Characterization, quantification, and yearly variation of the naturally occurring polyphenols in a common red variety of curly kale ( Brassica oleracea L. convar. acephala var. sabellica cv. 'Redbor')

Polyphenols in edible plant leaves: an overview of their occurrence and health properties

Edible plant leaves (EPLs) constitute a major renewable functional plant biomass available all year round, providing an essential source of polyphenols in the global diet. Polyphenols form a large family of antioxidant molecules. They protect against the harmful effects of free radicals, strengthen immunity and stimulate the body's natural defenses thanks to their antibacterial and antiviral functions. This study refers to phenolic compounds from 50 edible plant leaves divided into four categories: green leafy vegetables, underutilized leafy vegetables, leafy spices and leafy drinks. It provides data on the identification, occurrence and pharmacological functions of polyphenols contained in EPLs, and provides a better understanding of trends and gaps in their consumption and study. Certain EPLs, such as moringa (Moringa oleifera Lam.), tea (Camellia sinensis L.) and several leafy spices of the Lamiaceae family, reveal important characteristics and therapeutic potential. The polyphenol composition of EPLs makes them functional plants that offer relevant solutions in the fight against obesity, the management of food insecurity and the prevention of chronic diseases.

Investigation of the Key Genes Associated with Anthocyanin Accumulation during Inner Leaf Reddening in Ornamental Kale (Brassica oleracea L. var. acephala)

Ornamental kale (Brassica oleracea L. var. acephala) is a popular decorative plant in late autumn and winter. However, only during low-temperature color-changed periods below rough 15 °C can the plant accumulate anthocyanins and exhibit a diverse array of foliar color patterns. In this study, we probed into the potential mechanism of inner leaf reddening in a red-leaf pure line of ornamental kale by physiological, metabolic, and transcriptomic analyses. Determination of anthocyanin contents in the uncolored new white leaves (S0), the light red leaves (S1) in the reddening period and the red leaves (S2) completing color change, and analysis of anthocyanin metabolites at stage S2, revealed that the coloring of red leaves was mainly attributed to the accumulation of cyanidins. We further used transcriptomic sequencing between the pairwise S0, S1, and S2 stages to identify 21 differentially expressed genes (DEGs) involved in anthocyanin biosynthesis, among which the expression level of 14 DEGs was positively correlated with anthocyanin accumulation, and 6 DEGs were negatively correlated with anthocyanin accumulation. A total of 89 co-expressed genes were screened out, from which three DEGs (BoCHI, Bo4CL3, and BoF3H) were identified as hub genes in co-expression DEGs network. BoDFR and BoCHI were the DEGs with the highest expressions at S2. Moreover, two co-expressed DEGs related to stress response (BoBBX17 and BoCOR47) also exhibited upregulated expressions and positive correlations with anthocyanin accumulation. A deep dive into the underlying regulatory network of anthocyanin accumulation comprising these six upregulated DEGs from S0 to S2 was performed via trend, correlation, and differentially co-expression analysis. This study uncovered the DEGs expression profiles associated with anthocyanin accumulation during ornamental kale inner leaf reddening, which provided a basis for further dissecting the molecular mechanisms of leaf color characteristic change in ornamental kale at low temperatures.

Evaluation Study on Extraction of Anthocyanins from Red Cabbage Using High Pressure CO2 + H2O: A Fuzzy Logic Model and Metabolomic Analysis

In this work, a fuzzy logic model was developed to elucidate the extraction performance of high-pressure CO2 + H2O compared with traditional H2O extraction and aqueous ethanol extraction. The high-pressure CO2 + H2O group acquired the highest comprehensive score considering yield, quality and stability. Both targeted and untargeted metabolomics results proved that the polarity of water was slightly modified; in particular, with the evidence from the untargeted metabolomics data, a higher proportion of water-insoluble compounds (2-methylindole, 3-formylindole, guanine, tyrosine and tryptophan) obtained by high-pressure CO2 + H2O extraction compared with traditional H2O extraction has been reported for the first time. Finally, the “3I” extraction mechanism of high-pressure CO2 + H2O is proposed, which offers an improvement in the solid–liquid mass transfer efficiency of phytochemicals, improving the polarity of solution and the isolation of O2.

Acylated anthocyanins: A review on their bioavailability and effects on postprandial carbohydrate metabolism and inflammation

Anthocyanins, the natural red and purple colorants of berries, fruits, vegetables, and tubers, improve carbohydrate metabolism and decrease the risk factors of metabolic disorders, but their industrial use is limited by their chemical instability. Acylation of the glycosyl moieties of anthocyanins, however, changes the chemical properties of anthocyanins and provides enhanced stability. Thus, acylated anthocyanins are more usable as natural colorants and bioactive components of innovative functional foods. Acylated anthocyanins are common in pigmented vegetables and tubers, the consumption of which has the potential to increase the intake of health-promoting anthocyanins as part of the daily diet. For the first time, this review presents the current findings on bioavailability, absorption, metabolism, and health effects of acylated anthocyanins with comparison to more extensively investigated nonacylated anthocyanins. The structural differences between nonacylated and acylated anthocyanins lead to enhanced color stability, altered absorption, bioavailability, in vivo stability, and colonic degradation. The impact of phenolic metabolites and their potential health effects regardless of the low bioavailability of the parent anthocyanins as such is discussed. Here, purple-fleshed potatoes are presented as a globally available, eco-friendly model food rich in acylated anthocyanins, which further highlights the industrial possibilities and nutritional relevance of acylated anthocyanins. This work supports the academic community and industry in food research and development by reviewing the current literature and highlighting gaps of knowledge.

Chemical Characterization of Three Accessions of Brassica juncea L. Extracts from Different Plant Tissues

Indian mustard or Brassica juncea (B. juncea) is an oilseed plant used in many types of food (as mustard or IV range salad). It also has non-food uses (e.g., as green manure), and is a good model for phytoremediation of metals and pesticides. In recent years, it gained special attention due to its biological compounds and potential beneficial effects on human health. In this study, different tissues, namely leaves, stems, roots, and flowers of three accessions of B. juncea: ISCI 99 (Sample A), ISCI Top (Sample B), and “Broad-leaf” (Sample C) were analyzed by HPLC-PDA/ESI-MS/MS. Most polyphenols identified were bound to sugars and phenolic acids. Among the three cultivars, Sample A flowers turned were the richest ones, and the most abundant bioactive identified was represented by Isorhamnetin 3,7-diglucoside (683.62 µg/100 mg dry weight (DW) in Sample A, 433.65 µg/100 mg DW in Sample B, and 644.43 µg/100 mg DW in Sample C). In addition, the most complex samples, viz. leaves were analyzed by GC-FID/MS. The major volatile constituents of B. juncea L. leaves extract in the three cultivars were benzenepropanenitrile (34.94% in Sample B, 8.16% in Sample A, 6.24% in Sample C), followed by benzofuranone (8.54% in Sample A, 6.32% in Sample C, 3.64% in Sample B), and phytone (3.77% in Sample B, 2.85% in Sample A, 1.01% in Sample C). The overall evaluation of different tissues from three B. juncea accessions, through chemical analysis of the volatile and non-volatile compounds, can be advantageously taken into consideration for future use as dietary supplements and nutraceuticals in food matrices.

Study on Human Urinary Metabolic Profiles after Consumption of Kale and Daikon Radish using a High-resolution Mass Spectrometry-Based Non-targeted and Targeted Metabolomic Approach

In the present study, urine samples were collected from healthy human volunteers to determine the metabolic fates of phenolic compounds and glucosinolates after a single meal of kale and daikon radish. The major glucosinolates and phenolic compounds in kale and daikon radish were measured. The urinary metabolome after feeding at different time periods was investigated. A targeted metabolite analysis method was developed based on the known metabolic pathways for glucosinolates and phenolic compounds. Using a targeted approach, a total of 18 metabolites were found in urine: 4 from phenolic compounds and 14 from glucosinolates. Among these metabolites, 4-methylsulfinyl-3-butenyl isothiocyanate, 4-methylsulfinyl-3-butenyl isothiocyanate-cysteine, and 4-methylsulfinyl-3-butenylglucosinolate-N-acetyl cysteine were reported for the first time in human urine. The combination of non-targeted and targeted metabolomic approaches can gain a full metabolite profile for human dietary intervention studies.

Antioxidant effect of p-coumaric acid on interleukin 1-β and tumor necrosis factor-α in rats with renal ischemic reperfusion

BACKGROUND AND AIMS

Renal ischemia-reperfusion occurs in some clinical conditions such as kidney surgery that can leads to acute renal failure. The aim of this study was to investigate the effect of p-coumaric acid (CA) on ischemia reperfusion (I/R) injury.

METHODS

Thirty rats were randomly divided into five groups; control, CA (100mg/kg), I/R, propylene glycol (10%)+I/R and CA+I/R, (n=6 each). CA and propylene glycol were administered orally for 2 weeks. Then, the rats were subjected to bilateral renal ischemia for 45min and followed by reperfusion for 24h. All rats were killed and kidney function tests, tissue malondialdehyde and activity of antioxidant enzymes were determined. Histopathological evaluations were also performed. In addition, renal expression of the tumor necrosis factor-α and interleukin-1β were determined using enzyme-linked immunosorbent assay and immunohistochemistry.

RESULTS

CA significantly improved the Cr and BUN levels in CA+I/R group compared to I/R group (p<0.005 and p<0.001, respectively). Reduction of tissue superoxide dismutase, glutathione peroxidase and catalase, were significantly improved by CA (p<0.01, p<0.01 and p<0.05). Treatment with CA also resulted in significant reduction in tissue MDA (p<0.05), TNF-α (p<0.001) and interleukin-1β expression (p<0.001) that were increased by renal I/R. Also, the rats treated with CA had nearly normal structure of the kidney.

CONCLUSIONS

The present findings suggest that, CA protects the kidneys against I/R injury via its antioxidant and anti-inflammatory effects.

Comparative Analysis of the Metabolic Profiles of Yellow- versus Black-Seeded Rapeseed Using UPLC-HESI-MS/MS and Transcriptome Analysis

The high levels of secondary metabolites in rapeseed play important roles in determining the oil quality and feeding value. Here, we characterized the metabolic profiles in seeds of various yellow- and black-seeded rapeseed accessions. Two hundred and forty-eight features were characterized, including 31 phenolic acids, 54 flavonoids, 24 glucosinolates, 65 lipid compounds, and 74 other polar compounds. The most abundant phenolic acids and various flavonoids (epicatechin, isorhamnetin, kaempferol, quercetin, and their derivatives) were widely detected and showed significant differences in distribution between the yellow- and black-seeded rapeseed. Furthermore, the related genes (e.g., BnTT3, BnTT18, BnTT10, BnTT12, and BnBAN) involved in the proanthocyanidin pathway had lower expression levels in yellow-seeded rapeseed, strongly suggesting that the seed coat color could be mainly determined by the levels of epicatechin and their derivatives. These results improve our understanding of the primary constituents of rapeseed and lay the foundation for breeding novel varieties with a high nutritional value.

Determination of the Metabolite Content of Brassica juncea Cultivars Using Comprehensive Two-Dimensional Liquid Chromatography Coupled with a Photodiode Array and Mass Spectrometry Detection

Plant-based foods are characterized by significant amounts of bioactive molecules with desirable health benefits beyond basic nutrition. The Brassicaceae (Cruciferae) family consists of 350 genera; among them, Brassica is the most important one, which includes some crops and species of great worldwide economic importance. In this work, the metabolite content of three different cultivars of Brassica juncea, namely ISCI Top, “Broad-leaf,” and ISCI 99, was determined using comprehensive two-dimensional liquid chromatography coupled with a photodiode array and mass spectrometry detection. The analyses were carried out under reversed-phase conditions in both dimensions, using a combination of a 250-mm microbore cyano column and a 50-mm RP-Amide column in the first and second dimension (²D), respectively. A multi (three-step) segmented-in-fraction gradient for the ²D separation was advantageously investigated here for the first time, leading to the identification of 37 metabolites. In terms of resolving power, orthogonality values ranged from 62% to 69%, whereas the corrected peak capacity values were the highest for B. juncea ISCI Top (639), followed by B. juncea “Broad-leaf” (502). Regarding quantification, B. juncea cv. “Broad-leaf” presented the highest flavonoid content (1962.61 mg/kg) followed by B. juncea cv. ISCI Top (1002.03 mg/kg) and B. juncea cv. ISCI 99 (211.37 mg/kg).

Antioxidant effect of p-coumaric acid on interleukin 1-β and tumor necrosis factor-α in rats with renal ischemic reperfusion

BACKGROUND AND AIMS

Renal ischemia-reperfusion occurs in some clinical conditions such as kidney surgery that can leads to acute renal failure. The aim of this study was to investigate the effect of p-coumaric acid (CA) on ischemia reperfusion (I/R) injury.

METHODS

Thirty rats were randomly divided into five groups; control, CA (100mg/kg), I/R, propylene glycol (10%)+I/R and CA+I/R, (n=6 each). CA and propylene glycol were administered orally for 2 weeks. Then, the rats were subjected to bilateral renal ischemia for 45min and followed by reperfusion for 24h. All rats were killed and kidney function tests, tissue malondialdehyde and activity of antioxidant enzymes were determined. Histopathological evaluations were also performed. In addition, renal expression of the tumor necrosis factor-α and interleukin-1β were determined using enzyme-linked immunosorbent assay and immunohistochemistry.

RESULTS

CA significantly improved the Cr and BUN levels in CA+I/R group compared to I/R group (p<0.005 and p<0.001, respectively). Reduction of tissue superoxide dismutase, glutathione peroxidase and catalase, were significantly improved by CA (p<0.01, p<0.01 and p<0.05). Treatment with CA also resulted in significant reduction in tissue MDA (p<0.05), TNF-α (p<0.001) and interleukin-1β expression (p<0.001) that were increased by renal I/R. Also, the rats treated with CA had nearly normal structure of the kidney.

CONCLUSIONS

The present findings suggest that, CA protects the kidneys against I/R injury via its antioxidant and anti-inflammatory effects.

Identification and Characterization of Major Constituents in Different-Colored Rapeseed Petals by UPLC-HESI-MS/MS

Oilseed rape (Brassica napus L.) is the second highest yielding oil crop worldwide. In addition to being used as an edible oil and a feed for livestock, rapeseed has high ornamental value. In this study, we identified and characterized the main floral major constituents, including phenolic acids and flavonoids components, in rapeseed accessions with different-colored petals. A total of 144 constituents were identified using ultrahigh-performance liquid chromatography-HESI-mass spectrometry (UPLC-HESI-MS/MS), 57 of which were confirmed and quantified using known standards and mainly contained phenolic acids, flavonoids, and glucosinolates compounds. Most of the epicatechin, quercetin, and isorhamnetin derivates were found in red and pink petals of B. napus, while kaempferol derivates were in yellow and pale white petals. Moreover, petal-specific compounds, including a putative hydroxycinnamic acid derivative, sinapoyl malate, 1-O-sinapoyl-β-d-glucose, feruloyl glucose, naringenin-7-O-glucoside, cyanidin-3-glucoside, cyanidin-3,5-di-O-glucoside, petunidin-3-O-β-glucopyranoside, isorhamnetin-3-O-glucoside, kaempferol-3-O-glucoside-7-O-glucoside, quercetin-3,4'-O-di-β-glucopyranoside, quercetin-3-O-glucoside, and delphinidin-3-O-glucoside, might contribute to a variety of petal colors in B. napus. In addition, bound phenolics were tentatively identified and contained three abundant compounds (p-coumaric acid, ferulic acid, and 8-O-4'-diferulic acid). These results provide insight into the molecular mechanisms underlying petal color and suggest strategies for breeding rapeseed with a specific petal color in the future.

Kale (Brassica oleracea var. acephala) as a superfood: Review of the scientific evidence behind the statement

Kale (Brassica oleracea var. acephala) is a cruciferous vegetable, characterized by leaves along the stem, which, in recent years, have gained a great popularity as a ´superfood´. Consequently, in a popular culture it is listed in many ´lists of the healthiest vegetables´. Without the doubt, a scientific evidences support the fact that cruciferous vegetables included in human diet can positively affect health and well-being, but remains unclear why kale is declared superior in comparison with other cruciferous. It is questionable if this statement about kale is triggered by scientific evidence or by some other factors. Our review aims to bring an overview of kale's botanical characteristics, agronomic requirements, contemporary and traditional use, macronutrient and phytochemical content and biological activity, in order to point out the reasons for tremendous kale popularity.

Effects of Growth Temperature and Postharvest Cooling on Anthocyanin Profiles in Juvenile and Mature Brassica oleracea

The effects of growth temperatures on anthocyanin content and profile were tested on juvenile cabbage and kale plants. The effects of cold storage time were evaluated on both juvenile and mature plants. The anthocyanin content in juvenile plants ranged from 3.82 mg of cyanidin-3,5-diglucoside equivalent (Cy equiv)/g of dry matter (dm) at 25 °C to 10.00 mg of Cy equiv/g of dm at 16 °C, with up to 76% diacylated anthocyanins. Cold storage of juvenile plants decreased the total amount of anthocyanins but increased the diacylated anthocyanin content by 3-5%. In mature plants, cold storage reduced the total anthocyanin content from 22 to 12.23 mg/g after 5 weeks of storage in red cabbage, while the total anthocyanin content increased after 2 weeks of storage from 2.34 to 3.66 mg of Cy equiv/g of dm in kale without having any effect on acylation in either morphotype. The results obtained in this study will be useful for optimizing anthocyanin production.

Fluctuations in Phenolic Content and Antioxidant Capacity of Green Vegetable Juices during Refrigerated Storage

Shinseoncho and kale were made into green vegetable juices by building block [shinsenocho branch (SB), shinsenocho leaf (SL), kale branch (KB), and kale leaf (KL)]. Fluctuations in their phenolic contents and antioxidant capacities were analyzed during refrigerated storage at 4°C for 28 days. Total polyphenolic contents of leaf parts showed a decreasing tendency after 4 days (SL) or 7 days (KL), whereas branch parts showed fluctuating values during the entire storage period. The 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging capacity was rapidly decreased in SB and in SL at 28 days (P<0.001), whereas KL showed a slightly increasing tendency after 14 days. For the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity, SL showed a sharp fall at 28 days (P<0.001), and KL showed a decreasing tendency after 14 days (P<0.001). SB showed a steady decrease during the entire storage period and KB indicated a nearly zero (0.97%) at 28 days. Pearson's coefficients for the correlation between antioxidant capacities measured by the ABTS and DPPH assays, and the total polyphenolic contents were determined. The results showed that the ABTS assay (r=0.934, P<0.001) was more strongly positively correlated with the total phenolic contents than the DPPH assay (r=0.630, P<0.001). In conclusion, when considering all building blocks, green vegetable juices, including kale and shinseoncho may have kept antioxidant capacities for up to 14 days under refrigeration, and the ABTS assay better reflects a positive correlation with the total phenolic contents when compared to the DPPH assay.

Analysis of flavonoids and hydroxycinnamic acid derivatives in rapeseeds (Brassica napus L. var. napus) by HPLC-PDA--ESI(--)-MS(n)/HRMS

A comprehensive description of flavonoids and hydroxycinnamic acid derivatives in Brassica napus L. var. napus seeds is important to improve rapeseed quality. HPLC-PDA-ESI(-)-MS(n)/HRMS has been broadly applied to study phenolic compounds in plants. In the present study, crude phenolic compounds extracted from rapeseed were subjected to column chromatography, alkaline hydrolysis, and HPLC-PDA-ESI(-)-MS(n)/HRMS analysis. A total of 91 flavonoids and hydroxycinnamic acid derivatives were detected, including 39 kaempferol derivatives, 11 isorhamnetin derivatives, 5 quercetin derivatives, 6 flavanols and their oligomers, and 30 hydroxycinnamic acid derivatives. A total of 78 of these compounds were tentatively identified; of these, 55 were reported for the first time in B. napus L. var. napus and 24 were detected for the first time in the genus Brassica. This research enriches our knowledge of the phenolic composition of rapeseed and provides a reliable guide for the selection of rapeseed with valuable breeding potential.

Ultra(high)-pressure liquid chromatography-electrospray ionization-time-of-flight-ion mobility-high definition mass spectrometry for the rapid identification and structural characterization of flavonoid glycosides from cauliflower waste

In this paper, a strategy for the detection and structural elucidation of flavonoid glycosides from a complex matrix in a single chromatographic run using U(H)PLC-ESI-IMS-HDMS/MS(E) is presented. This system operates using alternative low and high energy voltages that is able to perform the task of conventional MS/MS in a data-independent way without re-injection of the sample, which saves analytical time. Also, ion mobility separation (IMS) was employed as an additional separation technique for compounds that are co-eluting after U(H)PLC separation. First, the fragmentation of flavonoid standards were analyzed and criteria was set for structural elucidation of flavonoids in a plant extract. Based on retention times, UV spectra, exact mass, and MS fragment characteristics, such as abundances of daughter ions and the presence of radical ions ([Y0-H](-)), a total 19 flavonoid glycosides, of which 8 non-acylated and 11 acylated, were detected and structurally characterized in a cauliflower waste extract. Kaempferol and quercetin were the main aglycones detected while sinapic and ferulic acid were the main phenolic acids. C-glycosides were also found although their structure could not be elucidated. The proposed method can be used as a rapid screening test for flavonoid identification and for routine analysis of plant extracts, such as these derived from cauliflower waste. The study also confirms that agroindustrial wastes, such as cauliflower leaves, could be seen as a valuable source of different bioactive phenolic compounds.

Comparison of leafy kale populations from Italy, Portugal, and Turkey for their bioactive compound content: phenolics, glucosinolates, carotenoids, and chlorophylls

BACKGROUND

Kales are primitive leafy Brassica oleracea L. forms, widespread in local farming systems of several European countries and employed in the preparation of traditional recipes. Kales are also potential sources of healthy bioactive phytochemical components. The present study compared the bioactive compound content of kale populations from Italy, Portugal, and Turkey, either from local sources or grown in an experimental field.

RESULTS

Total phenolics, glucosinolates (GLS), carotenoids, and chlorophylls were in the ranges 8310-38 110, 755-8580, 135-2354, and 1740-16,924 mg kg(-1) dry matter, respectively. On average, locally harvested samples showed a total GLS content about twice as high as populations from the experiment. Conversely, pigments were significantly more abundant in experimental than in local kales, owing to the higher soil fertility. Portuguese samples showed higher phenolic and GLS amounts than Italian and Turkish kales, whereas some of the Italian samples were the richest in carotenoids.

CONCLUSION

This paper represented the first cross-country comparison of local kale accessions with respect to bioactive compound amounts. Both geographic origin and growing environment appeared to be remarkable and discriminating factors in determining bioactive levels in leafy kales, with possible effects on their health-promoting and sensorial attributes.

Quantification of glucosinolates, anthocyanins, free amino acids, and vitamin C in inbred lines of cabbage (Brassica oleracea L.)

We profiled and quantified glucosinolates (GSLs), anthocyanins, free amino acids, and vitamin C metabolites in forty-five lines of green and red cabbages. Analysis of these distinct cabbages revealed the presence of 11 GSLs, 13 anthocyanins, 22 free amino acids, and vitamin C. GSL contents were varied amongst the different lines of cabbage. The total GSL content was mean 10.6 μmol/g DW, and sinigrin was the predominant GSL accounted mean 4.0 μmol/g DW (37.7% of the total) followed by glucoraphanin (1.9) and glucobrassicin (2.4). Amongst the 13 anthocyanins, cyanidin 3-(sinapoyl) diglucoside-5-glucoside levels were the highest. The amounts of total free amino acids in green cabbage lines ranged 365.9 mg/100g fresh weight (FW) to 1089.1mg/100g FW. Vitamin C levels were much higher in red cabbage line (129.9 mg/100g FW). Thus, the amounts of GSLs, anthocyanins, free amino acids, and vitamin C varied widely, and the variations in these compounds between the lines of cabbage were significant.

Effect of polyphenols extracts from Brassica vegetables on erythrocyte membranes (in vitro study)

The aim of this work was to estimate the in vitro effects of polyphenol extracts from Brassica vegetables (Brussels sprouts and red cabbage) on erythrocyte membranes with normal and high concentration of cholesterol. To determine the effect of phenolic compounds we prospectively studied cholesterol concentration, lipid peroxidation, membrane fluidity and ATPase activity. Polyphenol extracts from Brassica vegetables resulted in statistically significant reductions in cholesterol concentrations in hypercholesterolemic erythrocytes. For control erythrocytes, no significant reduction of cholesterol levels was observed for both extracts. Decreases in lipid peroxidation intensity were observed after incubation of hypercholesterolemic erythrocytes with the extracts. No changes in membrane fluidity for both extracts were noted for normal and hypercholesterolemic erythrocytes. The activity of ATPase decreased after incubation of normal and hypercholesterolemic erythrocytes with extract from Brassica vegetables. Our results indicate that polyphenols from red cabbage and Brussels sprout may directly influence erythrocyte membrane properties.

Metabolic profiling of glucosinolates, anthocyanins, carotenoids, and other secondary metabolites in kohlrabi (Brassica oleracea var. gongylodes)

We profiled and quantified glucosinolates, anthocyanins, carotenoids, and other secondary metabolites in the skin and flesh of pale green and purple kohlrabis. Analysis of these distinct kohlrabis revealed the presence of 8 glucosinolates, 12 anthocyanins, 2 carotenoids, and 7 phenylpropanoids. Glucosinolate contents varied among the different parts and types of kohlrabi. Glucoerucin contents were 4-fold higher in the flesh of purple kohlrabi than those in the skin. Among the 12 anthocyanins, cyanidin 3-(feruloyl)(sinapoyl) diglucoside-5-glucoside levels were the highest. Carotenoid levels were much higher in the skins than the flesh of both types of kohlrabi. The levels of most phenylpropanoids were higher in purple kohlrabi than in pale green ones. trans-Cinnamic acid content was 12.7-fold higher in the flesh of purple kohlrabi than that in the pale green ones. Thus, the amounts of glucosinolates, anthocyanins, carotenoids, and phenylpropanoids varied widely, and the variations in these compounds between the two types of kohlrabi were significant.

Antiproliferative effects of fresh and thermal processed green and red cultivars of curly kale (Brassica oleracea L. convar. acephala var. sabellica)

Brassica vegetables contain a diverse range of phytochemicals with biological properties such as antioxidant and anticancer activity. However, knowledge about how biological activities are affected by processing is lacking. A green cultivar and a red cultivar of curly kale were evaluated for water/methanol-soluble phytochemicals before and after processing involving blanching, freeze storage, and boil-in-bag heat treatment. In both kale cultivars, processing resulted in a significant decrease of total phenolics, antioxidant capacity, and content and distribution of flavonols, anthocyanins, hydroxycinnamic acids, glucosinolates, and vitamin C. Interestingly, the red curly kale cultivar had a higher capacity to withstand thermal loss of phytochemicals. The extracts of both green and red curly kale inhibited the cell proliferation of three human colon cancer cell lines (Caco-2, HT-29, and HCT 116). However, extracts from fresh plant material had a significantly stronger antiproliferative effect than extracts from processed plant material.

Multivariate associations of flavonoid and biomass accumulation in white clover (Trifolium repens) under drought

White clover (Trifolium repens L.) is an important pasture legume in temperate regions, but growth is often strongly reduced under summer drought. Cloned individuals from a full-sib progeny of a pair cross between two phenotypically distinct white clover populations were exposed to water deficit in pots under outdoor conditions for 9 weeks, while control pots were maintained at field capacity. Water deficit decreased leaf water potential by more than 50% overall, but increased the levels of the flavonol glycosides of quercetin (Q) and the ratio of quercetin and kaempferol glycosides (QKR) by 111% and by 90%, respectively. Water deficit reduced dry matter (DM) by 21%, with the most productive genotypes in the controls showing the greatest proportional reduction. The full-sib progeny displayed a significant increase in the root:shoot ratio by 53% under water deficit. Drought-induced changes in plant morphology were associated with changes in Q, but not kaempferol (K) glycosides. The genotypes with high QKR levels reduced their DM production least under water deficit and increased their Q glycoside levels and QKR most. These data show, at the individual genotype level, that increased Q glycoside accumulation in response to water deficit stress can be positively associated with retaining higher levels of DM production.

Quantitation of the hydroxycinnamic acid derivatives and the glycosides of flavonols and flavones by UV absorbance after identification by LC-MS

A general approach was developed to quantify hydroxycinnamic acid derivatives and the glycosides of flavonols and flavones using UV molar relative response factors (MRRFs). More than 90 standards were analyzed by LC-MS and divided into five groups based on the λ(max) of their band I absorbance profiles. For each group, a commercially available standard was chosen as the group reference standard. Response factors were determined for each standard in each group as purchased (MRRF) and, when possible, after vacuum drying (MRRF(D)). The MRRF(D) values for 17 compounds whose λ(max) values fell within ±2 nm of the group reference standard were 1.01 ± 0.03. MRRF values for compounds whose λ(max) values fell within ±10 nm of the group reference standard were 0.96 ± 0.13. Group reference standards were used to quantify 44 compounds in Chinese lettuce, red onion, and white tea. This approach allows quantitation of numerous compounds for which there are no standards.

UHPLC-PDA-ESI/HRMS/MS(n) analysis of anthocyanins, flavonol glycosides, and hydroxycinnamic acid derivatives in red mustard greens (Brassica juncea Coss variety)

An UHPLC-PDA-ESI/HRMS/MS(n) profiling method was used for a comprehensive study of the phenolic components of red mustard greens ( Brassica juncea Coss variety) and identified 67 anthocyanins, 102 flavonol glycosides, and 40 hydroxycinnamic acid derivatives. The glycosylation patterns of the flavonoids were assigned on the basis of direct comparison of the parent flavonoid glycosides with reference compounds. The putative identifications were obtained from tandem mass data analysis and confirmed by the retention time, elution order, and UV-vis and high-resolution mass spectra. Further identifications were made by comparing the UHPLC-PDA-ESI/HRMS/MS(n) data with those of reference compounds in the polyphenol database and in the literature. Twenty-seven acylated cyanidin 3-sophoroside-5-diglucosides, 24 acylated cyanidin 3-sophoroside-5-glucosides, 3 acylated cyanidin triglucoside-5-glucosides, 37 flavonol glycosides, and 10 hydroxycinnamic acid derivatives were detected for the first time in brassica vegetables. At least 50 of them are reported for the first time in any plant materials.

Polymorphism for novel tetraglycosylated flavonols in an Eco-model crucifer, Barbarea vulgaris

Nineteen apparent flavonoids were determined by HPLC-DAD in foliage of a chemotype (G-type) of Barbarea vulgaris , and four were isolated. Two were novel tetraglycosylated flavonols with identical glycosylation patterns, kaempferol 3-O-(2,6-di-O-β-d-glucopyranosyl)-β-d-glucopyranoside-7-O-α-l-rhamnopyranoside (1) and quercetin 3-O-(2,6-di-O-β-d-glucopyranosyl)-β-d-glucopyranoside-7-O-α-l-rhamnopyranoside (2). The identification of d/l configuration was tentatively based on susceptibility to α-l-rhamnosidase and β-d-glucosidases. A characteristic feature of 1 and 2 was appreciable water solubility, an expected consequence of the extensive glycosylation. A less complex pair of flavonols comprised 3-O-β-d-glucopyranoside-7-O-α-l-rhamnopyranosides of kaempferol and quercetin. Two natural chemotypes of B. vulgaris differed in levels of 1 and 2, with the P-type deficient in 1 and 2 and the insect-resistant G-type rich in 1 (ca. 3-4 μmol/g dry wt) and with moderate levels of 2 (ca. 0.3-0.8 μmol/g dry wt). However, there was only modest seasonal variation in flavonols 1 and 2, in contrast to a strong seasonal variation in insect resistance.