Lichens pigments

The advantage of DMSO as a solvent for the extraction of photosynthetic lichen pigments (Ronen and Galun, 1984) is that the extraction is simple, rapid, complete and that the extract is easily stored at low temperatures without degradation. An additional advantage is that small plant samples are sufficient since the procedure is not involved with any loss of extract and grinding or homogenizing are not required. Ronen and... 

Figure 9 In situ analysis of the pigment haemoventosin in the apothecia of a microlichen Haematomma ventosum using FT-LMMS. The structural assignment of the anions of major diagnostic interest is based on the high accuracy m/z data in Table 1. (Reprinted from Van Roy W, Mathey A, and Van Vaeck L (1996) In-situ analysis of lichen pigments by Fourier transform laser microprobe mass spectrometry with external ion source. Rapid Communications in Mass Spectrometry 10 562-572 Wiley.)...

Reprinted from Van Roy W, Mathey A, and Van Vaeck L (1996) In-situ analysis of lichen pigments by Fourier transform laser microprobe mass spectrometry with external ion source. Rapid Communications in Mass Spectrometry 10 562-572 Wiley. 

Hecht, H.-J., R. Reinhardt, and W. Steglich Structure Analysis of the Lichen Pigment Vulpinic Acid. Submitted for publication. 

Asano, M., and S. Huziwara Lichen Pigments of the Pulvinic Acid Series. VI. Synthesis of Atromentinic Acid. J. Pharmac. Soc. Japan 59, 675 (1939). 

Yosioka, L, T. Nakanishi, S. Izumi, and I. Kitagawa Structure of a Lichen Pigment Entothein and its Identity with Secalonic Acid A, a Major Ergot Pigment. Chem. Pharm. Bull. (Japan) 16, 2090 (1968). 

A 10-25% aqueous solution ofpotassium hydroxide is used as the reagent. The solution is stable, but etches glass vessels slowly. Quinonoid lichen pigments (anthraquinones, naphthoquinones, terphenylquinones) give a positive dark red to violet K test, whereas pulvinic-agid derivatives, xanthones, and usnic acids do not respond. Some depsides (e.g., atranorin, thamnolic acid) and many /5-orcinol depsidones exhibit yellow to red colors with K. 

Parent Peaks and Characteristic Fragment Ions of Lichen Pigments... 

Although they are pigments, quinones make only small contributions to the colors of tissues and organisms that produce them. Quinones play an important role in the coloration of some fungi, lichens, insects (Coccidae), and echinoderms, but they rarely contribute to the external colors of higher plants. 

On land, environmental pollution threatens especially the lichens. They are rarefying worldwide, which means that their particular pigments and otter metabolites (Table 16.2.5.1) are also disappearing (Huneck 1999). 

Besides playing a vital role in the oxidation-reduction processes of living organisms, quinones occur widely as natural pigments found mainly in plants, fungi, lichens, marine organisms, and insects (see alizarin, Section 28-4A, as representative of a natural anthraquinone-type dye). 

Some lichens are useful as a source of natural dyes. Pigments of some of the more colorful lichens, especially the orange, red, and brown ones, can be extracted by boiling and used to dye wool and other fibers. Other chemicals extracted from lichens include litmus, which was a commonly used acid-base indicator prior to the invention of the pH meter. 

Hall, R. S. B., Bomman, J. F., Bjom, L. O. 2002. UV-induced changes in pigment content and light penetration in the frutieose lichen Cladonia arbuscula ssp. mitis. J. Photochem. Photobiol B-Biol. 66 13-20. 

A second large group of polyketide metabolites that have been isolated from lichens are heptaketide xanthones. Their structures are mainly based on norli-chexanthone (7.54). An interesting feature of these compounds is the presence of chlorine in several of the metabolites. Lichens also produce some anthraquinone pigments, exemplified by physcion (7.6) from Xanthora species. 

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