Multidisciplinary approach study on Teucrium fruticans L.: from Micromorphology to the Essential Oil

This study is part of a wider project titled Botanic Garden, factory of molecules…work in progress (funded by Lombardy Region under the Call for the Enhancement of Museums Lr. 25/2016, year 2021). In this survey, we carried out a multidisciplinary research study on Teucrium fruticans L. (Lamiaceae), cultivated at the Ghirardi Botanic Garden Toscolano Maderno, BS, Italy), combining micromorphological, histochemical, and phytochemical approaches. Micromorphological observations were carried out using Light and Scanning Electron Microscopy. Five trichomes morphotypes were detected, with different distribution: peltates, short-stalked, ball-like mediumstalked capitates, ubiquitous on the whole plant, medium-stalked and long-stalked capitates, exclusive to the floral whorls. The histochemical survey revealed that the terpene production was considerably attributable to the peltate trichomes. Afterward, a phytochemical investigation was addressed to characterize the composition of the essential oil (EO) obtained from hydro-distillation of the aerial parts, with subsequent GC-MS analysis. The EO was dominated by sesquiterpene hydrocarbons (74.40%) and revealed a high percentage of β-selinene (54.08%), followed by β-caryophyllene (13.39%), 6,10,14-trimethyl-2-pentadecanone (8.93%), caryophyllene oxide (5.73%), and isoaromadendrene oxide (4.46%). Finally, extensive literature research was carried out with the purpose of evaluating the potential biological activity of the main detected compounds. β-Selinene was shown to have antioxidant, antibacterial, anti-inflammatory, analgesic, and antipyretic in vitro effects1,2. Antioxidant and anti-inflammatory properties could also be recognized to β- caryophyllene and caryophyllene oxide1,3,4. 6,10,14-Trimethyl-2-pentadecanone could have antibacterial, antioxidant, anti-inflammatory, and antifungal properties5, while the ability to inhibit the acetylcholinesterase enzyme, as well as antimicrobial and in vivo antinociceptive activities could be attributed to aromadendrene1. In the light of the current Open Science policies, these results will converge in the realization of novel educational apparatuses at the Ghirardi Botanic Garden, i.e., new dedicated iconographic labelling aimed at transmitting the results of the scientific research to the visitors.