Extraction, Composition and Comparisons–Free Volatile Compounds from Hydrosols of Nine Veronica Taxa

The extraction of bioactive plant components, which belong to specialized metabolites, is carried out by conventional and novel extraction methods. In this study, a classical (hydrodistillation, HD) and a novel technique (microwave-assisted water extraction, MAE) were used to isolate free volatile compounds from nine Croatian Veronica taxa (family Plantaginaceae). Each of these extracts consists of a lipophilic phase and an aqueous phase (hydrosol). Gas chromatography-mass spectrometry was used to identify the compounds in the hydrosol phase studied taxa Veronica. The compounds β-ionone and benzene acetaldehyde were detected in all nine Veronica hydrosols studied. Other compounds abundant in all investigated species are germacrene D, α-muurolol, (E)-β-damascenone, and β-ionone. Also, the compositions of hydrosols and lipophilic phases (published in our previous research) of these nine Veronica species were compared. Identification of the compounds in both extract parts is important for selecting the extract part for further biological research. According to the distribution of species in the PCA analyses comparing two methods, only two species showed a greater difference in the composition of the hydrosol by the two methods, therefore our conclusion is that for most species there is no significant difference in the composition. Microwave water extraction is a better choice with regards to more environmentally friendly working conditions. Furthermore, we conclude that hydrosol extracts are not waste products, but are a valuable source of compounds with great potential applications.