Essential oils and fragrant substances

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Physiological and pharmacological actions of fragrant substances

Aromatic oils have been used for over 5000 years as perfumes and for mental, spiritual and physical healing. The effects of an aroma can be instanteous and include both direct and indirect psychological effects – even thinking about a smell may have effects similar to the smell itself.

However, accumulating evidence that inhaled or dermally applied essential oils enter the blood stream and due to their hydrophobic nature are able to cross the blood-brain-barrier indicates that the beneficial effects of aromatic substances are primarily pharmacological. This conclusion is supported by increasing benefits of aromatherapy using specific essential oils in the management of chronic pain, depression, anxiety and some cognitive disorders, as well as insomnia and stress-related disorders. The use of flavours with CNS activity as therapeutics might revolutionise the psychotherapeutical praxis since there are no known adverse reactions of flavour known as today.

One possible docking point of fragrant substances within the CNS is the g-amino butyric acid (GABA) system. Ligands which contribute to GABAA receptor activation typically have anxiolytic, anticonvulsant, sedative, and muscle relaxant properties

Aromatic substances with affinity to the GABAA receptor comprise thymol, menthol or the fragrant fractions of whisky or Oolong tea. This binding of essential oil components to GABA receptors may contribute to the calmative effects of thyme, mint or whisky.

Another and not less interesting docking point of fragrant substances within the CNS are the voltage-sensitive calcium channels. They are a group of voltage-gated ion channels found in excitable cells (like muscle cells or neurons). The most prominent binding site in voltage-sensitive calcium channels is the so-called alpha2delta (a2d) subunit. a2d Ligands are an evolving drug class which bind to one of the auxiliary subunits constituing voltage-sensitive Ca2+ channels, thereby influencing Ca2+ transport into the cells. They have only minimal effects on physiological synaptic function, but they reduce excessive Ca2+ influx under hyperexicitable or pathological conditions. This modulation is characterised by a reduction of the excessive neurotransmitter release that is observed in stress and certain neurological and psychiatric disorders. In other words, the action of a2d ligands on the voltage-sensitive calium channels helps to bring a disturbed neuronal system back to balance.

Binding to the a2d  subunit of voltage sensitive calcium channels may be the molecular site of action of fragrant substances with known activity in the CNS like lavender and lemon balm oil and bergamot oil with their mood improving effects.

References:

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