Wild Species Veronica officinalis L. and Veronica saturejoides Vis. ssp. saturejoides—Biological Potential of Free Volatiles

Extracts from plants of the genus Veronica have been and continue to be used in traditional medicine to treat various diseases throughout the world. Although often considered a weed, many scientific reports demonstrate that these plants are a source of valuable biologically active compounds and their potential for horticulture should be investigated and considered. In this study, free volatile compounds of essential oils (EO) and hydrosols were extracted from two species: Veronica officinalis, which is most commonly used in traditional medicine, and Veronica saturejoides, an endemic plant that could be obtained by cultivation in horticulture. Volatiles were analyzed by gas chromatography coupled with mass spectrometry (GC, GC-MS). The most abundant compounds identified in the EOs were hexadecanoic acid in V. officinalis EO and caryophyllene oxide in V. saturejoides EO. The hydrosols were characterized by a high abundance of caryophyllene oxide in V. saturejoides hydrosol and of p-vinyl guaiacol for V. officinalis hydrosol. The sites where the volatile compounds are synthesized and stored were analyzed using SEM (Scanning Electron Microscopy); glandular and non-glandular trichomes were detected on stems, leaves and the calyx. Further, to investigate the activity of the free volatile compounds against pathogens, isolated volatile compounds were tested on the antiphytoviral activity against tobacco mosaic virus (TMV) infection. The hydrosols of both investigated species and EO of V. officinalis showed significant antiphytoviral activity. To further investigate the biological potential of these extracts they were also tested for their antiproliferative and antioxidant activities. The results indicate that these compounds are a valuable source of potential anticancerogenic agents that should be investigated in future studies. The presented results are the first report of hydrosol and EO activity against TMV infection, suggesting that these extracts from Veronica species may be useful as natural-based antiphytoviral agents.