The genotypic variation of the antioxidant potential of different tomato varieties

There is increasing interest in the ability of diets rich in polyphenols to modulate age-related diseases and promote healthy ageing. We have conducted a pilot experiment with eight tomato varieties to correlate the total antioxidant capacity of the tomato variants with the specific constituent flavonoids present. A strong correlation was observed with the flavonol rhamnoglucoside rutin but not with other flavonoids, such as naringenin chalcone, or hydroxycinnamates, such as chlorogenic, which are also present in the tomato. To test the rigor of this correlation a second study was undertaken with a further 37 tomato varieties selected for low, medium and high rutin levels. We show that the flavonol rutin contributes to the greatest extent to the antioxidant capacity of tomatoes and suggest that this flavonoid may be a useful target for up-regulation in tomatoes in order to improve their antioxidant status.     

Overexpression of petunia chalcone isomerase in tomato results in fruit containing increased levels of flavonols

Tomatoes are an excellent source of the carotenoid lycopene, a compound that is thought to be protective against prostate cancer. They also contain small amounts of flavonoids in their peel ( approximately 5-10 mg/kg fresh weight), mainly naringenin chalcone and the flavonol rutin, a quercetin glycoside. Flavonols are very potent antioxidants, and an increasing body of epidemiological data suggests that high flavonoid intake is correlated with a decreased risk for cardiovascular disease. We have upregulated flavonol biosynthesis in the tomato in order to generate fruit with increased antioxidant capacity and a wider range of potential health benefit properties. This involved transformation of tomato with the Petunia chi-a gene encoding chalcone isomerase. Resulting transgenic tomato lines produced an increase of up to 78 fold in fruit peel flavonols, mainly due to an accumulation of rutin. No gross phenotypical differences were observed between high-flavonol transgenic and control lines. The phenotype segregated with the transgene and demonstrated a stable inheritance pattern over four subsequent generations tested thus far. Whole-fruit flavonol levels in the best of these lines are similar to those found in onions, a crop with naturally high levels of flavonol compounds. Processing of high-flavonol tomatoes demonstrated that 65% of flavonols present in the fresh fruit were retained in the processed paste, supporting their potential as raw materials for tomato-based functional food products.     

Pathway engineering for healthy phytochemicals leading to the production of novel flavonoids in tomato fruit

Flavonoids are a large family of plant polyphenolic secondary metabolites. Although they are widespread throughout the plant kingdom, some flavonoid classes are specific for only a few plant species. Due to their presumed health benefits there is growing interest in the development of food crops with tailor-made levels and composition of flavonoids, designed to exert an optimal biological effect. In order to explore the possibilities of flavonoid engineering in tomato fruits, we have targeted this pathway towards classes of potentially healthy flavonoids which are novel for tomato. Using structural flavonoid genes (encoding stilbene synthase, chalcone synthase, chalcone reductase, chalcone isomerase and flavone synthase) from different plant sources, we were able to produce transgenic tomatoes accumulating new phytochemicals. Biochemical analysis showed that the fruit peel contained high levels of stilbenes (resveratrol and piceid), deoxychalcones (butein and isoliquiritigenin), flavones (luteolin-7-glucoside and luteolin aglycon) and flavonols (quercetin glycosides and kaempferol glycosides). Using an online high-performance liquid chromatography (HPLC) antioxidant detection system, we demonstrated that, due to the presence of the novel flavonoids, the transgenic tomato fruits displayed altered antioxidant profiles. In addition, total antioxidant capacity of tomato fruit peel with high levels of flavones and flavonols increased more than threefold. These results on genetic engineering of flavonoids in tomato fruit demonstrate the possibilities to change the levels and composition of health-related polyphenols in a crop plant and provide more insight in the genetic and biochemical regulation of the flavonoid pathway within this worldwide important vegetable.     

Effects of Food Processing on Flavonoids and Lycopene Status in a Mediterranean Tomato Variety

This research is focused on the antioxidant properties of dietary components, in particular phenolics and carotenoids and the assessment of the contribution of the combined antioxidants to the total antioxidant activity (TAA) of tomato fruit. The aim of this study was to analyse the effects of processing on the antioxidant properties of tomato. The effects of three different methods of processing fresh tomatoes into tomato sauce were investigated with respect to the antioxidant properties of the fruit. Identification and quantification of the main carotenoids and flavonoids present in tomatoes was achieved by HPLC analysis and the effect on the concentration and availability of these compounds was investigated at different stages of the processing. The processing affected mainly naringenin causing a reduction in the concentration. Conversely, levels of chlorogenic acid were increased suggesting an improvement in availability of this compound to extraction. The concentration of all- trans -lycopene was also increased following processing. Less than 10% isomerisation of all- trans -lycopene to the cis form was detected for all the methods analysed. The effects of processing on the overall antioxidant activity support the theory of a general improvement in availability of individual antioxidants. For both hydrophilic and lipophilic extracts TAA values were increased.     

Effects of food processing on flavonoids and lycopene status in a Mediterranean tomato variety

This research is focused on the antioxidant properties of dietary components, in particular phenolics and carotenoids and the assessment of the contribution of the combined antioxidants to the total antioxidant activity (TAA) of tomato fruit. The aim of this study was to analyse the effects of processing on the antioxidant properties of tomato. The effects of three different methods of processing fresh tomatoes into tomato sauce were investigated with respect to the antioxidant properties of the fruit. Identification and quantification of the main carotenoids and flavonoids present in tomatoes was achieved by HPLC analysis and the effect on the concentration and availability of these compounds was investigated at different stages of the processing. The processing affected mainly naringenin causing a reduction in the concentration. Conversely, levels of chlorogenic acid were increased suggesting an improvement in availability of this compound to extraction. The concentration of all- trans -lycopene was also increased following processing. Less than 10% isomerisation of all- trans -lycopene to the cis form was detected for all the methods analysed. The effects of processing on the overall antioxidant activity support the theory of a general improvement in availability of individual antioxidants. For both hydrophilic and lipophilic extracts TAA values were increased.     

Effect of irrigation on yield parameters and antioxidant profiles of processing cherry tomato

A two-year (2010 and 2011) open field experiment was conducted to study the effect of drip irrigation and seasonal variation on the yield parameters and main bioactive components, carotenoids (mainly all trans, cis lycopene, and β-carotene), polyphenols (chlorogenic acid, caffeic acid, gallic acid, quercetin, rutin, naringin, etc.), and tocopherols of processing Strombolino F1 cherry tomatoes. The irrigated plants (STI) gave a higher marketable yield (61% and 101% respectively), and rain fed plants showed a yield loss. Water supply had a strong positive (R²=0.98) effect on marketable yield in 2011, but weak (R²=0.69) in 2010. In both years, the antioxidant concentration (all carotenoids, total polyphenols, tocopherols) showed a decrease with irrigation. Water supply affected the composition of carotenoids to a considerable extent. The optimum water supply treatment gave a lower proportion of lycopene than the rain fed control (STC) treatment. We observed significant negative correlation between rutin concentration and irrigation. The α-tocopherol concentration was significantly higher in STC treatments. Irrigation negatively influenced antioxidant concentrations of cherry tomato fruits, but higher yield could account for the concentration loss of individual fruits by higher antioxidant production per unit area.     

The effect of flavones and flavonols on colonization of tomato plants by arbuscular mycorrhizal fungi of the genera Gigaspora and Glomus

No clear data are available on how flavonoids from different chemical groups affect root colonization by arbuscular mycorrhizal fungi (AMF) and whether flavonoids affecting the presymbiotic growth of AMF also affect root colonization by AMF. In the present work, we compared the effect of flavones (chrysin and luteolin) and flavonols (kaempferol, morin, isorhamnetin, and rutin) on root colonization (number of entry points and degree of root colonization) of tomato plants (Lycopersicum esculentum L.) with the effect of these flavonoids on the presymbiotic growth of these AMF, which has been reported in a recent study. With all tested AMF (Gigaspora rosea, Gigaspora margarita, Glomus mosseae, and Glomus intraradices) a correlation between the number of entry points and the percentage of root colonization was found. When the number of entry points was high, root colonization was also enhanced. Application of the flavones chrysin and luteolin and of the flavonol morin increased the number of entry points and the degree of colonization,whereas the flavonols kaempferol, isorhamnetin, and rutin showed no effect. These results show that in contrast to their effect on the presymbiotic growth of the AMF on the level of root colonization, the tested flavonoids do not exhibit a genus- and species-specificity. Moreover, comparison of our data with the data obtained by J.M. Scervino, M.A. Ponce, R. Erra-Bassells, H. Vierheilig, J.A. Ocampo, and A. Godeas. (2005a. J. Plant Interact. 15: 22-30) indicates that a positive effect on the hyphal growth of AMF does not necessarily result in an enhanced AM root colonization, further indicating that the mode of action of flavonoids at the level of root colonization is more complex.     

Antioxidant status and mineral contents in tissues of rutin and baicalin fed rats

The versatile benefit effects of flavonoids lead some nutritionists to believe that they are micronutrients. However, excess intake of flavonoids may cause side effects. In this paper, the effects produced by a higher intake of rutin and baicalin on antioxidant status as well as trace minerals such as iron, copper and zinc in rat tissues were studied. When rats were fed a rutin or baicalin containing diet (1%) for 20 days, the body weight gain was lower than that of the control group. Both rutin and baicalin caused significant a decrease of catalase activity and a moderate increase of total superoxide dismutase activity in the liver. The total antioxidant status of flavonoid fed rats was increased in the liver but decreased in the serum. In comparison to the control group, the lipid peroxidation level in the liver of the rutin fed group was significantly decreased; however, there was no statistical significance in the liver of the baicalin fed group and the brain of both flavonoids groups. The liver homogenates of both flavonoid fed rats significantly inhibited alkyl radical-induced lipid peroxidation. The iron contents in the liver of flavonoid fed rats were significantly decreased; rutin also caused zinc and copper decrease in the liver. These results indicated that high flavonoid intake can improve rat antioxidant systems in the liver; while it can also cause a trace mineral decrease and, in turn, reduce the activities of some metal-containing enzymes and may cause harmful effects on health.     

The compositional characterisation and antioxidant activity of fresh juices from sicilian sweet orange (Citrus sinensis L. Osbeck) varieties

Epidemiological evidence has suggested that consumption of fruit and vegetables reduces the risk of both cancer and cardiovascular diseases, potentially through the biological actions of components such as vitamin C, vitamin E, flavonoids and carotenoids. Citrus species are extremely rich sources in vitamin C and flavanones, a class of compounds which belongs to the flavonoids family. A comparison of the phenolic compositions, the ascorbic acid contents and the antioxidant activities of fresh Sicilian orange juices from pigmented (Moro, Tarocco and Sanguinello) and non-pigmented (Ovale, Valencia and Navel) varieties of orange (Citrus sinensis L. Osbeck), was undertaken. The simultaneous characterisation and quantification of the major flavanone, anthocyanin and hydroxycinnamate components were attained by HPLC with diode array detection. Differences between varieties in terms of the flavanone glycoside content, particularly hesperidin, were observed, with the Tarocco juices reporting the highest content. Furthermore, cyanidin-3-glucoside and cyanidin-3-(6"-malonyl)-glucoside were predominant in all the pigmented varieties, but their concentration was higher in the juices of the Moro variety. Quantitatively, the major antioxidant component of all juices was ascorbic acid and its concentration was significantly correlated (r = 0.74, P < 0.001) with the total antioxidant activity of the juices, determined in vitro using the ABTS radical cation decolorization assay. Similarly, hydroxycinnamates (r = 0.73, P < 0.01) and anthocyanins (r = 0.98, P < 0.001) content showed a good correlation with the determined antioxidant capacity. Therefore orange juices, particularly those rich in anthocyanins, may represent a significant dietary source of flavonoids.     

低海拔地区黑苦荞酚类物质含量、组成及抗氧化活性研究

为探究黑苦荞的市场利用价值,该研究选择种植于湖北江汉平原低海拔地区的川荞1号和九江苦荞作为材料,分析苦荞籽粒中游离酚、结合酚、总酚、游离黄酮、结合黄酮和总黄酮的含量,利用DPPH自由基法、ABTS自由基法和铁离子还原抗氧化法(FRAP)三种抗氧化测试模型综合评价其体外抗氧化活性,并运用高效液相色谱(HPLC)技术对其酚类物质的组成进行鉴定。结果表明:(1)川荞1号籽粒的总酚和总黄酮含量显著高于九江苦荞,分别为27.38 mg GAE·g~(-1)DW、31.46 mg RE·g~(-1)DW和12.71 mg GAE·g~(-1)DW、14.68 mg RE·g~(-1)DW;其中游离酚与游离黄酮含量显著高于结合酚与结合黄酮含量,均占总酚和总黄酮含量的79%以上,且九江苦荞中结合酚和结合黄酮的含量高于川荞1号。(2)苦荞籽粒中酚类物质主要由芦丁、槲皮素、表儿茶素、山奈酚、山奈酚-3-芸香糖苷和槲皮素-3-O-芸香糖苷-3'-O-吡喃葡萄糖苷等黄酮类化合物组成,其中游离酚以芦丁和槲皮素为主,结合酚以表儿茶素和芦丁为主。(3)苦荞籽粒提取物均具有一定的抗氧化活性,黑苦荞川荞1号游离态DPPH、ABTS和FRAP抗氧化能力值分别为30.14、11.03、18.84 mg TE·g~(-1)DW,高于九江苦荞,而结合态三种抗氧化能力值低于九江苦荞,但黑苦荞川荞1号总抗氧化能力显著高于九江苦荞。在低海拔地区江汉平原,种植的黑苦荞川荞1号籽粒具有较高含量的酚类物质,符合后续的食品加工的生产要求,市场开发前景广阔。     

Down-regulation of cinnamoyl-CoA reductase in tomato (Solanum lycopersicum L.) induces dramatic changes in soluble phenolic pools

Health-beneficial properties of many secondary plant metabolites have created much interest into the control of their biosynthesis in crop species. Phenolic compounds, including flavonoids, hydroxycinnamates, and tannins, make up an important group of such phytonutrients. They are formed via the phenylpropanoid pathway and share common precursors with lignin, an insoluble cell wall-associated polymer. In this study, the aim was to reduce lignin biosynthesis so as to enhance the availability of these precursors and, thereby, stimulate the production of soluble, potentially health-promoting, phenolic compounds in tomato (Solanum lycopersicum L.). First two tomato genes encoding cinnamoyl-CoA reductase (CCR), a key enzyme in the formation of lignin monomers, were identified and characterized. Transgenic plants exhibiting a reduced lignin content were subsequently obtained through an RNAi strategy targeting one of these genes. As anticipated, the total level of soluble phenolics was higher in stems and leaves of the transformants as compared with control plants. This was correlated with an increased antioxidant capacity of the corresponding plant extracts. Analysis of the soluble phenolic fraction by HPLC-MS revealed that vegetative organs of CCR down-regulated plants contained higher amounts of chlorogenic acid and rutin, and accumulated new metabolites undetectable in the wild type, such as N-caffeoyl putrescine and kaempferol rutinoside. In fruits, CCR down-regulation triggered the moderate accumulation of two new compounds in the flesh, but the total phenolic content was not affected. Although the prospects of exploiting such a strategy for crop improvement are limited, the results provide further insight into the control of the phenylpropanoid pathway in the Solanaceae.     

The introduction of the stilbene synthase gene enhances the natural antiradical activity of Lycopersicon esculentum mill

Tomato (Lycopersicon esculentum) is a vegetable rich in antioxidants, such as lycopene, lutein, and zeaxanthin. Their presence is responsible for the characteristic ability of this product to inhibit the formation of reactive oxygen species, including singlet oxygen. The grapes and wines derived from grapes also contain powerful antioxidants. The antioxidant effect is derived from the polyphenols such as resveratrol and proanthocyanidin. Resveratrol is phytoalexin that is synthesized via the activation of the gene, stilbene synthase (STS). We decided to determine if the introduction of this gene into Lycopersicon esculentum Mill could modify its antioxidant activity. Using Electronic Paramagnetic Resonance (EPR) spectroscopy, which permits the detection of antiradical activity, especially ^•OH (hydroxyl radical), we showed that the antioxidant activity of the products, into which the gene STS had been introduced, was almost double than that of natural products and that their activity was especially pronounced due to ripening. Moreover, resveratrol concentrations in modified tomatoes were much higher than that found in the individual fruit. In the isolated hearts subjected to ischemia/reperfusion, the rats fed with modified tomato exhibited better cardiac performance, reduced myocardial infarct size and decreased number of apoptotic cardiomyocytes, and reduced oxidative stress compared to unmodified tomato or resveratrol alone indicating superior cardioprotective abilities of modified tomatoes.     

Dietary flavonoids interact with trace metals and affect metallothionein level in human intestinal cells

Flavonoids are natural compounds found in food items of plant origin. The study examined systematically the interaction of structurally diverse dietary flavonoids with trace metal ions and the potential impact of dietary flavonoids on the function of intestinal cells. Spectrum analysis was first performed to determine flavonoid-metal interaction in the buffer. Among the flavonoids tested, genistein, biochanin-A, naringin, and naringenin did not interact with any metal ions tested. Members of the flavonol family, quercetin, rutin, kaempferol, flavanol, and catechin, were found to interact with Cu(II) and Fe(III). On prolonged exposure, quercetin also interacted with Mn(II). Quercetin at 1:1 ratio to Cu(II) completely blocked the Cu-dependent color formation from hematoxylin. When quercetin was added to the growth medium of cultured human intestinal cells, Caco-2, the level of metal binding antioxidant protein, metallothionein, decreased. The effect of quercetin on metallothionein was dose and time-dependent. Genistein and biochanin A, on the contrary, increased the level of metallothionein. The interaction between dietary flavonoids and trace minerals and the effect of flavonoids on metallothionein level imply that flavonoids may affect metal homeostasis and cellular oxidative status in a structure-specific fashion.     

Modifying role of dietary factors on the mutagenicity of aflatoxin B1: in vitro effect of plant flavonoids

Eighteen flavonoids have been tested for their ability to inhibit the mutagenicity of aflatoxin B1 (AFB1) towards strains TA100 and TA98 of Salmonella typhimurium provided with a rat liver activation system. These flavonoids belong to 5 different groups: flavone, isoflavone, flavanone, flavanol and flavonol, and many individual members are natural products present in edible portions of a variety of food plants. Several flavonoids exhibited significant inhibitory ability in both strains. Flavonols in general are more active in this regard, while flavanones show a strain-specific response. The flavanol group of compounds did not display any activity. Among the most effective flavonoids are kaempferol, morin, fisetin, biochanin A and the glycoside rutin, all of which exhibit a dose-dependent inhibition pattern. Kaempferol and rutin, in particular, show exceptional activity inasmuch as, on a molar basis, only a 10-fold excess dose of each can inhibit the mutagenic activity of AFB1 in strain TA98 by 50%. The action of flavonoids is possibly mediated through interaction with microsomal activating enzymes. Previous evidence from this laboratory about their inhibitory action on DNA-adduct formation and metabolic activation together with the present results suggests that certain flavonoids, notably polyhydroxylated flavonols, may have potential anticarcinogenic activity against AFB1.     

The small intestine can both absorb and glucuronidate luminal flavonoids.

We have studied the perfusion of the jejunum and ileum in an isolated rat intestine model with flavonoids and hydroxycinnamates and the influence of glycosylation on the subsequent metabolism. Flavone and flavonol glucosides and their corresponding aglycones are glucuronidated during transfer across the rat jejunum and ileum and this glucuronidation occurs without the need for gut microflora. Furthermore, this suggests the presence of glycosidases as well as UDP-glucuronyl transferase in the jejunum. In contrast, quercetin-3-glucoside and rutin are mainly absorbed unmetabolised. The results suggest that the more highly reducing phenolics are absorbed predominantly as glucuronides (96.5%+/-4.6) of the amount absorbed, whereas monophenolic hydroxycinnamates and monophenolic B-ring flavonoids are less predisposed to glucuronidation and higher levels of aglycone (88.1%+/-10.1) are detected on absorption through both the jejunum and ileum.     

Flavonoids content of tomato plants for the study of the nutritional status

Summary Alterations occur in the normal contents of the total and individual flavonoids with P, Mn and B deficiencies in tomato plants. Differences in flavonoid levels of several organs of the plant have been detected. P, Mn and B deficiencies display absence of flavonol in tomato roots. Flavanone concentration in tomato fruit increases 8-fold as compared with average concentration in the other organs.     

菝葜与土茯苓黄酮类化合物的比较研究

对菝葜和土茯苓根茎中黄酮类化合物进行了定量测定和定性分析.结果表明：在菝葜和土茯苓根茎中均含有黄酮,黄酮醇,二氢黄酮,二氢黄酮醇等多种黄酮类化合物.以芦丁为标准品,用分光光度法测知菝葜和土茯苓根茎中总黄酮含量分别为3.36%和2.22%.