Noralashinol A,a new norlignan from stem barks of Syringa pinnatifolia

One new norlignan, namely noralashinol A (1), one known analogue (2), together with seven known lignans (3–9) were isolated from the stem barks of Syringa pinnatifolia. Their structures were elucidated extensively by spectroscopic methods, including mass spectrometry and 1D and 2D NMR spectroscopies. Compound 8 significantly inhibited NO production in LPS-induced BV-2 murine microglia cells with its IC₅₀ value of 20.7 μM, compared to a positive control quercetin with its IC₅₀ value of 15.3 μM.