Non-cytotoxic doses of shikonin suppress LPS-induced TNF-α expression in primary murine BMDMs via AMPK activation. After treating with the indicated doses of shikonin for 24 h, the survival and death rates of primary murine BMDMs were evaluated by (A) MTT and (B) trypan blue exclusion assays, respectively. (C) Expression levels of ACC, p-ACC, AMPKα and p-AMPKα were detected by western blotting. Relative ROS intensity and NF-κB activation were examined by (D) flow cytometry and (E) p65 DNA-binding activity assay, respectively. Extracellular contents and relative mRNA levels of TNF-α were examined by (F) ELISA and (G) reverse transcription-quantitative PCR, respectively. *P<0.05 vs. LPS alone group. #P<0.05 vs. corresponding shikonin combined with LPS group. C, control; LPS, lipopolysaccharide; TNF-α, tumor necrosis factor α; p-, phosphorylated; ACC, acetyl-CoA carboxylase; AMPK, AMP-activated protein kinase; IKKα/β, IκB kinase α/β; CC, Compound C; ROS, reactive oxygen species; BMDMs, bone marrow-derived macrophages.