Flavonoids from two Lonchocarpus species of the Yucatan Peninsula

Leaves, stem bark and root of Lonchocarpus xuul and Lonchocarpus yucatanensis were studied separately. A chalcone, 2′,4-dimethoxy-6′-hydroxylonchocarpin (1), and the flavones 5,4′-dihydroxy-3′-methoxy-(6:7)-2,2-dimethylpyranoflavone (2) and 5,4′-dimethoxy-(6:7)-2,2-dimethylpyrano-flavone (3), together with the known carpachromene (4), were isolated from the leaves of both species. Similarly, the previously reported flavans xuulanin (5) and 3β-methoxyxuulanin (6), together with the novel 3β,4β,5-trimethoxy-4′-hydroxy-(6:7)-2,2-dimethylpyranoflavan (7), 3-hydroxy-4,5-dimethoxy-(6:7)-2,2-dimethyl-pyranoflavan (8), and 3,4-dihydroxy-5-methoxy-(6:7)-2,2-dimethylpyranoflavan (10), were isolated from the stem bark and root of both species. Finally, the known 2′,4′-dihydroxy-3′-(3-methylbut-2-enyl) chalcone (13) was obtained from the root of L. xuul only. The structures of the various metabolites were established by interpretation of their spectroscopic data.