Flavonoid compounds in roots of Sophora tetraptera

Two novel flavonoid compounds, an isoflavanone, tetrapterol A, and a pterocarpan, tetrapterol B, and three new isoflavanones, tetrapterols C-E, were isolated from the roots of Sophora tetraptera, in addition to eight known phenolic compounds (kenusanone A, lespedeol B, euchenone a9, lonchocarpol A, cajanone, (−)-maackiain, isoneorautenol and pentacosanyl caffeate). The two novel compounds had a common characteristic partial structure which is derived from a geranyl group which forms a new aromatic ring after cyclization with a hydroxyl group located at a side ring in a flavonoid framework and dehydrogenation. The new isoflavanones had a geranyl or an isoprenyl group on their A or B ring. The structures were determined by analysis of spectral data, in particular, 2D-NMR.