In vitro Pro- and Anti-Inflammatory Screening of Pappea capensis Extracts

Abstract

Pappea capensis has been used traditionally in the Limpopo province of South Africa to treat different diseases caused by viruses or infectious microorganisms such as fungi and bacteria. To date no reports of pro- and anti-inflammatory activity of this plant has been reported so far. The aim of the study was to determine the intro pro- and anti-inflammatory activity of water, ethanoic and methanolic extracts of the pappea capensis wood material. Serial dilutions were prepared at 0, 12.5, 25, 50, 100 and 200 μg/mL from each extract, which were subjected to the determination of the pro- and anti-inflammatory activity in vitro by RAW 264.7 cells using Resveratrol as a reference drug. The in vitro screening results for anti- and pro-inflammatory assays showed an increased nitric oxide (NO) production which correlated with each extract cytotoxicity in LPS-activated macrophages. Resveratrol, a known inhibitor of iNOS expression served as a positive control to the regime. There was a noticeable macrophage activation observed which was extracts concentrations depended. This response to treatment with different concentrations of pappea capensis extracts corresponded with nitric oxide production a similar trend was observed with the analysis of cell viability which predicts the corresponding cytotoxicity of all extracts. However, there was a high nitric oxide production and observable macrophage activation in the presence of water extract A confirmatory test was done to ascertain if this effect is owed to plant constituents or due to endotoxin contamination. Then, nitric oxide production was analyzed in the presence and absence of polymyxin B (PMB) and it can be concluded that polymyxin B counteracts the pro-inflammatory effect suggesting that this activity is possibly a result of endotoxins in this wood part of the plant. The determination of endotoxin as a cofactor perpetrating pro-inflammatory activity tested with polymyxin B was used and indicated the presence of a toxin in water extract. The low anti-inflammatory effect seen in the three extracts at 200 μg/mL are not physiologically active.