Characterization of the essential oils of two species of Piperaceae by one- and two-dimensional chromatographic techniques with quadrupole mass spectrometric detection

Abstract

The essential oils are a notably complex natural mixture, and due to the complexity of the sample and of the analysis, new methods, such as two-dimensional gas chromatography, should be tested to show the enhanced sensitivity and superior resolution of comprehensive two-dimensional gas chromatography (GC×GC). In the present work, the chemical composition of the essential oils of two species of Piperaceae was investigated. The essential oils were analyzed using GC×GC and were compared with one-dimensional gas chromatography (GC–MS); both techniques used quadrupole mass spectrometry detection under the same chromatographic conditions. The yield of the aerial parts of Manekia obtusa was 0.04%, and for Piper cubataonum, the yields were 1.96% and 0.44% for the leaves and the branches, respectively. In the essential oil of M. obtusa, 80 compounds were identified by GC×GC–qMS, whereas only 22 compounds were identified by GC–MS. In both analyses, the oxygenated sesquiterpenes comprised the largest group, the primary constituents of which were (GC×GC vs GC–MS): sphatulenol (10.24% vs 17.41%), E-nerolidol (8.16% vs 13.44%) and selin-11-en-4α-ol (5.92% vs 7.33%). For the essential oils in the leaves and branches of P. cubataonum, 57 and 66 compounds, respectively, were identified by GC×GC–qMS compared to 14 and 20 compounds, respectively, by GC–MS. In both analyses, the chromatograms were characterized by two large peaks assigned to dillapiol and apiol, which represented approximately 40% of the total essential oil in GC×GC vs 90% in GC–MS. The results showed the high resolving power of GC×GC–qMS to separate several components. In total, 128 compounds were identified, representing at least three times more than the number identified by GC–qMS. For M. obtusa and P. cubataonum essential oils, the antimicrobial activity was tested, and the antiproliferative activity was tested only for P. cubataonum. The essential oil of M. obtusa revealed a stronger (30μgmL−1) activity for C. albicans than that of the reference nystatin (50μgmL−1).