Cytotoxic effects of aqueous extract of Ocimum gratissimum using Allium cepa assay

Abstract

The Allium cepa assay serves as a significant in vivo model for evaluating the cytotoxic and genotoxic potential of various substances. The increasing use of herbal remedies has raised concerns over their potential cytogenotoxic effects. This study evaluated the cytotoxic impacts of aqueous leaf extract of Ocimum gratissimum using the Allium cepa assay. Onion bulbs were exposed to different concentrations (0%, 20%, 40%, 60%, 80%, and 100%) of the extract for 10 days. The 0% treatment (containing distilled water) serves as the control. Chromosome spreads were prepared using standard protocols. Root length, mitotic index (MI), and chromosomal aberrations (CAs) were assessed. Results showed a concentration-dependent reduction in root growth and mitotic activity. The mitotic index significantly decreased with increasing extract concentration, while chromosomal abnormalities, including stickiness, bridges, and laggards, were observed. Although lower concentrations (20-40%) had less effect on the cells, the treatments still showed a significant cytotoxic effect (p < 0.05) compared to the control. The higher the concentration, the greater the clastogenic changes. This study demonstrated that O. gratissimum has potential cytotoxic and genotoxic effects at high concentrations, warranting its cautious use in traditional medicine.