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Abstract
The aim of the project was to identify and extract metabolites from heather, with the intention of adding value to these invasive plants. Hexane Soxhlet extracts of Calluna vulgaris, Erica tetralix and Erica cinerea were analysed for their lipid composition. Here we report the first extraction and quantification of lipids from Erica cinerea, which demonstrated the largest concentrations of fatty alcohols (670 μg/g dry plant) and triterpenoids (23,132 μg/g dry plant) of these three species. This plant also demonstrated the greatest total yield of lipids (3.4% dry wt.). Calluna vulgaris exhibited the largest abundance of alkanes (1,852 μg/g dry plant), with relatively equal proportions of hentriacontane (C31) and tritriacontane (C33). High concentrations of unsaturated fatty acids were detected in the three species, which were previously unreported components. The extracts demonstrated similar melting point properties to commercial waxes and their potential applications include cosmetics, polishes and coatings. The seasonal variation of epicuticular wax and phenolics in Calluna vulgaris were significant, with the largest concentrations of these components demonstrated during August. This accumulation profile displayed similarities with the rate of photosynthesis in this plant. An important dietary supplement for the reduction of blood cholesterol, policosanols (C24-C34 fatty alcohols) were extracted in concentrations of 966 μg/g dry Calluna vulgaris during August. The antioxidant activities of Calluna vulgaris were comparable to synthetic antioxidants, BHT and BHA. The first use of supercritical fluids for the extraction of Calluna vulgaris demonstrated lipid yields (1.75% dry wt.) approaching those of traditional extractions (1.89%). Isolation was achieved by a release of pressure and required no further purification. Statistical experimental design was employed and a model based on the yields indicated that both temperature and pressure had a positive effect on the extraction. The lipid composition was manipulated by varying the temperature and pressure of the system. Oxidation of unsaturated fatty acids was reduced in the supercritical extractions as compared with the hexane soxhlet extractions. Expanded starch was developed as a highly porous, high surface area, biodegradable stationary phase for column chromatography. This novel phase demonstrated effective separation of lipids, pigments and organometallics. Expanded starch stationary phases required lower polarity and reduced volumes of solvent to produce comparable separations of waxes compared to that of silica.
