Characterisation of in vitro antioxidative properties of aqueous ethanolic (45%v/v) extract of Lemon Balm (Melissa officinalis L.)

The plant Melissa officinalis (L.) has been used in European traditional system of medicine for its cognitive enhancing properties. Based on its traditional use and cholinergic properties, this plant was recently assessed for its clinical efficacy in Alzheimer's Disease (AD) in a trial conducted by the Institute of Medicinal Plant (IMP), Tehran, Iran [1]. The plant was found to be effective in the management of mild to moderate AD patients. Since it has been proposed that oxidative stress plays a cardinal role in the pathogenesis of the disease [2], we wanted to investigate if the efficacy of the plant extract in the clinical trial is due to its antioxidative properties. Therefore based on the IMP research M. officinalis was extracted by a similar procedure using the same solvent (45% v/v ethanol) and plant material (cultivar). The method of extraction was Medium Pressure Solid Liquid Extraction. The total phenol content was estimated as gallic acid acid equivalents using Folin-Ciocalteu reagent method and the in vitro antioxidant activities assayed were iron (III) reduction, iron (II) chelation, 1,1-diphenyl-2-picrylhydrazyl, 2,2'-azinobis(3-ethylbenzothiazoline-6-sulphonate) free radical scavenging activities, inhibiton of β-carotene-linoleic acid bleaching. The extract demonstrated activity in all the assays, however it was not as potent as the positive controls except in the β-carotene-linoleic acid bleaching assay where its antioxidant activity was superior to that of gallic and caffeic acid and statistically indistinguishable from quercetin and butylated hydroxyanisole.

Acknowledgements: Institute of Medicinal Plants, Iranian Academic Center for Education, Culture and Research, Tehran, Iran

References: 1. Akhondzadeh, S. et al. (2003), J. Neurol. Neurosurg. Psychiatry 74: 863–866. 2. Varadarajan, S. et al. (1999), J. Struct. Biol. 309: 746–768.