Most essential oils are comprised of chemical compounds known collectively as “terpenoid” compounds. A typical essential oil profile will have several dozen different compounds, all of which have differing structures, aromas and therapeutic properties. In my book, “Chemistry of Aromatherapeutic Essential Oils” which was published in 2003, I group the different compounds by their so-called “skeleton” and then by their functional group, which is a small part of the molecule usually containing double C=C bonds or an oxygen atom or two.
How pinene molecules interact with our body systems At the bacterial level, much interest is being shown in molecules that interact with bacterial chemical communication, one key feature of which is known as quorum sensing (Fig.2). This is the ability of a group of bacteria to sense when there are enough of them present to “go pathogenic.” Most bacteria that infect animals do so as single-celled creatures. But when they have replicated to a critical number, the
Fig. 2 Quorum sensing Caroline Dahl-Wikimedia Commons
chemicals they use to communicate with reach a high enough concentration to switch on other behaviours that allow the bacteria to work together, almost like a multi-cellular organism. They group together in colonies, produce mats of slime, and start pumping out nasty toxins that allow them to kill off competing bacteria, and in our case, body cells, all in an effort to control the access to nutrients which allow an even greater increase in numbers. Some plant compounds have been shown to either mimic or block the ability of bacteria to carry out quorum sensing (Table 1), which effectively blocks their ability to “go pathogenic,” and thus means that no disease state occurs (although the bacteria are still present, and in some cases, still alive). The essential oil compounds discovered so far that inhibit quorum sensing in various micro-organisms include citral (geranial-neral mixture), α-pinene, β-pinene, 1,8-cineole, α-zingiberene and pulegone (Jaramillo-Colorado et al, 2012). From a therapeutic point of view, particularly for dermal and mucous membrane infections (nose, throat, lung), there are exciting possibilities that continually vaporising essential oils containing these compounds could prevent existing bacteria in our respiratory systems from developing into infections and disease.
by E. Joy Bowles, PhD, BSc (Hons)
The full article can be seen in the Summer 2013 issue of the International Journal of Professional Holistic Aromatherapy (IJPHA-Vol. 2, Issue 1). Go to http://www.ijpha.com to subscribe.