North America: Tea Tree and Monarda-3
Proteins and Lipid Membranes
Proteins are inserted into the lipid membranes in different ways. They can assume heliz-like structures in such a way thet their hydrophobic (water-repelling) segments are turned to the outside so they can interact with the lipophilic parts of the membrane.
These surface proteins can carry different functional structures on either side and they can traverse the membrane more than once. Proteins can also attach to the membrane via lipophilic and hydrophilic substances, it is no wonder that strongly lipophilic essential oils can cause a number of modifications to the cell membrane.
Inhibition of HMG CoAV Reductase
HMG CoA reductase is a key enzyme in mammalian as well as plant life. It controls terpene, cholesterol, and ultimately sexual hormone synthesis. Essential oils can inhibit this enzyme and thereby the synthesis of cholesterol, which in turn is relevant for the prevention or inhibition of carcinogensis and tumor growth.
The HMG CoA reductase enzyme in tumor cells is defective; it keeps producing much more cholesterol then normally needed, thereby sustaining the growth of the tumor. Research hs demonstrated that the defective - permanently switched on - HMG CoA reductase of tumor cells is shut off ( inhibited) by essential oils.
Interaction With membrane Receptors
Surface proteins-receptors-in and top of the cellular membrane are instrumental in regulating cellular processes. Receptors are membrane-bound molecules that respond to mobile molecules, typically called ligands, with great specificity. Components of essential oils influence receptor activity in two ways.
They can act as substrate for a receptor and thereby trigger whatever biological activity is induced by the specific receptor. Often these essential oils-receptor interactions result in a change in ion flow or electric potentials across the cell membrane and hence have antispasmodic or similar relaxing effects.
The second, indirect, way in which essential oils influence receptor activity is by modifying the expression and formation of the receptors. Studies performed on loggers in Sweden showed that their exposure to the terpenoids of the needle tree increased metabolic turnover as well as expression of surface proteins.
Interaction With Nuclear Receptors
Receptors are the initial agents that transmit outside messages into the cell, which trigger biological responses. While the purpose and function of receptors present in the cellular membrane are relatively well understood, receptors sitting in evolutionary biology.
Their function is not clear at this time. It is, however, obvious that the native substrates or ligands that interact with these receptors are either endogenous or from the natural world. An example, is farnesens, present in many floral essential oils, which attaches directly to the farnesene receptor on the cell nucleus.
Translation factors such as NF-kappa beta are key regulators of inflammatory and immune responses. They are essential for the transcription of multiple pro-inflammatory molecules. Sesquiterpene lactones, for instance, from Arnica herb or Inula graveolens or Tanacetum annum essential oil, have been demonstrated to be effective against inflammatory processes by prevention activation of translation factors such as NF-kappa beta by different inflammation stimuli.
HMG CoA Reductase
In plants hydroxymethyglutaryl CoA reductase is mainly found in the cells of growing tissue. The amino acid sequence of its protein shows an extremely high degree of uniformity between different species.
there is also a high degree of identical sequences in the HMG CoA reductase in insect (Drosophila) and mammalian (hamsters, humans) organisms. The super structures of these enzymes are also equivalent between plant and animal: their spatial domains present identical structures.
Initial scientific knowledge about physiological effects of essential oils developed within the framework of the active ingredient concept. For most of the twentieth century the physiological effects of essential oils were explained as the consequence of a specific, physiologically active, component with a specific molecular structure.
Lemongrass and its main component citral serve as a good example. Since citral showed efficacy in some "crude" pharmacological models of the time, it was deemed the active ingredient. In the mind of the early twentieth-century chemist,
Lemongrass oil had value because it contained citral. Two assumptions went into this way of thinking:
A. The active ingredient was responsible for the physiological effect of the oil.
B. The effect, that is, a spasmolytic effect, was the intrinsic property of the citral molecule.
While assumption A is slowly giving way (at least in aromatherapy circles) to the understanding that essential oils display healing properties as a consequence of all the substances present in an oil, assumption B-that healing properties are the intrinsic quality of a molecule- has survived mostly unchallenged.
Prior to the most recent understanding, pharmacology considered it patently irrational to entertain the idea that the effect of a substance was not based in its molecular makeup. While the concept of molecular agency has allowed us to build an enormous body of knowledge about essential oils, it has also become a trap, as it has subjected essential oils and aromatherapy to the limitations of pharmacology and reductionist thought.
More recently the perspective of organicism and evolutionary biology have come to remedy this. They provide rational explanations for phenomena too complex for a reductionist narrative. This development is of the highest signifcance for aromatherapy. To explore we shall proceed step by step.
Reference:The Healing Intelligence Of Essential Oils: Kurt chnaubelt, Ph.D.