Essential oils from four Piper species

The essential oils from Piper capense, P. nigrum, P. guineense and P. umbel latum from S. Tome e Principe were investigated for the first time. They we re analysed by GC, GC-mass spectrometry and C-13 NMR. Monoterpene hydrocarb ons 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. beta-Pinene (32 .5%) and beta-caryophyllene (12.6%) were the major compounds in the volatil e oil of P. capense. Dillapiole (44.8%), followed by myristicin (9.8%), wer e the main constituents of P. guineense. The most important constituents in the essential oil of P. nigrum were limonene (18.8%), beta-caryophyllene ( 15.4%), sabinene (16.5%) and beta-pinene (10.7%). The essential oil of P. u mbellatum was characterised by its high beta-pinene (26.8%), alpha-pinene ( 17.6%) and (E)-nerolidol (12.4%) content. (C) 1998 Elsevier Science Ltd. Al l rights reserved.