Essential Oils Biological Components

Essential Oils Biological Components Essential oils are complex mixtures of many components, about 20-60 can be present at different concentrations depending on the oil.According to Bakkali et al(2008) they are characterized by components of the highest concentrations, there are usually 2 or 3 main components in each oil compared to some components in trace amounts. Major components of the oils determine the biological activity of the oils however the components in smaller amounts produce an additive effect(Bakkali et al, 2007). Chemical analysis of lemongrass and cinnamon oil distinguished several compounds. Terpenes are able to form structurally and functionally different classes. They are made from combinations of several 5 carbon units called isoprenes (Pichersky and Gershenzon). According to Bakkali et al (2007) terpenes constitute 90% of essential oils. Tyagi and Malik (2010) found that phenols and aldehydes exhibited the highest vapour activity followed by alcohols, ketones and esters and lastly hydrocarbons. Gas Chromatography Mass Spectrometry (GC MS) analysis found cinnamon oil contains high amounts of trans cinnamldehyde at 86.9% and eugenol at 6.2% as major components. Eugenol has been found to have antifungal activity (Cheng et al, 2008) as has Cinnamyl acetate, 4-terpineol, 1,8 cineole. The additive effects of the main components have been reported in one study, a mixture of cinnamaldehyde and eugenol inhibited growth of staphylococcus species whereas when they were applied individually they did not inhibit growth (Marei et al, 2007). Lemongrass exhibited a high concentration of citral, this has two isomers, geranial (trans citral) which presented at 51.3% and neral (cis citral) at 37.4% as major components of this oil. Usually one isomer does not occur without the other. In addition to the essential oil consists of small quantities of geraniol(alcohol) which often co exists with geranial and neral (Chen and Vilojen, 2010).,This study found strong activity of geraniol against Candida albicans (Chen and Vilojen, 2010). Geranyl acetate (Hanaa et al,2012)and limonene (Gehan et al 2012) have also been found to have antifungal properties. Similar concentration found in this analysis have been previously reported by Inouye et al (2003) A study also found lemongrass oil to show higher anticandidal activity against strains of superficial mycoses than citral suggesting additive effects of minor components (Kumar et al 2012) 4.2 Vapour phase Using the vapour phase has been a fairly recent advancement, Tyagi and Malik (2010) found that essential oils in the liquid medium form micelles and supress the attachment of the essential oils to the organism, however the vapour state allows for free attachment although studies have been carried out there is no standard assay to evaluate inhibition by vapour phase contact (Avila-Sosa et al,2012).A further study also stated that in liquid medium the diffusability and solubility of the essential oil whilst in vapour depends on the volatility of each compound and in a vapour form can facilitate the solubilisation of lipophilic monoterpenes better by inflicting higher cell damage on the cell membrane(Taweechaisupapong et al, 2012) Rana (2012) found with Candida dublienesis ,where the essential oil is placed directly under the fungi the growth is completely inhibited as the vapours are the most volatile here .So growth is fungicidal until a certain point, as the volatile vapours spread out the concentration of the vapours is not high enough to inhibit growth so a fungistatic effect is produced. Although this effect was not produced with Candida albicans it demonstrates how the vapours work. Therefore a dispersal method would be more effective as there would be an even distribution of the oil. If volatile compounds retained less effectively therefore allowing more molecules in the vapour phase with increased antifungal activity promotes fungicidal effect at lower concentrations(Lopez et al ,2005) thought to be due to better penetration and contact(Tyagi and Malik, 2010). 4.3 Bonding and compounds Essentail oils cannot be used on their own as they are classed as irritants according to health and safety (Look at COSHH form)therefore a method is required where the oil is not as concentrated and can be used in application such as sprays where it is easier to distribute. Essential oils are expensive therefore if mixed with a carrier oil which are usually cheaper and more readily available. The essential oils blended with carrier oils showed a significant difference in the results for example at 25Â µl(p