Complexation of copper(II) with L-alanine and its N-alkyl derivatives

Abstract

A series of mono- and di- alkylated L-alaninates, as well as their copper(II) complexes, were prepared as model compounds for superoxidedismutase (SOD)-mimetic activity. Two independent methods (glass electrode potentiometry, GEP and square wave voltammetry, SWV) were applied in order to determine their concentration stability constants and speciation under the physiological conditions (μ = 0.15 M). The chelates formed by copper(II) and mono- and di-alkylated L-alaninates are less stable (by factor >10) than the parent copper(II) L-alaninates. From a thorough examination of the data obtained, a conclusion may be drawn that further lengthening the alkyl chain (diethyl- and more) on nitrogen atom of L-alanine will not essentially change the values of the stability constants of copper(II) complexes with N-alkylated L-alaninates which was confirmed by the conformational analyses performed on the same compounds. © 1999 Taylor and Francis Group, LLC.