Antiprotozoal activity of essential oils derived from Piper spp. grown in Colombia

Plant species of the genus Piper are widely distributed throughout the Colombian territory. Eleven Piper spp. essential oils (EO1-EO11) were chemically characterized and tested against Trypanosoma cruzi, Leishmania (Leishmania) infantum and mammalian cells using standard in vitro assays. The selectivity index (SI) was calculated by the ratio of CC50 host cells to IC50 parasites. The EO from Piper var. brachypodom, obtained from two different locations (EO10 and EO11) in Choco (Colombia), was active on the T. cruzi. It inhibited growth of epimastigotes (EO10: IC50 0.34g/mL; SI: 89.82) and amastigotes (EO11: IC50 22.72g/mL; SI: 2.31). EO11 was active against Leishmania (L.) infantum promastigotes (IC50 23.68g/mL; SI: 2.65), and less active on amastigotes (IC50 62.82g/mL). The EO10's major component was trans--caryophyllene, which inhibited the T. cruzi (IC50 24.54g/mL) and L. the infantum (IC50 53.39g/mL), intracellular forms with some toxicity on Vero (CC50 12.93g/mL) and THP-1 (CC50 143.85g/mL). -Pinene, the main constituent of Piper bredermeyeri, was active against the T. cruzi epimastigotes (IC50 2.74g/mL; SI: 4.22) and amastigotes (IC50 1.92g/mL; SI: 6.02). Linalool, limonene, 1,8-cineole and safrole were not active on intracellular parasites. The low SI obtained with both Piper brachypodon and trans--caryophyllene indicates a narrow window in their parasite-specific activity. Novel formulations contained active EOs or components could be designed in order to avoid toxicities and improve the cell internalization.