| Abstract: | Two new polymethoxylated flavonoids, 2',5',6'-trimethoxy-2',3' : 3',4']furano dihydrochalcone and 2,4',4,5-tetramethoxy-2',3' : 6,7]-furanodihydroaurone, were isolated from the root barks of Lonchocarpus araripensis, along with the known compounds 3,4,5,6-tetramethoxy-2',3' : 7,8]-furanoflavan, 3,6-dimethoxy-1',1'-dimethylcromene-2',3' : 7,8]-flavone, 3',4'-methylenodioxy-5,6-dimethoxy-2',3' : 7,8]-furanoflavone, 3,5,6-trimethoxy-2',3' : 7,8]-furanoflavanone, 3,5,6-trimethoxy-2',3' : 7,8]-furanoflavone, and 6alpha-hydroxy-medicarpin. The complete (1)H and (13)C NMR assignments of the new furan flavonoids were performed using 1D and 2D pulse sequences, including COSY, HSQC, and HMBC experiments, and comparison with spectral data for analog compounds from the literature, particularly for the new furanodihydroaurone because of several inconsistencies on the carbonyl chemical shifts from the literature. |
