Fluorescent pigments: New perspectives in betalain research and applications
ABSTRACT Betaxanthins are natural water-soluble yellow pigments found in plants of the order Caryophyllales. The fluorescence of five of these compounds, derived from the amines, tyramine and dopamine, and from the amino acids, methionine sulphoxide, glutamic acid and aspartic acid, was detected and characterized for the first time. Fluorescence in betacyanins, the violet counterpartner of betaxanthins was not detected.We report here not only the fluorescent properties of the betaxanthins but also a new method for determining the pigment content in complex samples by HPLC using a fluorescence detector for the first time. The method was successfully applied to the analysis of the betaxanthins present in Mirabilis jalapa (Nyctaginaceae) flowers. Our findings concerning fluorescence may open up new possibilities for the detection of betaxanthins, improve existent HPLC protocols and represent a new field for biochemical investigations.
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ABSTRACT: The use of colorants as additives for foods and drinks is a significant factor to food consumers in determining the acceptability of processed foods. In recent years, the number of previously used artificial colorants/dyes suitable for food use has been drastically reduced as a result of toxicological studies. Therefore, the use of natural pigments such as anthocyanins and betacyanins that were known to have anticancer and antioxidant activities is increasingly required. In this study, the water-soluble plant pigments, anthocyanins and betacyanins, were easily extracted with a very simple method using a few organic solvents such as ethyl acetate, ethyl ether, and chloroform. After the extraction of them, these two major plant pigments could be also simply and rapidly separated and discriminated by a solely one-stepped agarose gel electrophoresis in a citrate buffer (pH 3.0).The Journal of the Korea Contents Association. 03/2009; 9(3).
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ABSTRACT: Betalains are natural antioxidant pigments responsible for the visible fluorescence of flowers. Although these compounds are almost exclusively soluble in water, they are very sensitive to both hydrolysis and water-catalyzed isomerization. We show that three representative betalains are soluble in 2,2,2-trifluoroethanol (TFE) and that the hydrolytic stability of these model compounds in hydroalcoholic solutions increases with increasing amount of TFE. Furthermore, TFE increases the fluorescence quantum yields of betaxanthins. .Monatshefte fuer Chemie/Chemical Monthly 04/2013; 144:567-571. · 1.35 Impact Factor
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ABSTRACT: The plant pigment betanin is investigated as a dye-sensitizer on TiO 2 with regard to its potential to undergo two-electron oxidation following one-photon excitation. Electrochemical, spectroelectrochemical and transient absorption measurements provide evidence for two-electron proton-coupled photo-oxidation leading to a quinone methide interme-diate which rearranges to 2-decarboxy-2,3-dehydrobetanin. Time-resolved spectroscopy measurements of betanin on nanocrystalline TiO 2 and ZrO 2 films were performed on femtosecond and nanosecond time-scales and provide evidence for transient species with absorption bands in the blue and the red. The results shed light on previous reports of high quantum efficiencies for electron injection and point the way to improved solar conversion efficiency of organic dye-sensitized solar cells.Physical Chemistry of Interfaces and Nanomaterials XIII, San Diego, CA; 08/2014