Cytogenotoxic effect of essential oil from Backhousia citriodora L. (Myrtaceae) on meristematic cells of Lactuca sativa L.

The objective of this study was to evaluate the cytogenotoxic effects of essential oil (EO) extracted from Backhousia citriodora L. (Myrtaceae) on the plant model Lactuca sativa L. EO was obtained through hydrodistillation, using a modified Clevenger apparatus (2 h), and subsequently analyzed by GC/MS and GC-FID. Germinated seeds of L. sativa with root length of 1-2 mm were exposed to different concentrations of EO (5, 25, 50, 100, 200 and 500 μg mL− 1) for 48 h. Distilled water was used as negative control. Cytogenetic analyses, cell cycle evaluation, TUNEL test, agarose gel electrophoresis and flow cytometry were performed. The main constituent found in the EO was citral (91.19%). Overall, EO interferes with the normal dynamics of the cell cycle (mitotic index or frequency of each dividing stage). Here, both clastogenic chromosomal abnormalities (e.g. chromosome bridges, fragments and stickiness) and aneugenic alterations (e.g. delayed segregation and c-metaphases) were observed in meristematic cells exposed to EO. TUNEL-positive nuclei revealed the occurrence of DNA fragmentation. In agarose gel, DNA laddering pattern was not observed. EO genotoxicity was reinforced by flow cytometry analysis, which revealed loss of DNA content, decrease in the frequency of dividing cells, increase of nuclear complexity and reduction of nuclear diameter in cells exposed to the EO of B. citriodora. We conclude that B. citriodora EO presents cytogenotoxic effects besides inducing cell death and therefore constitutes a promising source of biologically active compounds.