ABSTRACT Various lichens were collected at different locations in Saudi Arabia in order to analyse UV-absorbing substances. The following lichens were investigated: Psora decipiens, Caterpyrenium lachneum, Pyscia siriana, Usnea articulata, Teloschistes villosus, Physconia perisidiosa, Acarospora strigata, Fulgensia fulgens, Lecanoria laevis, Ramalina fascinanacea, Anaptychia kaspica, Xanthoria fallax and a not determined species. Additionally, an unknown lichen from the Patagonian steppe (Argentina) was investigated. In order to identify parietin and scytonemin, the samples were extracted with 100 % acetone. In the following samples parietin was found: Xanthoria fallax, Usnea atriculata, Teloschistes villosus, Parmelia austroafricana, Caloplaca irrubescens and the Patagonian desert lichen. Scytonemin was detected in Thyrea nigritella, Psora decipiens, Caterpyrenium lachneum and Xanthoria fallax. For analysis of water soluble UV-absorbing substances the samples were extracted with 20 % MeOH and the extract was subjected to HPLC. The analysis revealed a variety of compounds, from which many of them are probably worth to be analyzed in more detail.
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