Metal Complexes in Biology and Medicine: The System Aluminum(III)/Chromium (III)/Iron (III) – Norvaline

Abstract

In coordination compounds studies, knowledge of the stability constants of complexes is necessary for preliminary quantitative treatment. Metal complexes can offer their action such as anti – inflammatory, antimicrobial, antibiotic, anti – thyroid and anticancer compounds. Metal based drugs bioactivity can be increased by metal chelation, which in turn increase their absorbance and stability. Recent advances in inorganic chemistry have made possible formation of number of transition metal complexes with organic ligands of interest which can be used as therapeutic agents. Aluminum prefers oxygen donor groups for complexation. The stability of complexes in biological systems depends on pH, which in blood plasma is 7.4. Chromium is a very adaptable metal, and it can form copious species with variable oxidation numbers from (- VI) to (+VI). Iron is a component of heme and chlorophyll and serves as micronutrients of plants and animals. Ferric ion from Industrial effluent has the potential to poison animals and plants. The present technique involving the use of paper ionophoresis is described for the study of equilibria in binary complex systems in solutions. The method is based on the movement of a spot of a metal ion
in an electric field at various pH’s of background electrolyte. A graph of pH versus mobility was used to obtain information in the binary complexes and to calculate its stability constants. Using this method, the stability constants of binary complexes metal (III) – norvaline have been determined to be (8.73 ± 0.03, 7.20 ± 0.04); (9.00 ± 0.01, 7.41± 0.07) and ((9.43 ± 0.01, 7.66 ± 0.11) (logarithm stability constant values) for aluminum (III) chromium (III) and iron (III) complexes, respectively, at ionic strength 0.1 Mol/L and a temperature of 35°C. The first and second stability constants of metal complexes follow the order Fe (III) > Cr (III) > Al (III).