Anti-inflammatory effects of Portulaca oleracea L. on the LPS-induced RAW 264.7 cells

Portulaca oleracea L. (Portulacaceae) has been widely used as a folk medicine in many countries. The present study investigated the effects of aqueous extract of P. oleracea (PO) on pro-inflammatory mediators secreted from lipopolysaccharide (LPS) - activated macrophage cells (RAW 264.7) as an established inflammation model. The reference drug indomethacin was used for comparison purpose. PO did not show cytotoxic effects at the concentrations tested. When RAW 264.7 macrophages were treated with PO together with LPS, a significant concentration, dependent inhibition of nitrogen oxide (NO) production was detected. Western blotting revealed that PO blocked protein expression of iNOS in LPS - stimulated RAW 264.7 macrophages, significantly. The change in the contents of PGE2, IL-6 and TNF-α were monitored by enzyme linked immunosorbent assay (ELISA). Compared with indomethacin, PO has much more potency and inhibited the production of PGE2, IL-6 and TNF-α in LPS- induced RAW 264.7 cells at concentrations of 0.05, 0.1, and 0.2 mg/ml (p < 0.05). These results suggested that PO might have a potential therapeutic effect by inhibiting the inflammation process such as arthritis.   Key words: Portulaca oleracea, inflammation, extract, therapeutic effect.