Antioxidant and Antiinflammatory Effects of Epilobium parviflorum, Melilotus officinalis and Cardiospermum halicacabum Plant Extracts in Macrophage and Microglial Cells

Background: We investigated the phenolic content characterizing different plant extracts from Epilobium parviflorum, Cardiospermum halicacabum, and Melilotus officinalis, their antioxidant, antiinflammatory effects, and their mechanism of action. Methods: plant samples were macerated in 40% ethanol or hot/ cold glycerate and assessed for polyphenols content. The antioxidant activity was investigated by DPPH radical scavenging assay and H2DCFDA test in LPS-stimulated RAW264.7 macrophages and N9 microglial cells. MTS experiments and antiinflammatory properties verified cellular toxicity through NO assay. Interaction with A2A adenosine receptors was evaluated through binding assays using [3H]ZM241385 radioligand. Results: Polyphenols were present in 40% ethanol plant extract, which at 0.1–10 µg/µL achieved good antioxidant effects, with a DPPH radical scavenging rate of about 90%. In LPS-stimulated cells, these plant extracts, at 1μg/μL, did not affect cell vitality, displayed significant inhibition of H2DCFDA and NO production, and inhibited ZM 241385 binding in CHO cells transfected with A2A receptors. RAW 264.7 and N9 cells presented a density of them quantified in 60 ± 9 and 45 ± 5 fmol/mg of protein, respectively. Conclusion: Epilobium parviflorum, Cardiospermum halicacabum, and Melilotus officinalis extracts may be considered a source of agents for treating disorders related to oxidative stress and inflammation.