Pharmacological profile of essential oils derived from leaves of lemon verbena (Aloysia citriodora Palau) and Lemon balm (Melissa officinalis L.): cholinergic, anti-oxidant and iron chelation properties.

S Abuhamdah2, R Abuhamdah1, M-J Howes3, S Al-Khali2, A Ennaceur4, PL Chazot1. 1University of Durham, Durham, County Durham, UK, 2University of Jordan, Amman, Jordan, 3Royal Botanic Gardens, Kew, Surrey, UK, 4Sunderland Pharmacy School, Sunderland, Tyne & Wear, UK

In traditional medical practice, numerous plants have been used to treat symptoms common in neurodegenerative diseases (Howes & Houghton, 2012). A detailed pharmacological study of essential oils derived from Aloysia citriodora Palau (Lamiaceae) leaves, cultivated in Jordan and locally known as ‘melissa’, was performed in comparison to the pharmacological properties of the essential oil from Melissa officinalis L. (Lamiaceae), known as ‘melissa’ and cultivated in Europe. Both of these plants has been used in traditional herbal medicine as calming agents, raise attention and help to counter depression with a good safety profile (Catalan et al., 2002).

Essential oils derived from dried and fresh leaves of Aloysia citriodora Palau (Lamiaceae) and Melissa officinalis L. (Lamiaceae) were analysed by GC/MS and were investigated by a selection of radioligand receptor-binding assays (Abuhamdah et al., 2008),. Anti-cholinesterase inhibitory activities were determined by the modified spectrophotometric method of Ellman (Mukherjee et al.2007). Ferrous ion chelating effects were estimated by Fe2+ ferrozine test system (Zhao et al., 2006), and Radical scavenging potency was investigated using a DPPH (2,2-diphenyl- 1-(2,4,6-trinitrophenyl)hydrazyl) assay (Hanato et al. 1988)..

Major components detected in Aloysia citriodora oils from dried and fresh leaves included: limonene (20.1, 13.6%), geranial (6.3, 20.1%), neral (3.7, 15.1%), 1,8-cineole (9.4, 9.2%), curcumene (6.3, 3.5%), spathulenol (5.0, 3.1%) and caryophyllene oxide (8.4, 2.2%), respectively. A number of these components were shared with Melissa officinalis (Abuhamdah et al., 2008), but a number were distinct. Fresh Aloysia citriodora leaf essential oil inhibited [3H] nicotine binding to well washed rat forebrain membranes (IC50 = 0.0018 ± 0.0008 mg/ml) (this study), whereas Melissa officinalis elicited no significant effect (Abuhamdah et al., 2008). In contrast, the former elicited no effects on GABAA receptors, while the latter elicited a dose-dependent inhibition of [35S] TBPS binding to the GABAA receptor (IC50 0.040 ± 0.001 mg/ml) (Abuhamdah et al., 2008). All values are means ± SD, from at least three independent experiments, with P < 0.05 considered to be statistically significant.. Aloysia citriodora have concentration-dependent inhibition against anti-cholinesterase (AChE), a large DPPH radical scavenging effect (90%) and moderate (70%) anti-oxidant activity in the ferrous chelating test (all at 0.01 mg/ml and above), while Melissa officinalis lacked these properties (up to 1 mg/ml).

In conclusion, this study demonstrated that the lemon verbena essential oil has cholinergic and antioxidant activities, and thus it has great potential as a source for the treatment of many neurodegenerative diseases..

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Zhao, H. et al., J.Agric.Food Chem., (2006) 54, 7277-7286.

This study was supported by the Scientific Research Support Fund, Ministry of Higher Education, Jordan, grant No (2011/63) and a Durham WRIHW small grant