Flavonoid dyes

Domenech A, Domenech-Carbo MT, Sauri MC (2005) Electrochemical identification of flavonoid dyes in work of art samples by abrasive voltammetry at paraffin-impregnated graphite electrodes. Talanta 66 769-782. 

Park, J. H. Gatewood, B. M. Ramaswamy, G. N. Naturally occurring quinones and flavonoid dyes for wool Insect feeding deterrents. J. Appl. Polym. Sci. 2005, 98,322-328. 

Sap green was made from a flavonoid dye extracted from the ripe berries of buckthorn (Rhamnus cathartica L.) and various other Rhamnus species. The related Chinese green and lokao were greens produced by Rhamnus species found in China (see the entry for lokao). 

Flavone [525-82-6 Flavone dyes Flavone synthase Flavonoids... 

The chromophores contained in natural dyes are mainly flavonoids, antrachinoids, indigoids and gallotannins. Other molecular types include carotenoids, benzochinons and anthocyanidins. 

E.S.B. Ferreira, A. Quye, H. McNab, A.N. Hulme, Photo oxidation products of quercetin and morin as markers for the characterisation of natural flavonoid yellow dyes in ancient textiles, Dyes in History and Archaeology 18, 63 72 (2002). 

Yellow dyes are obtained only from plants and can generally be divided into two classes, i.e. flavonoids and others among which there are mainly carotenoids and diarylheptanoids. Most are water-soluble, and procedures for their extraction are similar to those recommended for red colourants. Although they were popular as textile colourants, analytical... 

The optimized RPLC UV-Vis ESI MS method for all typical blue colourants (indi-goids, hematein, tannins, anthocyanins and selected flavonoids) was used for the identification of dyes extracted from a thread taken from an Italian tapestry of unknown origin from the collection of the National Museum in Warsaw (Poland). It was found that to obtain the red-blue colour of the fibre a mixture of dyestuffs was probably used. The presence of indigotin, tannic and ellagic acid (at m/z 301, NI), as well as carminic acid, suggested the use of indigo and cochineal. Reseda luteola could also have been used due to the presence of luteolin and apigenin. 

D. Cristea, I. Bareau and G.Vilarem, Identification and quantitative HPLC analysis of the main flavonoids present in weld (Reseda luteola L.), Dyes and Pigments, 57, 267 272 (2003). 

I. Surowiec, B. Szostek and M. Trojanowicz, HPLC MS of anthraquinoids, flavonoids, and their degradation products in analysis of natural dyes in archeological objects, J. Sep. Sci., 30, 2070 2079 (2007). 

Aqueous or methanolic ferric chloride is a general spray reagent for phenolic compounds and gives a blue-black coloration with flavonoids. Similarly, Fast Blue Salt B forms blue or blue-violet azo dyes. 

Scheme 2.1 Structural representations of typical anthraquinonic, flavonoid, and flavonoid-related dyes...

In addition to organic dyes, natural dyes extracted from plants can be used as photosensitizers [36,140,141]. A nanocrystalline 2 solar cell using a san-talin dye extracted from red sandalwood can produce 1.8% efficiency under 80 mW/cm2 irradiation [141]. Cherepy et al. reported that a nanocrystalline 2 solar cell using flavonoid anthocyanin dyes extracted from blackberries could convert sunlight to electrical power with an efficiency of 0.6% (Jsc = 1.5-2.2 mA/cm2 and Voc = 0.4-0.5 V) under AM 1.5 [36]. 

The flavonoids, derivatives of flavone (353) and of isoflavone (354), are widely distributed among plants of many kinds. They provide colour (from pale yellow to orange) in flowers and their potential as dyes is being revived now that awareness of the toxicity of some synthetic dyes is increasing, for example morin (355 CI. Natural Red) is one of many... 

Phenylpropanoids have an aromatic ring with a three-carbon substituent. Caffeic acid (308) and eugenol (309) are known examples of this class of compounds. Phenylpropanoids are formed via the shikimic acid biosynthetic pathway via phenylalanine or tyrosine with cinnamic acid as an important intermediate. Phenylpropanoids are a diverse group of secondary plant compounds and include the flavonoids (plant-derived dyes), lignin, coumarins, and many small phenolic molecules. They are known to act as feeding deterrents, contributing bitter or astringent properties to plants such as lemons and tea. 

Natural dyes are almost entirely napthoquinoid, anthraquinoid, or flavonoid compounds having one or more hydroxyls as the primary functional group. Considerable variation in structure occurs among natural dyes, and a single HPLC system that could separate all natural dye samples was not found. Nevertheless, several workable systems were found in which all dye components eluted except for indigo-carmine, which eluted with the solvent, and indigo and turmeric, which remained on the column. For an isocratic system, we consider this situation to be very satisfactory. 

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