QSAR analysis of metal ion toxicity data in sunflower callus cultures (Helianthus annuus “Sunspot”)

Abstract

AbstractToxicity data in sunflower callus cultures were determined for 12 metal ions: Ca(II), Cd(II), Co(II), Cu(II), K(I), Li(I), Mg(II), Mn(II), Na(I), Ni(II), Zn(II) and La(III). Based on fresh and dry weight measurements, in vitro EC50 values in solution and in callus tissue were determined. The correlations of the two toxicity data sets were modest. Pearson's correlation analysis of the toxicity data set determined in callus tissue and numerous parameters considered relevant in QSAR analysis showed the existence of a lower number of significant relationships, compared to the analogous analysis of EC50 values in solution. Presented here are the corresponding significant regression equations. Different types of properties appeared to correlate with toxicity, making it difficult to identify their potential significance, for example properties of the metallic state like densities, atomic properties like atomic radii and ionisation energies, chemical properties of metals like electronegativity and other surrogate measures considered to reflect qualities affecting interaction with ligands included as the chemical softness parameter, the covalent index, the first hydrolysis constant, quantitative measures of the stability of a metal complex in solution and hydration data.