Xylomexicanins K-N: limonoids from the leaves and twigs of Xylocarpus granatum

Six new compounds, xylomexicanins K-N (1-4), granasteroid (5) and 5-methoxy-2-pentylbenzofuran-7-ol (6), along with nine known compounds were isolated from the leaves and twigs of Xylocarpus granatum. Among them, 1 was a biogenetic precursor of 1,8,9-phragmalin limonoid, and 4 represent the first example of degraded A-ring limonoid. The structures of them were elucidated on the basis of one- and two-dimensional NMR spectroscopic data (including H-1, C-13-NMR, DEPT, H-1-H-1 COSY, HSQC, HMBC, and NOESY) and confirmed by high-resolution mass spectrometry.