Chemometric Comparison and Classification of Some Essential Oils Extracted from Plants Belonging to Apiaceae and Lamiaceae Families Based on Their Chemical Composition and Biological Activities

Abstract

This study is focused on the comparison and classification of parsley, lovage, basil, and thyme essential oils (EOs) based on their chemical composition, total phenolic content, antioxidant and antibacterial activities by using appropriate chemometric methods: Principal component analysis (PCA) and hierarchical cluster analysis (HCA). The results showed that parsley, lovage, and thyme EOs are rich in monoterpene hydrocarbons, but basil EO is rich in oxygenated monoterpenes and phenylpropanoids, and that both PCA and HCA separated essential oils into two main groups of which one contains two sub-groups. β-Phellandrene was the major component identified in parsley and lovage EOs, estragole was the major component in basil EO, and p-cymene was the major component in thyme EO. Thyme EO showed the highest level of total phenolics, the highest antioxidant capacity, and exhibited the stronger antibacterial activity, results that were emphasized by both chemometric methods used. Among tested essential oils, the one of parsley was distinguished by a low total TPC, weak antioxidant activity, and weak antibacterial activity against S. enteritidis (ATCC 13076); lovage EO by low TPC, weak antioxidant activity, but moderate antibacterial activity; and basil EO by low TPC, moderate antioxidant activity, and weak antibacterial activity against L. monocytogenes (ATCC 19114).

Keywords: antibacterial activity; antioxidant activity; chemical composition; chemometrics; essential oils; total phenolic content.

Figure 1

PCA and HCA performed on essential oil volatile compounds and their chemical classes. (a) The PCA biplot of essential oils based on their individual volatile compounds; (b) HCA dendrogram of essential oils based on their individual volatile compounds; (c) The PCA biplot of essential oils based on their chemical compound classes; (d) HCA dendrogram of essential oils based on their chemical compound classes. The numbers of chemical compounds are presented in Table 1; C1—monoterpene hydrocarbons; C2—sesquiterpene hydrocarbons; C3—oxygenated monoterpenes; C4—phenylpropanoids; C5—other compounds, and C6—unidentified compounds.

Figure 2

PCA and HCA performed on TPC and TEAC of essential oils. (a) The PCA biplot of essential oils based on their TPC and TEAC; (b) HCA dendrogram of essential oils based on their TPC and TEAC; (c) The PCA biplot of essential oils based on their MICs and MBCs; (d) HCA dendrogram of essential oils based on their MICs and MBCs. TPC—total phenolic content; TEAC—Trolox equivalent antioxidant capacity; MIC—minimum inhibitory concentration; MBC—minimum bactericidal concentration; LM—L. monocytogenes; SE—S. enteritidis.