pH Effect on Stoichiometry and Stability of Ferrous Complexes of (-)-3-(3,4-dihydroxyphenyl)-L-alanine

Living organisms contain many bio-molecules that are comprised of oxygen and nitrogen donor atoms and therefore have high affinity for metal ions, such as iron, present in the body. The stability constants of these chelates are very high in general. One of such molecules is (-)-3-(3,4-dihydroxyphenyl)-L-alanine which is present in brain to control the normal function of neurons. In case of neurodisorder disease, Parkinson’s, this molecule is orally administered in the form of tablets. The pH of stomach is acidic and blood is about neutral, therefore in the present work, the chelation, stoichiometry and stability of iron complexes of (-)-3-(3,4- dihydroxyphenyl)-L-alanine is studied at acidic to neutral pH. Reaction of this molecule in vitro showed interesting results. Stoichiometry of the complex is found 1:3 and it remains pH independent (in buffered & non buffered solutions).While stability of the complex increases with the rise of pH as revealed by molar extinction coefficient values.