The interaction of anthocyanins with bilitranslocase

Bilitranslocase (TC 2.A.65.1.1) is an organic anion membrane carrier expressed at the sinusoidal domain of the liver plasma membrane and in epithelial cells of the gastric mucosa. Its substrates are sulfobromophthalein, bilirubin, and nicotinic acid. This work reports on the identification of a new class of bilitranslocase substrates, i.e., anthocyanins. Seventeen out thes 20 compounds tested behaved as competitive inhibitors of bilitranslocase transport activity (K(I)=1.4-22 microM). Their structure-activity relationship reveals that mono- and di-glucosyl anthocyanins, the anthocyanin species occurring in food, are better ligands than the corresponding aglycones. Moreover, the first interaction of anthocyanins with the carrier occurs through hydrophilic moieties, such as the 3-glucosyl moiety and the B ring for the monoglucosides, through the 5-glucosyl moiety and the A ring for the diglucosides, and through either the B or the A ring for the aglycones. These findings suggest that bilitranslocase could play a role in the bioavailability of anthocyanins.     

THE DIFFERENTIATION OF PIGMENTATION IN FLOWER PARTS. III. METABOLISM OF SOME EXOGENOUS ANTHOCYANINS BY DETACHED PETALS OF IMPATIENS BALSAMINA

The anthocyanins of mature petals of Impatiens balsamina L. are distinct from the pigments found in vegetative tissue. In the red genotype (llHHP^rP^r) a sequential elaboration of the characteristic anthocyanins has been previously demonstrated through the examination of buds at successive stages of development. The metabolism of anthocyanins, especially pelargonidin-3-mono-glucoside, was examined by infiltration into developing petals of a genetically white strain. This anthocyanin appears to play a central role in the biochemical sequences involved and it has been observed that the genetically white flowers possess the enzymatic potential to metabolize this substrate, producing the same final products which are produced in the red genotype. There is a pattern of change in the relative amounts of each anthocyanin during the incubation period which follows closely the pattern which occurs during normal development of the colored genotypes. This indicates that the enzymes which are normally produced in the colored flowers are also produced in flowers which never produce anthocyanins. The metabolic capabilities of several other genetic strains and the influence of light and puromycin have been examined.     

Importance of flavonoids in insect--plant interactions: feeding and oviposition

Jeffrey Harborne and colleagues have been responsible for collating the majority of data on the role of flavonoids in insect plant interactions. This article examines some of this information and assesses our knowledge about the role flavonoids play in insect feeding and oviposition behaviour. It is clear that insects can discriminate among flavonoids and that these compounds can modulate the feeding and oviposition behaviour of insects, but further work is required to understand the neural mechanisms associated with these behavioural responses. Despite the wealth of data about the diversity of flavonoids in plants, very few of these compounds have been tested against insects and their role in the evolution of host range in insect--plant interactions has yet to be determined.     

Dietary anthocyanins protect endothelial cells against peroxynitrite-induced mitochondrial apoptosis pathway and Bax nuclear translocation: an in vitro approach

Anthocyanins have received increasing attention because of their relatively high intake in humans and wide range of potential health-promoting effects, including anti-atherogenic properties. Evidences support their vascular protective effects but the involved molecular mechanisms have not been well clarified. The endothelium seems to have a central role in atherogenesis and apoptosis is emerging as a crucial event in this disease progression. Following our previous work on the biochemical pathways underlying peroxynitrite-triggered apoptosis in endothelial cells, here we investigated potential mechanisms responsible for the cytoprotective actions of three common anthocyanins, namely cyanidin- delphinidin- and pelargonidin-3-glucoside, against this process. Beyond their antioxidant properties, all these flavonoids, possessing either catecholic or monophenolic structures, were able to counteract peroxynitrite-induced apoptotic effects in endothelial cells through the inhibition of several crucial signaling cascades. Actually, pre-incubation of cells with 25 μM anthocyanins prevented them from peroxynitrite-mediated apoptosis, which was evaluated by the loss of mitochondrial membrane potential, caspases-9 and-3 activation, the increase in cytoplasmatic Bax levels and the inactivation of the PI3 K/Akt pathway. Moreover, they counteracted the translocation of Bax into the nucleus, as observed by immunocytochemistry and immunoblot, an event shown for the first time in endothelial cells apoptotic process. Such cellular actions could not be inferred from their in vitro antioxidant properties. These results suggest a potential role of dietary anthocyanins in the modulation of several apoptotic signaling pathways triggered by peroxynitrite in endothelial cells, supporting mechanistically their health benefits in the context of prevention of endothelial dysfunction and, ultimately, of atherosclerosis.     

Soret and Dufour Effects on MHD Peristaltic Flow of Jeffrey Fluid in a Rotating System with Porous Medium

The objective of present paper is to examine the peristaltic flow of magnetohydrodynamic (MHD) Jeffrey fluid saturating porous space in a channel through rotating frame. Unlike the previous attempts, the flow formulation is based upon modified Darcy''s law porous medium effect in Jeffrey fluid situation. In addition the impacts due to Soret and Dufour effects in the radiative peristaltic flow are accounted. Rosseland’s approximation has been utilized for the thermal radiative heat flux. Lubrication approach is implemented for the simplification. Resulting problems are solved for the stream function, temperature and concentration. Graphical results are prepared and analyzed for different parameters of interest entering into the problems.     

Strength of winter leaf redness as an indicator of stress vulnerable individuals in Pistacia lentiscus

Leaf anthocyanins are believed to afford protection against photoinhibition, yet the dependence of protection on actual anthocyanin concentrations has not been investigated. To that aim, non-invasive optical methods (spectral reflectance and chlorophyll fluorescence) were used to assess the levels of anthocyanins and chlorophylls as well as photosystem II photochemical efficiency in hundreds of leaves from the mastic tree (Pistacia lentiscus), which displays in the field a continuum of leaf tints during winter from fully green to fully red. Contrary to expectations based on the photoprotective hypothesis, the strength of leaf redness was positively correlated to the extent of mid-winter chronic photoinhibition and negatively correlated to leaf chlorophyll contents. Hence, a photoprotective role for anthocyanins is not substantiated. Instead, we argue that winter leaf redness may be used reliably, quickly and non-invasively to locate vulnerable individuals in the field.     

植物次生代谢基因工程研究进展

随着对植物代谢网络日渐全面的认识,应用基因工程技术对植物次生代谢途径进行遗传改良已取得了可喜的进展.对次生代谢途径进行基因修饰的策略包括:导入单个、多个靶基因或一个完整的代谢途径,使宿主植物合成新的目标物质;通过反义RNA和RNA干涉等技术降低靶基因的表达水平,从而抑制竞争性代谢途径,改变代谢流和增加目标物质的含量;对控制多个生物合成基因的转录因子进行修饰,更有效地调控植物次生代谢以提高特定化合物的积累.作者结合对大豆种子异黄酮类代谢调控和基因工程改良的研究,着重介绍了花青素和黄酮类物质、生物碱、萜类化合物和安息香酸衍生物等次生代谢产物生物合成的基因工程研究进展.     

二氢黄酮醇 4 还原酶在花青素合成中的功能及调控研究进展

植物色素主要有花青素、类胡萝卜素和生物碱类色素三大类,其中花青素是决定大部分被子植物组织或器官颜色的重要色素。花青素通过类黄酮途径合成,该途径是生物学上研究较多且较为清楚的代谢途径之一。近年来的研究表明,在该途径中除了查尔酮合成酶(chalcone synthase,CHS)、查尔酮异构酶(chalcone isomerase,CHI)和黄烷酮-3-羟化酶(flavanone-3-hydrolase,F3H)起着关键作用外,二氢黄酮醇-4-还原酶(dihydroflavonol 4-reductase,DFR)对花青素的合成也至关重要。DFR可催化3种二氢黄酮醇和2种黄烷酮生成5种不同的花青素前体,且DFR基因家族不同成员对各个底物的催化效率不同,因此它在一定程度上决定着植物中花青素的种类和含量,从而影响植物组织或器官的颜色。该文对近年来国内外有关DFR在花青素合成过程中的生物学功能与调控,包括DFR的特征、作用机制和系统进化以及环境、转录因子和一些结构基因与DFR的关系等方面的研究进展进行了综述,以期为DFR今后的研究和利用基因工程改变植物组织或器官的颜色提供理论依据。     

Changes in abscisic acid and flower pigments during floral senescence of petunia

The present work was focused on abscisic acid (ABA) changes in three differently coloured petunias during flower development and senescence. The ABA content was studied in correlation with changes of flower pigments and other phytohormones. The variations of anthocyanins and endogenous hormones were induced by treatments with 1 or 2 mM amino-oxyacetic acid (AOA), 50, 100 μM thidiazuron (TDZ) and 50 μM 6-benzyladenine (BA). ABA content decreased during bud development and increased during senescence. The AOA reduced the anthocyanins content and avoided ABA increase, while the cytokinins (BA and TDZ) did not significantly affected anthocyanin contents but increased ABA content. TDZ doubled the ABA content compared to the control. However, the treatments did not affected flower life, confirming the secondary role of ABA during flower senescence.     

Anthocyanins: structural characteristics that result in unique metabolic patterns and biological activities

Interest in anthocyanins has increased immensely during the past decade. From these studies, it is clear that anthocyanins have unique properties: Anthocyanins are absorbed intact and absorption can be saturated; acylation of anthocyanins lowers their apparent absorption; anthocyanidin diglycosides in the form of sambubioside or rutinoside impart increased stability to the anthocyanin molecule; and the quantities excreted in urine are less than 0.1% of intake. However, 60-90% of the anthocyanins may disappear from the gastrointestinal tract within 4 h after a meal. What happens to the bulk of the anthocyanins that disappear is not clear. Degradation accounts for a part of this disappearance, but differs for the various aglycones and may be modified further by the nature of the aglycone glycosylation, which further complicates our understanding of this process. Anthocyanins may play an important role in health promotion in terms of obesity prevention, cardiovascular health, anti-inflammatory and anti-cancer effects.     

花青素主要成分与HER-2激酶区的分子对接

用分子对接方法预测天然植物化学物质与受体蛋白的相互作用位点并探究作用机制。利用MVD(Molecular Virtual Docker 5.5)软件,以HER-2激酶区为受体模板建立活性位点,与12种花青素成分进行分子对接。结果表明12种化合物均能在同一活性腔中与HER-2激酶区对接(MolDock Score:苷元–105 kJ/mol,单葡糖苷–130 kJ/mol),主要作用力是疏水作用和氢键;该活性腔也是ATP与HER-2激酶区的结合(MolDock Score=–161 kJ/mol)位点,花青素的结合可能会干扰ATP与HER-2之间氢键的形成。提示花青素可能以竞争性结合方式阻碍ATP与HER-2的结合,抑制HER-2磷酸化激活及下游信号通路的激活,从而发挥抑癌活性。     

Photoprotection by foliar anthocyanins mitigates effects of boron toxicity in sweet basil (Ocimum basilicum)

Boron (B) toxicity is an important agricultural problem in arid environments. Excess edaphic B compromises photosynthetic efficiency, limits growth and reduces crop yield. However, some purple-leafed cultivars of sweet basil (Ocimum basilicum) exhibit greater tolerance to high B concentrations than do green-leafed cultivars. We hypothesised that foliar anthocyanins protect basil leaf mesophyll from photo-oxidative stress when chloroplast function is compromised by B toxicity. Purple-leafed ‘Red Rubin’ and green-leafed ‘Tigullio’ cultivars, grown with high or negligible edaphic B, were given a photoinhibitory light treatment. Possible effects of photoabatement by anthocyanins were simulated by superimposing a purple polycarbonate filter on the green leaves. An ameliorative effect of light filtering on photosynthetic quantum yield and on photo-oxidative load was observed in B-stressed plants. In addition, when green protoplasts from both cultivars were treated with B and illuminated through a screen of anthocyanic protoplasts or a polycarbonate film which approximated cyanidin-3-O-glucoside optical properties, the degree of photoinhibition, hydrogen peroxide production, and malondialdehyde content were reduced. The data provide evidence that anthocyanins exert a photoprotective role in purple-leafed basil mesophyll cells, thereby contributing to improved tolerance to high B concentrations.     

Foliar anthocyanins in Pelargonium × hortorum are unable to alleviate light stress under photoinhibitory conditions

Photosynthetic organs are often characterized by anthocyanins being accumulated either in the epidermal or in the mesophyll cells making these tissues to turn reddish-brown in colour. It has been hypothesized that these pigments protect underlying chloroplasts from light-stress because they absorb photons of the photosynthetically active waveband. However, the photoprotective role of anthocyanins has not been undoubtedly shown on a broad range of species. In this study, green and anthocyanic areas of leaves of Pelargonium × hortorum, the latter possessing variable levels of anthocyanins, were compared using pigment analysis and pulse amplitude modulated in vivo chlorophyll (Chl) fluorescence. Quenching analysis of the induction and dark relaxation curves of slow Chl fluorescence kinetics showed that at photoinhibitory conditions [by applying above-saturation light intensity of 1,600 ??mol(quantum) m^?2 s^?1 white light at low (4°C) temperature], anthocyanic areas were at least equally sensitive to photoinhibition as green leaf areas. In fact, the level of photoinhibition tended to be proportional to the level of anthocyanin accumulation suggesting that this characteristic was indicative of the photoinhibitory risk. The results of the present study clearly show that anthocyanins in leaf areas of Pelargonium do not afford a photoprotective advantage.     

花青素及其生物活性的研究进展

花青素是存在于自然界中的天然的水溶性色素,它赋予水果、蔬菜和植物鲜艳的颜色,主要来源于蓝莓、樱桃、覆盆子、草 莓、紫葡萄和红酒等。它属于黄酮类化合物,其结构和化学成分使得花青素具有多种生物活性,如：抗氧化、抗炎、抗衰老、抗心血 管、抗癌等,对于人类的健康具有重要作用。花青素对于人类各种疾病的治疗以及作为一种药方都具有积极的效果,花青素通过 抗细胞增殖、诱导凋亡等多种机制来抑制肿瘤的发生;通过清除活性氧自由基等机制来发挥抗氧化作用;通过抑制各种炎症因子 的表达来发挥抗炎效应,这一系列的生物活性都给人们对抗各种疾病带来了无限的希望。本文就花青素的特点、提取及生物活性 进行了总结,重点介绍了花青素的生物活性。     

Short communication. Do anthocyanins play a role in UV protection of the red juvenile leaves of Syzygium?

The biological function of juvenile leaves pigmented with anthocyanin is poorly understood. The role anthocyanins play in UV protection was assessed in juvenile leaves of two Syzygium species (S. luehmannii and S. wilsonii) which contain high anthocyanin concentrations. HPLC was used to separate UV-absorbing anthocyanins from other soluble UV-absorbing phenolic compounds. The isolated anthocyanins (predominantly malvidin-3,5-diglucoside) contributed little to the total absorbance of UV-A and UV-8 radiation. This was because the non-acylated anthocyanins only effectively absorbed shortwave UV-B radiation and the strong absorbance by other compounds. These results suggest that the UV protection hypothesis is not valid for anthocyanins in juvenile Syzygium leaves.     

Cloning of FaPAL6 gene from strawberry fruit and characterization of its expression and enzymatic activity in two cultivars with different anthocyanin accumulation

The accumulation of anthocyanin pigments is one of the most important traits that turn strawberry fruit attractive to consumers. During ripening, strawberry fruit color development is associated to anthocyanin synthesis through the phenylpropanoid pathway. Phenylalanine ammonia-lyase (PAL) is a key enzyme in this pathway, having a determining role in strawberry fruit quality. In this work, we studied the level of anthocyanins during fruit ripening of two cultivars that differ in color development (Camarosa and Toyonoka). Toyonoka showed a lower anthocyanin accumulation that was limited to external fruit tissue, while Camarosa accumulated higher amount of anthocyanins in both internal and external sections. In addition, we cloned a full-length gene (FaPAL6) and analyzed its expression in different strawberry plant tissues. The expression of this gene is fruit specific, and increases during fruit ripening in both cultivars along with anthocyanin accumulation. The mRNA level of FaPAL6 was higher in Camarosa. PAL enzyme activity increased at similar rates in both cultivars at early ripening stages, but at the end of ripening PAL activity diminished in Toyonoka while it rose markedly in Camarosa. PAL activity was higher in internal fruit tissue, showing no correlation with anthocyanin level of the same section in both cultivars. The higher FaPAL6 expression and activity detected in Camarosa could be associated to the enhanced anthocyanin accumulation found in this cultivar.     

Profiles of photosynthesis within red and green leaves of Quintinia serrata

We have measured photosynthesis at the cellular, tissue, and whole leaf levels to understand the role of anthocyanin pigments on patterns of light utilization. Profiles of chlorophyll fluorescence through sections of red and green leaves of Quintinia serrata showed that anthocyanins in the mesophyll restricted absorption of green light to the uppermost palisade mesophyll. The distribution was further restricted when anthocyanins were also present in the upper epidermis. Mesophyll cells located beneath a cyanic light-filter assumed the characteristic photosynthetic features of shade-adapted cells. As a result, red leaves showed a 23% reduction in CO₂ assimilation under light-saturating conditions, and a lower threshold irradiance for light-saturation, relative to those of green leaves. The photosynthetic characteristics of red leaves are comparable to those of shade-acclimated plants.     

Functional role of anthocyanins in the leaves of Quintinia serrata A. Cunn

The protective functions that have been ascribed to anthocyanins in leaves can be performed as effectively by a number of other compounds. The possibility that anthocyanins accumulate most abundantly in leaves deficient in other phytoprotective pigments has been tested. Pigment concentrations and their histological distribution were surveyed for a sample of 1000 leaves from a forest population of Quintinia serrata, which displays natural polymorphism in leaf colour. Eight leaf phenotypes were recognized according to their patterns of red coloration. Anthocyanins were observed in almost all combinations of every leaf tissue, but were most commonly located in the vacuoles of photosynthetic cells. Red leaves contained two anthocyanins (Cy-3-glc and Cy-3-gal), epicuticular flavones, epidermal flavonols, hydroxycinnamic acids, chlorophylls, and carotenoids. Green leaves lacked anthocyanins, but had otherwise similar pigment profiles. Foliar anthocyanin levels varied significantly between branches and among trees, but were not correlated to concentrations of other pigments. Anthocyanins were most abundant in older leaves on trees under canopies with south-facing gaps. These data indicate that anthocyanins are associated with photosynthesis, but do not serve an auxiliary phytoprotective role. They may serve to protect shade-adapted chloroplasts from brief exposure to high intensity sunflecks.     

Anthocyanins Protect Against Ethanol-Induced Neuronal Apoptosis via GABAB1 Receptors Intracellular Signaling in Prenatal Rat Hippocampal Neurons

Here, we investigated the possible involvement of gamma-aminobutyric acid B1 receptor (GABA_B1R) in mediating the protective effects of black soybean anthocyanins against ethanol-induced apoptosis in prenatal hippocampal neurons because GABARs are known to play an important role in the development of central nervous system. Treatments were performed on primary cultures of prenatal rat hippocampal neurons transfected with or without GABA_B1R small interfering RNA (siRNA). The results showed that, when ethanol treatment was followed by anthocyanins treatment, cellular levels of proapoptotic proteins such as Bax, activated caspase-3, and cleaved poly (ADP-ribose) polymerase 1 (PARP-1) were decreased, and the cellular level of the antiapoptotic protein Bcl-2 was increased compared to treatment with ethanol alone. Furthermore, the effects of ethanol on cellular levels of GABA_B1R and its downstream signaling molecules such as protein kinase A, calcium/calmodulin-dependent protein kinase II (CaMKII), and phosphorylated cAMP response element binding protein were diminished or reversed by anthocyanins treatment. The ability of anthocyanins to reverse the effects of ethanol on cellular levels of Bax, Bcl-2, active caspase-3, cleaved PARP-1, GABA_B1R, and CaMKII were abrogated in cells transfected with GABA_B1R siRNA. In a GABA_B1R-dependent manner, anthocyanins also inhibited the ability of ethanol to elevate intracellular free Ca²⁺ level and increase the proportion of cells with low mitochondrial membrane potential in the population. Cell apoptosis assay and morphological studies also confirmed the neuroprotective effect of anthocyanins against ethanol via GABA_B1R. Our data suggest that GABA_B1R plays an important role in the neuroprotective effects of anthocyanins against ethanol.