Hydrodistillation and Microwave Extraction of Volatile Compounds: Comparing Data for Twenty-One Veronica Species from Different Habitats

Abstract

Free volatile compounds were isolated from 21 Croatian Veronica species studied by hydrodistillation (HD) and microwave extraction (ME) and analyzed by gas chromatography coupled with mass spectrometry. Principal Component Analysis (PCA) distinguished some clusters based on the relative proportion of major compounds, such as hexadecanoic acid, hexahydrofarnesyl acetone, phytol, E-caryophyllene, and caryophyllene oxide, which were identified in all species studied by both isolation methods. In addition to these compounds, germacrene D, δ-selinene, and eicosane were also identified in five samples from dry habitats isolated using ME. Allo-aromadendrene and β-ionone are particularly abundant in five species from wet habitats isolated by both methods. The peculiarities of Veronica species from moderate habitats isolated with HD are benzene acetaldehyde, n-nonanal, and the identification of significant compounds from the hydrocarbon class, while the peculiarity of ME is (E)-β-damascenone. In this article, we present new results on the phytochemical characterization of Veronica species from different habitats. The biological potential of these compounds should be further investigated for a better understanding and utilization of the specialized plant metabolites.

Isolation of Volatile Compounds by Microwave-Assisted Extraction from Six Veronica Species and Testing of Their Antiproliferative and Apoptotic Activities

“…In the composition of the EO extract of V. anagalloides, the dominant compounds are hexahydrofarnesyl acetone (16.17%) and β-ionone (13.13%). Comparing the composition of the oil components of this species with the data previously published in the article by Dunkić et al [2], we note a similarity in the concentration value of hexahydrofarnesyl acetone. In that research, the composition of oil components obtained by classical (Clevenger apparatus, HD) and modern hydrodistillation (MAE) was compared, so the value of hexahydrofarnesyl acetone in the EO of V. anagalloides was 14.33% for HD and 19.12% for MAE [2].…”

“…Comparing the composition of the oil components of this species with the data previously published in the article by Dunkić et al [2], we note a similarity in the concentration value of hexahydrofarnesyl acetone. In that research, the composition of oil components obtained by classical (Clevenger apparatus, HD) and modern hydrodistillation (MAE) was compared, so the value of hexahydrofarnesyl acetone in the EO of V. anagalloides was 14.33% for HD and 19.12% for MAE [2]. Moreover, in Nazlić et al article [7], a much lower β-ionone relative percentage was found in this sample obtained by MAE compared to this study: only 4.22%.…”

“…Chromatographic analyses were performed using a GC (model 3900; Varian Inc., Lake Forest, CA, USA) equipped with a flame ionization detector and a mass spectrometer (model 2100 T; Varian Inc., Lake Forest, CA, USA), a nonpolar capillary column VF-5 ms (30 m × 0.25 mm i.d., coating thickness 0.25 µm, Palo Alto, CA, USA), and a polar CP Wax 52 (30 m × 0.25 mm i.d., coating thickness 0.25 µm, Palo Alto, CA, USA). The chromatographic methods and conditions for hydrosol fraction analysis were the same as described in the article by Dunkić et al [2]: the condition for the VF-5-ms column was a temperature of 60 • C (isothermal) for 3 min, which was then increased to 246 • C at a rate of 3 • C min −1 and maintained for 25 min (isothermal). The condition for the CP Wax 52 column was a temperature of 70 • C (isothermal) for 5 min, which was then increased to 240 • C at a rate of 3 • C min −1 and maintained for 25 min (isothermal).…”

Hydrosols of Veronica Species—Natural Source of Free Volatile Compounds with Potential Pharmacological Interest

“…For this reason, a systematic study of the specialized metabolites that make up the free volatile compounds (FVCs) is being conducted. Dunkić et al [6] investigated the composition of FVCs of the 21 Croatian Veronica species contained in the lipophilic layer of extracts obtained by classical (hydrodistillation, HD) and green (microwave-assisted, MAE) extraction [6]. These extraction methods yield the two layers mentioned earlier, the lipophilic layer (LL) or essential oil (EO) and the aqueous layer (hydrosols).…”

“…Therefore, another important part of this research is focused on the comparison of the composition of FVCs from the hydrosols and the lipophilic layer obtained by both extraction methods. The compositions of the LL of all 10 Veronica species studied that will be used for comparison were published in our previous work [6].…”