Composition and Antifungal Activity of the Essential Oil of the Brazilian Chenopodium ambrosioides L.

The antifungal activity of essential oil (EO) from the Brazilian epazote ( Chenopodium ambrosioides L.) was evaluated by the poison food assay at concentrations of 0.3%, 0.1%, and 0.05% with eight postharvest deteriorating fungi ( Aspergillus flavus , Aspergillus glaucus , Aspergillus niger , Aspergillus ochraceous , Colletotrichum gloesporioides , Colletotrichum musae , Fusarium oxysporum , and Fusarium semitectum ). EO components were tentatively identified by Kováts retention indices (RIs) using gas chromatography and gas chromatography combined with mass spectrometry (GC-MS). Growth of all fungi was completely inhibited at 0.3% concentration, and by 90% to 100% at 0.1% concentration. The following 13 tentatively identified compounds (relative percent) accounted for 90.4% of the total volatile oil: α-terpinene (0.9), p -cymene (2.0), benzyl alcohol (0.3), p -cresol (0.3), p -mentha-1,3,8-triene (0.2), p -cimen-8-ol (0.6), α-terpineol (0.5), ( Z )-ascaridole (61.4), piperitone (0.9), carvacrol (3.9), ( E )-ascaridole (18.6), ( E )-piperitol acetate (0.5), and ( Z )-carvyl acetate (0.3). Autobiographic thin layer chromatography of the EO to separate the principal fungitoxic fraction yielded only one fraction that completely inhibited the growth of all test fungi at a concentration of 0.1%. This fraction was characterized by RIs and GC-MS presenting a composition (%) of p -cymene (25.4), ( Z )-ascaridole (44.4), and ( E )-ascaridole (30.2). The results suggest ascaridoles were the principal fungitoxic components of the EO.