Noralashinols D–F, New Norlignans from Syringa Pinnatifolia and Its Anti‐inflammation in BV2 Cells

Four new norlignans, noralashinols D–F (1a/b–3), and two known analogues (4 and 5) were isolated from the peeled stems of Syringa pinnatifolia Hemsl. The structures were elucidated by analysis of spectroscopic data, such as IR, HR‐ESI‐MS, 1D and 2D NMR, and ECD. All compounds were evaluated for anti‐inflammatory activities against NO production induced by LPS in BV2 microglia cells. Compounds 1b and 2 exhibited moderate activities with IC50 values of 32.39 ± 9.1 and 47.83 ± 10.44 μM, respectively, compared with positive control indomethacin (IC50 = 21.62 μM). It is worth to note that 1, 3, and 4 have a distinctive woody fragrance.