Lichen Acids of the Stereocaulon ramulosum Group in Central East Africa

Abstract

Chemical investigations have been carried out on lichen specimens of the Stereocaulon ramulosum group from Central East Africa (Zaire/ Kivu, Rwanda and Burundi). Thin-layer chromatography and UV spectrum studies have shown the existence of atranorin and perlatolic acid in both Stereocaulon ramulosum (Sw.) Rdusch. and Stereocaulon meyeri Stein; specimens identified as S. meyeri subsp. atlanticum Lamb contain atranorin, perlatolic, stictic and norstictic acids. A large amount of Stereocaulon has been recently collected in the mountains of Central East Africa (Zaire/Kivu, Rwanda and Burundi). The specimens belonging to the S. ramulosum group turned out to be difficult to identify without chemical data. This paper deals with that chemical investigation. MATERIALS AND METHODS The collection is preserved at the Department of Botany in the University of Liege (LG). The studied specimens belonging to the Stereocaulon ramulosum group are numbered "Lambinon 71/1343, 72/252, 72/263, 72/264, 72/265, 72/328, 72/363, 72/690, 72/692, 72/787, 72/806, 72/811t, 72/827, 72/828, 72/900, 72/901, 74/1545, 74/1546." Dried and pulverized material was successively extracted in the following phases: light petroleum ether (d = 0.60), peroxide free anhydrous ethyl ether and anhydrous acetone. Two thinThis content downloaded from 40.77.167.54 on Wed, 06 Jul 2016 05:36:11 UTC All use subject to http://about.jstor.org/terms 416 THE BRYOLOGIST [Volume 81