Antimycobacterial Butanolides from the Root of Lindera akoensis

Three racemic butanolides, majorenolide (1), majorynolide (2). and majoranolide (3), with 18 known compounds, including ten butanolides, i.e., litsenolide A(2) (4), litsenolide B-2 (5), litsenolide C-1 (6), litsenolide C-2 (7), hamabiwalactone A (8). hamabiwalactone B (9), litseakolide A (10), litseakolide B (11). isoobtusilactone (12), and obtusilactone (13); one lignan. i.e., (+/-)-syringaresinol (14). two flavans, i.e., (+)-catechin (15), and (-)-epicatechin (16), one coumarin, i.e., scopoletin (17), and four steroids, i.e., a mixture of beta-sitosterol (18) and stigmasterol (19), and a mixture of beta-sitosteryl-3-O-beta-D-glucoside (20) and stigmasteryl-3-O-beta-D-glucoside (21) were isolated from the root of Lindera akoensis. The structures of the isolates were elucidated by in-depth spectroscopic analysis. Compounds 1-3 were previously assigned a delta-lactone structure, which was then revised to a gamma-lactone structure, based on 1D-NMR data. The cigar-HMBC technique was used to confirm the accuracy of the gamma-lactone structure, and the zero [alpha](D)(20) value of compounds 1-3 suggested that they were considerably racemized. Nine butanolides 1-3, 4-8, and 10 showed antimycobacterial activities against M. tuberculosis H(37)Rv, with MIC values of 15-50 mu g/ml.