British Journal of Nutrition

Molecular Nutrition

Monoamine reuptake inhibition and mood-enhancing potential of a specified oregano extract

Annis O. Mechana1 c1, Ann Fowlera1, Nicole Seiferta1, Henry Riegera1, Tina Wöhrlea1, Stéphane Ethevea1, Adrian Wyssa1, Göde Schülera1, Biagio Collettoa1, Claus Kilperta1, James Astona2, J. Martin Elliotta2, Regina Goralczyka1 and M. Hasan Mohajeria1

a1 DSM Nutritional Products Limited, Research and Development Human Nutrition and Health, PO Box 2676, CH-4002 Basel, Switzerland

a2 Leicester School of Pharmacy, De Montfort University, The Gateway, Leicester LE1 9BH, UK

Abstract

A healthy, balanced diet is essential for both physical and mental well-being. Such a diet must include an adequate intake of micronutrients, essential fatty acids, amino acids and antioxidants. The monoamine neurotransmitters, serotonin, dopamine and noradrenaline, are derived from dietary amino acids and are involved in the modulation of mood, anxiety, cognition, sleep regulation and appetite. The capacity of nutritional interventions to elevate brain monoamine concentrations and, as a consequence, with the potential for mood enhancement, has not been extensively evaluated. The present study investigated an extract from oregano leaves, with a specified range of active constituents, identified via an unbiased, high-throughput screening programme. The oregano extract was demonstrated to inhibit the reuptake and degradation of the monoamine neurotransmitters in a dose-dependent manner, and microdialysis experiments in rats revealed an elevation of extracellular serotonin levels in the brain. Furthermore, following administration of oregano extract, behavioural responses were observed in mice that parallel the beneficial effects exhibited by monoamine-enhancing compounds when used in human subjects. In conclusion, these data show that an extract prepared from leaves of oregano, a major constituent of the Mediterranean diet, is brain-active, with moderate triple reuptake inhibitory activity, and exhibits positive behavioural effects in animal models. We postulate that such an extract may be effective in enhancing mental well-being in humans.

(Received April 12 2010)

(Revised October 09 2010)

(Accepted November 01 2010)

(Online publication December 21 2010)

Correspondence:

c1 Corresponding author: Dr A. O. Mechan, fax +41 61 815 8740, email annismechan@mac.com

Footnotes

Abbreviations: 5-HIAA, 5-hydroxyindoleacetic acid; 5-HT, 5-hydroxytryptamine; ASP, 4-(4-(dimethylamino)-styryl)-N-methylpyridinium; CAR, carvacrol; CLO, clobazam; DMSO, dimethylsulphoxide; FLU, fluoxetine; hDAT, human dopamine transporter; hNAT, human noradrenaline transporter; hSERT, human serotonin transporter; IC50, half maximal inhibitory concentration; IMI, imipramine; i.p., intraperitoneal; MAO, monoamine oxidase; NA, noradrenaline; p.o., per os; TQ, thymoquinone; VEH, vehicle; VEN, venlafaxine

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