This study examined the total polyphenol content of eight wild edible plants from Ethiopia and their effect on NO production in Raw264.7 cells. Owing to its relatively high polyphenol concentration and inhibition of NO production, the methanol extract of Adansonia digitata L. leaf (MEAD) was subjected to detailed evaluation of its antioxidant and anti-inflammatory effects. Antioxidant effects were assessed by measuring free-radical-scavenging activity using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and oxygen-radical-absorbance capacity (ORAC) assays, while anti-inflammatory effects were assessed by measuring inducible nitric oxide synthase (iNOS) expression in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. In the ORAC assay, MEAD was 10.2 times more potent than vitamin C at eliminating peroxyl radicals. In DPPH assay, MEAD also showed a strong ROS scavenging effect. MEAD significantly inhibited iNOS activity (IC50=28.6 μg/ml) of LPS-stimulated Raw264.7 cells. We also investigated the relationship between iNOS expression and nuclear factor kappa B (NF-κB) activation. MEAD inhibited IκBα degradation and NF-κB translocation from the cytosol to the nucleus in LPS-induced RAW264.7 cells without significant cytotoxic effects, as confirmed by MTT assay. These results suggest that MEAD inhibits anti-inflammatory iNOS expression, which might be related to the elimination of peroxyl radicals and thus the inhibition of IκBα-mediated NF-κB signal transduction.

Harungana(Harungana madagascarensis) is a commonly used medicinal plant in DRCongo. The aim of the study was to investigate potentials to develop an ethnomedicinal drug by evaluating the antioxidant activities and cytotoxicity of Harungana stem bark extract. A methanol(MeOH) extract and fractions of MeOH of Harungana stem bark were studied in vitro for total antioxidant activities by DPPH and ABTs and total phenol content was assessed with Folin‐Ciocalteau reagent. MTT and Griess reaction were used to test toxicity and nitric oxide(NO) production in RAW264.7 cells. We found no toxicity of ethyl acetate and aqueous extracts on RAW264.7. The methanol extract showed significant antioxidant activities(IC(50)22.89μg/mL and 20.37μg/mL in the DPPH and ABTs, respectively). The MeOH extract(100mg) yielded 271.96mg tannic acid‐equivalent phenolic content. Ethyl acetate and butanol extracts also expressed similar antioxidant effects as MeOH extract. Hexane and butanol extracts decreased NO production by RAW264.7 (IC(50)22.2 μg/mL). The present study provides an evidence that methanol, butanol and ethyl acetate extracts of Harungana stem bark are potential sources of natural antioxidants.