Chemical Composition and Biological Activity of Five Essential Oils from the Ecuadorian Amazon Rain Forest

Abstract

The chemical composition and biological activity of essential oils isolated from the leaves of <i>Siparuna aspera</i>, <i>Siparuna macrotepala</i>, <i>Piper leticianum</i>, <i>Piper augustum</i> and the rhizome of <i>Hedychium coronarium</i> were evaluated. These species are used medicinally in different ways by the Amazonian communities that live near the Kutukú mountain range. Chemical studies revealed that the main components for the two <i>Siparuna</i> species were germacrene D, bicyclogermacrene, α-pinene, δ-cadinene, δ-elemene, α-copaene and β-caryophyllene; for the two <i>Piper</i> species β-caryophyllene, germacrene D, α-(<i>E,E</i>)-farnesene, β-elemene, bicyclogermacrene, δ-cadinene and for <i>H. coronarium</i> 1,8-cineole, β-pinene, α-pinene and α-terpineol. The antioxidant activity of all essential oils was evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), photochemiluminescence (PCL) quantitative assays, and DPPH and ABTS bioautographic profiles, with different results for each of them. Antimicrobial activity studies were carried out on three yeasts, six Gram positive and four Gram negative bacteria, by means of the disc diffusion method. The essential oil of <i>H. coronarium</i> showed the most relevant results on <i>L. grayi</i>, <i>K. oxytoca</i> and <i>S. mutans</i>, <i>P. augustum</i> and <i>P. leticianum</i> on <i>S. mutans</i>. An antibacterial bioautographic test for <i>H. coronarium</i> was also carried out and highlighted the potential activity of terpinen-4-ol and 1,8-cineole.