Chromones and anthrones from Aloe marlothii and Aloe rupestris

A phytochemical investigation of the leaf exudate of Aloe marlothii has res ulted in the isolation of a new chromone (7-O-methylaloeresin A) and a new anthrone (5-hydroxyaloin A 6'-O-acetate). Furthermore 7-O-methylaloesin was isolated as a natural product for the first time from the leaf exudate of Aloe rupestris. The structure elucidation of these compounds was based on s pectral data including 2D NMR. The chemotaxonomic value of 7-O-methylaloesi n in Aloe series Asperifoliae and section Pachydendron on is discussed. (C) 2000 Elsevier Science Ltd. All rights reserved.