Essential oils from four Piper species

The essential oils from Piper capense, P. nigrum, P. guineense and P. umbellatum from S. Tomé e Prı́ncipe were investigated for the first time. They were analysed by GC, GC-mass spectrometry and 13C NMR. Monoterpene hydrocarbons were the main group of constituents in three of the samples (P. capense, P. nigrum and P. umbellatum), whereas for the other species (P. guineense) phenylpropanoid derivatives were the most important ones. β-Pinene (32.5%) and β-caryophyllene (12.6%) were the major compounds in the volatile oil of P. capense. Dillapiole (44.8%), followed by myristicin (9.8%), were the main constituents of P. guineense. The most important constituents in the essential oil of P. nigrum were limonene (18.8%), β-caryophyllene (15.4%), sabinene (16.5%) and β-pinene (10.7%). The essential oil of P. umbellatum was characterised by its high β-pinene (26.8%), α-pinene (17.6%) and (E)-nerolidol (12.4%) content.