Three Novel Flavonoid Derivatives From the Roots of <i>Dalbergia odorifera</i>

Three novel flavonoid derivatives, named dalberavonoids A-C (1-3), were isolated from the roots of Dalbergia odorifera T. C. Chen. The structures of these flavonoid derivatives were determined by comprehensive spectroscopic analyses. Compounds 1 and 2 represent rare examples of isopentenyl-substituted flavanes from the genus Dalbergia. Compound 3 is a rare flavonoid containing 16 carbon atoms on the carbon skeleton. The inhibitory activities of dalberavonoids A-C against the nitric oxide (NO) production induced by lipopolysaccharide in mouse macrophage RAW 264.7 cells in vitro were evaluated. Compounds 1 and 2 exhibited significant inhibitory activities, possessing the minimum inhibitory concentration (IC₅₀) values of 9.13 ± 0.11 and 12.58 ± 0.14 µM. The positive control, indometacin, displayed an inhibitory activity against NO production with an IC₅₀ value of 23.86 ± 0.08 µM.