skin diseases--the juice of the leaves is used to treat warts. However, the main use of broccoli stems from its health-promoting properties. Some criteria have been proposed to evaluate the possibilities of developing new "functional foods" to reduce the risk of specific cancers; largely in broccoli, which is associated with cancer protection. Processing conditions, transport, domestic cooking, etc., affect the health-promoting properties of broccoli and these have been widely studied. This review makes an in-depth study of the chemical and biological characterization of the phytochemicals of broccoli and the effects on the bioactive composition of broccoli.

High-performance liquid chromatographic separation of natural and synthetic desulphoglucosinolates and their chemical validation by UV, NMR and chemical ionisation-MS methods

Methods are described for the optimised extraction, desulphation and HPLC separation of desulphoglucosinolates. These methods provide rapid separation, identification and quantitative measurements of glucosinolates extracted from Brassica napus L and related crops, of unusual glucosinolates found in crucifer weed species, and also of synthetic alkylglucosinolates. The desulphoglucosinolates used in these studies were either chemically synthesised (at least one example from each major structural class), or purified from various plant sources. Validation of the identities of the desulphoglucosinolates was by comparison of retention times with standards, and by UV, 1H- and 13C-NMR and chemical ionisation MS analysis. A list of useful species, and the specific tissues, from which high concentrations of standards can be extracted is included.

Effect of glucosinolate breakdown products on beta-naphthoflavone-induced expression of human cytochrome P450 1A1 via the Ah receptor in Hep G2 cells

The ability of glucosinolates, the main bioactive components of brassica vegetables, to influence beta-naphthoflavone-induced transcription of human cytochrome P450 1A1 was examined. Human Hep G2 cells, which contain a functional Ah receptor, were transiently transfected with a reporter construct containing the entire promoter sequence of the human CYP1A1 gene. Breakdown products of four of the glucosinolates tested (prop-2-enyl, 3-methylsulphinylpropyl, 2-hydroxybut-3-enyl and p-hydroxybenzyl), at a concentration as low as 1 microM, reduced the level of beta-naphthoflavone-induced transcription of CYP1A1. It is already known that certain glucosinolate breakdown products can induce phase II enzymes and inhibit the catalytic activity of some cytochrome P450 isoenzymes. This study demonstrates that certain alkyl and aromatic glucosinolates may also influence cytochrome P450 1A1 transcription.

Isolation of glucosinolate degrading microorganisms and their potential for reducing the glucosinolate content of rapemeal

A range of microorganisms were assessed for their ability to degrade glucosinolates, using sinigrin (2-propenyl glucosinolate) as a model compound. Eight different species capable of growing on sinigrin as a sole carbon source were isolated. These were predominantly Gram-positive bacteria which also degraded the natural glucosinolates within rapemeal. Growth of the majority of these organisms in a sinigrin/glucose liquid medium wass biphasic; glucose was utilised during the initial rapid phase of growth. The ability to degrade sinigrin was found to be unstable and was rapidly and irreversibly lost when organisms were cultured on sinigrin-free media.

Rapeseed meal-glucosinolates and their antinutritional effects. Part 1. Rapeseed production and chemistry of glucosinolates

This review, which will be presented in seven parts is concerned with the use of rapeseed meal as an animal feeding stuff. The presence of glucosinolates in the meal limits its use due to a number of antinutritional and physiological effects. Whilst not in itself exhaustive, this review updates earlier reviews by reference to recent papers on the above topics. In this first paper the history of the crop and the current production situation are presented and the nature of glucosinolates and methods for their analysis are reviewed in order to facilitate a better appreciation of the problems referred in later sections.