Free-radical scavenging activity of wormwood (Artemisia absinthium L) extracts

In an effort to discover new antioxidant natural compounds, wormwood (Artemisia absinthium L) an aromatic-bitter herb, was screened. The sequential extraction was realized with five solvents of different polarities (70% methanol, petroleum ether, chloroform, ethyl acetate, n-butanol). The antioxidative activity was tested by measuring their ability to scavenge stable 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical and reactive hydroxyl radical during the Fenton reaction trapped by 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), using electron spin resonance (ESR) spectroscopy. Results demonstrated that the antiradical and antioxidative activity depend on the type and concentration of applied extracts and increased in the order ethyl acetate > methanol > n-butanol > chloroform > petroleum ether > remaining water extracts. The investigation showed that the antiradical activity increased with increasing concentration of all extracts. The high contents of total phenolic compounds (25.6 mg g(-1)) and total flavonoids (13.06 mg g(-1)) indicated that these compounds contribute to the antiradical and antioxidative activity. In a model system, the formation of o-semiquinone radicals from quercetin and chlorogenic acid was obtained to prove the mechanism (hydrogen donating and/or one-electron reduction) of free-radical scavenging activity. (C) 2004 Society of Chemical Industry.