Flavonoids isolated from the aerial parts of Baeckea frutescens L. with anti-inflammatory activities

A new dihydroflavone (1) and ten known flavonoids (2–11) were isolated from the aerial parts of Baeckea frutescens L., with their structures elucidated by spectroscopic analyses and ECD calculations. The anti-inflammatory effects were then evaluated in LPS-stimulated RAW 264.7 cells. Among them, compound 8 exhibited the most potent NO inhibition (IC50 = 7.51 ± 1.11 μM). Furthermore, compounds 1, 4, 5, and 9 showed stronger NO inhibitory activity than the positive control dexamethasone (IC50 = 24.12 ± 1.38 μM), with IC50 values of 15.92–21.98 μM. In addition, the production of TNF-α and IL-6 was moderately inhibited by compounds 4, 5, 8, and 9 (IC50 = 25.46–34.87 μM) and compounds 4 and 5 (IC50 = 27.63 and 27.89 μM), respectively. These findings suggest that the isolated flavonoids, particularly compounds 4, 5, 8, and 9, possess promising anti-inflammatory activity.