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Luteolin, a plant flavonoid, has potent anti-inflammatory properties both in vitro and in vivo. However, the molecular mechanism of luteolin-mediated immune modulation has not been fully understood. In this study, we examined the effects of luteolin on the production of nitric oxide (NO) and prostaglandin E(2) (PGE(2)), as well as the expression of inducible NO synthase (iNOS), cyclooxygenase-2 (COX-2), tumor necrosis factor-alpha (TNF-alpha), and interleukin-6 (IL-6) in mouse alveolar macrophage MH-S and peripheral macrophage RAW 264.7 cells. Luteolin dose-dependently inhibited the expression and production of these inflammatory genes and mediators in macrophages stimulated with lipopolysaccharide (LPS). Semi-quantitative reverse-transcription polymerase chain reaction (RT-PCR) assay further confirmed the suppression of LPS-induced TNF- alpha, IL-6, iNOS and COX-2 gene expression by luteolin at a transcriptional level. Luteolin also reduced the DNA binding activity of nuclear factor-kappa B (NF-kappaB) in LPS-activated macrophages. Moreover, luteolin blocked the degradation of IkappaB-alpha and nuclear translocation of NF-kappaB p65 subunit. In addition, luteolin significantly inhibited the LPS-induced DNA binding activity of activating protein-1 (AP-1). We also found that luteolin attenuated the LPS-mediated protein kinase B (Akt) and IKK phosphorylation, as well as reactive oxygen species (ROS) production. In sum, these data suggest that, by blocking NF-kappaB and AP-1 activation, luteolin acts to suppress the LPS-elicited inflammatory events in mouse alveolar macrophages, and this effect was mediated, at least in part, by inhibiting the generation of reactive oxygen species. Our observations suggest a possible therapeutic application of this agent for treating inflammatory disorders in lung.

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Hispolon, an active ingredient in the fungi Phellinus linteus was evaluated with analgesic and anti-inflammatory effects. Treatment of male ICR mice with hispolon (10 and 20 mg/kg) significantly inhibited the numbers of acetic acid-induced writhing response. Also, our result showed that hispolon (20 mg/kg) significantly inhibited the formalin-induced pain in the later phase (P<.01). In the anti-inflammatory test, hispolon (20 mg/kg) decreased the paw edema at the fourth and fifth hour after λ-carrageenin (Carr) administration, and increased the activities of superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GRx) in the liver tissue. We also demonstrated that hispolon significantly attenuated the malondialdehyde (MDA) level in the edema paw at the fifth hour after Carr injection. Hispolon (10 and 20 mg/kg) decreased the nitric oxide (NO) levels on both the edema paw and serum level at the fifth hour after Carr injection. Also, hispolon (10 and 20 mg/kg) diminished the serum TNF-α at the fifth hour after Carr injection. The anti-inflammatory mechanisms of hispolon might be related to the decrease in the level of MDA in the edema paw by increasing the activities of SOD, GPx and GRx in the liver. It probably exerts anti-inflammatory effects through the suppression of TNF-α and NO.

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