Tadahiro Nagata

Identification of Catechin Oligomers from Apple (Malus pumila cv. Fuji) in Matrix‐assisted Laser Desorption/Ionization Time‐of‐flight Mass Spectrometry and Fast‐atom Bombardment Mass Spectrometry

Molecular size information for polymerized catechin larger than the decamer in unripe apple was obtained by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and by fast-atom bombardment mass spectrometry. Matrix-assisted laser desorption/ionization time of flight mass spectrometry provided evidence for the pentadecamer using trans-3-indoleacrylic acid as the matrix in the presence of silver ion. Even in the absence of silver ion, the dodecamer and undecamer were observed in the positive- and negative-ion modes, respectively. Fast-atom bombardment mass spectrometry also afforded evidence for the undecamer in both positive- and negative-ion modes.

Identification of aluminium forms in tea leaves by 27Al NMR

Abstract To identify forms of accumulated aluminium in tea leaves, 27 Al NMR spectroscopy was applied to the analysis of intact tea leaves and model Al complexes such as Al-catechin, Al-F, Al-phenolic acid and Al-organic acid. Although mature or old leaves contained more than two forms of Al, both buds and young leaves give virtually one signal. The chemical shifts for the dominant peaks of intact leaves were from 16 to 20 ppm, which is in good accordance with the peak for the Al-catechin complex. The chemical shifts for Al complexes formed with chlorogenic, gallic, citric, malic and oxalic acid were from 14 to 21 ppm. On the basis of the NMR results and leaf constitution, we concluded that most of the Al was bound to catechins, while some portion was bound to phenolic and organic acids. However, peaks for Al-F at ca − 1 ppm were only detectable in one spectrum of mature leaves.

Fractionation of apple procyanidins by size-exclusion chromatography

Oligomeric constituents of apple procyanidins were fractionated by size-exclusion chromatography using a TSKgel Toyopearl HW-40F column. The best separation was obtained using a mobile phase of acetone-8 M urea (6:4; adjusted to pH 2) at a flow-rate of 1.0 ml/min. In this chromatographic system, the use of 8 M urea in the mobile phase resulted in a molecular sieve effect without any surface affinity interaction between the gel beads and the procyanidin molecules. Each fraction obtained was examined by reversed-phase high-performance liquid chromatography and time-of-flight mass spectrometry. The order of elution of the procyanidins from the column was coincident with their degree of polymerization.

Aluminium kinetics in the tea plant using 27Al and 19F NMR

Abstract To clarify aluminium kinetics in the tea plant, 27 Al and 19 F NMR spectroscopy was applied to the analysis of intact tissues. Although most of t

Triacylated anthocyanins from Ajuga reptans flowers and cell cultures

Four anthocyanins were isolated from Ajuga reptans flowers and one from the cell cultures. By FAB mass spectrometry measurements, the structures of these pigments were determined as delphinidin and cyanidin glucosides acylated with two cinnamic acids, while three of them were also malonylated. A delphinidin-based pigment in the crude extract from cell cultures was identical to the major flower pigment as shown by HPLC co-chromatography. Moreover, by application of 1H and 13C NMR consisting of DQF-COSY, NOESY, ROESY, 2D-HOHAHA, HSQC and HMBC methods, the structures of two new anthocyanins were identified as delphinidin and cyanidin 3-O-(2-O-(6-O-(E)-p-coumaryl-beta-D-glucopyranosyl)-(6-O-(E)-p- coumaryl)-beta-D-glucopyranosyl)-5-O-(6-O-malonyl-beta-D-glucopyranoside ). The deacylated anthocyanins were confirmed as delphinidin and cyanidin 3-sophoroside-5-glucosides.

Estimated Daily Intake and Seasonal Food Sources of Quercetin in Japan

Quercetin is a promising food component, which can prevent lifestyle related diseases. To understand the dietary intake of quercetin in the subjects of a population-based cohort study and in the Japanese population, we first determined the quercetin content in foods available in the market during June and July in or near a town in Hokkaido, Japan. Red leaf lettuce, asparagus, and onions contained high amounts of quercetin derivatives. We then estimated the daily quercetin intake by 570 residents aged 20–92 years old in the town using a food frequency questionnaire (FFQ). The average and median quercetin intakes were 16.2 and 15.5 mg day−1, respectively. The quercetin intakes by men were lower than those by women; the quercetin intakes showed a low correlation with age in both men and women. The estimated quercetin intake was similar during summer and winter. Quercetin was mainly ingested from onions and green tea, both in summer and in winter. Vegetables, such as asparagus, green pepper, tomatoes, and red leaf lettuce, were good sources of quercetin in summer. Our results will help to elucidate the association between quercetin intake and risks of lifestyle-related diseases by further prospective cohort study and establish healthy dietary requirements with the consumption of more physiologically useful components from foods.

Acylated anthocyanidin 3-sophoroside-5-glucosides from Ajuga reptans flowers and the corresponding cell cultures

Four anthocyanins from Ajuga reptans flowers and its cell cultures were isolated, and a fifth was also characterized by HPLC-mass spectrometry. By means of chemical and spectroscopic analyses, their structures were identified as delphinidin 3-(p-coumaroyl-feruloyl)sophoroside-5-malonylglucoside, delphinidin 3-(diferuloyl)sophoroside-5-malonylglucoside, and cyanidin 3-(di-p-coumaroyl)sophoroside-5-glucoside, respectively. The other two were tentatively identified as delphinidin 3-(diferuloyl)sophoroside-5-glucoside and cyanidin 3-(feruloyl-p-coumaroyl)sophoroside-5-malonylglucoside. In neutral aqueous solution, the crude extract from A. reptans flower cell cultures and the major anthocyanin cyanidin 3-(di-p-coumaroyl)sophoroside-5-malonylglucoside were more stable than cyanidin 3-glucoside, and also prevented more efficiently peroxidation than did the latter. A. reptans flower cell culture anthocyanins may have a potential as natural colorants for food utilities or other purposes.

Purine base pattern of camellia irrawadiensis

Abstract Theobromine and caffeine in the flush shoot leaves of hybrids of tea and other camellia plants were assayed by HPLC. In C. sinensis and C. taliensis of section Thea the caffeine content exceeded 2% and the theobromine content was below 0.2%. However, in C. irrawadiensis of the same section, the theobromine content was more than 0.5% while the caffeine content was below 0.02%. The theobromine content of tea hybrids was also below 0.2%. In sections other than Thea, C. sasanqua, C. japonica and C. vernalis did not contain detectable amounts of theobromine or caffeine.

Extraction and identification of antioxidant components from Artemisia capillaris herba

The antioxidant activities of various organic solvent extracts from Artemisia capillaris herba were investigated. The results indicated that methanol extracts of Artemisia capillaris herba possessed higher contents of phenolic compounds and showed stronger antioxidant activities than other organic solvent extracts. The methanol extracts of Artemisia capillaris herba exhibited 91.1% of the scavenging effect at a dose of 200 ppm on the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and showed strong antioxidant activity in the Β-carotene bleaching system. The methanol extracts were separated into three fractions by preparative HPLC using a Wakopak C18 reversed-phase column. After purifing with preparative HPLC, AC-1, 2 and 3 compounds were obtained. Their structures were established as chlorogenic acid (AC-1), 3,5-dicaffeoylquinic acid (AC-2) and 3,4-dicaffeoylquinic acid (AC-3) on the basis of UV-vis spectral, HPLC and FAB-MS data. The scavenging effect of purified compounds on DPPH radical equaled that of tert-butyl-4-hydroxytoluene (BHT) and α-tocopherol at a dose of 10 ppm.

Binding of Barley and Wheat α-Thionins to Polysaccharides

An antimicrobial peptide termed BCP-2 was purified from barley grain by chitin-affinity treatment and HPLC. The results of amino acid analysis and mass spectrometry of BCP-2 indicate that the peptide is very similar to barley α-thionin. BCP-2 and wheat α1-thionin were also bound to β-glucan but not to starch. The binding of BCP-2 to laminarin (β-1,3-1,6-glucan) and laminarioligosaccharides was supported by fluorescence polarization data. This is the first report on the binding of α-thionins to polysaccharide containing chitin and β-1,3-glucan, which construct fungal cell walls.