Anti-inflammatory effect of buddlejasaponin IV through the inhibition of iNOS and COX-2 expression in RAW 264.7 macrophages via the NF-κB inactivation

摘要

1 Buddlejasaponin IV isolated from Pleurospermum kamtschatidum is an anti-inflammatory compound that inhibits NO, PGE_2 and TNF-α production. Here, we studied the mode of action of this compound. 2 Buddlejasaponin IV (2.5-10 μM) reduced lipopolysaccaride (LPS (1 μg ml~(-1))-induced levels of iNOS and COX-2 at the protein levels, and iNOS, COX-2, TNF-α, interleukin (IL)-1β and IL-6 mRNA expression in RAW 264.7 macrophages in a concentration-dependent manner, as determined by Western blotting and RT-PCR, respectively. 3 Buddlejasaponin IV inhibited the LPS-induced activation of nuclear factor-κB (NF-κB), a transcription factor necessary for proinflammatory mediators, iNOS, COX-2, TNF-α, IL-1β and IL-6 expression. This effect was accompanied by a parallel reduction in IκB-α degradation and phosphorylation, and by the nuclear translocation of the NF-κB p65 subunit. 4 The effects of buddlejasaponin IV on acute phase inflammation were studied on serotonin- and carrageenan-induced paw edema. The antiedematous effect of buddlejasaponin IV was compared with 10 mg kg~(-1) of indomethacin p.o. Maximum inhibitions of 26 and 41% were noted at a dose of 20 mg kg~(-1) for serotonin- and carrageenan-induced paw edema, respectively. 5 The analgesic effect of buddlejasaponin IV was evaluated using acetic acid-induced writhing and hot-plate tests. Buddlejasaponin IV (10 and 20 mg kg~(-1), p.o.) was found to have a marked analgesic effect in both models. 6 These results suggest that the inhibitions of the expressions of iNOS, COX-2, TNF-α, IL-1β and IL-6 by blocking NF-κB activation, are responsible for the anti-inflammatory effects of buddlejasaponin IV isolated from P. kamtschatidum.