Anti-Inflammatory effects of herbal-derived factors are mediated by down regulation of pro-inflammatory cytokines

The aim of the present in vitro study is to evaluate the role of pro-inflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin 6 (IL-6) in the observed anti-inflammatory effects of Hypericum triquetrifolium and Peganum harmale. Therefore, water extracts from the aerial parts of the two plants were tested for their anti-inflammatory effects in vitro using cells from the human monocyte cell line THP-1. Anti-inflammatory effects were assessed by measuring the levels of secretory proteins and mRNA of TNF-α and IL-6 production of LPS-activated THP- 1 cells. Cells were treated with 5µg lipopolyssacharide/ml (LPS) in the absence and presence of increasing concentrations of plant extracts. During the entire experimental period, we used plant extracts concentrations (up to 250µg/ml) that had no cytotoxicity as measured in MTT assay. Hypericum triquetrifolium extracts totally reduced the LPS induced TNF-α expression and secretion. Peganum harmale extracts inhibited the IL-6 production in a dose dependent manner reaching the control levels of untreated cells at a concentration of 125 µg/ml. These results demonstrate that the anti-inflammatory effects of the two plants are mediated through the inhibition of the pro-inflammatory cytokines TNF-α and IL-6.