Flavonoids from Lonchocarpus muehlbergianus

Abstract

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)-furanoflavan; 2,4-cis-2-prenyloxy-4-hydroxy-5,8-dimethoxy-(2″,3″:6,7) -furanoflavan; 2',5',6'-trimethoxy9-(1,1-dimethylallyoxy)-[2″,3″:3′,4′] -furanochalcone; 5,6-dimethoxy-(2″,3″:7,8)-furanoflavone, identified 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.