DNA-based identification of Brassica vegetable species for the juice industry

Since kale (Brassica oleracea var. acephala), a cruciferous vegetable with a high level of vitamins and functional compounds beneficial to health and wellness, has become widely used in the juice industry, a precise method for quality control of vegetable species is necessary. We describe here a DNA-based identification method to distinguish kale from cabbage (Brassica oleracea var. capitata), a closely related species, which can be inadvertently mixed with kale during the manufacturing process. Using genomic DNA from these vegetables and combinatory sets of nucleotide primers, we screened for random amplified polymorphic DNA (RAPD) fragments and found three cabbage-specific fragments. These RAPD fragments, with lengths of 1.4, 0.5, and 1.5 kb, were purified, subcloned, and sequenced. Based on sequence-tagged sites (STS), we designed sets of primers to detect cabbage-specific identification (CAI) DNA markers. Utilizing the CAI markers, we successfully distinguished more than 10 different local cabbage accessions from 20 kale accessions, and identified kale juices experimentally spiked with different amounts of cabbage.     

Comparative mineral composition among canola cultivars and other cruciferous leafy greens

The potential of canola (Brassica napus L.) leafy greens as a food source for human consumption is being considered to increase the variety of nutritious vegetables available to consumers. Scientific evidence supports that the consumption of cruciferous vegetables may reduce individual risk factors for some diseases. Five canola cultivars were grown at Alabama A & M University, Winfred Thomas Agricultural Research Station, in Hazel Green, AL, USA, and were analyzed to determine mineral composition of raw canola leafy greens for comparison to those of collard greens (Brassica oleraceae var. viridis), kale (Brassica oleraceae L. acephala) and cabbage (Brassica oleraceae L. var. capitata). Results showed that collard greens were significantly higher in potassium (K) than the other crops tested; however, canola was significantly higher in K than cabbage and kale. The essential micronutrient, iron (Fe), (24.77 mg/100 g dry weight), was significantly higher in canola and lowest in cabbage (7.65 mg/100 g dry weight). Zinc (Zn) and manganese (Mn) contents of canola (3.00 and 16.40 g/100 g dry weight, respectively) were greater than cabbage and collard. Among the three canola harvest stages (rosette, budding and blooming), K content increased with growth, while Fe and aluminum (Al) decreased; sodium (Na) was lowest at the budding stage compared to the other two stages. The results of this research indicate that canola greens can be an acceptable substitute for traditional leafy green vegetables.     

Customized cooking method improves total antioxidant activity in selected vegetables

The present study compares water-soluble phenolic content (WPC) and antioxidant activities in Chinese long bean (Vigna unguiculata), bitter gourd (Momordica charantia), water convolvulus (Ipomoea aquatica) and broccoli (Brassica olearacea) prior to and after subjecting to boiling, microwaving and pressure cooking. The total antioxidant activity was increased in cooked water convolvulus, broccoli and bitter gourd, estimated based on the ferric reducing antioxidant power, the Trolox equivalent antioxidant capacity and 2,2-diphenyl-1-picryl-hydrazyl radical scavenging activity. Pressure cooking did not cause any significant decline in the antioxidant property. Boiling generally improved the overall antioxidant activity in all the vegetables. Correlation analysis suggests that WPC contributed to significant antioxidant activities in these vegetables. Thus, prudence in selecting an appropriate cooking method for different vegetables may improve or preserve their nutritional value.     

Customized cooking method improves total antioxidant activity in selected vegetables

The present study compares water-soluble phenolic content (WPC) and antioxidant activities in Chinese long bean (Vigna unguiculata), bitter gourd (Momordica charantia), water convolvulus (Ipomoea aquatica) and broccoli (Brassica olearacea) prior to and after subjecting to boiling, microwaving and pressure cooking. The total antioxidant activity was increased in cooked water convolvulus, broccoli and bitter gourd, estimated based on the ferric reducing antioxidant power, the Trolox equivalent antioxidant capacity and 2,2-diphenyl-1-picryl-hydrazyl radical scavenging activity. Pressure cooking did not cause any significant decline in the antioxidant property. Boiling generally improved the overall antioxidant activity in all the vegetables. Correlation analysis suggests that WPC contributed to significant antioxidant activities in these vegetables. Thus, prudence in selecting an appropriate cooking method for different vegetables may improve or preserve their nutritional value.     

Change in the ascorbic acid, total phenol and antioxidant activity of sun-dried commonly consumed green leafy vegetables in Nigeria

Sun-drying of green leafy vegetables is popularly practised in many homes in Nigeria, as a way of preserving green leafy vegetables for future use. This project sought to investigate the effect of this method of preservation of vegetables on the antioxidant phytoconstituent (Vitamin C and Total phenol) and activity (reducing property and free radical scavenging ability) of some commonly consumed green leafy vegetables in Nigeria namely Structium sparejanophora (Ewuro-odo), Amarantus cruentus (Atetedaye), Telfairia occidentalis (Ugu), Baselia allia (Amunu tutu), Solanum macrocarpon (Igbagba), Corchorus olitorius (Ewedu), Vernonia anygdalina (Ewuro) and Occimum graticimum (Efinrin). The edible portions of the green leafy vegetables were sun-dried for seven days before determining the Vitamin C and total phenol content, as well as the reducing property and free radical scavenging ability. The result of the study revealed that sun-drying of green leafy vegetables cause a significant (P < 0.05) decrease in the Vitamin C content (16.67-64.68% loss). Conversely it leads to a significant increase in the total phenol content (6.45-223.08% gain), reducing property (16.00-362.50% gain) and free radical scavenging ability (126.00-5757.00% gain) of the green leafy vegetables. It could therefore be concluded that a significant decrease (P < 0.05) in Vitamin C content caused by sun- drying will not reduce the antioxidant activity of the green leafy vegetable, moreover, the phenol constituent of the green leafy vegetables contributes more to the antioxidant properties of vegetables than ascorbic acid, as its increase on sun-drying cause a significant (P < 0.05) increases in the antioxidant properties of the green leafy vegetables, irrespective of the decrease in the ascorbic acid content.     

In Vitro Evidence on Bioaccessibility of Flavonols and Cinnamoyl Derivatives of Cruciferous Sprouts

Cruciferous sprouts are rising in popularity as a hallmark of healthy diets, partially because of their phytochemical composition, characterized by the presence of flavonols and cinnamates. However, to shed light on their biological activity, the ability to assimilate (poly)phenols from sprouts (bioaccessible fraction) during gastrointestinal digestion needs to be studied. In this frame, the present work studies the effect of the physicochemical and enzymatic characteristics of gastrointestinal digestion on flavonols and cinnamoyl derivatives, by a simulated static in vitro model, on different cruciferous (red radish, red cabbage, broccoli, and white mustard) sprouts. The results indicate that, although the initial concentrations of phenolic acids in red radish (64.25 mg/g fresh weight (fw)) are lower than in the other sprouts studied, their bioaccessibility after digestion is higher (90.40 mg/g fw), followed by red cabbage (72.52 mg/g fw), white mustard (58.72 mg/g fw), and broccoli (35.59 mg/g fw). These results indicate that the bioaccessibility of (poly)phenols is not exclusively associated with the initial concentration in the raw material, but that the physico-chemical properties of the food matrix, the presence of other additional molecules, and the specific characteristics of digestion are relevant factors in their assimilation.     

Determination of Vitamin C, b-carotene and Riboflavin Contents in Five Green Vegetables Organically and Conventionally Grown

As consumer interest in organically grown vegetables is increasing in Malaysia, there is a need to answer whether the vegetables are more nutritious than those conventionally grown. This study investigates commercially available vegetables grown organically and conventionally, purchased from retailers to analyse β-carotene, vitamin C and riboflavin contents. Five types of green vegetables were selected, namely Chinese mustard (sawi) (Brassica juncea), Chinese kale (kai-lan) (Brassica alboglabra), lettuce (daun salad) (Lactuca sativa), spinach (bayam putih) (Amaranthus viridis) and swamp cabbage (kangkung) (Ipomoea aquatica). For vitamin analysis, a reverse-phase high performance liquid chromatography was used to identify and quantify β -carotene, vitamin C and riboflavin. The findings showed that not all of the organically grown vegetables were higher in vitamins than that conventionally grown. This study found that only swamp cabbage grown organically was highest in β -carotene, vitamin C and riboflavin contents among the entire samples studied. The various nutrients in organically grown vegetables need to be analysed for the generation of a database on nutritional value which is important for future research.     

Antioxidant activity of commonly consumed vegetables in yemen

Of late, more attention has been paid to the role of natural antioxidants, especially phenolic compounds, which may act both by reducing the content of toxic compounds in foods and by supplying the human body with exogenous antioxidants. The total phenolic contents and the total antioxidant activities (% AA) of 17 commonly consumed vegetables in Yemen were determined. Total phenolics was measured colorimetrically using the Folin-Ciocalteu reagent with D-catechin as the standard. The antioxidant activity (%AA) of vegetables using their juices at different levels (50μl, 100μl, 200μl) was assayed in vitro by the inhibition of liver homogenate oxidation mediated by FeSO4 / ascorbate system. The % AA was measured by the TBAR method. The results showed that for all vegetable juices, increased antioxidant activity or decreased prooxidant activity increased with volume of juice. With the addition of 50μl from each sample, most vegetable juices showed antioxidant activity and it appears that coriander had exceptionally high antioxidant activity (60%). However, garlic, yellow onion, parsley, red onion and Cissus rotundifolia showed considerably high antioxidant activities (54-41 %). Other vegetables with low antioxidant activities (27 to 3 %) showed an order of increase in %AA as follows: tomato > spinach > horseradish-leaves > carrot > cabbage > chilli > leek > horseradish-roots. At the same, time some vegetable juices such as that of green pepper, cucumber and lettuce showed initial prooxidant activities (-11 to -40 %). The complete inhibition of oxidation was noticed when the highest level of juices (200μl) was used in the cases of coriander, onions, garlic and parsley. The correlation between total phenolics and the antioxidant activities of vegetables with different levels of juices (50μl, 100μl and 200μl) showed positive but not significant correlations (R = 0.41 - 0.55). Some vegetables such as carrots and tomatoes show the highest relative antioxidant efficiencies despite the small content of total phenolics compared to other vegetables tested in this study.     

Mineral content of traditional leafy vegetables from western Kenya

Socio-economic changes that have taken place in Africa have influenced people's eating habits in both rural and urban set-ups. Most people prefer introduced foods to traditional foods, including plant foods whose consumption is widely regarded as a primitive culture manifesting poor lifestyles. However, recent studies on traditional plant foods have shown that some are highly nutritious; containing high levels of both vitamins and minerals. They also have potential as a remedy to counter food insecurity since most are well adapted to the local environment, enabling them to resist pests, drought and diseases. This paper describes the mineral (calcium, iron and zinc) contents in some 54 traditional vegetable species collected from Nyang'oma area of Bondo district, western Kenya. Atomic absorption spectroscopy was used to determine the mineral content. We found that most traditional leafy vegetables, domesticated and wild, generally contain higher levels of calcium, iron and zinc compared with the introduced varieties such as spinach (Spanacia oleracea), kale (Brassica oleracea var. acephala) and cabbage (Brassica oleracea var. capitata). The results of this study could contribute towards identification, propagation and subsequent domestication and cultivation promotion of nutrient-rich and safe species within the farming systems of the local communities in Kenya, sub-Saharan Africa or elsewhere.     

Total phenolics and antioxidant capacity of indigenous vegetables in the southeast United States: Alabama Collaboration for Cardiovascular Equality Project

Collard greens, mustard greens, kale, okra, green onion, butter beans, butter peas, purple hull peas, rutabagas, and eggplant are frequently consumed by African Americans in the southeast United States. Sweet potato greens and purslane are two novel vegetables in this region. The objective of this study was to analyze total phenolics and antioxidant capacity in these indigenous vegetables. The total phenolic content was analyzed using the Folin–Ciocalteu method and ranged from 7.4 to 53.5 mg gallic acid equivalents per gram of dried sample. The antioxidant capacity was analyzed using the radical DPPH^? scavenging capacity assay and oxygen radical absorbance capacity assay (ORAC). At a concentration of 10.0 mg dried vegetable equivalent/ml, the extract of these vegetables was able to quench 13.2–88.5% DPPH^? radical in 30 min. The ORAC value ranged from 2.5 to 100.7 µmoles of trolox equivalents per gram of dried sample. The antioxidant capacity of the vegetable samples was highly related to their total phenolic content. The results suggest that these indigenous vegetables consumed by African Americans in the southeastern United States are good sources of the phenolic compounds, which might provide anti-oxidative protection against free radicals in the human body. Consumption of these vegetables might reduce the risk of chronic diseases.     

Total phenolics and antioxidant capacity of indigenous vegetables in the southeast United States: Alabama Collaboration for Cardiovascular Equality Project

Collard greens, mustard greens, kale, okra, green onion, butter beans, butter peas, purple hull peas, rutabagas, and eggplant are frequently consumed by African Americans in the southeast United States. Sweet potato greens and purslane are two novel vegetables in this region. The objective of this study was to analyze total phenolics and antioxidant capacity in these indigenous vegetables. The total phenolic content was analyzed using the Folin-Ciocalteu method and ranged from 7.4 to 53.5 mg gallic acid equivalents per gram of dried sample. The antioxidant capacity was analyzed using the radical DPPH(?) scavenging capacity assay and oxygen radical absorbance capacity assay (ORAC). At a concentration of 10.0 mg dried vegetable equivalent/ml, the extract of these vegetables was able to quench 13.2-88.5% DPPH(?) radical in 30 min. The ORAC value ranged from 2.5 to 100.7 μmoles of trolox equivalents per gram of dried sample. The antioxidant capacity of the vegetable samples was highly related to their total phenolic content. The results suggest that these indigenous vegetables consumed by African Americans in the southeastern United States are good sources of the phenolic compounds, which might provide anti-oxidative protection against free radicals in the human body. Consumption of these vegetables might reduce the risk of chronic diseases.     

Brassica vegetables and prostate cancer risk: a review of the epidemiological evidence

Epidemiological studies have yielded conflicting results on the associations of diet with prostate cancer. We review evidence that Brassica vegetables are associated with reduced prostate cancer risk. Brassica vegetables, which include broccoli, cabbage, mustard and collard greens, and bok choy, contain glucosinolates, the metabolic breakdown products of which are potent modulators of xenobiotic-metabolizing enzymes that protect DNA from damage. Twelve published studies give some information about Brassica vegetables and prostate cancer risk; six of these studies can be clearly interpreted. Of these, three reported statistically significant reduced risks (P < 0.05) and one reported a borderline significant reduced risk (P = 0.06) with high Brassica vegetable consumption. The epidemiological literature provides modest support for the hypothesis that high intakes of Brassica vegetables reduce prostate cancer risk.     

Comparison of the antioxidant activity of roasted tea with green, oolong, and black teas

Although the antioxidant properties of green, oolong, and black teas have been well studied, antioxidant activity has not been examined in roasted tea. Therefore, in the current studies, we investigated the antioxidant activity of roasted tea in comparison with those of green, oolong, and black teas. Using water extracts of the various teas, we examined the total phenolic content as well as the antioxidant activities, including the reducing power, the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, and the inhibition of hemolysis caused by 2,2'-azo-bis(2-amidinopropane) dihydrochloride (AAPH)-induced lipid oxidation in erythrocyte membranes. The roasted tea contained lower levels of total phenolics than green, oolong, or black tea (green tea > oolong tea > black tea > roasted tea). The relative reducing power and DPPH scavenging activity decreased in the following order: green tea > roasted tea > oolong tea > black tea. Also, green tea was more effective against AAPH-induced erythrocyte hemolysis than other teas (green tea>roasted tea = oolong tea = black tea). These results suggest that roasted tea is beneficial to health, in humans, because of its high antioxidant activity.     

Radical scavenging-linked antioxidant activities of commonly used herbs and spices in Korea

Herbs and spices not only variety and racy flavour to Korean foods, they also are the richest source for antioxidant power. The present study evaluates the radical scavenging-linked antioxidant activities of hot water extracts from commonly used herbs and spices in Korea. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical and superoxide anion scavenging activities of bay extract were 39.5% and 22.1%, respectively. The hydroxyl radical scavenging activity was in order of dill (50.0%) > bay (31.3%) > garlic (27.9%) > white pepper and black pepper (15.1-15.3%) > onion (10.1%) extracts. Bay extract had the highest total phenolic content (17.86?μg CE/g). High correlation coefficients were found between the total phenol content and DPPH radical scavenging activity (R?=?0.9162). These results indicate that herbs and spices had high antioxidant activity that is partly due to the phenolic compounds and provide basic data for further development of processed food products.     

Antioxidant and free radical scavenging activities of some leafy vegetables

Some leafy vegetables were studied for their nutritional composition, antioxidant and free radical scavenging activities. The aerial parts of Coriandrum sativum, Spinacia oleracea, Trigonella corniculata and Trigonella foenum-graecum showed lower inhibitory concentration values (4.1-7.9 mg/ml), efficiency concentration values (178-321 mg/mg DPPH) and higher values of anti-radical power (0.31-0.51) as compared with their seeds. Thermal treatment reduced the total phenolic contents, antioxidant and free radical scavenging activities. The leaves of C. sativum were found with good amounts of caffeic acid, ferulic acid, gallic acid and chlorogenic acid.     

苦瓜等91种食用植物抗促癌作用的研究

方法：采用ＥＢ病毒早期抗原（ＥＢＶ－ＥＡ）诱导抑制实验的方法，对包括１６个科‘、９１种食用植物（其中大部分为中国常用蔬菜），共计３０２个样品的防癌抗促癌活性进行了检测。结果：７４个样品（占总数的２４．５％）显示出强抑制活性，１３５个样品（占总数的４４．４％）显示出中等抑制活性，其中唇形花科（Ｌａｂｉａｔａｅ）的蔬菜样品８７．５％显示了强抑制活性。紫苏、羽衣甘兰、苦瓜种子、苋菜及山药等，即使在低浓度下也表现出较强的抑制活性；一些中国原产的十字花科蔬菜，如：芥菜、红菜苔、独行菜等，也表现了很高的抑制率。结论：抗促癌物质广泛存在于中国蔬菜之中，抗促癌活性因蔬菜的种类、品种、植物部位、提取溶剂及成熟程度而异，且与栽培的环境条件有关。     

Mechanisms of action and antiproliferative properties of Brassica oleracea juice in human breast cancer cell lines

Cruciferous vegetables are an important source of compounds that may be useful for chemoprevention. In this study, we evaluated the antiproliferative activity of juice obtained from leaves of several varieties of Brassica oleracea on both estrogen receptor (ER)-positive (ER+; MCF-7 and BT474) and ER-negative (ER-; MDA-MB-231 and BT20) human breast cancer cell lines. The effect of juice on cell proliferation was evaluated on DNA synthesis and on cell cycle-related proteins. Juice markedly reduced DNA synthesis, evaluated by [3H]thymidine incorporation, starting from low concentrations (final concentration 5-15 mL/L), and this activity was independent of ER. All cauliflower varieties tested suppressed cell proliferation in a dose-dependent manner. Cell growth inhibition was accompanied by significant cell death at the higher juice concentrations, although no evidence of apoptosis was found. Interestingly, the juice displayed a preferential activity against breast cancer cells compared with other mammalian cell lines investigated (ECV304, VERO, Hep2, 3T3, and MCF-10A) (P < 0.01). At the molecular level, the inhibition of proliferation was associated with significantly reduced CDK6 expression and an increased level of p27 in ER+ cells but not in ER- cells, whereas a common feature in all cell lines was significantly decreased retinoblastoma protein phosphorylation. These results suggest that the edible part of Brassica oleracea contains substances that can markedly inhibit the growth of both ER+ and ER- human breast cancer cells, although through different mechanisms. These results suggest that the widely available cruciferous vegetables are potential chemopreventive agents.     

Effects of cooking on in vitro sinigrin bioaccessibility,total phenols,antioxidant and antimutagenic activity of cauliflower (Brassica oleraceae L. var. Botrytis)

Cauliflower (Brassica oleraceae L. var. Botrytis) is a good source of bioactive compounds, such as glucosinolates, phenolic compounds and vitamins. In this study, the effects of some processes (i.e. boiling, steaming) on the sinigrin bioaccessibility as a major glucosinolate found in cruciferous vegetables after in vitro digestion, also in vitro antimutagenic activities, total phenols and total antioxidant capacities of cauliflower were determined. The sinigrin content was reduced by approximately 9.6% and 29.1% in steamed and boiled cauliflower (p > 0.05), respectively. After in vitro simulated digestion, sinigrin content was decreased by 26.4% in raw samples, increased by 29.5% and 114.7% in steamed and boiled samples, respectively. In all samples, mutagenic effect to Salmonella typhimurium TA 100 was not seen. When samples were steamed, phenol content was increased by 14.83%. After boiling total phenol content of cauliflower was decreased by 1.8%. Total antioxidant capacities (TAC) measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3 ethylbenzothiazoline-6-sulfonic acid) (ABTS) methods were increased by 47% and 39%, respectively (p < 0.05) in steamed samples and decreased by 8% and 7% with boiling, respectively (p > 0.05). TAC in raw sample of cauliflower, which was investigated in phosphomolybdenum assays, was determined as 18.7 mg ascorbic acid equivalents (AAE)/100 g. In all cases, the highest antioxidant activity was determined in the steamed samples, while the lowest antioxidant activity was in boiled samples.     

Antioxidant enzymes activity and phenolic compounds content in red cabbage seedlings exposed to copper stress

The phenolics: anthocyanin (ATH), sinapoyl esters and activity of antioxidant enzymes: superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (POX), ascorbate peroxidase (APX), glutathione peroxidase (GPX) and glutathione reductase (GR), in red cabbage seedlings subjected to Cu2+ stress were investigated. Cu2+ at low doses (0.5 mM), increased the levels of ATH and sinapoyl derivatives in red cabbage. High Cu2+ concentration (2.5 mM) provoked oxidative stress and enhanced thiobarbituric acid reactive substances (TBARS) content in tissues. A lower level of TBARS was correlated with high ATH content. It seems that synthesis of these isoflavonoids is an effective strategy against reactive oxygen species (ROS). The analysis of the antioxidant enzymes activity suggested that peroxidases were the most active enzymes in red cabbage seedlings exposed to Cu2+ stress. It could results from the fact that phenolic compounds (PhC), which could be also substrates for different peroxidases, were the first line of defence against metal stress.     

高效液相色谱法检测几种蔬菜中啶虫脒农药残留

[目的]建立高效液相色谱法测定西红柿、结球甘蓝、菜豆等蔬菜样品啶虫脒农药残留的检测方法。[方法]样品经乙腈提取、盐析、LC-NH2小柱净化,采用高效液相色谱仪进行测定。[结果]啶虫脒在2～5.0μg/ml的添加范围内线性良好,线性关系系数r为0.9978,添加水平为0.10～1.00mg/kg,西红柿样品的平均回收率为102.7%～111.2%,相对标准偏差为0.29%～1.60%。[结论]该方法具有快速、灵敏、准确等优点,适合蔬菜中啶虫脒农药残留的测定。