Study of the Structure and Physicochemical Properties of Chelate Complexes of the Essential Microelement Zinc with 3-Pyridinecarboxamide and Essential Amino Acids

Abstract

Zinc deficiency affects over 2 billion people globally, posing a significant public health challenge. To address this issue, we developed triple chelate complexes of zinc with essential amino acids and 3-pyridinecarboxamide (vitamin B3). Quantum-chemical modeling demonstrated energetically favorable complex formation with an energy difference exceeding 1774 kcal/mol and high chemical stability (0.025-0.036 eV). The most effective complex identified was zinc-isoleucine-nicotinate, featuring interactions via carboxyl and α-amino groups. Spectroscopic analysis revealed maximum absorption in the 260-268 nm range. Optimized synthesis conditions achieved the following parameters: 3-pyridinecarboxamide concentration 0.516 mol/L, amino acid concentration 0.377-0.528 mol/L, zinc sulfate concentration 0.451 mol/L, pH 7, temperature 94 °C, duration 5 minutes. Elemental composition analysis confirmed zinc presence in all complexes. The synthesized complexes exhibit promising potential for food fortification, particularly in dairy products, due to their improved absorption and metabolic activity compared to inorganic zinc salts. This approach offers a viable solution to combat zinc deficiency in human nutrition, providing enhanced bioavailability and stability.