Phenolic antioxidants from the heartwood of Acacia confusa

In the present study, the ethanolic extracts from the heartwood of Acacia confusa, a species indigenous to Taiwan, exhibit strong antioxidant effects. Among all the fractions from ethanolic extracts of heartwood, the EtOAc soluble fraction exhibits the best antioxidant activity. The 80% 1,1-diphenyl-2- picrylhydrazyl radical inhibitory activity by the EtOAc extract was observed at a concentration of 5 μg/mL, and at the same dosage there was a similar free radical scavenging activity for (-)-ascorbic acid and (+)-catechin, both of which are well-known antioxidants. In addition, the EtOAc extract also protects ΦX174 supercoiled DNA against strand scission induced by hydroxyl radical. Furthermore, following by column chromatography and reverse-phase high-performance liquid chromatorgrapy, 10 pure phenolic compounds, including three major antioxidants (3,7,8,3′,4′-pentahydroxyflavone, 7,8,3′,4′-tetrahydroxy-3-methoxyflavone, and 3,4,2′,3′, 4′-pentahydroxy-trans-chalcone) and a new flavonoid (3,7,8,3′- tetrahydroxy-4′-methoxyflavone), were isolated from the ethanolic extracts of A. confusa heartwood.