Exploring the chemotaxonomic significance of selected <i>Citrus</i> essential oils through GC-MS/FID and multivariate correlation analyses

The volatile chemical composition and qualitative as well as quantitative variation of the leaf and peel essential oils of five species belonging to <i>Citrus</i> genus were studied. The investigated <i>Citrus</i> species were <i>Citrus aurantifolia</i> (Christm.) Swingle, <i>Citrus limon L</i>. (Osbeck), <i>Citrus maxima</i> (Burm.f.) Merr. R, <i>Citrus medica L</i>. and <i>Citrus medica</i> *<i>Citrus limon.</i> Essential oils were isolated by hydrodistillation and analysed using GC-MS/FID. In total 49 compounds comprising of 83.1-99.0% of the volatile compositions were identified in five leaf essential oils whereas 45 compounds comprising of 97-99.4% of the volatile compositions were identified in peel essential oils. Oxygenated monoterpenes were the predominant composition present in the leaf oils of all <i>Citrus</i> species whereas sesquiterpene hydrocarbons were the main composition found in <i>C. maxima</i> leaf oil (39.9%). Monoterpene hydrocarbons were predominating in the isolated peel oils. Principal component analysis of <i>Citrus</i> species was employed to provide a comprehensive evaluation of essential oil components. Both PCA and cluster analysis of both leaf and peel essential oils were classified into two clusters and then subsequent subclusters, characterized according to the major essential oil components. Monoterpene hydrocarbons, oxygenated hydrocarbons and diterpenes were identified as the significant category of compounds characterised for <i>Citrus</i> essential oils.