Evaluation of genotoxic and cytotoxic activities of the ethanol extract of <i>Alchornea laxiflora<i/> on root meristem of <i>Allium cepa</i> bulb

Alchornea laxiflora [Benth.] Pax and K.Hoffm (Euphorbiaceae) leaves are indigenously used by many communities in the Southern part of Nigeria to cure various ailments. Using Allium cepa test, the impact of the leaf extract was examined for genotoxic and cytotoxic effects on the root meristem cells of A. cepa (onion bulbs). The onion bulbs were exposed to 2.5 mg/mL, 5mg/mL, and 10 mg/mL concentrations of the leaf extract and macroscopic and microscopic analyses done. Tap water and Methotrexate (0.1 mg/mL) were used as negative and positive controls respectively. There was statistically significant (p<0.05) inhibition of root growth depending on concentration by the extract when compared with the negative control group. All the tested concentrations of the extract were seen to exert cytotoxic effect on cell division in A. cepa. Induction of chromosomal aberrations in A. cepa root tip cells were observed and were significant (p<0.05) when compared with control group. No micronuclei (MNC) formations were observed. Further treatment with the leaf extract caused cell death, ghost cells (altered cell membrane patterns), cell membrane damage, and binucleated cells. These findings suggest that the leaf extract of A. laxiflora has cytotoxic and genotoxic effects on A. cepa.