Figure 3: Effect of solvent fractions of Zanthoxylum rhetsa extract on the production of pro-inflammatory cytokines (a) tumor necrosis factor-alpha, (b) interleukin-6, and (c) interleukin-1 beta in lipopolysaccharide-stimulated mouse RAW 264.7 macrophages. Cytokine production following incubation with the indicated concentrations of the various fractions (methanol, butanol, ethyl acetate, chloroform, and hexane) for 24 h was determined by enzyme-linked immunosorbent assay. Tumor necrosis factor-alpha, interleukin-6, and interleukin-1 beta levels are expressed in pg/ml, and the values shown in the graph are mean ± standard deviation obtained from triplicate experiments.^###P < 0.001, lipopolysaccharide-treated group versus control; **P < 0.01 and *P < 0.05, significant difference from the lipopolysaccharide-treated group