Antioxidant activity, genotoxicity and cytotoxicity evaluation of lemon balm (Melissa officinalis L.) ethanolic extract: Its potential role in neuroprotection

The antioxidant activity of Melissa officinalis (MO) was evaluated to understand the mechanism of its pharmacological properties as well as its potential genotoxic and cytotoxic effects in human leukocytes. The results showed that MO scavenged DPPH radical in a concentration dependent-manner with IC50 values of 48.76 +/- 1.94 mu g/mL. MO showed strong reducing power and exhibited a significant inhibition of deoxyribose degradation. MO interfered with the formation of 1,10-phenanthroline-Fe2+ complex, suggesting that it has chelating activity and captures Fe2+ before 1,10-phenanthroline. The addition of 5 mM ascorbic acid to the reaction mixture dramatically reduced Fe3+ (formed during the incubation time) to Fe2+ indicating that it was an "apparent" chelation. MO was neither genotoxic nor cytotoxic at the concentrations tested, indicating that the popular use of the extract might possibly not result in any genotoxic or cytotoxic effects. Our results suggest that MO is a potential source of natural antioxidants, and could be relevant for the management of oxidative stress. Of particular importance, for neurodegenerative diseases, the capacity of MO to "chelate" and to maintain Fe2+ in a Fe3+ state can contribute to its neurotherapeutic effects, because iron plays a central role in brain damage. (C) 2013 Elsevier B.V. All rights reserved.