Scutellaria caucasica A. Ham.: Morphological features and headspace characterization

In the context of a wide research project, a micromorphological and phytochemical characterization was performed on the vegetative and reproductive organs of Scutellaria caucasica A. Ham. (Lamiaceae), cultivated at the Ghirardi Botanic Garden (Toscolano Maderno, BS, Lombardy, Italy). The morphological survey revealed the presence of both non-glandular and glandular trichomes. The latter belonged to three different morphotypes: peltate, short-stalked and long-stalked capitate. Histochemical assays demonstrated that the terpenes biosynthesis mainly took place in the peltates, while short-stalked capitates secreted only polysaccharides; the long-stalked ones mainly produced polysaccharides, coupled with terpene and polyphenolic fractions. An element of novelty was represented by the characterization of the VOC emission profile. Leaves and flowers showed differences in their emissions: the floral profile had a higher number of compounds than that of the leaves (37 vs 29), with a higher heterogeneity. The almost totality of the leaf profile was characterized by sesquiterpene hydrocarbons (98.8 %), while the flowers presented a more varied composition, with sesquiterpene hydrocarbons (87.2 %), monoterpenes (10.4 % oxygenated, 1.8 % hydrocarbons) and non-terpenes derivatives (0.6 %). The most abundant compounds were γ-muurolene (42.6 %) and β-caryophyllene (35.0 %) in the leaves and in the flowers, respectively. In the flower headspace, 16 exclusive compounds were identified, among which germacrene D (31.7 %) dominated; leaves had 8 exclusive compounds, with valencene (1.8 %) as the most represented one. 21 common compounds were revealed: β-caryophyllene (34.1 % leaves; 35.0 % flowers), α-humulene (3.0 % leaves; 3.1 % flowers), alloaromadendrene (2.4 % leaves; 1.0 % flowers), α-copaene (2.1 % leaves; 2.7 % flowers) and β-copaene (2.2 % leaves; 1.5 % flowers) were the most abundant ones. γ-Muurolene relative abundances (42.6 % leaves; 0.7 % flowers) were very different between the two profiles.Overall, this work represented the first multidisciplinary study on S. caucasica, combining a scientific research approach with the policies of the Open Science.