Chemical and antioxidative assessment of dietary turnip (Brassica rapa var. rapa L.)

The phenolic compounds and organic acids of turnip (Brassica rapa var. rapa L.) edible parts (leaves and stems, flower buds and roots) were determined by HPLC–DAD and HPLC–UV, respectively. The results revealed a profile composed of 14 phenolics (3-p-coumaroylquinic, caffeic, ferulic and sinapic acids, kaempferol 3-O-sophoroside-7-O-glucoside, kaempferol 3-O-sophoroside-7-O-sophoroside, kaempferol 3-O-(feruloyl/caffeoyl)-sophoroside-7-O-glucoside, kaempferol 3,7-O-diglucoside, isorhamnetin 3,7-O-diglucoside, kaempferol 3-O-sophoroside, 1,2-disinapoylgentiobiose, 1,2′-disinapoyl-2-feruloylgentiobiose, kaempferol 3-O-glucoside and isorhamnetin 3-O-glucoside) and six organic acids (aconitic, citric, ketoglutaric, malic, shikimic and fumaric acids). The quantification of the identified compounds showed kaempferol 3-O-sophoroside-7-O-glucoside, kaempferol 3-O-(feruloyl/caffeoyl)-sophoroside-7-O-glucoside, isorhamnetin 3,7-O-diglucoside and isorhamnetin 3-O-glucoside as the main phenolics, and malic acid as the organic acid present in highest amounts. A screening of the antioxidative potential was also performed by means of the DPPH radical scavenging assay. Turnip flower buds exhibited the strongest antioxidant capacity.     

Selection of elderberry (Sambucus nigra L.) genotypes best suited for the preparation of elderflower extracts rich in flavonoids and phenolic acids

The importance of raw material and extraction parameters for obtaining a high content of flavonoids and phenolic acids in elderflower extracts was investigated. Nine phenolic acids (3-O-, 4-O-, and 5-O-caffeoylquinic acid, 3-O- and 5-O-p-coumaroylquinic acid, 1,5-di-O-, 3,4-di-O-, 3,5-di-O- and 4,5-di-O-caffeoylquinic acid) and six flavonol glycosides (quercetin-3-O-rutinoside, quercetin-3-O-glucoside, kaempferol-3-O-rutinoside, isorhamnetin-3-O-rutinoside, isorhamnetin-3-O-glucoside, and quercetin-3-O-6″-acetylglucoside) were identified and quantified in elderflowers and/or extracts thereof by liquid chromatography-mass spectrometry (LC-MS) and high-performance liquid chromatography-diode array detection (HPLC-DAD), respectively. The yield of elderflower extracts depended significantly on processing conditions and raw material properties and the maximum yield of elderflower extract was obtained by extraction for a maximum of 10 days at 4 °C using an extraction liquid consisting of a maximum of 20 w/w % sugars and 5% citric acid. The effects of the extraction liquid composition and raw material on the concentration of phenolic acids and flavonol glycosides in elderflower extracts were determined by factor analysis. Several elderberry genotypes were found to be useful for processing of elderflower extracts with a relative high concentration of phenolic acids and flavonol glycosides.     

Identification of flavanones from peel of Citrus changshan-huyou Y. B. Chang, by HPLC–MS and NMR

High-performance liquid chromatography coupled with a UV photodiode-array detector and a mass spectrometer (HPLC–MS) was used to analyze the constituents of an extract of Citrus changshan-huyou Y. B. Chang peel. Structures of two flavanones were identified based on their abundant [M+H]⁺ ions, UV spectra, and ¹HNMR and ¹³CNMR spectrometer as 5,4′-dihydroxy flavanone-7-O-α-glucoside (naringenin-7-O-α-glucoside) and 5,3′-dihydroxy-4′-methoxy flavanone-7-O-α-glucoside (hesperetin-7-O-α-glucoside). The two flavanones were first identified from peel of Citrus changshan-huyou Y. B. Chang.     

Inflorescences of Brassicacea species as source of bioactive compounds: A comparative study

Two Brassica oleracea varieties (B. oleracea L. var. costata DC and B. oleracea L. var. acephala) and Brassica rapa L. var. rapa inflorescences were studied for their chemical composition and antioxidant capacity. Phenolic compounds and organic acids profiles were determined by HPLC–DAD and HPLC–UV, respectively. B. oleracea var. costata and B. oleracea L. var. acephala inflorescences presented a similar qualitative phenolic composition, exhibiting several complex kaempferol derivatives and 3-p-coumaroylquinic acid, while B. rapa var. rapa was characterized by kaempferol and isorhamnetin glycosides and several phenolic acids derivatives. B. oleracea L. var. costata and B. rapa var. rapa showed the highest phenolics content. The three Brassica exhibited the same six organic acids (aconitic, citric, pyruvic, malic, shikimic and fumaric acids), but B. oleracea L. var. acephala presented a considerably higher amount. Each inflorescence was investigated for its capacity to act as a scavenger of DPPH radical and reactive oxygen species (superoxide radical, hydroxyl radical and hypochlorous acid), exhibiting antioxidant capacity in a concentration dependent manner against all radicals. These samples were also studied for its antimicrobial potential against Gram-positive and Gram-negative bacteria and fungi, displaying antimicrobial capacity only against Gram-positive bacteria.     

Characterisation of flavonoids in Orostachys japonicus A. Berger using HPLC–MS/MS: Contribution to the overall antioxidant effect

Orostachys japonicus cultivated in the Republic of Korea was analysed for flavonoid content via HPLC coupled to MS/MS. Amongst 16 compounds that were characterised, eight flavonoids and one alkaloid were characterised for the first time: two procyanidin dimer gallate isomers (1 and 2), epigallochatechin-3-gallate (3), two procyanidin dimer digallate isomers (4 and 9), quercetin 3-O-rhamnosyl-7-O-glucoside (6), myricetin 3-O-glucoside (10), kaempferol (16) and N¹,N⁵,N¹⁰-tri-p-(E,E,E)-coumaroylspermidine (15). The identified compounds were quantified by HPLC–UV/DAD. The antioxidant activity of the O. japonicus flavonoids was determined via 2,2-diphenyl-1-picrylhydrazyl radical (DPPH^•), 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulphonic acid) radical cation (ABTS^•+) and nitric oxide radical (NO^•) scavenging assays.     

Novel acetylated flavonoid glycosides from the leaves of Allium ursinum

Seven flavonoid glycosides, kaempferol 3-O-α-L-rhamnopyranosyl (1→2)-[3-O-acetyl]-β-D-glucopyranoside (1), kaempferol 3-O-α-L-rhamnopyronosyl (1→2)-[6-O-acetyl]-β-D-glucopyranoside (2), kaempferol 3-O-α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranoside (3), kaempferol 3-O-β-D-glucopyranoside (4), kaempferol 3,7-di-O-β-D-glucopyranoside (5), 7-O-β-D-glucopyranosyl kaempferol 3-O-α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranoside (6), kaempferol 3-O-α-L-rhamnopyranosyl (1→2)-β-D-glucopyranoside-7-O-[2-O-(trans-p-coumaroyl)]-β-D-glucopyranoside (7) were isolated from the n-butanol fraction of Allium ursinum L. and the structures of these compounds were elucidated on the basis of mass spectrometry, ¹H NMR, ¹³C NMR, HMQC and HMBC data. Among them, 1 and 2 are novel compounds and compounds 4 and 5 were isolated from this plant species for the first time.     

Preparative separation of phenylpropenoid glycerides from the bulbs of Lilium lancifolium by high-speed counter-current chromatography and evaluation of their antioxidant activities

Preparative separation of seven phenylpropenoid glycerides from the bulbs of Liliumlancifolium (lily), was conducted by high-speed counter-current chromatography (HSCCC) with a two-phase solvent system composed of n-hexane-ethyl acetate-methanol-0.05% aqueous trifluoroacetic acid (TFA) (3:5:3:5, v/v/v/v). These phenylpropenoid glycerides were identified as 1-O-feruloylglycerol (1), 1-O-p-coumaroylglycerol (2), 1-O-caffeoyl-3-O-p-coumaroylglycerol (3), 1,2-O-diferuloylglycerol (4), 1,3-O-diferuloylglycerol (5), 1-O-feruloyl-3-O-p-coumaroylglycerol (6), and 1,3-O-di-p-coumaroylglycerol (7), respectively, by ESI-MS, ¹H NMR and ¹³C NMR. Their antioxidant activities were evaluated by DPPH radical scavenging activity, ABTS radical cation scavenging activity, and ferric-reducing antioxidant power (FRAP). The trend in antioxidant capacity was similar in all the three assays, with 3 > 1, 4, 5, 6 > 2, 7. This is the first report on simultaneous separation of seven antioxidantive phenylpropenoid glycerides from L. lancifolium by HSCCC.     

Analysis and metabolite profiling of glucosinolates,anthocyanins and free amino acids in inbred lines of green and red cabbage (Brassica oleracea L.)

We profiled and quantified glucosinolates (GSLs), anthocyanins and free amino acids in thirty-seven inbred lines green and red cabbage. Analysis of these distinct cabbages revealed the presence of 8 GSLs, 13 anthocyanins and 12 free amino acids. GSL contents were varied among the different lines of cabbage. The maximum levels of glucoraphanin (14.91 μmol/g DW) and glucobrassicin (12.37) were found in FX 1-28 and FX 1-32 lines, respectively. Total GSLs in red cabbage lines were 50% higher than those of green cabbage. Anthocyanin contents in red cabbage were ranged from 4.11 to 6.81 mg/g DW in FX 2-3 and FX 1-34 lines, respectively. Among the 13 anthocyanins, both cyanidin 3-(feruloyl) (sinapoyl)diglucoside-5-glucoside and cyanidin 3-(sinapoyl) (sinapoyl)diglucoside-5-glucoside levels were the highest amounts. The amounts of total free amino acids were ranged from 523.5 to 1308 mg/100 g fresh weight (FW) in green cabbage and 484.8 to 1271 in red cabbage, respectively. In red cabbage lines, 9.4% of the total free amino acids accounted essential amino acids such as valine, threonine, isoleucine, leucine and lysine. Thus, the amounts of GSLs, anthocyanins, and amino acids varied widely, and the variations in these compounds between the lines of cabbage were significant.     

The polyphenolic profiles of common bean (Phaseolus vulgaris L.)

Based on the phenolic profiles obtained by high performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-DAD-ESI/MS), 24 common bean samples, representing 17 varieties and 7 generic off-the-shelf items, belonging to ten US commercial market classes can be organized into six different groups. All of them contained the same hydroxycinnaminic acids, but the flavonoid components showed distinct differences. Black beans contained primarily the 3-O-glucosides of delphinidin, petunidin and malvidin, while pinto beans contained kaempferol and its 3-O-glycosides. Light red kidney bean contained traces of quercetin 3-O-glucoside and its malonates, but pink and dark red kidney beans contained the diglycosides of quercetin and kaempferol. Small red beans contained kaempferol 3-O-glucoside and pelargonidin 3-O-glucoside, while no flavonoids were detected in alubia, cranberry, great northern, and navy beans. This is the first report of the tentative identification of quercetin 3-O-pentosylhexoside and flavonoid glucoside malonates, and the first detailed detection of hydroxycinnamates, in common beans.     

Antioxidant activity of lignans from fringe tree (Chionanthus virginicus L.)

Fringe tree (Chionanthus virginicus L.), a shrub of the eastern part of America, used as a raw material by pharmaceutical industries for cholagoque, diuretic, tonic and the preparation of homeopathic tinctures. The identification of lignans as major antioxidant components and determination of their antioxidant activities are of considerable interest, because of the role they play in pharmacological actions. The potential antioxidant activity of the lignans such as phillyrin, pinoresinol-β-d-glucoside (PDG) and pinoresinol di-β-d-glucoside (PDDG) from root bark of fringe tree (C. virginicus L.) were examined by different antioxidant tests including; 2,2-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging, 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH^•) scavenging, superoxide anion radical (O₂ ^•-) scavenging, total antioxidant activity by ferric thiocyanate method, reducing activity by Fe³⁺–Fe²⁺ transformation, hydrogen peroxide (H₂O₂) scavenging and ferrous metal (Fe⁺²) chelating activities. Phillyrin, PDG and PDDG, as antioxidants, neutralized the activities of radicals and inhibited the peroxidation reactions of linoleic acid emulsion. The total antioxidant activity was determined according to the ferric thiocyanate method. Butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), α-tocopherol and trolox, which is a water-soluble analogue of tocopherol, were used as the reference antioxidant compounds. Phillyrin, PDG and PDDG showed 67.6, 77.3 and 64.2% inhibition on lipid peroxidation of linoleic acid emulsion, respectively, at the concentration of 20 μg/mL. On the other hand, BHA, BHT, α-tocopherol and trolox exhibited 74.4, 71.2, 54.7 and 20.6% inhibition on peroxidation of linoleic acid emulsion, respectively, at the above mentioned concentration. In addition, phillyrin, PDG and PDDG were effective on DPPH^•, ABTS^•+ and O₂ ^•- scavenging, H₂O₂ scavenging, total reducing power and metal chelating effect on ferrous ions activities. Also, BHA, BHT, α-tocopherol and trolox were used as references antioxidants for these various antioxidant activities.     

Composition and content of flavonol glycosides in broccoli florets (Brassica olearacea) and their fate during cooking

The two main flavonol glycosides present in broccoli florets were identified as quercetin 3-O-sophoroside and kaempferol 3-O-sophoroside. Three minor glucosides of quercetin and kaempferol were also detected, namely isoquercitrin, kaempferol 3-O-glucoside and a kaempferol diglucoside. The sophorosides of quercetin and kaempferol were present in raw florets at a level of 65 mg kg⁻¹ and 166 mg kg⁻¹ fresh weight, respectively. The total content of quercetin and kaempferol glycosides expressed as aglycone was 43 and 94 μg g⁻¹ fresh weight, respectively, and these agree with other recently published data. During the cooking process only 14–28% of the individual glucosides were retained in the cooked tissue, the remainder being largely leached into the cooking water with only a small loss attributed to the formation of the respective aglycones. © 1998 SCI.     

A new flavone from antioxidant extracts of Pistacia terebinthus

Acetone and methanol extracts of the fruits of Pistacia terebinthus L. subsp. terebinthus L. were studied for their antioxidant activity by investigating their total phenolic and flavonoid contents, β-carotene bleaching potential, DPPH radical scavenging effect, scavenging activity on superoxide anion radical, reducing power, and metal chelating effect on ferrous ion. Both extracts showed very similar chemical profile by checking on TLC plates, and exhibited high scavenging activity on superoxide anion radical and DPPH radical. Due to these similarities they were combined and fractionated on a silica gel column for their constituents, and the most active three fractions in DPPH assay were purified to afford a new flavone 6′-hydroxyhypolaetin 3′-methyl ether (1) besides a group of known flavonoids apigenin, luteolin, luteolin 7-O-glucoside, quercetin, quercetagetin 3-methyl ether 7-O-glucoside, isoscutellarein 8-O-glucoside. Their structures were established by UV, UV shift reagents, and ¹H NMR spectroscopic techniques. Antioxidant activity of the new flavone was investigated by β-carotene bleaching and DPPH radical scavenging activity methods, and it showed a high activity in the first system, but not so good in the latter.     

Identification of phenolic antioxidants from Sword Brake fern (Pteris ensiformis Burm.)

Sword Brake fern (Pteris ensiformis Burm.) is one of the most common ingredients of traditional herbal drinks in Taiwan. In an effort to identify antioxidants from the aqueous extract of Sword Brake fern (SBF), the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity-guided isolation was employed. Three new compounds, kaempferol 3-O-α-l-rhamnopyranoside-7-O-[α-d-apiofuranosyl-(1-2)-β-d-glucopyranoside] (1), 7-O-caffeoylhydroxymaltol 3-O-β-d-glucopyranoside (3) and hispidin 4-O-β-d-glucopyranoside (4), together with five known compounds, kaempferol 3-O-α-l-rhamnopyranosid-7-O-β-d-glucopyranoside (2), caffeic acid (5), 5-O-caffeoylquinic acid (6), 3,5-di-O-caffeoylquinic acid (7) and 4,5-di-O-caffeoylquinic acid (8) were isolated and determined on the basis of spectroscopic analyses. HPLC with UV detector was further employed to analyze the content of each compound in SBF based on the retention time by comparison with isolated pure compounds. It was found that the most abundant phenolic compound was compound 3, followed by compounds 7 and 4. The di-O-caffeoylquinic acids (7 and 8) have the strongest DPPH scavenging potential with IC₅₀ around 10 μM and the highest Trolox equivalent antioxidant capacity (TEAC) about 2 mM. This data indicates that SBF is rich in phenolic antioxidants.     

A study of polyphenols in the seeds and leaves of guar (Cyamopsis tetragonoloba L. Taub)

Gallotannins, gallic acid, gallic acid derivatives, myricetin-7-glucoside-3-glycoside, kaempferol-7-glucoside-3-glycoside, kaempferol-3-rutinoside, kaempferol-3-glucoside, chlorogenic acid, caffeic acid and ellagic acid were derived from guar seeds and identified by chromatographic and spectral analysis. Myricetin-7-glucoside-3-glycoside, kaempferol-7-glucoside-3-glycoside, kaempferol-3-rutinoside, kaempferol-3-glucoside, quercetin-3-rutinoside, 2,3,4-trihydroxybenzoic acid, texasin-7-O-glucoside, daidzein-7-O-glucoside, chlorogenic acid and p-coumaryl quinic acid were found in guar leaves. The polyphenolic content of guar seeds depended on the stage of maturity varying from 1.26 to 0.69% total phenols; 0.49 to 0.12% gallic acid; 0.5 to 0.21% gallotannins; and 0.13 to 0.23% flavonols (all as percentage dry matter). The polyphenolic content of guar leaves varied from 0.74 to 1.24% total phenols; 0.18 to 0.84% flavonols; and 0.05 to 0.24% hydroxycinnamic acids in the dry matter of guar leaves.     

Characterization of the components present in the active fractions of health gingers (Curcuma xanthorrhiza and Zingiber zerumbet) by HPLC–DAD–ESIMS

Curcuma xanthorrhiza and Zingiber zerumbet are two of the most commonly used ingredients in Indo-Malaysian traditional medicines, health supplements and tonics. Recently, a number of products derived from the aqueous extracts of these species have appeared in the market in the form of spray-dried powder packed in sachet or bottle. On-line high performance liquid chromatography, coupled with diode array detection and electrospray ion trap tandem mass spectroscopy (HPLC–DAD–ESI–MSⁿ), was used to analyze the components in the antioxidant-active fractions from the rhizomes of these species. Three components were identified from C. xanthorrhiza, including bisdemethoxycurcumin (1), demethoxycurcumin (2) and curcumin (3). The active fraction from Z. zerumbet consisted of five components, including kaempferol 3-O-rhamnoside (4), compound 5 [kaempferol 3-O-(2″-O-acetyl)rhamnoside (5a) or kaempferol 3-O-(3″-O-acetyl)rhamnoside (5b)], kaempferol 3-O-(4″-O-acetyl)rhamnoside (6), kaempferol 3-O-(3″,4″-O-diacetyl)rhamnoside (7) and kaempferol 3-O-(2″,4″-O-diacetyl)rhamnoside (8). To confirm their identities, the components from Z. zerumbet were isolated conventionally and were analyzed by spectroscopic techniques as well as by comparison with literature data.     

Phenolic profile in the quality control of walnut (Juglans regia L.) leaves

Qualitative and quantitative determinations of phenolic compounds were carried out on walnut leaves samples from six different cultivars, with the same agricultural, geographical and climatic conditions. The evolution of major phenolic compounds amounts was monitored from May to September. Two extractive procedures were assayed and best results were obtained using acidified water and a solid phase extraction column purification step. Qualitative analysis was performed by HPLC-DAD/MS and, in all samples, seven phenolic compounds were identified (3-caffeoylquinic, 3-p-coumaroylquinic and 4-p-coumaroylquinic acids, quercetin 3-galactoside, quercetin 3-arabinoside, quercetin 3-xyloside, quercetin 3-rhamnoside) and two other partially identified phenolics (quercetin 3-pentoside and kaempferol 3-pentoside derivatives) were also detected. Quantification of phenolic compounds was performed by HPLC-DAD, which revealed that quercetin 3-galactoside was always the major compound while 4-p-coumaroylquinic acid was the minor one. The highest content of phenolics was found in May and July.     

Kaempferol acetylated glycosides from the seed cake of Camellia oleifera

The seed cake is a big by-product after crushing cooking oil from the seeds of Camellia oleifera Abel. Chemical investigation on the seed cake of C. oleifera led to the isolation of two new kaempferol acetylated glycosides (1 and 2). In addition, five kaempferol glycosides (3–7) and their aglycone, kaempferol (8), were also obtained, in addition to gallic acid (9). Their structures were determined by the detailed spectroscopic analysis and acidic hydrolysis. The new compounds were characterised as kaempferol-3-O-[4′′′′-O-acetyl-α-l-rhamnopyranosyl-(1→6)]-[β-d-glucopyranosyl-(1→2)]-β-d-glucopyranoside (1) and kaempferol-3-O-[4′′′′-O-acetyl-α-l-rhamnopyranosyl-(1→6)]-[β-d-xylopyranosyl-(1→2)]-β-d-gluco-pyranoside (2), respectively. The DPPH radical scavenging activity of all the isolated compounds was described.     

Influence of Dekkera bruxellensis on the contents of anthocyanins,organic acids and volatile phenols of Dão red wine

The anthocyanin, organic acid and volatile phenol compositions of red wine obtained from Touriga Nacional grapes growing in the Dão region (Portugal) were determined by HPLC/DAD, HPLC/UV and GC/FID, respectively. By these means, nine anthocyanic compounds (malvidin-3,5-O-diglucoside, cyanidin-3-O-galactoside, cyanidin-3-O-glucoside, peonidin-3-O-glucoside, malvidin-3-O-glucoside, delphinidin, cyanidin, pelargonidin and malvidin), six organic acids (ketoglutaric, tartaric, malic, quinic, lactic and shikimic acids) and two volatile phenols (4-ethylguaiacol and 4-ethylphenol) were identified and quantified. Malvidin-3-O-glucoside, the pair lactic plus shikimic acids and 4-ethylguaiacol were the main anthocyanin, organic acids and volatile phenol, respectively. The effects of nine different Dekkera bruxellensis strains on these chemical parameters were also evaluated. The results obtained indicate that some strains of D. bruxellensis yeast are able to cause deterioration of red wine from the Dão region during its maturation by the production of volatile phenols, namely 4-ethylphenol.