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

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 (30 μg mL− 1) activity for C. albicans than that of the reference nystatin (50 μg mL− 1).