Identification of a Novel GABAA Receptor Channel Ligand Derived from Melissa officinalis and Lavandula angustifolia Essential Oils.

ABSTRACT

Aims: Melissa officinalis (Mo) and Lavandula angustifolia (La) essential oils and their major constituents ((E) - caryophyllene, caryophyllene oxide, geranyl acetate, linalool, nerol, Oct-1-en-3-ol, 3-Octanone, myrcene, allo-ocimene, p-cymene and α- terpineol) assessed by GC-MS) which are shared by these two essential oils were probed in an attempt to identify the GABAAR ligand(s). Study Design: [35S] t-butylbicyclophosphorothionate (TBPS) radioligand binding assay to GABAA receptors. In vitro neuronal viability assay. Place and Duration of Study School of Biological and Biomedical Sciences, Durham University, United Kingdom (December 2012 and January 2013). Results: One of the major component (s) of (Mo), trans-ocimene, inhibited [35S] (TBPS) binding to native GABAA receptors in a concentration-dependent manner with an apparent IC50 of 40μM. Concentrations (0.001 mg/ml) of whole (Mo) were shown to display modest beneficial effects upon neuronal viability while at a higher concentration (0.1 mg/ml) of (Mo) and (La) oils induced a neurotoxicity effect. Conclusion: These data provide the first evidence that allo-ocimene is an neuroactive GABAA R inhibitory component found in both (Mo) and (La), and represents a novel GABAA receptor channel chemotype derived from a natural product.