A Comparative Study on Chemical Compositions and Biological Activities of Four Amazonian Ecuador Essential Oils: Curcuma longa L. (Zingiberaceae), Cymbopogon citratus (DC.) Stapf, (Poaceae), Ocimum campechianum Mill. (Lamiaceae), and Zingiber officinale Roscoe (Zingiberaceae).

Essential oils (EOs) and their vapour phase of (Zingiberaceae), (Poaceae), (Lamiaceae), and (Zingiberaceae) of cultivated plants grown in an Amazonian Ecuador area were chemically characterised by Gas Chromatography-Flame Ionization Detector (GC-FID), Gas Chromatography-Mass Spectrometry (GC-MS), and Head Space-Gas Chromatograph-Flame Ionization Detector-Mass Spectrometry (HS-GC-FID-MS).figure The EOs analyses led to the identification of 25 compounds for (99.46% of the total; ar-turmerone: 23.35%), 18 compounds for (99.59% of the total; geraniol: 39.43%), 19 compounds for (96.24% of the total; eugenol: 50.97%), and 28 for (98.04% of the total; α-Zingiberene: 15.45%). The Head Space fractions (HS) revealed mainly characterised by limonene and 1,8-cineole (37.35%) and α-phellandrene (32.33%); and showed camphene (50.39%) and cis-Isocitral (15.27%) as the most abundant compounds, respectively. EO revealed a higher amount of sesquiterpenes (10.08%), mainly characterised by E-caryophyllene (4.95%), but monoterpene fraction remained the most abundant (89.94%). The EOs were tested for antioxidant, antimicrobial, and mutagen-protective properties and compared to the EO as a positive reference. EO was the most effective in all the bioactivities checked. Similar results emerged from assaying the bioactivity of the vapour phase of EO. The antioxidant and antimicrobial activity evaluation of EO were repeated through HP-TLC bioautography assay, pointing out eugenol as the lead compound for bioactivity. The mutagen-protective evaluation checked through Ames's test properly modified evidenced a better capacity of EO compared with the other EOs, reducing the induced mutagenicity at 0.1 mg/plate. However, even with differences in efficacy, the overall results suggest important perspectives for the functional use of the four studied EOs.