RESUMO
Abstract The scientific basis corresponding with the folkloric use of Albizia myriophylla Benth., Fabaceae, for the treatment of inflammation-related diseases was established by measuring antioxidant potential using 2,2-diphenyl-1-picrylhydrazyl, 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) free radicals, and ferric reducing antioxidant power assays as well as anti-inflammatory effect using nitrite assay and ethyl phenylpropiolate (EPP)-induced rat ear edema model. Both ethanol extract (DPPH, IC50 46.23 µg/ml; ABTS, IC50 57.14 µg/ml; FRAP, 950.14 mM Fe (II)/g) and dichloromethane fraction (DPPH, IC50 29.54 µg/ml; ABTS, IC50 40.36 µg/ml; FRAP, 946.69 mM Fe (II)/g) from A. myriophylla demonstrated a promising antioxidant activity. Furthermore, it was found that the ethanol extract of A. myriophylla showed significant inhibitory activity against lipopolysaccharide (LPS)-induced nitric oxide production in murine macrophage cells (IC50 13.8 µg/ml). The ethanol extract (15% w/v) also exhibited the maximum percentage inhibition (81-95%) of inflammation in the ear edema model at all assessment times comparable to indomethacin (0.5 mg/ear). Among all isolates 1-5 from the active extract of A. myriophylla, indenoic acid (1) (DPPH, IC50 8.96 µg/ml; ABTS, IC50 10.12 µg/ml) and 8-methoxy-7,3′,4′-trihydroxyflavone (2) (DPPH, IC50 5.05 µg/ml; ABTS, IC50 7.89 µg/ml) had potent free radical scavenging effects comparable to those of ascorbic acid (DPPH, IC50 2.12 µg/ml; ABTS, IC50 3.26 µg/ml). Compound 2 also displayed remarkable reducing power in FRAP test (261.81 mg QE/g) and showed a marked inhibition of the cellular nitric oxide production (IC50 27.7 µg/ml). Our results suggest that the anti-inflammatory mechanism of A. myriophylla is most probably based on its capacity to suppress nitric oxide production as well as to be free radical scavenger.