A new mechanism for the decomposition of erythromycin A in acidic aqueous solutions

Abstract A new degradation mechanism for erythromycin A and erythromycin A enol ether in acidic aqueous solutions is proposed. It consists of an equilibrium between erythromycin A and erythromycin A enol ether coupled to a direct conversion reaction from erythromycin A to anhydroerythromycin A. The modelling of the experimentally obtained concentration profiles of erythromycin A, erythromycin A enol ether and anhydroerythromycin A is carried out using the BMDP statistical package containing a multiparameter fitting program based on the DUD algorithm. The values for the rate constants deduced from the erythromycin A and erythromycin A enol ether decays are in good agreement yielding support for the proposed mechanism.