Assessment of cytotoxicity induced by heavy metal arsenic trioxide and azo-dye metanil yellow in Allium cepa assay and aqueous plant extracts mediated amelioration

Abstract

Allium cepa (2n=16) assay is used to determine cytotoxicity of environmental pollutants like heavy metal arsenic (in the form of arsenic trioxideconcentration used: 0.010, 0.050, 0.075 and 0.100mgL1 for 24h duration) and azo-dye metanil yellow (concentration used: 100, 150, 200 and 400mgL1 for 24h duration) with an objective to understand the toxic effects of the test materials on cells and chromosomes of a plant-based system. Assessment of cytotoxicity reveals that arsenic trioxide can induce chromosomal breakages, affects spindle organization and causes cellular metabolic defects; whereas, metanil yellow predominantly affects cellular metabolism. Cytological disturbances are mostly dose-dependent, and arsenic trioxide depicts pronounced effectivity in inducing mitotic aberrations in root tip cells of A. cepa than metanil yellow (in relation to employed doses). Furthermore, aqueous plant extracts (used due to its operational simplicity and cost-effectivity) of the leaf (Coriandrum sativum L., Ocimum tenuiflorum L., and Pteris vittata L.) and seed (Nigella sativa L.) samples are used to ascertain their amelioration potentiality against the environmental toxicants. The ameliorative study (decrement in their observed values) involves attributes like mitotic index, total abnormal dividing cell frequency and frequency of giant and anucleate cells in resting stages. Results suggest that all the employed extracts are ameliorative, and can be explored further for their role in bioremediation.