Comportement électrochimiques des hétérocycles azotés et des biomolécules biologiquement actifs.

Abstract

This work presents the electrochemical behavior of three types of molecules: synthetic, biosynthetic and natural. Heterocyclic compounds from nitrophenyl acetic acid were synthetized and evaluated for their electroactivities and cytotoxic properties. The electrochemical oxidation of native and denatured BEVA was investigated in solution over a wide pH range and using BEVA-thin film voltammetry on a glassy carbon electrode. For native BEVA, only one pH-dependent oxidation peak, corresponding to tyrosine and tryptophan amino acid residues oxidation, was observed. On the other hand, the electrochemical oxidation of denatured BEVA thin film on GCE showed additional cysteine and histidine residues oxidation peaks. Flavonoids present in the extracts of Mediterranean freeze-dried fruits: apricot, cherry, plum, pomegranate, date, prickly pear and nectarine were detected by high-performance liquidphase chromatography with inverse phase (RP-HPLC) coupled with photodiode array (PDA) and electrochemical detection (ED). The total antioxidant activity of these extracts was investigated by differential pulse voltammetry (electrochemical index-EI and peak area-Parea) and chronoamperometry (peak intensity-Ia). A comparative study was carried out by free radical scavenger efficient concentration (EC50), using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay.