The use of chemometric modelling to determine chemical composition-antimicrobial activity relationships of essential oils used in respiratory tract infections

• Published in: Fitoterapia 2021-10, Vol.154, p.105024, Article 105024
• Main Authors: Rapper, Stephanie Leigh-de, Tankeu, Sidonie Yankam, Kamatou, Guy, Viljoen, Alvaro, van Vuuren, Sandy
• Format: Article
• Language: English
• Subjects: Antimicrobial activity; Chemistry; Chemometrics; Essential oil; Putative biomarker; Respiratory tract infection
• ISSN: 0367-326X
• DOI: 10.1016/j.fitote.2021.105024

The antimicrobial effects of essential oils are commonly cited within aromatherapeutic texts for use in respiratory tract infections. These essential oils are inhaled or applied to the skin to treat infections and manage symptoms associated with these conditions. A limited number of these essential oils have been scientifically studied to support these claims, specifically, against respiratory pathogens. This study reports on the minimum inhibitory concentration (MIC) of 49 commercial essential oils recommended for respiratory tract infections, and identifies putative biomarkers responsible for the determined antimicrobial effect following a biochemometric workflow. Essential oils were investigated against nine pathogens. Three essential oils, Amyris balsamifera (amyris), Coriandrum sativum (coriander) and Santalum austrocaledonicum (sandalwood) were identified as having greater activity (MIC value = 0.03–0.13 mg/ml) compared to the other essential oils investigated. The essential oil composition of all 49 oils were determined using Gas Chromatography coupled to Mass Spectroscopy (GC-MS) analysis and the GC-MS data analysed together with the antimicrobial data using chemometric tools. Eugenol was identified as the main biomarker responsible for antimicrobial activity in the majority of the essential oils. The ability of a chemometric model to accurately predict the active and inactive biomarkers of the investigated essential oils against pathogens of the respiratory tract was 80.33%. [Display omitted] •First known study to report on the antimicrobial activity of essential oils A. balsamifera, S. austrocaledonicum and C. sativum against selected respiratory tract pathogenic micro-organisms.•The effect of essential oils against pathogens most commonly isolated in bacterial respiratory tract infections such as S. pyogenes and S. pneumoniae have been reported here for the first time for some essential oils.•Eugenol was identified as the most frequently reoccurring biomarker.•The ability of chemometrics to accurately predict the active biomarkers of essential oils against the pathogens assessed was confirmed by 92.3% accuracy.