Chemical characterization and antifungal activity of essential oil of capitula from Indian Tagetes patula L.

The essential oil extracted by steam distillation from the capìtula of Indian Tagetes patula, Asteraceae, was evaluated for its antifungal properties and analyzed by gaschromatography and gas-chromatography-mass spectrometry. Thirthy compounds were indentified, representing 89.1% of the total detected. The main components were piperitone (24.74%), piperitenone (22.93%), terpinolene (7.8%), dihydrotagetone (4.91%), cis-tagetone (4.62%), limonene (4.52%), and allo-ocimene (3.66%). The oil exerted a good antifungal activity against two phytopathogenic fungi, Botrytis cinerea and Penicillium digitatum, providing complete growth inhibition at 10 microl/ml and 1.25 microl/ml, respectively. The contribution of the two main compounds, piperitone and piperitenone, to the antifungal efficacy was also evaluated and ultrastructural modifications in mycelia were observed via electron microscopy, evidencing large alterations in hyphal morphology and a multisite mechanism of action.