Formation of phenol compounds in various cultivars of wheat (Triticum aestivum L.)

The formation of soluble phenol compounds, including flavonols, was studied in winter (Erythrospermum, Lutescens 230, and R 47-28) and spring cultivars (Lada) of wheat (Triticum aestivum L.). The contents of soluble phenol compounds and flavonols were 1.8-2.6 and 0.5-1.3 mg/kg fresh weight, respectively. These results illustrate the similarity of phenol metabolism in leaves of winter and spring wheat cultivars. The exception was the cultivar R 47-28 that accumulated the maximum amount of phenol compounds (e.g., flavonols). In this cultivar the ratio of flavonols reached 50% of total soluble phenol content. In other cultivars, this parameter did not exceed 25-35%. The data indicate that the cultivar R 47-28 differs from other wheat cultivars in the metabolism of phenol compounds. The observed differences are probably related to genetic modifications of the cultivar R 47-28 during selection.     

Antioxidant flavonols from fruits, vegetables and beverages: measurements and bioavailability

Flavonols are polyphenolic secondary plant metabolites that are present in varying levels in commonly consumed fruits, vegetables and beverages. Flavonols have long held an interest for nutritionists, which has increased following a Dutch study in the early 1990's showing that dietary intake of flavonols was inversely correlated with the incidence of coronary heart disease. The main factors that have hindered workers in the field of flavonol research are (i) the accurate measurement of these compounds in foods and biological samples, and (ii) a dearth of information on their absorption and metabolism. This review aims to highlight the work of the authors in attempting to clarify the situation. The sensitive and selective HPLC procedure to identify and quantify common flavonols and their sugar conjugates is described. In addition, the results of an on-going screening program into the flavonol content of common produce and beverages are presented. The bioavailability of dietary flavonols is discussed with reference to an intervention study with onions, as well as pilot studies with tea, red wine and cherry tomatoes. It is concluded that flavonols are absorbable and accumulate in plasma and that consuming high flavonol-containing varieties of fruits and vegetables and particular types of beverages could increase their circulatory levels.     

Addition of milk does not affect the absorption of flavonols from tea in man

Tea is a major source of flavonols, a subclass of antioxidant flavonoids present in plant foods which potentially are beneficial to human health. Milk added to tea, a frequent habit in the United Kingdom, could inhibit absorption of tea flavonoids, because proteins can bind flavonoids effectively. Eighteen healthy volunteers each consumed two out of four supplements during three days: black tea, black tea with milk, green tea and water. A cup of the supplement was consumed every 2 hours each day for a total of 8 cups a day. The supplements provided about 100 μmol quercetin glycosides and about 60 – 70 μmol kaempferol glycosides. Addition of milk to black tea (15 ml milk to 135 ml tea) did not change the area under the curve of the plasma concentration-time curve of quercetin or kaempferol. Plasma concentrations reached were about 50 nM quercetin and 30 – 45 nM kaempferol. We conclude that flavonols are absorbed from tea and that their bioavailability is not affected by addition of milk.     

Addition of milk does not affect the absorption of flavonols from tea in man

Tea is a major source of flavonols, a subclass of antioxidant flavonoids present in plant foods which potentially are beneficial to human health. Milk added to tea, a frequent habit in the United Kingdom, could inhibit absorption of tea flavonoids, because proteins can bind flavonoids effectively. Eighteen healthy volunteers each consumed two out of four supplements during three days: black tea, black tea with milk, green tea and water. A cup of the supplement was consumed every 2 hours each day for a total of 8 cups a day. The supplements provided about 100 μmol quercetin glycosides and about 60 - 70 μmol kaempferol glycosides. Addition of milk to black tea (15 ml milk to 135 ml tea) did not change the area under the curve of the plasma concentration-time curve of quercetin or kaempferol. Plasma concentrations reached were about 50 nM quercetin and 30 - 45 nM kaempferol. We conclude that flavonols are absorbed from tea and that their bioavailability is not affected by addition of milk.     

Formation of phenolic compounds in various cultivars of wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

The formation of soluble phenolic compounds, including flavonols, was studied in winter (Erythrospermum , Lutescens 230, and R 47-28) and spring cultivars (Lada) of wheat (Triticum aestivum L.). The contents of soluble phenolic compounds and flavonols were 1.8–2.6 and 0.5–1.3 mg/g fresh weight, respectively. These results illustrate the similarity of phenol metabolism in leaves of winter and spring wheat cultivars. The exception was the cultivar R 47-28 that accumulated the maximum amount of phenolic compounds (e.g., flavonols). In this cultivar the ratio of flavonols reached 50% of total soluble phenol content. In other cultivars, this parameter did not exceed 25–35%. The data indicate that the cultivar R 47-28 differs from other wheat cultivars in metabolism of phenolic compounds. The observed differences are probably related to genetic modifications of the cultivar R 47-28 during selection.Translated from Prikladnaya Biokhimiya i Mikrobiologiya, Vol. 41, No. 1, 2005, pp. 113–116.Original Russian Text Copyright © 2005 by Zagoskina, Olenichenko, Chzhou Yunvei, Zhivukhina.     

茶园间作柑桔杨梅或吊瓜对叶蝉及蜘蛛类群数量和空间格局的影响

为评价茶园间作几种常见经济作物对重要害虫假眼小绿叶蝉及其主要天敌蜘蛛类群数量和空间格局的影响,遂选乌牛早品种纯茶园、乌牛早分别与柑桔、杨梅和吊瓜的间作茶园、以及安吉白茶与吊瓜间作茶园,2007年9月上旬—2008年12月下旬,每旬1次调查茶丛上、中、下层叶蝉和各种蜘蛛的数量。结果表明:(1)与纯茶园相比,间作茶园叶蝉种群数量和蜘蛛类群个体数量显著地增加,间作茶园蜘蛛种数显著地增加;(2)间作茶园茶丛上、中、下层叶蝉、蜘蛛个体数量分布明显区别于纯茶园茶丛上、中、下层叶蝉、蜘蛛个体数量分布;(3)茶丛上层的嫩梢是制作高档茶的原料,而纯茶园茶丛上层叶蝉虫口百分率为54.16%,间作茶园茶丛上层叶蝉虫口百分率皆减小,并且叶蝉高峰期间蜘蛛的跟随效应增强;(4)间作增加了经济收入并减少了防治次数。认为:(1)间作可在一定程度上调控叶蝉种群、蜘蛛类群的数量和空间格局;(2)间作可减轻叶蝉为害造成的产值损失,增强了茶园群落对于叶蝉的自然控制潜能。     

Tea flavonols in cardiovascular disease and cancer epidemiology

Tea is an important dietary source of flavonols in countries such as the Netherlands, the United Kingdom and Japan. Flavonols may have beneficial health effects because of their antioxidant properties and their inhibitory role in various stages of tumor development in animal studies. The association between flavonol intake and cancer risk was investigated in three prospective studies (Zutphen Elderly Study in the Netherlands, a Finnish cohort, and the Netherlands Cohort Study). Only one study (Finnish cohort) showed an inverse association with cancer mortality. The intake of flavonols with subsequent cardiovascular disease was studied in six prospective epidemiological studies. In some populations (Seven Countries Study, Zutphen Elderly Study, a Finnish cohort) a clear protective effect was observed. In a large US cohort, a protective effect was only found in a subgroup with previous history of coronary heart disease, whereas in Welsh men, flavonol intake, mainly from tea, was associated with an increased risk of coronary heart disease. These conflicting results may be due to confounding by coronary risk factors associated with tea consumption. The question of whether flavonols protect against cardiovascular disease remains still open; a protective effect of flavonols against cancer is less likely.     

On some biochemical physiognomies of two common Darjeeling tea cultivars in relation to blister blight disease

Abstract

Tea, Camellia sinensis (L.) O. Kuntze, an agro-based industry, is considered as one of the prime sector of exporting resources and thus considered as “cash-crop”. Earlier report shows that tea is native to eastern and northern India, which was cultivated and consumed there since long back. Presently, more scientific reports confirmed the health-benefit traits of tea and awareness increased to a greater extent and in this regard, tea has gained its best worldwide popularity. Darjeeling Tea attained its highest acceptance globally for its pre-eminence in flavour, colour and taste and thus crop improvement is the prime interest to the Indian Scientific Community. Blister blight disease, a common disorder of tea bushes (Exobasidium vexans, a Basidiomycetes fungus) causes drastic damage of tea plantation. Depending on quality production, two common cultivars were released by TRA, Jorhat, Assam viz. Bannockburn – 157 (B-157) and Ambei Valai - 2 (AV-2), of which B-157 is susceptible to the Blister Blight and AV-2 is fairly resistant cultivar. Some biochemical considerations between the two cultivars have been made here for understanding the biochemical reasons behind the resistant characteristics. Plant secondary metabolites, like total phenol, proanthocynadin, total soluble protein provide defending feature against disease onset. AV-2 cultivar shows advantage over B-157 in these regard. Depending on band intensity analysis of native gels, acid phosphatase, catechol oxidase, peroxidase and superoxide dismutase occur in superior amount in AV-2 cultivar than that of B-157. The specific role of these enzymes in blister blight disease compatibility of two cultivars studied has been discussed.     

Antioxidant properties of flavonol glycosides from tea

We have determined the antioxidant activity of the major flavonols found in tea: a monoglycoside, a diglycoside and two triglycosides of kaempferol and three monoglycosides, a diglycoside and two triglycosides of quercetin. The Trolox equivalent antioxidant capacity (TEAC) and inhibition of iron/ascorbate-induced lipid peroxidation of phosphatidyl choline vesicles were measured. In the aqueous phase TEAC assay, the quercetin monoglycosides and diglycoside were approximately half as effective as quercetin aglycone. The quercetin triglycosides were much less effective than the monoglycosides and the diglycoside. The kaempferol glycosides were 32-39% less effective in the aqueous phase antioxidant assay compared to the kaempferol aglycone. Quercetin monoglycosides and diglycoside were potent inhibitors of lipid peroxidation, in contrast to the triglycoside which was much less effective. All the kaempferol glycosides were significantly less potent inhibitors of lipid peroxidation compared to the kaempferol aglycone. The compounds described herein demonstrate the antioxidant activity of the major flavonols in tea and indicate the effect of substituting a range of sugar moieties in the phenolic C ring.     

(Z)-3-hexenyl and trans-linalool 3,7-oxide beta-primeverosides isolated as aroma precursors from leaves of a green tea cultivar.

6-O-beta-D-Xylopyranosyl-beta-D-glucopyranosides (beta-primeverosides) of (Z)-3-hexenol and trans-linalool 3,7-oxide were newly isolated from fresh leaves of a tea cultivar (Camellia sinensis var. sinensis cv. Yabukita). In addition, the already identified beta-primeverosides of benzyl alcohol, methyl salicylate, and trans-linalool 3,6-oxide from an oolong tea cultivar were isolated from the Yabukita cultivar. It was confirmed that all aglycones of the linalool oxide glycosides isolated here were of the optically active S-form by chiral GC after enzymatic hydrolysis with glycosidase.     

Antioxidant properties of flavonol glycosides from tea

Abstract

We have determined the antioxidant activity of the major flavonols found in tea: a monoglycoside, a diglycoside and two triglycosides of kaempferol and three monoglycosides, a diglycoside and two triglycosides of quercetin. The Trolox equivalent antioxidant capacity (TEAC) and inhibition of iron/ascorbate-induced lipid peroxidation of phosphatidyl choline vesicles were measured. In the aqueous phase TEAC assay, the quercetin monoglycosides and diglycoside were approximately half as effective as quercetin aglycone. The quercetin triglycosides were much less effective than the mono-glycosides and the diglycoside. The kaempferol glycosides were 32–9% less effective in the aqueous phase antioxidant assay compared to the kaempferol aglycone. Quercetin monoglycosides and diglycoside were potent inhibitors of lipid peroxidation, in contrast to the triglycoside which was much less effective. All the kaempferol glycosides were significantly less potent inhibitors of lipid peroxidation compared to the kaempferol aglycone. The compounds described herein demonstrate the antioxidant activity of the major flavonols in tea and indicate the effect of substituting a range of sugar moieties in the phenolic C ring.     

主要产茶国茶树资源与红茶育种研究进展

茶树种质资源是茶树品种选育的材料基础。本文系统阐述了世界茶叶主产国在茶树资源收集、保存和鉴定评价方面所取得的进展,着重对红茶化学特性、红茶育种的研究成果进行论述。同时,对未来茶树育种的发展方向进行探讨。     

Apple flavonols during fruit adaptation to solar radiation: spectral features and technique for non-destructive assessment

Spectral properties of flavonols of three varieties (Golden Delicious, Antonovka, and Renet Simirenko) of anthocyanin-free apple fruit were investigated with reflectance spectroscopy. The results of spectral and biochemical analyses suggested that fruit reflectance in a broad spectral range 365-430 nm is strongly dependent on and, in sunlit fruit surfaces, governed by flavonols. The build up of peel flavonols (mainly rutin and other quercetin glycosides) resulted in a dramatic decrease of fruit reflectance in this range, flattening of the spectrum, and extending the region with low reflectance (4-5%) to ca. 410 nm. The spectral features observed suggest that flavonols contribute significantly to screening of excessive radiation, not only UV-A, but in the short-wave bands of chlorophyll and carotenoid absorption in the visible part of the spectrum as well. To retrieve quantitatively flavonol content from reflectance spectra, we tested the applicability of an inversion technique developed for non-destructive leaf pigment assessment. The model for flavonol content assessment was suggested in the form (R(-1)410 - R(-1)460)R800, where Rlambda is reflectance at wavelength lambda. The model was linearly related to flavonol content between 8 and 220nmol/cm2 with the coefficient of determination r2=0.92 and root mean square error of flavonol estimation of 20 nmol/ cm2 regardless of cultivar, chlorophyll, and carotenoid content.     

Glycosidic flavonoids as rat-liver injury preventing compounds from green tea

A glycosidic flavonoids-rich fraction from green tea leaves was purified to isolate five glycosidic flavonoids, guided by the detection of a preventive effect on D-galactosamine-induced liver injury in rats. These were identified as a flavone C-glycoside (1) and trisaccharide flavonols (2-5) based on the spectroscopic analyses. These compounds suppressed the D-galactosamine-induced increase of plasma alanine aminotransferase and asparatate aminotransferase activities in rats.     

Black tea represents a major source of dietary phenolics among regular tea drinkers

The phenolic composition and antioxidant activities [TEAC, ORAC, FRAP] of consumer brews (1 tea bag in 230 ml for 1 min) of seven different brands of black tea from the British market were investigated. The main phenolic compounds identified were epigallocatechin gallate, four theaflavins, as well as epicatechin gallate, theogallin (tentative assignment), quercetin-3-rutinoside and 4-caffeoyl quinic acid. Thearubigins represented an estimated 75-82% of the total phenolics. Further, polyphenol fractions were in decreasing order theaflavins, flavan-3-ols, flavonols, gallic acids and hydroxycinnamates. On average, a cup of a consumer brew of black tea is providing polyphenols at the level of 262 mg GAE/serving, of which 65 mg were assigned to individual polyphenols. The antioxidant activity of black tea preparations is higher than that of most reported dietary agents on a daily basis. Correlations were observed between the antioxidant activities and the sum of all quantified polyphenols by HPLC analysis as well as with the total phenolics. Treatment of the black tea brew with simulated gastric juice resulted in a significant increase of the identified theaflavins implying a partial cleavage of thearubigins in the environment of the gastric lumen. Therefore, black tea can be considered to be a rich source of polyphenols and/or antioxidants.     

Black Tea Represents a Major Source of Dietary Phenolics Among Regular Tea Drinkers

The phenolic composition and antioxidant activities [TEAC, ORAC, FRAP] of consumer brews (1 tea bag in 230 ml for 1 min) of seven different brands of black tea from the British market were investigated. The main phenolic compounds identified were epigallocatechin gallate, four theaflavins, as well as epicatechin gallate, theogallin (tentative assignment), quercetin-3-rutinoside and 4-caffeoyl quinic acid. Thearubigins represented an estimated 75-82% of the total phenolics. Further, polyphenol fractions were in decreasing order theaflavins, flavan-3-ols, flavonols, gallic acids and hydroxycinnamates. On average, a cup of a consumer brew of black tea is providing polyphenols at the level of 262 mg GAE/serving, of which 65 mg were assigned to individual polyphenols. The antioxidant activity of black tea preparations is higher than that of most reported dietary agents on a daily basis. Correlations were observed between the antioxidant activities and the sum of all quantified polyphenols by HPLC analysis as well as with the total phenolics. Treatment of the black tea brew with simulated gastric juice resulted in a significant increase of the identified theaflavins implying a partial cleavage of thearubigins in the environment of the gastric lumen. Therefore, black tea can be considered to be a rich source of polyphenols and/or antioxidants.     

Absorption of ferulic acid from low-alcohol beer

Flavonoids and monophenolic compounds have been well-described over recent years for their properties as antioxidants and scavengers of reactive oxygen and nitrogen species. A number of epidemiological studies implicate a role for flavonoids in reducing the risk of coronary heart disease. In particular, the focus has been on flavonol-rich fruit and vegetables and flavonoid-rich beverages, especially tea and red wine. Mechanisms of protection are unclear since the absorption, distribution, metabolism and elimination of dietary phenolics have not yet been extensively investigated. Here we report the bioavailability of ferulic acid, 4-hydroxy-3-methoxy-cinnamic acid, the major hydroxycinnamate in beer. Studies of the pharmacokinetics of urinary excretion of ferulic acid from low alcohol beer consumption in humans have been undertaken. The results show that ferulic acid is absorbed with a peak time for maximal excretion of ca. 8 h and the mean cumulative amount excreted is 5.8±3.2 mg. These findings are consistent with the uptake of ferulic acid from dietary sources, such as tomatoes, and suggest that ferulic acid is more bioavailable than individual dietary flavonoids and phenolics so far studied.     

优质红碎茶资源的鉴定与筛选

我国生产的红碎茶在国际市场竞争力一直不强,缺乏适制红碎茶品种是原因之一.近年来,对原生起源中心云南茶区为主的120份茶树资源进行系统的发掘和鉴定,探明了我国适制红碎茶资源的基本情况,筛选出一批优异资源.加速这些资源的利用,将促进我国红碎茶品种的改良和红碎茶品质的提高.     

Biochemical analysis as a measure of dynamic equilibrium in genomic setup during processing of tea

The genetic characteristic such as ‘fermentability’ of a tea cultivar could be utilised to obtain maximum colour/bloom during manufacture of black tea. Pigment profile analysis has been used as a tool to assess the characteristic of a black tea brew. Fine plucking and optimum processing conditions are two basic requirements in producing good quality black tea. The assamica variety is characterised by linalool content while geraniol is specific in chinary clones. The higher amounts of terpenoids improved the flavour characteristic of second flush tea of north east India in general and Darjeeling in particular. Further, the surplus fatty acid degradation products lower the quality of black tea during monsoon flush. Presented at the 3rd National Symphosium on Bioorganic Chemistry, 1987, Hyderabad.     

Absorption of ferulic acid from low-alcohol beer

Flavonoids and monophenolic compounds have been well-described over recent years for their properties as antioxidants and scavengers of reactive oxygen and nitrogen species. A number of epidemiological studies implicate a role for flavonoids in reducing the risk of coronary heart disease. In particular, the focus has been on flavonol-rich fruit and vegetables and flavonoid-rich beverages, especially tea and red wine. Mechanisms of protection are unclear since the absorption, distribution, metabolism and elimination of dietary phenolics have not yet been extensively investigated. Here we report the bioavailability of ferulic acid, 4-hydroxy-3-methoxy-cinnamic acid, the major hydroxycinnamate in beer. Studies of the pharmacokinetics of urinary excretion of ferulic acid from low alcohol beer consumption in humans have been undertaken. The results show that ferulic acid is absorbed with a peak time for maximal excretion of ca. 8 h and the mean cumulative amount excreted is 5.8±3.2 mg. These findings are consistent with the uptake of ferulic acid from dietary sources, such as tomatoes, and suggest that ferulic acid is more bioavailable than individual dietary flavonoids and phenolics so far studied.