Bioactive components, antioxidant, and anti-inflammatory activities of the wood of Albizia myriophylla

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, IC 50 46.23 μg/ml; ABTS, IC 50 57.14 μg/ml; FRAP, 950.14 mM Fe (II)/g) and dichloromethane fraction (DPPH, IC 50 29.54 μg/ml; ABTS, IC 50 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 (IC 50 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, IC 50 8.96 μg/ml; ABTS, IC 50 10.12 μg/ml) and 8-methoxy-7,3′,4′-trihydroxyflavone ( 2 ) (DPPH, IC 50 5.05 μg/ml; ABTS, IC 50 7.89 μg/ml) had potent free radical scavenging effects comparable to those of ascorbic acid (DPPH, IC 50 2.12 μg/ml; ABTS, IC 50 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 (IC 50 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.