Cytogenotoxicity potentials of cocoa pod and bean-mediated green synthesized silver nanoparticles on Allium cepa cells

Abstract

Nanotechnology is a ground-breaking scientific innovation, but there are possible hazards to environment and human health. Therefore, there is a need to understand the toxic potential of nanoparticles. Cytotoxic and genotoxic effects of biogenic cocoa pod husk and cocoa bean silver nanoparticles (CPHE-AgNPs and CBE-AgNPs, respectively), and silver nitrate salts (Ags) were evaluated using the A. cepa root assay. Twenty onion bulbs were exposed to various concentrations (0.01, 0.10, 1.0, 10.0, and 100.0 μg ml–1) of AgNP and Ags solutions. Effects on cell division and chromosomes were observed at 24, 48 and 72 h, while root number and growth inhibition were evaluated at 72 h. Both biogenic AgNPs have potential to be cytotoxic with disturbances to mitotic phases. Mitotic index was less than one half the values of control for almost all concentrations throughout exposure periods. The highest concentration of both AgNPs induced complete cell arrest at both 48 and 72 h, except for Ags. Induction of chromosomal aberrations (chromosomal bridge, c-mitosis, vagrant chromosome, sticky chromosome) pointed to potential for genotoxicity. AgNPs demonstrated a clear mito-depressive effect culminating in growth inhibition of the A. cepa roots, except for 0.01 μg ml–1 of CPHE-AgNPs (p < 0.05). EC50 values showed that growth inhibition was in the order of CPHE-AgNPs>Ags>CBE-AgNPs. While indiscriminate usage of AgNPs might have an impact on the health status of exposed organisms, raising concerns, the cell arresting potential of both AgNPs can be explored in the control of growth of cancerous cells.