Anti-inflammatory and Antioxidant Activity of Eugenial D from Eugenia astringens

Eugenia astringens Cambess. (syn. Eugenia umbelliflora O.Berg), Myrtaceae, is a plant widely used in the Brazilian traditional medicine due to its anti-inflammatory and antibacterial properties. Its fruits are an important natural source of phloroglucinols such as eugenial D. In this study, the in vitro antioxidant and anti-inflammatory activity of this compound were investigated, which was isolated from the methanol extract of E. umbelliflora unripe fruits. The antioxidant activity was evaluated through the 2-diphenyl-1-picrylhydrazyl (DPPH), oxygen radical absorbance assay (ORAC), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS^•+), and metal chelating assays whereas the anti-inflammatory activity by nitric oxide inhibitory assay in RAW 264.7 macrophages after stimulation with lipopolysaccharide. The results demonstrated a pro-oxidant effect of the eugenial D due to its ability to neutralize reactive oxygen species and metal ions. In addition, a significant anti-inflammatory activity, through the inhibition of NOx production (58.65%) at the lowest tested concentration (1 µM), was observed. Given that the compound showed to be cytotoxic for RAW 264.7 macrophages from a concentration of 30 µM (CC₁₀) and high anti-inflammatory activity was found at low concentrations, a selective action is expected for this phloroglucinol. In vivo studies are encouraged to confirm these findings.