Anti-inflammatory Effects of Pelargonium endlicherianum Fenzl. Extracts in Lipopolysaccharide-stimulated Macrophages

Objectives: This study was designed to investigate the anti-inflammatory effects of Pelargonium endlicherianum Fenzl. and Pelargonium quercetorum Agnew. root extracts compared with the effects of commercial Pelargonium sidoides root extract by production of pro-inflammatory substances and inflammatory signal transduction on LPS-stimulated macrophages.

Materials and methods: To measure the effects of root extracts on pro-inflammatory mediators, we used the following methods: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay (cell viability or cytotoxcicity), enzyme-linked immunosorbent assay (cytokine production, prostoglandin E2 production), reverse transcriptase-polymerase chain reaction (COX-2, iNOS mRNA), Western blotting analysis [MAPK activation and NF-κB (p65) traslocation] and the Griess reaction (NO production).

Results: Stimulation of the RAW 264.7 cells with LPS (0.5 µg/mL, 6 hrs treatment) caused an elevated production of pro-inflammatory cytokines (TNF-α and IL-6), increased mRNA expression of COX-2 and inducible NO synthase with release of PGE2 and NO, activated MAPK (phosphorylation of c-Jun N-terminal kinase, extracellular signal-regulated kinase, P38) signalling pathway, and nuclear translocation of NF-κB (p65), which were markedly inhibited by the pre-treatment with 11% ethanol and 70% methanol root extracts of P. endlicherianum without causing any cytotoxic effects. P. quercetorum root extract only decreased TNF-α production and P. sidoides root extract alleviated P38/MAPK activation and COX-2 mRNA expression with PGE2 production.

Conclusion: Our data indicate that especially 11% ethanol root extract of P. endlicherianum targets the inflammatory response of macrophages via inhibition of COX-2, IL-6, and TNF-α through inactivation of the NF-κB signalling pathway, supporting the pharmacologic basis of P. endlicherianum as a traditional herbal medicine for the treatment of inflammation and its associated disorders.

Keywords: Pelargonium species; cyclooxygenase-2; cytokines; inflammation; macrophages.