Chemometric study of essential oils from Thai cinnamomum species

Abstract

The leaf essential oils of Thai Cinnamomum species were investigated by headspace GC-MS and chemometric method. Forty-two mature leaf samples representing nine species and six unidentified samples were collected from various locations in Thailand. One hundred and twenty-eight chemical constituents were identified from these samples and used as dependent variables for chemometric analysis. Hierarchical cluster analysis (HCA) and principal component analysis (PCA) were employed to classify samples in the terms of their chemical profiles. It is clear that cluster analysis using Pearson correlation with the between group linkage is an adequate chemometric method in making chemical classification analysis for this study. Based on the results of cluster analysis, samples of the same species were grouped into one cluster even though there are some differences in the major components. Six samples of C. camphora appeared in two chemotypic forms: camphor type and linalool type. Eight samples of C. verum also fall into two chemotypes: linalool type and eugenol type. Most C. iners, as well as C. subavenium, were rich in (E)-caryophyllene. A prominent compound in another group of C. iners appeared to be linalool. They were, therefore, classified in the same cluster of the linalool type of C. camphora. Based on these results, it is clear that the use of the chemical compositions of the leaf essential oils of genus Cinnamomum is a very promising tool in making taxonomic judgement by using chemometric cluster analysis.