1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 © 2016 Pharmacognosy Magazine | Published by Wolters Kluwer ‑ Medknow 1 Pharmacogn. Mag. A multifaceted peer reviewed journal in the feld of Pharmacognosy and Natural Products www.phcog.com | www.phcog.net ORIGINAL ARTICLE INTRODUCTION Te genus Mentha, one of the important members of the Lamiaceae family, is represented by many species commonly identifed as mint, which has been known for its medicinal and aromatherapy properties. Te insecticidal activity of Mentha oil and its main components has been tested and established against various insects/pests. [1] Mentha’s repellent properties against agricultural pests were investigated in a series of experiments by Odeyemi et al. [2] and Kumar et al. [3] Its repellent activity was also demonstrated in mosquito control, and thus for diseases of public health concern such as malaria, yellow fever, dengue, and viral encephalitis. [4–6] Many assays have reported insect mortality caused by Mentha toxicity, [7,8] and some have evaluated its antifeedant activity. [3,9] Species of the genus Mentha have been reported to contain a range of components. [10] Te monocyclic ketones most commonly found in Mentha species are pulegone, menthone, carvone, and, to a lesser extent, dihydrocarvone. [11,12] Te GABA A receptor (GABA A -R) is a major insecticide target along with the voltage-dependent sodium channel, the nicotinic receptor, and acetylcholinesterase. [13,14] Important insecticides acting at the GABA A -R (e.g., lindane, α-endosulfan, dieldrin, and fpronil) recognize the picrotoxinin site, a noncompetitive antagonist site, to block GABA-induced chloride fux. [15] GABA A -R in mammalian, and even in various insect species, difers a lot in their subunit combinations and sensitivities to diferent ligands. [16–18] Te structure and nature of binding sites in housefy GABA receptors have been shown to be diferent from those in rat GABA receptors, and the di ferences may be related to the selectivity of antagonists for housefy versus rat receptor. [19] Efects of Insecticidal Ketones Present in Mint Plants on GABA A Receptor from Mammalian Neurons Mariela Eugenia Sánchez‑Borzone, Leticia Delgado Marin, Daniel Asmed García Instituto de Investigaciones Biológicas y Tecnológicas (IIBYT), CONICET-Universidad Nacional de Córdoba, Av. Vélez Sarsfeld 1611, Córdoba 5016, Argentina ABSTRACT Background: The genus Mentha, an important member of the Lamiaceae family, is represented by many species commonly known as mint. The insecticidal activity of Mentha oil and its main components has been tested and established against various insects/pests. Among these, the ketone monoterpenes that are most common in different Mentha species demonstrated insect toxicity, with pulegone being the most active, followed by carvone and menthone. Considering that the GABA A receptor (GABA A -R) is one of the main insecticide targets on neurons, and that pulegone would modulate the insect GABA system, it may be expected that the insecticidal properties of Mentha ketones are mediated by their interaction with this receptor. Objective: In order to discern the pharmacological actions of these products when used as insecticides on mammalian organisms, we evaluated the pharmacologic activity of ketones, commonly present in Mentha plants, on native GABA A -R from rats. Materials and Methods: Determination of ketones effects on allosterically enhanced benzodiazepine binding, using primary cultures of cortical neurons, which express functional receptors and MTT assay to evaluate their cell toxicity. Results: Our results seem to indicate that ketone components of Mentha, with proven repellent or insecticide activity, were able to behave as GABA A -R negative allosteric modulators in murine cells and consequently could exhibit convulsant activity in mammalians. Only pulegone at the highest assayed concentration (2 mM) showed a significant reduction in cell viability after exposure for 24 hr. Conclusion: The present results strongly suggest that the ketone components of Mentha are able to exhibit convulsant activity in mammalian organisms, but functional assays and in vivo experiments would be necessary to corroborate this proposed action. Key words: Cell culture, GABA A receptor, insecticide, ketones, Mentha, toxicity SUMMARY • The pharmacological activity of insecticide ketones, commonly present in Mentha plants, was evaluated on native GABA A receptor from mammalian neurons. • All studied compounds: pulegone, menthone and dihydrocarvone, were able to behave as negative allosteric modulators and could exhibit convulsant activity in mammalian organisms. • Citotoxicity assays demonstrated that only pulegone affected the cell viability. Correspondence: Dr. Daniel Asmed García, Instituto de Investigaciones Biológicas y Tecnológicas (IIBYT), CONICET-Universidad Nacional de Córdoba, Cátedra de Química Biológica, FCEFYN, Av. Vélez Sarsfield 1611, Córdoba 5016, Argentina. E-mail: dagarcia@efn.uncor.edu Submitted: 31‑01‑2016 Revised: 08‑02‑2016 Published: 00‑00‑0000 pm_62_16 This is an open access article distributed under the terms of the Creative Commons Attribution‑Non Commercial‑Share Alike 3.0 License, which allows others to remix, tweak, and build upon the work non‑commercially, as long as the author is credited and the new creations are licensed under the identical terms. For reprints contact: reprints@medknow.com Cite this article as: FPO Abbreviations used: GABA: gamma aminobutyric acid, GABAA-R: GABAA receptor, MTT: 1-(4,5-dimethylthiazol-2-yl)-3,5-diphenylformazam, DMEM: Dulbecco’s modified minimum essential médium, [3H]TBOB: [3H] t-Butylbicycloorthobenzoate brought to you by CORE View metadata, citation and similar papers at core.ac.uk provided by CONICET Digital