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Volatile compounds profile and trichome micromorphology of the endemic Veronica saturejoides Vis. ssp. saturejoides

Genus Veronica is the largest genus of the Plantaginaceae family and is divided into 13 subgenuses according to morphological and molecular evidence. Veronica saturejoides Vis. ssp. saturejoides is endemic to Croatia and it belongs to Central European hemicryptophytes Aerial parts of the flowering Veronica saturejoides Vis. ssp. saturejoides were collected from Dinara mountain in July 2017 and air dried for three weeks in a single layer in a well ventilated room, and protected from direct sunlight. The profile of volatile compounds and micromorphology of the trichomes of this species endemic to Croatia was investigated. Clevenger-type apparatus was used for the isolation of the essential oil (EO). Water distilled volatile compounds (VC) from the essential oil and hydrolate have been analyzed by GC and GC/MS (Adams, 2014) using VF-5ms capillary column. The total yield of VC in the EO was 0.04%, based on dry weight of the samples. Thirteen compounds were determined representing 84.5% of the total VC. The most abundant compounds identified were hexadecanoic acid, hexahydrofarnesyl acetone and docosane. In the hydrolate using headspace injection needle, eight compounds were identified representing 84.3% of the total VC. The most abundant compounds were trans-1(7), 8-p- mentadien-2-ol, allo-aromadendrene, and Z- methyl isoeugenol. Scanning electron microscopy was conducted and non-glandular (unbranched, bi-cellular to multicellular) and glandular (composed of one stalk cell and two elliptically formed head cells) trichomes could be observed on stems, leaves, and the calyces. In our review we found just few Veronica species that were investigated in the field of volatile compounds profile. GC-MS studies have been performed on Veronica thymoides subsp. pseudocinerea where the most abundant constituent was hexatriacontene (21%) (Ertas et al., 2015). In another research, Feng (2002) identified essential oil components of Veronica linariifolia Pall. ex Link, and found that the main constituents were cyclohexene (25.83%), β- pinene (11.61%), 1S-α-pinene (10.65%), β- phellandrene (10.49%), β-myrcene (10.42%), and germacrene D (4.99%). In our previous research in the oil of V. spicata the most abundant compound was phytol (Dunkić et al., 2015). Given the diversity of the presented results we can say that the present study gives additional knowledge about volatile compounds and trichome micromorphology of the genus Veronica.

Veronica saturejoides Vis. ssp. saturejoides ; hexadecanoic acid, ; hexahydrofarnesyl acetone ; docosane

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