Anti-inflammatory effects of the Portulaca oleracea hydroalcholic extract on human peripheral blood mononuclear cells

Portulaca oleracea, known as Purslane, is an annual growing herb with wide distribution around the world and traditionally used to manage several diseases. Different therapeutic properties as an anti-fever agent as well as anti-inflammatory and analgesic effects have been attributed to P. oleracea. The aim of this study was to investigate the effects of P. oleracea aerial extract on production of pro- and anti-inflammatory cytokines by human peripheral blood mononuclear cells (PBMCs). Aerial parts of P. oleracea (stems and leaves) were collected and extracted by percolation using methanol. The optimal and non-cytotoxic dose of hydro-alcoholic extract for cell culture analysis was determined by MTT assay. To assess the anti-inflammatory effects of P. oleracea, PBMCs obtained from 12 normal volunteers were cultured in RPMI complete medium and co-treated with E. coli lipopolysaccharide (LPS) and P. oleracea hydro-alcoholic extract. Following 18-hour incubation, culture supernatants were harvested for measurement of secreted TNF-α, IL-6 and IL-10 by ELISA. Statistical analyses were performed using the SPSS v.20, and data analyzed by Kolmogorov-Smirnov, Mann-Whitney U, Kruskal-Wallis and post Hoc tests. P-values<0.05 were considered significant. The optimal non-cytotoxic concentration of P. oleracea aerial extract was defined as 100 μg/ml based on MTT viability assay. P. oleracea hydro-alcoholic extract significantly decreased the concentration of both pro-inflammatory cytokines TNF-α and IL-6 in LPS-stimulated PBMCs (p<0.001 and p<0.001, respectively). However, the concentration of IL-10 as an anti-inflammatory cytokine, did not show any statistically significant change (p=0.390). Our findings highlighted the potential anti-inflammatory properties of P. oleracea in herbal medicine. Future analysis on different constituents of total extract may confirm its therapeutic effects as a promising anti-inflammatory compound.