In vitro evaluations of cytotoxicity and anti-inflammatory effects of Peganum harmala seed extracts in THP-1-derived macrophages

Aim: Based on knowledge from traditional Greco-Arab herbal medicine, this in vitro study aims to evaluate the cytotoxicity and the anti-inflammatory mechanism of Peganum harmala (P. harmala) seeds by measuring the expression and release of both anti-inflammatory (IL-10) and proinflammatory (IL-1, IL-2, IL-6 and TNF-α) cytokines in human THP-1-derived macrophages. Methodology: Cells were treated with 1µg lipopolyssacharide/ml (LPS) in the absence and presence of increasing concentrations of extracts from the P. harmala seeds (PHS-extract). During the entire experimental period, we used extract concentrations (up to 250 µg/ml) that had no cytotoxic effects as measured with MTT and LDH assays. The anti-inflammatory effects were assessed by measuring the levels of secretory proteins and mRNA of IL-1, IL-2, IL-6, IL-10 and TNF-α in LPS-activated (1µg/ml) human THP-1-derived macrophages. Results: PHS-extract remarkably increased IL-10 release and mRNA expression at a concentration of 64µg/ml and suppressed the expression and release of IL-1, IL-6 and TNF-α in dose-dependent manner. No significant effects on the expression levels of IL-2 were observed after treatment with PHS-extract. Conclusions: These results indicate that PHS-extract probably exert anti-inflammatory properties throughout increasing the release and expression of IL-10 mRNA as well as by suppressing IL-1, IL-6 and TNF-α mRNA expression in THP-1 cells.