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Journal ArticleDOI

The Systematic Identification of Flavonoids

01 Jan 1972-Kew Bulletin-Vol. 27, Iss: 1, pp 208
About: This article is published in Kew Bulletin.The article was published on 1972-01-01. It has received 641 citations till now. The article focuses on the topics: Identification (biology).
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01 Jan 2006
TL;DR: Findings in chemical ecology concerning the role of phenolics in the resistance mechanisms of plants against fungal pathogens and phytophagous insects are examined.
Abstract: Plant phenolics are secondary metabolites that encompass several classes structurally diverse of natural products biogenetically arising from the shikimate-phenylpropanoids-flavonoids pathways. Plants need phenolic compounds for pigmentation, growth, reproduction, resistance to pathogens and for many other functions. Therefore, they represent adaptive characters that have been subjected to natural Correspondence/Reprint request: Prof. Vincenzo Lattanzio, Dipartimento di Scienze Agro-Ambientali, Chimica e Difesa Vegetale, Universita degli Studi di Foggia, 71100-Foggia, Italy. E-mail: v.lattanzio@unifg.it Vincenzo Lattanzio et al. 24 selection during evolution. Plants synthesize a greater array of secondary compounds than animals because they cannot rely on physical mobility to escape their predators and have therefore evolved a chemical defence against such predators. This article, after a short review of plant phenols and polyphenols as UV sunscreens, signal compounds, pigments, internal physiological regulators or chemical messengers, examines some findings in chemical ecology concerning the role of phenolics in the resistance mechanisms of plants against fungal pathogens and phytophagous insects.

867 citations


Cites background from "The Systematic Identification of Fl..."

  • ...and betacyanins show rather similar absorption in visible region (475-560 nm and 535-545 nm, respectively) and a subsidiary peak at about 270-275 nm [3, 4]....

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Journal ArticleDOI
TL;DR: Phenolic compounds are a large class of plant secondary metabolites, showing a diversity of structures, from rather simple structures, e.g. phenolic acids, through polyphenols such as flavonoids, to polymeric compounds based on these different classes as discussed by the authors.
Abstract: Phenolic compounds are a large class of plant secondary metabolites, showing a diversity of structures, from rather simple structures, e.g. phenolic acids, through polyphenols such as flavonoids, that comprise several groups, to polymeric compounds based on these different classes. Phenolic compounds are important for the quality of plant based foods: they are responsible for the colour of red fruits, juices and wines and substrates for enzymatic browning, and are also involved in flavour properties. In particular, astringency is ascribed to precipitation of salivary proteins by polyphenols, a mechanism possibly involved in defence against their anti-nutritional effects. Finally, phenolic compounds are considered to contribute to the health benefits associated to dietary consumption of fruits and vegetables. During food processing and storage, plant phenolics are converted to a variety of derived compounds. While methods to analyse lower molecular weight phenolic compounds are well developed, analysis of polymeric compounds remains a challenge. Indeed, strong interactions of polymeric phenolics with plant cell wall material limit their extraction. Besides, their polydispersity results in poor resolution and detection, especially of derived structures such as oxidation products. However, recent advances of the analytical techniques have allowed some progress in their structural characterisation. This review summarizes the current knowledge on methods to analyse polyphenols. It presents their reactions in foods and beverages and the resulting structures, and highlights some aspects related to their impact on colour, flavour and health properties, with examples taken mostly from wine research.

354 citations


Cites background from "The Systematic Identification of Fl..."

  • ...UV–visible spectrophotometry distinguishes the different phenolic families on the basis of their characteristic absorbance spectra and can also serve to determine the substitution patterns of flavonoids, using specific reagents such as AlCl3, as detailed by Mabry et al. (1970)....

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Journal ArticleDOI
TL;DR: Data indicate that anthocyanins are associated with photosynthesis, but do not serve an auxiliary phytoprotective role, and may serve to protect shade-adapted chloroplasts from brief exposure to high intensity sunflecks.
Abstract: 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.

324 citations

Journal ArticleDOI
TL;DR: In this paper, the authors give a per- sonal account on the development of the field through a retrospective evaluation of their own research which covers approximately 40 complexes of flavonoids from different subclasses (rutin, quercetin, morin and hespe- ridin) with several metal ions or groups and suggest directions for future research.
Abstract: Flavonoids constitute a large group of polyphenolic phytochemicals with antioxidant properties which are overwhelmingly exerted through direct free radical scavenging. Flavonoids also exhibit antioxidant properties through chelating with tran- sition metals, primarily Fe(II), Fe(III) and Cu(II), which participate in reactions ge- nerating free radicals. Metal-flavonoid chelates are considerably more potent free radical scavengers than the parent flavonoids and play a prominent role in protec- ting from oxidative stress. To unravel the origin of their potent biological action ex- tensive physico-chemical studies were undertaken to reveal the chemical structure, chelation sites, assess the impact of the metal/ligand ratio on the structure of the com- plexes and the capacity of flavonoids to bind metal ions. In spite of such extensive efforts, data on the composition, structure and complex-formation properties are in- complete and sometimes even contradictory. The aim of this paper is to give a per- sonal account on the development of the field through a retrospective evaluation of our own research which covers approximately 40 complexes of flavonoids from dif- ferent flavonoids subclasses (rutin, quercetin, 3-hydroxyflavone, morin and hespe- ridin) with several metal ions or groups and suggest directions for future research. Special emphasis will be given to the site of the central ion, the composition of the complexes, the role of pH in complex formation, the stability of metal-flavonoid com- plexes and their potential application for analytical purposes.

284 citations

Journal ArticleDOI
TL;DR: It was demonstrated that the concentration but not the classes of compounds present in the epidermis that are responsible for UV-screening is affected by the side and the age of the leaves, and that the logFER in the UV is independent of the emission wavelength.
Abstract: In this study a method was designed to assess non-destructively the type of UV-screening compounds present in the leaf epidermis. The method is based on the recording and calculation of the ratio of UV-excitation spectra of chlorophyll fluorescence (FER) from the adaxial and abaxial sides of bifacial leaves, or from older and younger segments of monocotyledonous leaves. The logarithm of this ratio (logFER) matched the absorption spectrum of the UV-absorbers present in the leaf, as confirmed by its overlap with the absorption spectrum of the methanolic extract of the leaf or of the isolated epidermis. By using the logFER approach, it was possible to demonstrate that the concentration but not the classes of compounds present in the epidermis that are responsible for UV-screening is affected by the side and the age of the leaves. In contrast, measurements from the leaves of seven dicots and one monocot indicated large difference in the classes of these compounds between species. Finally, it was shown that the logFER in the UV is independent of the emission wavelength, and that the method can be used for quantitative measurements. This method expands to the spectral domain the use of ChlF for the estimation of the leaf epidermal transmittance.

260 citations