Cytotoxicity of essential oils from two species of Heterothalamus (Asteraceae)

Essential oils are widely found in plant species. They can be involved in a variety of ecological interactions and may act as inhibitors of germination, suppressing root apical-meristem growth in some species. The present study aimed to determine the potential cytotoxicity of essential oils from leaves of Heterothalamus psiadioides Less. and H. alienus (Sprengel) O. Kuntze on root tips of lettuce (Lactuca sativa L.) and onion (Allium cepa L.). Lettuce seeds germinated with essential oils from H. psiadioides and H. alienus had a reduced mitotic index (MI) for all treatments. Onion seedlings treated with H. psiadioides oil showed a decrease in MI, and seedlings treated with H. alienus oil showed a decrease in MI of 89% in the most concentrated treatment. Analysis of the results showed chromosomal abnormalities, including stickiness, c-mitosis, micronuclei and anaphase bridges in lettuce and onion root tips exposed to essential oils of Heterothalamus.