Antioxidant activity of supercritical extract of Melissa officinalis subsp officinalis and Melissa officinalis subsp inodora

The antioxidant activity of Melissa officinalis subsp. officinalis and of Melissa officinalis subsp. inodora extracts, obtained by using carbon dioxide under supercritical conditions was investigated. The samples were prepared in two steps. A preliminary extraction at 90 bar and 50 degreesC eliminated the essential oil, then a further extraction at 300 bar and 50 degreesC obtained the high molecular mass extract. These samples were tested for autoxidation and the iron or EDTA-mediated oxidation of linoleic acid at 37 degreesC in the absence of solvent, in in vitro systems. During linoleic acid autoxidation and its EDTA-mediated oxidation both M. officinalis and M. inodora extracts showed an antioxidant activity, and no significant differences in their efficacy were observed. None showed any prooxidant activity. Copyright (C) 2004 John Wiley Sons, Ltd.