Variation of glucosinolates in vegetable crops of Brassica oleracea

Glucosinolates were evaluated in 5 groups and 65 accessions of Brassica oleracea (50 broccoli, 4 Brussels sprouts, 6 cabbage, 3 cauliflower, and 2 kale) grown under uniform cultural conditions. Glucosinolates and their concentrations varied among the different groups and within each group. The predominant glucosinolates in broccoli were 4-methylsulfinylbutyl glucosinolate (glucoraphanin), 3-butenyl glucosinolate (gluconapin), and 3-indolylmethyl glucosinoate (glucobrassicin). Glucoraphanin concentration in broccoli ranged from 0.8 micromol g(-1) DW in EV6-1 to 21.7 micromol g(-1) DW in Brigadier. Concentrations of the other glucosinolates in broccoli varied similarly over a wide range. In Brussels sprouts, cabbage, cauliflower, and kale, the predominant glucosinolates were sinigrin (8.9, 7.8, 9.3, and 10.4 micromol g(-1) DW, respectively) and glucobrassicin (3.2, 0.9, 1.3, and 1.2 micromol g(-1) DW, respectively). Brussels sprouts also had significant amounts of gluconapin (6.9 micromol g(-1) DW). Wide variations in glucosinolate content among genotypes suggest differences in their health-promoting properties and the opportunity for enhancement of their levels through genetic manipulation.     

Changes in broccoli (Brassica oleracea L. Var. italica) health-promoting compounds with inflorescence development

Changes in phenolic compounds, total glucosinolates, and vitamin C were monitored during the productive period along five inflorescence development stages of three broccoli commercial cultivars (Marathon, Monterrey, and Vencedor). In an attempt to identify differences due to agronomic factors, broccoli cultivars were grown under different sulfur fertilization with poor (15 kg/ha) and rich (150 kg/ha) rates. Phenolic compounds and vitamin C concentrations showed, in all broccoli cultivars, a rising trend from the first stage until the over-maturity stage, both for rich and poor sulfur fertilization. Significant differences were detected in the first two stages between rich and poor sulfur fertilization in total glucosinolates for all broccoli cultivars, where the highest concentration was always observed in the second development stage (used as minimally processed product) during poor fertilization. With regard to the last three stages, the glucosinolate concentration in the poor sulfur fertilization started to slope down until the over-maturity stage. Where rich sulfur fertilization is concerned, the highest level was reached during the third stage (used as minimally processed product also), and after that, glucosinolate concentration decreased until the fifth stage.     

Thermally induced degradation of sulfur-containing aliphatic glucosinolates in broccoli sprouts (Brassica oleracea var. italica) and model systems

Processing reduces the glucosinolate (GSL) content of plant food, among other aspects due to thermally induced degradation. Since there is little information about the thermal stability of GSL and formation of corresponding breakdown products, the thermally induced degradation of sulfur-containing aliphatic GSL was studied in broccoli sprouts and with isolated GSL in dry medium at different temperatures as well as in aqueous medium at different pH values. Desulfo-GSL have been analyzed with HPLC-DAD, while breakdown products were estimated using GC-FID. Whereas in the broccoli sprouts structural differences of the GSL with regard to thermal stability exist, the various isolated sulfur-containing aliphatic GSL degraded nearly equally and were in general more stable. In broccoli sprouts, methylsulfanylalkyl GSL were more susceptible to degradation at high temperatures, whereas methylsulfinylalkyl GSL were revealed to be more affected in aqueous medium under alkaline conditions. Besides small amounts of isothiocyanates, the main thermally induced breakdown products of sulfur-containing aliphatic GSL were nitriles. Although they were most rapidly formed at comparatively high temperatures under dry heat conditions, their highest concentrations were found after cooking in acidic medium, conditions being typical for domestic processing.     

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.     

Multi-Compartmental Modeling of Nitrogen Translocation in Sorghums Differing in Nitrogen Use Efficiency

Some cultivars of sorghum [Sorghum bicolor (L.) Moench] are more efficient than others in using nitrogen (N) from the soil to produce grain. A study was conducted to test the hypothesis, that the processes involved in the translocation of N differed between two sorghum lines, China 17, a N-efficient genotype, and Tx623, a less efficient genotype, during their ontogenetic development. Both cultivars were grown in the field and periodically sampled to determine the amount of N in above-ground parts of the plants, i.e. stalk, leaves, and grain. Compartmental modeling, which is based on sets of differential equations that describe the flow of material through compartments, was used as the basis for analysis of the rates and rate constants of N which had moved among parts of the plant. Compartmental models are relatively simple, systematic mathematical representations that can be used to aid in understanding how different plant parts influence plant-N dynamics. China 17's rate constants between upper parts of the stalk and between the upper stalk and grain were larger in the earlier part of the season and became smaller toward the end than Tx623 meaning that China 17 was more capable of moving N to the upper parts of the plant earlier in the season than was Tx623. However, no differences in rate constants were detected for stalk to leaves and within leaves rate constants, meaning that the N-movement processes in the leaves were essentially the same between the two genotypes. The model also detected pseudo-compartments associated with the upper leaves in both genotypes which indicated that there are several processes or other rate-controlling factors associated with N flow in the leaves. A multi-compartmental model, based on rather simple assumptions and which only required N for each plant part over time, was used to describe N translocation between plant parts for two different sorghum genotypes. The model was able to detect fundamental differences between the genotypes in terms of N translocation processes, however more work is needed to understand the physiological processes underlying the results.     

Kinetics of the stability of broccoli (Brassica oleracea Cv. Italica) myrosinase and isothiocyanates in broccoli juice during pressure/temperature treatments

The Brassicaceae plant family contains high concentrations of glucosinolates, which can be hydrolyzed by myrosinase yielding products having an anticarcinogenic activity. The pressure and temperature stabilities of endogenous broccoli myrosinase, as well as of the synthetic isothiocyanates sulforaphane and phenylethyl isothiocyanate, were studied in broccoli juice on a kinetic basis. At atmospheric pressure, kinetics of thermal (45-60 degrees C) myrosinase inactivation could be described by a consecutive step model. In contrast, only one phase of myrosinase inactivation was observed at elevated pressure (100-600 MPa) combined with temperatures from 10 up to 60 degrees C, indicating inactivation according to first-order kinetics. An antagonistic effect of pressure (up to 200 MPa) on thermal inactivation (50 degrees C and above) of myrosinase was observed indicating that pressure retarded the thermal inactivation. The kinetic parameters of myrosinase inactivation were described as inactivation rate constants (k values), activation energy (Ea values), and activation volume (Va values). On the basis of the kinetic data, a mathematical model describing the pressure and temperature dependence of myrosinase inactivation rate constants was constructed. The stability of isothiocyanates was studied at atmospheric pressure in the temperature range from 60 to 90 degrees C and at elevated pressures in the combined pressure-temperature range from 600 to 800 MPa and from 30 to 60 degrees C. It was found that isothiocyanates were relatively thermolabile and pressure stable. The kinetics of HP/T isothiocyanate degradation could be adequately described by a first-order kinetic model. The obtained kinetic information can be used for process evaluation and optimization to increase the health effect of Brassicaceae.     

Profiling glucosinolates, flavonoids, alkaloids, and other secondary metabolites in tissues of Azima tetracantha L. (Salvadoraceae)

Azima tetracantha L. (needle bush; bee sting bush; Salvadoraceae) is used as a food and for various herbal medicines in Africa, India, and Madagascar, but there is very little information on the secondary metabolites in this species. High concentrations of N-methoxy-3-indolylmethyl-glucosinolate, a common glucosinolate of Brassica crops such as Brussels sprouts and broccoli, were found in the roots and seeds of A. tetracantha. Lower concentrations were detected in the stems and young leaves. The roots also contained another indole glucosinolate that was provisionally identified, from MS data and comparison with indole glucosinolate standards, as N-hydroxy-3-indolymethyl-glucosinolate. The roots, stems, and leaves contained neoascorbigen (the condensation product of N-methoxy-indole-3-carbinol and ascorbic acid). The seeds of A. tetracantha contained a complex mixture of 26 flavonoids predominantly as glycosides and acyl-glycosides, with traces of aglycones. The core aglycones of these flavonoids were identified as quercetin, isorhamnetin (3'-O-methylquercetin), rhamnetin (7-O-methylquercetin), and rhamnazin (7, 3'-di-O-methylquercetin). No flavonoids or anthocyanins were detected in other tissues, and procyanidins were undetectable. The dimeric piperidine alkaloids azimine, azcarpine, and carpaine were found in all tissues of A. tetracantha.     

Degradation of malathion, in aqueous extracts of asparagus (Asparagus officinalis)

Malathion was incubated in water extracts of vegetables at various temperatures and pH, and the amount of malathion present over time was analyzed by a gas chromatograph with a flame photometric detector. Malathion was degraded to a nondetectable level in a 1% asparagus extract incubated at pH 7.4 and 37 degrees C for 4 h. Carrot extract showed the second highest rate of malathion degradation (76%), followed by kale extract (23.7%), spinach extract (9.7%), and broccoli extract (1.5%) under the same conditions. The highest degradation rates of malathion were observed at 37 degrees C, when three different temperatures were tested (5, 25, and 37 degrees C) at pH 7.4. Rate constants were 0.134 min(-)(1) from a 1% asparagus solution and 0.095 min(-)(1) from a 0.5% asparagus solution. The highest degradation rate of malathion was achieved at pH 9 among the pHs tested (pH 4, 7.4, and 9) in a 0.5% asparagus solution. The 0.5% asparagus solution degraded dicarboxylic acid esters by almost 100% for dimethyl succinate and diethyl adipate, by 64% for diethyl acetyl succinate, and 30% for diethyl benzyl malonate when incubated at pH 9 for 20 min. The results support the hypothesis that the enzyme that degrades malathion in the asparagus solutions is a carboxylesterase.     

Factors affecting the glucosinolate content of kale (Brassica oleracea acephala group)

Kales (Brassica oleracea acephala group) are important vegetable crops in traditional farming systems in the Iberian Peninsula. They are grown throughout the year to harvest their leaves and flower buds. The glucosinolate content of kales is dependent upon the environmental factors, plant part examined, phenological stage of plant growth, and level of insect damage. The objectives of this study were to evaluate the changes in the total and individual glucosinolate concentrations during plant development and to determine if significant variation of glucosinolate levels can be explained by insect pests attack and other environmental factors in four locations in northwestern Spain. The total glucosinolate concentration in leaves of B. oleracea increased with plant age from seedling to early flowering stages. At that stage, the aliphatic glucosinolate content in leaves of B. oleracea declined drastically over time as the content in the flower buds increased. The highest contents of indolyl glucosinolate (glucobrassicin) and of the aromatic glucosinolate occurred in leaves harvested at the optimum consumption stage while flower buds contained the highest concentration of aliphatic glucosinolates, especially sinigrin. Sinigrin is reported to have anticarcinogenic properties. There appears to be a loss of total and individual glucosinolate concentrations related to pest attack. Leaves damaged by lepidopterous pests contained a lower total glucosinolate content (25.8 micromol g-1 dw) than undamaged leaves (41 micromol g-1 dw). The amounts of sinigrin, glucoiberin, and glucobrassicin were also lowest in insect-damaged leaves. Environmental factors such as soil properties and temperature appear to influence the glucosinolate content in leaves although more research on this subject is needed.     

Epithiospecifier protein from broccoli (Brassica oleracea L. ssp. italica) inhibits formation of the anticancer agent sulforaphane

In some cruciferous plants, epithiospecifier protein (ESP) directs myrosinase (EC 3.2.3.1)-catalyzed hydrolysis of alkenyl glucosinolates toward epithionitrile formation. Here, for the first time, we show that ESP activity is negatively correlated with the extent of formation of the health-promoting phytochemical sulforaphane in broccoli (Brassica oleracea L. ssp. italica). A 43 kDa protein with ESP activity and sequence homology to the ESP of Arabidopsis thaliana was cloned from the broccoli cv. Packman and expressed in Escherichia coli. In a model system, the recombinant protein not only directed myrosinase-dependent metabolism of the alkenyl glucosinolate epi-progoitrin [(2S)-2-hydroxy-3-butenyl glucosinolate] toward formation of an epithionitrile but also directed myrosinase-dependent hydrolysis of the glucosinolate glucoraphanin [4-(methylsulfinyl)butyl glucosinolate] to form sulforaphane nitrile, in place of the isothiocyanate sulforaphane. The importance of this finding is that, whereas sulforaphane has been shown to have anticarcinogenic properties, sulforaphane nitrile has not. Genetic manipulation designed to attenuate or eliminate expression of ESP in broccoli could increase the fractional conversion of glucoraphanin to sulforaphane, enhancing potential health benefits.     

氮素水平对芥蓝生长及芥子油苷含量的影响

采用溶液培养方法,研究了不同供氮水平对芥蓝生物量及抗癌次生代谢物芥子油苷含量的影响。结果表明,氮素水平从N100 mg/L到常规营养液的 N 200 mg/L范围内,芥蓝地上部、根部及菜苔鲜重均随供N水平的提高而显著增加,但菜苔总芥子油苷含量却随供N水平提高而显著降低;当N素水平提高到N 300~400 mg/L时,芥蓝生物量不再显著增加;而菜苔总芥子油苷含量相对于N 150和200 mg/L处理却显著增加。由于脂肪族和吲哚族芥子油苷分别来源于不同的氨基酸,两者的含量随供N水平的变化趋势不同。脂肪族芥子油苷含量以N 100 mg/L处理最高,是常规供N (200 mg/L)处理的1.2倍,吲哚族芥子油苷以400 mg/L处理最高,是常规供N处理的1.5倍。显然,在常规营养液的供N水平下,可以获得理想的芥蓝生物产量;但适当提高供N水平,在保证高产的同时可显著提高芥蓝菜苔的芥子油苷含量,有利于提高其抗癌品质。     

Comparison of isothiocyanate metabolite levels and histone deacetylase activity in human subjects consuming broccoli sprouts or broccoli supplement

Increased consumption of cruciferous vegetables such as broccoli may reduce the risk of various cancers. Myrosinase is required to convert dietary glucosinolates from broccoli into bioactive isothiocyanates. We evaluated isothiocyanate excretion profiles in healthy subjects who consumed broccoli sprouts or broccoli supplement (no myrosinase) with equivalent glucosinolate content. Urinary metabolites of two major isothiocyanates, sulforaphane and erucin, were measured by liquid chromatography coupled with tandem mass spectrometry. Peak excretion of sulforaphane and erucin was higher and occurred sooner in subjects who consumed broccoli sprouts as compared to subjects who consumed the supplement. A subject-dependent shift in the ratio of urinary sulforaphane to erucin metabolites was observed in both groups, indicating conversion of sulforaphane to erucin. Lower histone deacetylase activity was observed in the peripheral blood mononuclear cells only in subjects consuming sprouts. Fresh broccoli sprouts differ from broccoli supplements in regards to excretion of isothiocyanates and bioactivity in human subjects.     

Influence of temperature and ontogeny on the levels of glucosinolates in broccoli (Brassica oleracea Var. italica) sprouts and their effect on the induction of mammalian phase 2 enzymes

Broccoli inflorescences have been recognized as components of healthy diets on the basis of their high content of fiber, vitamin C, carotenoids, and glucosinolates/isothiocyanates. Broccoli sprouts have been recently shown to have high levels of glucoraphanin (4-methylsulfinylbutyl glucosinolate), the precursor of the chemoprotective isothiocyanate, sulforaphane. This study evaluated the effects of temperature and developmental stage on the glucosinolate content of broccoli sprouts. Seedlings cultivated using a 30/15 degrees C (day/night) temperature regime had significantly higher glucosinolate levels (measured at six consecutive days postemergence) than did sprouts cultivated at lower temperatures (22/15 and 18/12 degrees C; p < 0.001). Both higher (33.1 degrees C) and lower (11.3 degrees C) constant temperatures induced higher glucosinolate levels in sprouts grown to a uniform size. Glucosinolate levels were highest in cotyledons and lowest in roots of sprouts dissected both early and late in the 11 day developmental span investigated. Nongerminated seeds have the highest glucosinolate levels and concordantly greater induction of mammalian phase 2 detoxication enzymes. Levels decline as sprouts germinate and develop, with consistently higher glucosinolate content in younger developmental stages, independent of the temperature regime. Temperature stress or its associated developmental anomalies induce higher glucosinolate levels, specific elevations in glucoraphanin content, and parallel induction of phase 2 chemoprotective enzymes.     

Portuguese perennial kale: a relic leafy vegetable crop

Portuguese perennial kale is a rare leafy vegetable and forage crop in Portugal. It may be a relic of a primitive kale form which could have been grown on a large scale in Portugal and in West Europe. This kale has strong branching habit with rosettes of leaves in the stems. It shows a strongly reduced flowering ability and for this reason is vegetatively propagated. In the past, perennial kale has probably been widely distributed in West Europe, but the crop has gradually declined in occurrence in this area. At present it is an almost extinct vegetable crop and by this reason deserves to be preserved.     

The effect of post-harvest and packaging treatments on glucoraphanin concentration in broccoli (Brassica oleracea var. italica)

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.     

注意力与多尺度特征融合的水培芥蓝花蕾检测

准确辨识水培芥蓝花蕾特征是区分其成熟度,实现及时采收的关键。该研究针对自然环境下不同品种与成熟度的水培芥蓝花蕾外形与尺度差异大、花蕾颜色与茎叶相近等问题,提出一种注意力与多尺度特征融合的Faster R-CNN水培芥蓝花蕾分类检测模型。采用InceptionV3的前37层作为基础特征提取网络,在其ReductionA、InceptionA和InceptionB模块后分别嵌入SENet模块,将基础特征提取网络的第2组至第4组卷积特征图通过FPN特征金字塔网络层分别进行叠加后作为特征图输出,依据花蕾目标框尺寸统计结果在各FPN特征图上设计不同锚点尺寸。对绿宝芥蓝、香港白花芥蓝及两个品种的混合数据集测试的平均精度均值mAP最高为96.5%,最低为95.9%,表明模型能实现不同品种水培芥蓝高准确率检测。消融试验结果表明,基础特征提取网络引入SENet或FPN模块对不同成熟度花蕾的检测准确率均有提升作用,同时融合SENet模块和FPN模块对未成熟花蕾检测的平均准确率AP为92.3%,对成熟花蕾检测的AP为98.2%,对过成熟花蕾检测的AP为97.9%,不同成熟度花蕾检测的mAP为96.1%,表明模型设计合理,能充分发挥各模块的优势。相比VGG16、ResNet50、ResNet101和InceptionV3网络,模型对不同成熟度花蕾检测的mAP分别提高了10.8%、8.3%、 6.9%和12.7%,检测性能具有较大提升。在召回率为80%时,模型对不同成熟度水培芥蓝花蕾检测的准确率均能保持在90%以上,具有较高的鲁棒性。该研究结果可为确定水培芥蓝采收期提供依据。     

Effect of differential N and S competition in inter- and sole cropping of Brassica species and lettuce on glucosinolate concentration

Field and greenhouse pot experiments were conducted to evaluate the potential to use intercropping as an alternative method to increase glucosinolates in Brassicas by manipulating nitrogen (N) and sulfur (S) balance by intercropping with lettuce (Lactuca sativa L. var. capitata). In both experiments, four combinations of N and S fertilization were used. In the field experiment no effect of intercropping on the total glucosinolate concentration was found as the growing lettuce was strongly inhibited by the presence of broccoli (Brassica oleracea L. var. italic). In contrast to this, in the pot experiment both total and individual glucosinolate concentrations in red leaf mustard (Brassica juncea L.) increased by intercropping. Fertilization treatments influenced glucosinolate concentrations in both experiments, and an interaction between N and S fertilization was noticed.     

Carotene, tocopherol, and ascorbate contents in subspecies of Brassica oleracea

Cruciferous vegetables contain high levels of vitamins that can act as antioxidants, compounds that may protect against several degenerative diseases. The edible portions of 50 broccoli and 13 cabbage, kale, cauliflower, and Brussels sprouts accessions were assayed to determine variation in alpha-carotene, beta-carotene, alpha-tocopherol, gamma-tocopherol, and ascorbate contents within and between subspecies of Brassica oleracea. Ascorbate content was estimated in fresh samples using HPLC. Tissues for carotene and tocopherol analysis were lyophilized prior to extraction. Carotene and tocopherol concentrations were simultaneously measured using a reverse phase HPLC system. Results indicate that there is substantial variation both within and between subspecies. Kale had the highest levels of vitamins, followed by broccoli and Brussels sprouts with intermediate levels and then by cabbage and cauliflower, with comparatively low concentrations. Variability in vitamin content among the broccoli accessions suggests that potential health benefits that accrue with consumption are genotype dependent.     

Kinetics of chlorophyll degradation and color loss in heated broccoli juice

Degradation of chlorophyll in broccoli juice occurred at temperatures exceeding 60 degrees C. Chemical analysis revealed that degradation of chlorophyll a and b to pheophytin a and b, respectively, followed first-order kinetics and that chlorophyll a was more heat sensitive than chlorophyll b. Temperature dependencies of chlorophyll a and b degradation rate constants could be described by Arrhenius equations with activation energies (E(a)) of 71.04 +/- 4.89 and 67.11 +/- 6.82 kJ/mol, respectively. Objective greenness measurements, using the -a value as the physical property, together with a fractional conversion kinetic analysis, indicated that green color degradation followed a two-step process. Kinetic parameters for the first degradation step were in accordance with the kinetic parameters for pheophytinization of the total chlorophyll content, as determined by chemical analysis (E(a) approximately 69 kJ/mol). The second degradation step, that is, the subsequent decomposition of pheophytins, was characterized by an activation energy of 105.49 +/- 4.74 kJ/mol.