Alashinol H, an epoxylignan with an unusual six-membered cyclic hemiacetal from Syringa pinnatifolia

Abstract A new 7, 9′-epoxylignan, alashinol H ( 1 ), which features a rare six-membered cyclic hemiacetal, was isolated from the stem barks of Syringa pinnatifolia . The structure was elucidated based on spectroscopic data including HRESIMS and NMR. Its absolute configuration was resolved by GIAO NMR shifts and ECD calculations. A putative biosynthetic pathway of this compound is proposed. Alashinol H showed a moderate inhibitory effect against NO production in BV-2 murine microglia cells.