OBJECTIVE: To study anti-inflammatory effect and mechanism of the luteolin · 4, 4' -dipyridy co-crystal.METHODS: Using macrophage RAW264. 7 of normal mice as control, the inflammation model was established with lipopolysaccharide (LPS) -induced RAW264. 7 cells. MTT assay was used to detect cells activity 2 h after treatment of different concentrations of luteolin (10, 20, 40, 80 μmol/L), 4, 4' -dipyridy (10,20, 40,80 μmol/L) and luteolin·4, 4' -dipyridy co-crystal (10, 20, 40, 80 μmol/L). The mRNA expression of iNOS and COX-2 in RAW264. 7 cells at 40 μmol/L were determined by qRT-PCR. The protein expression of TNF-α and IL-6 in RAW264. 7 cells at 40 μmol/L were determined by ELISA. The protein expression of NF-κB p65 in RAW264. 7 cells at 40 μmol/L were determined by Western bolt. RESULTS: Compared with normal cells, the activity of RAW264. 7 cells was decreased significantly after induced by LPS (P<0. 01); mRNA expression of iNOS and COX-2, protein expression of TNF-α, IL-6 and NF-κB p65 were increased significantly (P<0. 01). Both luteolin and luteolin · 4, 4' -dipyridy co-crystal could enhance the activity of RAW264. 7 cells after induced by LPS (P<0. 05 or P<0. 01) in concentration-dependent manner. 4, 4' -dipyridy had no significant effect on the activity of RAW264. 7 cells after induced by LPS. After luteolin and luteolin· 4, 4' -dipyridy co-crystal at 40 μmol/L, mRNA expression of iNOS and COX-2, protein expression of TNF-α, IL-6 and NF-κB p65 in RAW264. 7 cells after induced by LPS were decreased significantly (P<0. 05 or P<0. 01); the luteolin · 4, 4' -dipyridy co-crystal was better than luteolin (P<0. 05 or P<0. 01). CONCLUSIONS: The luteolin·4, 4' -dipyridy co-crystal can inhibit the generation of inflammatory factors by down-regulating NF-κB signal, and its anti-i nflammatory effect is better than luteolin.