Flavonoids from the stem bark of Lonchocarpus xuul

The stem bark of Lonchocarpus xuul (Leguminosae) has yielded four flavonoids which have been identified by spectroscopic methods as the novel 4 beta,5-dimethoxy-6 ",6 "-dimethyl-2H-pyrano-(2 ",3 ":7,6)-flavan (xuulanin), 3 beta,4 beta,5-trimethoxy-6 ",6 "-dimethyl-2H-pyrano-(2 ",3 ":7,6)-flavan (3 beta-methoxyxuulanin), 4 beta-ethoxy-5-methoxy-6 ",6 "-dimethyl-2H-pyrano-(2 ",3 ":7,6)-flavan (4 beta-demethylxuulanin-4 beta-ethyl other), and the known 5,7-dihydroxy-6,8-di(3-methylbut-2-enyl)flavanone (spiniflavanone-B). The ethyl derivative is considered likely to be an artefact. (C) 2000 Elsevier Science Ltd. All rights reserved.