标题：Dibenzylbutyrolactone Lignans from Forsythia koreana Fruits Attenuate Lipopolysaccharide-Induced Inducible Nitric Oxide Synthetase and Cyclooxygenase-2 Expressions through Activation of Nuclear Factor-κB and Mitogen-Activated Protein Kinase in RAW264.7 Cells
摘要：Previously, we reported that dibenzylbutyrolactone lignans (DBLLs) from the fruit of Forsythia koreana N AKAI (Oleaceae) has anti-inflammatory, antioxidant, and anti-asthmatic effects. In this study, to clarify the anti-inflammatory mechanisms of DBLL, we evaluated the effects of DBLLs on lipopolysaccharide-stimulated inducible nitric oxide synthetase (iNOS) and cyclooxygenase-2 (COX-2) expressions, nitric oxide (NO) and prostaglandin E2 (PGE2) productions, nuclear factor-κB (NF-κB) and mitogen-activated protein kinase (MAPK) activations, inhibitor of κB (IκB) and inhibitor of κB kinase (IKK) phosphorylations in cytosolic proteins, and cytotoxicity in Raw264.7 cells. DBLLs potently suppressed both the enzyme expression and DNA-binding activity of NF-κB. Arctiin, arctigenin (1.0 μ M ) and matairesinol (10 μ M ) inhibited the expression of iNOS by 37.71±2.86%, 32.51±4.28%, and 27.44±2.65%, respectively, and arctiin, arctigenin (0.1 μ M ) and matairesinol (1.0 μ M ) inhibited COX-2 expression by 37.93±7.81%, 26.70±4.61% and 29.37±5.21%, respectively. The inhibitory effects of DBLLs on NO and PGE2 productions were the same patterns as those seen for the reductions in iNOS and COX-2 expression, respectively. Arctiin, arctigenin (1.0 μ M ) and matairesinol (10 μ M ) significantly ( p <0.05) inhibited NF-κB DNA binding by 44.85±6.67%, 44.16±6.61%, and 44.79±5.62%, respectively, and arctiin (0.1 μ M ) and arctigenin (1.0 μ M ) significantly ( p <0.05) inhibited the phosphorylation of IκB by 20.58±3.86% and 25.99±6.18%, respectively. Furthermore, arctiin, matairesinol (1.0 μ M ) and arctigenin (10 μ M ) inhibited the phosphorylation of IKK by 38.80±6.64%, 38.33±6.65%, and 38.57±8.14%, respectively. In addition, DBLLs potently inhibited the lipopolysaccharide (LPS)-induced activation of MAPKs (SAPK/c-Jun NH2-terminal kinase (JNK), p38, and extracellular signal receptor-activated kinase (ERK)1/2). Overall, arctiin was the most effective; its effect was nearly the same as that of 10 μ M helenalin. These findings suggest that treatment with non-toxic DBLLs inhibits not only NF-κB and NF-κB-regulated protein activation, but also potently inhibits the activations of specific MAPKs.
