Genotoxic and Cytotoxic Activities of Leaf Extract of Stachytarpheta cayenensis (Rich). Vahl

The many pharmacological potentials of Stachytarpheta cayennensis (L.C. Rich) Vahl, (Verbenaceae), commonly called blue snakeweed and its use in traditional medicine in Nigeria such as in the treatment of hypertension, diabetes, mental illness and infections, could position it as a medicinal plant of abuse, necessitating the need to ascertain its safety. This study therefore investigated the genotoxic and cytotoxic activity of ethanolic leaf extract of Stachytarpheta cayennensis using the Allium cepa test. The effect of the leaf extract on the root meristem cells of Allium cepa was investigated using onion bulbs exposed to 2.5 mg/mL, 5 mg/mL, and 10 mg/mL concentrations of the extract for macroscopic and microscopic analysis. Tap water was used as a negative control and Methotrexate (0.1 mg/mL) was used as a positive control. There was statistically significant (p<0.05) inhibition of root growth depending on concentration of the extract when compared with the negative control group. All the tested concentrations of the extract were observed to exert cytotoxic effects on cell division in A. cepa. The extract-induced chromosomal aberrations and micronuclei (MNC) formations in A. cepa root tip cells were significant (p<0.05) when compared with control group. The leaf extract treatment further induced cell death, ghost cells, cells membrane damage, and binucleated cells. These results suggest that the leaf extract of Stachytarpheta cayennensis possess cytotoxic and genotoxic effects on A. cepa.