Four Undescribed Compounds From the Leaves of Zanthoxylum avicennea and Their NO Inhibitory Activity

Zanthoxylum avicennea (Rubiaceae family) has been used in traditional medicine. Study on the leaves of Z. avicennea resulted in four undescribed compounds, zanthoavicenneas A-D (1-4), along with twelve known ones (5-16). Their structures were elucidated by spectroscopic techniques, including HR-ESI-MS, 1D and 2D NMR spectroscopy. The absolute configurations of compounds 3 and 4 were further determined by ECD spectroscopy. Among the known isolates, the complete NMR data assignments for compound 5 were also reported for the first time. In addition, compounds 1, 3, and 5 exhibited favorable inhibitory effects on NO production in LPS-activated RAW264.7 macrophages, showing IC₅₀ values of 22.73 ± 1.12, 37.61 ± 1.25, and 28.96 ± 1.66 µM, respectively, as compared to a well-known NO inhibitor, dexamethasone (IC₅₀ = 13.12 ± 0.92 µM). The remaining compounds displayed moderate to weak inhibitory activity, showing IC₅₀ values from 57.20 ± 1.50 to 84.56 ± 2.18 µM.