Anti-Inflammatory and Antioxidant Properties of the Aqueous Extracts of the Leaves of <i>Opilia amentacea</i> (Opiliaceae)

Opilia amentacea (Opiliaceae) is a woody plant with multiple medicinal claimed effects. The present study aimed to assess the anti-inflammatory and antioxidant activities of the decoction and macerate extracts from the leaves of Opilia amentacea. Moreover, acute toxicity and phytochemical analysis were performed. The acute toxicity was evaluated on NMRI mice at 2000 mg/kg bw. The anti-inflammatory activity was studied using the carrageenan-induced mouse paw edema and the lipoxygenase inhibition assay. The radical scavenging (DPPH and ABTS), ferric-reducing antioxidant power (FRAP), and lipid peroxidation (LPO) assays were used to measure the antioxidant capacity of the extracts. Qualitative and quantitative methods served for identifying and quantifying the extract’s phytoconstituents. The decoction demonstrated low acute toxicity; the lethal dose was therefore estimated to be superior to 2000 mg/kg bw. The extracts significantly reduced the mouse paw’s thickness at 600 mg/kg bw. The extracts developed weak radical scavenging and lipid peroxidation inhibitory effects. However, the macerate showed a high ability (664.90 ± 0.71 mol Ascorbic Acid Equivalent/g dry extract) to reduce the ferric ions. Saponins, sterols, triterpenes, and flavonoids were qualitatively detected in the two extracts. Total phenolics (TP) and total flavonoids (TF) were found abundant in the extracts, especially the decoction (TP content (TPC) = 94.03 ± 2.66 mg GAE/g; TF content (TFC) = 35.05 ± 0.32 mg QE/g). Strong positive correlations existed between ferric-reducing capacity and TPC (r = 0.959) for the macerate, while TFC was mainly involved in the DPPH radical scavenging of the two extracts. Instead, most correlations were negative between the polyphenol compounds and the anti-inflammatory assays. The results indicate potent in vivo anti-inflammatory and in vitro antioxidant effects of the aqueous extracts from the leaves of Opilia amentacea. Further studies are needed to find the anti-inflammatory and antioxidant effects mechanism.