Chemical composition of essential oils from four Piper species, differentiation using multivariate analysis and antioxidant activity.

Essential oils from the leaves of four species of Piper obtained through hydrodistillation were analyzed using GC-MS andmultivariate data analysis. The chemical analysis enabled the identification of qualitative and quantitative differences among the oils. β-selinene (32.44 ± 1.14%), (E)-nerolidol (44.23 ± 2.23%), β-caryophyllene (19.11 ± 0.40%) and caryophyllene oxide (16.92 ± 0.21%) were identified as the major constituents of the P. mollipilosum, P. brachypetiolatum, P. glandulosissimum and P. madeiranum oils, respectively. The differences in the chemical profiles of the oils were confirmed by principal component analysis. All four species exhibited antioxidant activity. The oil from P. brachypetiolatum achieved the best results on the DPPH test (EC50 = 64.8 µg/ml) and with the ABTS radical (EC50 = 159.7 µg/ml).