Isoalantolactone inhibits NO production and suppresses iNOS expression in BMDMs. a Chemical structure of IAL. b NO production analysis of BMDM. c The protein expression of iNOS in BMDM was determined by western blotting. BMDMs were pre-treated with IAL at 0, 2.5, 5, 10, and 20 μM for 30 min before stimulation with LPS (100 ng/mL) for 12 h. The supernatant was collected for NO production analysis, and cell lysates were collected for Western blotting. β-Actin was used as a loading control. d Statistical analysis of iNOS expression in diagrams. The data represent the mean ± SEM of three independent experiments (*P < 0.05, **P < 0.01, and ***P < 0.001)