Chemical variability of essential oils of Protium colombianum from two tropical life zones and their in vitro activity against isolates of Fusarium

Abstract

ABSTRACT: There is considerable interest in finding replacements for the synthetic fungicides and preservatives that are currently used to control fungal pathogens; however, any alternative compounds must be safe and must prevent the development of microbial resistance. In this regard, essential oils have received special attention. Protium colombianum Cuatrecasas is an endemic tree found in tropical rainforests and possesses aromatic and resinous characteristics. To date, there have been no reports concerning the chemistry of this species, which belongs to a genus that represents an interesting source of essential oils that are occasionally used as antimicrobial agents. Therefore, the chemical composition of the essential oils found in P. colombianum collected from two life zones over a five-month period was analyzed using gas-chromatography/mass-spectrometry. A total of 92 components, comprising 97.7–99.9 % of the total composition, were identified based on their mass spectra and the retention indices. Precedence markers were identified for each life zone, and seasonality affected the samples from one life zone when rainfall was maximum. The in vitro activity against Fusarium oxysporum isolates from carnation and chrysanthemum, as well as a Fusarium solani isolate from chrysanthemum, was tested by determining the minimum inhibitory concentration. Assays using essential oils and control substances showed that terpenoid and phenolic compounds are mainly responsible for the observed antifungal activity. These results suggest that P. colombianum essential oils exhibit cytotoxicity against Fusarium isolates and that the search for new sources of anti-fungal essential oils should include sources that contain different ratios of terpenoid and phenolic compounds.