Volatile fractions and sssential oils: Key tools for exploring specialized metabolites in medicinal and aromatic plants

Plant specialized (secondary) metabolites, especially volatile compounds, are important both for the ecology of plants and for their potential biological activity. Medicinal and aromatic plants rich in bioactive volatile metabolites (referred to as volatile fraction or volatilome) are widely used in the food, cosmetic and health industries. Understanding the chemical composition and biological properties of the volatile fraction is crucial for their safe and effective use. The volatile fraction can be analyzed using solvent-free headspace sampling techniques, useful for rapid qualitative and quantitative analysis and as an analytical decision maker [ 1 ]. However, if biological properties are to be investigated, the volatiles need to be isolated by steam/hydrodistillation to obtain essential oils. These are complex mixtures of odorous compounds, mainly terpenes, which are characterized by high volatility and very low water solubility and exhibit various biological properties, including inhibition of enzymes related to human diseases. Many studies in the literature are often limited to evaluating the overall bioactivity of essential oils without identifying the active compounds. This lecture investigates the usefulness of volatile fractions and essential oils for the study of plant metabolites and their bioactivity. Sixty essential oils were investigated for their enzymatic inhibition of amylase and cholinesterases, followed by chemical characterization by gas chromatography/mass spectrometry. A bio-guided fractionation approach was used to identify the specific compounds responsible for bioactivity. The results emphasize the importance of selecting the right conditions and enzymatic models [ 2 ] for reliable bioactivity data and show how bio-guided fractionation can detect active compounds. Publication History Article published online: 05 March 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany