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 β ‐sitosterol ( 18 ) and stigmasterol ( 19 ), and a mixture of β ‐sitosteryl‐3‐ O‐β ‐ D ‐glucoside ( 20 ) and stigmasteryl‐3‐ O‐β ‐ 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 δ ‐lactone structure, which was then revised to a γ ‐lactone structure, based on 1D‐NMR data. The cigar‐HMBC technique was used to confirm the accuracy of the γ ‐lactone structure, and the zero [ α ] $\rm{ _{\rm{D}}^{20} }$ 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 μg/ml.