OBJECTIVETo observe the effect of pretreatment with puerarin on activation of LPS -induced RAW264. 7 cells and secretory cytokines, and discuss its anti-inflammatory mechanism.

METHODWell-grown RAW264. 7 cells in the exponential phase were collected and randomly divided them into the blank control group, the LPS group and the puerarin pretreatment + LPS group. The cellular toxic effect of puerarin on RAW264. 7 cells was examined by CCK-8 assay, cell morphology was detected by Giemsa stain method, the changes in TNF-alpha and MIP-2 were tested by ELISA, and the expression of NF-kappaB p65 mRNA were determined by qRT-PCR.

RESULTSWhen puerarin was cultured with 1 mg x L(-1) LPS at a concentration of lower than 400 micromol x L(-1), it had not showed the cellular toxic effect (P < 0.05). Compared with the control group, the LPS group could significantly change the morphology of RAW264. 7 cells (increase in cell body, irregular shape, with a large number of pseudopodia extending). After intervention, the puerarin 100 micromol x L(-1) group could significantly inhibit LPS-induced cell morphological changes, while the puerarin 200 micromol x L(-1) and 400 micromol x L(-1) puerarin groups showed more notable inhibitory effects. However, there was no obvious difference between the two groups. The pretreatment with puerarin could inhibit the expression of TNF-alpha and MIP-2 in cell supernatant and NF-kappaB p65 mRNA in cells (P < 0.05). With increase in the puerarin concentration, its inhibitory effect gradually grew (P < 0.05), but did not reach the level of the blank control group.

CONCLUSIONAs a safe and effective natural anti-inflammatory drug, puerarin can significantly reduce the expression of inflammatory cytokines (TNF-alpha, MIP-2). Its mechanism may be related to the reduction of NF-kappaB p65 mRNA expression.