The Lichenologist

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FT-Raman spectroscopy of the Christmas wreath lichen, Cryptothecia rubrocincta (Ehrenb.:Fr.) Thor


Howell G. M.  EDWARDS a1 , Luiz F. C.  de OLIVEIRA a2 and Mark R. D.  SEAWARD a3 c1
a1 Chemical and Forensic Sciences, School of Pharmacy, University of Bradford, Bradford BD7 1DP, UK
a2 Nucleo de Espectroscopia e Estrutura Molecular, Departamento de Quimica, Instituto de Ciencias Exatas, Universidade Federal de Juiz de Fora, Campus Universitario, Juiz de Fora, MG 36036-330, Minas Gerais, Brazil
a3 Department of Geography and Environmental Science, University of Bradford, Bradford BD7 1DP, UK

Article author query
edwards hg   [PubMed][Google Scholar] 
de oliveira lf   [PubMed][Google Scholar] 
seaward mr   [PubMed][Google Scholar] 

Abstract

FT-Raman spectra have been obtained from the highly pigmented lichen Cryptothecia rubrocincta from a Brazilian vestigial rainforest habitat. Spectral signatures of the two main lichen substances, chiodectonic acid and confluentic acid, were identified in adjacent zones of the thallus. Of the characteristic zonal colours displayed by the thallus, the outer red zone contained chiodectonic acid and no calcium oxalate, and graded into by a pink zone with calcium oxalate monohydrate (whewellite) in association with chiodectonic acid, to the inside of which is a concentric white zone containing calcium oxalate dihydrate (weddellite); however, chemically differentiated sites (elliptical brown flecks with a major axis of c. 15 μm) in both the pink and red zones contained chiodectonic acid and calcium oxalate monohydrate. The role of Raman spectroscopy in the spatial identification of lichen substances in the thallial structures is demonstrated.

(Accepted November 15 2004)


Key Words: Brazil; calcium oxalate; chiodectonic acid; confluentic acid; Cryptothecia rubrocincta; FT-Raman spectroscopy; lichen.

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c1 Corresponding author