Chemical Composition and Evaluation of Antitumoral Activity of Leaf and Root Essential Oils of Conyza canadensis (Asteraceae)

The leaf and root oils of Conyza canadensis were studied for chemical composition and antitumor activity. The results showed that there is a significant variation in the composition of the oils obtained from different parts. The main components in the leaf oil were limonene, caryophyllene oxide and spathulenol. In the root oil, the major component was the acetylenic ester lachnophyllum methyl ester. It was observed that according to the collection time (6 a.m. and 4 p.m.), significant variations in the content of the main components of this essential oil of leaves can occur. Limonene, spathulenol and caryophyllene oxide presented a distribution of 61% / 5.4% / 12.5% and 38% / 10.7%/ 22.3% in oils obtained from plants collected at 6 a.m. and 4 p.m., respectively. The evaluation of antitumor activity of the oils showed that leaf oil had a more pronounced potential of inhibition, and this oil was distinguished by the activity against neoplastic cell lines K562 (leukemia) and NCI-ADR / RES (ovary with multidrug resistance phenotype) with TGI values of 16.8 and 19.0 mu g.mL(-1), respectively. Comparing the leaf oils and their tumor cell inhibition potentials, it was noted that this activity is higher in the oil with higher contents of monoterpene limonene.