Teucrium fruticans L., a Multi‐Scale Study: From Trichomes to Essential Oil

Abstract

AbstractThis work represents the first multi‐scale study on Teucrium fruticans L. cultivated at the Ghirardi Botanic Garden (Lombardy, Northern Italy), combining a micromorphological and a phytochemical survey on the plant's aerial parts. Micromorphological investigations, performed by Light Microscopy, Fluorescence Microscopy and Scanning Electron Microscopy, highlighted the presence of five trichomes morphotypes, distinguished by a different distribution pattern: peltates, short‐stalked and ball‐like medium‐stalked capitates, ubiquitous on the whole plant, medium‐stalked and long‐stalked capitates, exclusive to the floral whorls. Both peltates and medium‐stalked capitates were recognized as the main terpene production sites. Phytochemical characterization focused on the essential oils (EOs), obtained by Clevenger‐type hydrodistillation in February and April 2022 and characterized by Gas Chromatography‐Mass Spectrometry (GC/MS), which resulted mainly formed by sesquiterpene hydrocarbons. The February EO profile was characterized by β‐caryophyllene (28.30 %) and germacrene D (19.16 %) as main compounds, while in April β‐myrcene was detected at high percentage (13.77 %), in addition to the previous two components (15.72 % and 11.55 %, respectively). Literature data, dealing with the biological activities of the main oil constituents, highlighted an anti‐microbial, anti‐inflammatory, and anti‐tumor potential, due to the high content in sesquiterpenes and, particularly, of β‐caryophyllene and germacrene D.