Heterophyllaea pustulata Hook. (Rubiáceas) is native to the Andean Region of Bolivia and the Northwest of Argentina (2500-3000 m above sea level). It is popularly known as ?Cegadera?, ?Ciegadera? and ?Saruera?, and it has toxic effects on cattle, due to the fact that it produces blindness (keratoconjunctivitis) and dermatitis. Its toxic effects on animals has been studied by Hansen and Martiarena, who described it as a photosensitization reaction but could not establish which components produce it.
In order to find an answer to this problem, we undertook a chemical study. In previous scientific events the presence of anthraquinones (3-hydroxy-1-metoxyanthraquinone-2-aldehide and 1,3-dihydroxy-2-methylanthraquinone) and flavonoids (quercetin, 3-O-b-D-glucosil quecetin and 3-O-b-D-(6?-acetilglucosil) quercetin) was reported. In this work we present the structural elucidation of other three anthraquinonic derivatives of H. pustulata.
Different chromatographic techniques (Si-gel column, chromatotron, Sephadex LH-20 column, and preparative scale TLC) were used for their separation and purification. By means of 1H-NMR and 13C spectroscopy, and IR, EM, and UV-V techniques as complements, their structure was determined as 3-hydroxy-1-metoxy-2-methyl anthraquinone, 2-hydroxy-3-methyl anthraquinone and 1,6-dihydroxy-2-methyl anthraquinone. In the case of the latter component, it was necessary to resort to bidimensional NMR (COLOC experiment) in order to unmistakeably establish the substitution in position 6. Thus, the problem of ambiguously informing the said derivative as 1-6 or (1-7)-dihydroxy-2-methyl anthraquinone was solved.
