Cyclic diarylheptanoids from Myrica nana inhibiting nitric oxide release Original Research Article

Investigation of the roots of Myrica nana afforded five new cyclic diarylheptanoids, myricananins A–E (1–5), two new artifacts of myricananins A and B (6–7), and four known compounds, 12-hydroxymyricanone (8), alnusonol (9), myricatomentogenin (10), and actinidione (11). The structures of these new compounds were established by detailed spectroscopic methods. The stereochemistry of compounds 1 and 2 were determined by single-crystal X-ray diffraction. In exception of compounds 2, 6 and 10, all the other compounds were examined for their inhibitory effects on nitric oxide production in lipopolysaccharides-activated macrophages. Compounds 1, 3, 7, 8 and 9 inhibited the release of nitric oxide with IC50 values of 45.32, 63.51, 52.81, 30.19 and 46.18 μM, respectively. Furthermore, compound 1 was found to inhibit the expression of inducible nitric oxide synthase.