Flavonoids from the stem bark of Lonchocarpus xuul

The stem bark of Lonchocarpus xuul (Leguminosae) has yielded four flavonoid s 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 be ta,4 beta,5-trimethoxy-6 ",6 "-dimethyl-2H-pyrano-(2 ",3 ":7,6)-flavan (3 b eta-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 kn own 5,7-dihydroxy-6,8-di(3-methylbut-2-enyl)flavanone (spiniflavanone-B). T he ethyl derivative is considered likely to be an artefact. (C) 2000 Elsevi er Science Ltd. All rights reserved.