The light petroleum extract from the roots of Lonchocarpus muehlbergianus Hassl contained nine flavonoids, including six new ones. These are 2,4-cis-2,4,5,8-tetramethoxy-(2´´,3´´:6,7)-furanoflavan; 2,4-cis-4-hydroxy-2,5,8-trimethoxy-(2´´,3´´:6,7)-furanoflavan; 2,4-cis-2-prenyloxy-4,5,8-trimethoxy-(2´´,3´´:6,7)-fu-ranoflavan; 2,4-cis-2-prenyloxy-4-hydroxy-5,8-dimethoxy-(2´´,3´´:6,7)-furanoflavan; 2',5',6'-trimethoxy-9-(1,1-dimethylallyoxy)-[2´´,3´´:3´,4´]-furanochalcone;

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... 8)-furanoflavone, identi-fied by analysis of their spectral data (UV, IR, ¹H and 13C NMR, 2D-NMR, NOE and MS). The natural occurrence of 2,4-dioxygenated flavan derivatives is being reported for the first time. Quantitative analysis of the petrol extract, by using reversed-phase HPLC, showed that the most abundant flavonoid in the extract is 2,4-cis-2,4,5,8- tetramethoxy-(2´´,3´´:6,7)-furanoflavan.