5-Hydroxyaloin A in the Genus Aloe Thin Layer Chromatographic Screening and High Performance Liquid Chromatographic Determination

Hans W. Rauwald and Anette Beil Institut für Pharmazeutische Biologie, Johann Wolfgang Goethe-Universität, Georg-Voigt-Straße 16, D-W-6000 Frankfurt am Main 11, Bundesrepublik Deutschland Z. Naturforsch. 48c, 1 -4 (1993); received December 12, 1992 Aloe, Asphodelaceae, 5-Hydroxyaloin A, Quinones, Chemotaxonomy By a comparative thin layer chromatographic screening of the methanol-soluble leaf exu­ dates from more than 400 Aloe plants (183 species), 5-hydroxyaloin A was identified in 20 species. Whilst 13 of the 20 species revealed interindividual variations concerning to the oc­ currence of 5-hydroxyaloin A, this anthrone-C-glucosyl was unambiguously detected in each individual of 6 Aloe species. In the leaf exudates from A. marlothii Berger 5-hydroxyaloin A was only traceable in the aloin-containing chemivars. The complete anthrone-C-glucosyl pat­ tern of these 7 clearly characterized species has been determined additionally by qualitative and quantitative high performance liquid chromatography: The results obtained demonstrate that 5-hydroxyaloin only occurs in the more stable A-configuration (10 R, 1 'S), thus being till now the only anthrone-C-glycosyl which has not been found as diastereomeric pair genuinely in plants. As well, 5-hydroxyaloin A characterizes a quantitatively significant hydroxylating pathway in biosynthesis of anthranoids. It is discussed as a chemotaxonomic marker of the genus Aloe, especially of the sections Pachydendron and Eualoe.